package DBIO::Storage::DBI;
# ABSTRACT: DBI storage handler
# -*- mode: cperl; cperl-indent-level: 2 -*-

use strict;
use warnings;

use base qw/DBIO::Storage::QueryRewrite DBIO::Storage::DBI::Capabilities DBIO::Storage::DBI::DataTypeClassifier DBIO::Storage::DBI::AccessBroker DBIO::Storage/;
use mro 'c3';

use DBIO::Carp;
use Scalar::Util qw/refaddr weaken reftype blessed/;
use Context::Preserve 'preserve_context';
use Try::Tiny;
use DBIO::Util qw(is_plain_value is_literal_value);
use DBIO::Util qw(quote_sub perlstring serialize dump_value sigwarn_silencer is_windows is_dev_release old_mro help_url);
use DBIO::Skills;
use DBIO::Storage::Composed;
use namespace::clean;

# default cursor class, overridable in connect_info attributes
__PACKAGE__->cursor_class('DBIO::Storage::DBI::Cursor');

__PACKAGE__->mk_group_accessors('inherited' => qw/
  sql_quote_char sql_name_sep
/);

# Class-level hook to redact bind values before they are interpolated into
# the trace output. The default is the identity function (returns the value
# unchanged) which preserves the historical plaintext trace behavior.
# Install a custom coderef on the storage class:
#
#   __PACKAGE__->redact_bind_value(sub {
#     my ($colname, $value) = @_;
#     return $colname eq 'password' ? '***' : $value;
#   });
#
# The coderef receives the column name (or undef if no column metadata is
# attached to the bind slot) and the raw bind value, and must return the
# value to interpolate into the trace. The original bind value passed to
# the database is *not* modified - only the trace string is.
__PACKAGE__->mk_classdata('redact_bind_value' => sub { return $_[1] });

__PACKAGE__->mk_group_accessors('component_class' => qw/sql_maker_class datetime_parser_type/);

__PACKAGE__->sql_maker_class('DBIO::SQLMaker');
__PACKAGE__->datetime_parser_type('DateTime::Format::MySQL'); # historic default

# Identifier quoting is ON by default (security hardening). Concrete drivers
# override sql_quote_char with their RDBMS-native quote; the bare base storage
# falls back to the ANSI SQL standard double quote so the default-on path never
# has to warn about a missing quote_char.
__PACKAGE__->sql_quote_char('"');
__PACKAGE__->sql_name_sep('.');

__PACKAGE__->mk_group_accessors('simple' => qw/
  _connect_info _dbio_connect_attributes _driver_determined
  _dbh _dbh_details _conn_pid _sql_maker _sql_maker_opts _dbh_autocommit
  _perform_autoinc_retrieval _autoinc_supplied_for_op _async_mode
/);

# Async mode registry (ADR 0030): maps a connect-time mode name to the embedded
# backend class that answers the six *_async methods for an instance connected
# with { async => $mode }. Generic modes (e.g. 'forked', 'future_io') register
# on a base class and are inherited by every driver; native modes (e.g. 'ev')
# are registered by the concrete driver storage class, so the same logical mode
# name resolves to a DB-specific backend. Lookup walks the instance's MRO, so a
# driver registration shadows/extends the generic ones. 'immediate' is the
# in-process degrade mode (no event loop, no embedded backend): it maps to the
# immediate Future class and is recognised by NOT being a DBIO::Storage::Async
# subclass. Core registers only 'immediate' -- 'forked'/'future_io'/'ev' come
# from their add-on/driver dists, never auto-wired here.
my %_async_mode_registry;
__PACKAGE__->register_async_mode( immediate => 'DBIO::Future::Immediate' );

# the values for these accessors are picked out (and deleted) from
# the attribute hashref passed to connect_info. karr #66: the names live once
# on DBIO::Storage and are consumed by both this sync path and the async strip
# (DBIO::Storage::Async), so the two lists can never drift.
my @storage_options = __PACKAGE__->_dbio_storage_option_names;
__PACKAGE__->mk_group_accessors('simple' => @storage_options);


# Capability detection lives in DBIO::Storage::DBI::Capabilities (mixin).

# Each of these methods need _determine_driver called before itself
# in order to function reliably. We also need to separate accessors
# from plain old method calls, since an accessor called as a setter
# does *not* need the driver determination loop fired (and in fact
# can produce hard to find bugs, like e.g. losing on_connect_*
# semantics on fresh connections)
#
# The construct below is simply a parameterized around()
my $storage_accessor_idx = { map { $_ => 1 } qw(
  sqlt_type
  datetime_parser_type

  sql_maker
  cursor_class
)};
for my $meth (keys %$storage_accessor_idx, qw(
  deployment_statements

  build_datetime_parser

  txn_begin

  insert
  update
  delete
  select
  select_single

  _insert_bulk

  with_deferred_fk_checks

  get_use_dbms_capability
  get_dbms_capability

  _server_info
  _get_server_version
)) {

  my $orig = __PACKAGE__->can ($meth)
    or die "$meth is not a ::Storage::DBI method!";

  my $is_getter = $storage_accessor_idx->{$meth} ? 0 : 1;

  quote_sub
    __PACKAGE__ ."::$meth", sprintf( <<'EOC', $is_getter, perlstring $meth ), { '$orig' => \$orig };

    if (
      # only fire when invoked on an instance, a valid class-based invocation
      # would e.g. be setting a default for an inherited accessor
      ref $_[0]
        and
      ! $_[0]->{_driver_determined}
        and
      ! $_[0]->{_in_determine_driver}
        and
      # if this is a known *setter* - just set it, no need to connect
      # and determine the driver
      ( %1$s or @_ <= 1 )
        and
      # Only try to determine stuff if we have *something* that either is or can
      # provide a DSN. Allows for bare $schema's generated with a plain ->connect()
      # to still be marginally useful
      $_[0]->_dbi_connect_info->[0]
    ) {
      $_[0]->_determine_driver;

      goto $_[0]->can(%2$s);
    }

    goto $orig;
EOC
}


sub new {
  my $new = shift->next::method(@_);

  $new->_sql_maker_opts({});
  $new->_dbh_details({});
  $new->{_in_do_block} = 0;

  # read below to see what this does
  $new->_arm_global_destructor;

  $new;
}

# This is hack to work around perl shooting stuff in random
# order on exit(). If we do not walk the remaining storage
# objects in an END block, there is a *small but real* chance
# of a fork()ed child to kill the parent's shared DBI handle,
# *before perl reaches the DESTROY in this package*
# Yes, it is ugly and effective.
# Additionally this registry is used by the CLONE method to
# make sure no handles are shared between threads
{
  my %seek_and_destroy;

  sub _arm_global_destructor {

    # quick "garbage collection" pass - prevents the registry
    # from slowly growing with a bunch of undef-valued keys
    defined $seek_and_destroy{$_} or delete $seek_and_destroy{$_}
      for keys %seek_and_destroy;

    weaken (
      $seek_and_destroy{ refaddr($_[0]) } = $_[0]
    );
  }

  END {
    local $?; # just in case the DBI destructor changes it somehow

    # destroy just the object if not native to this process
    $_->_verify_pid for (grep
      { defined $_ }
      values %seek_and_destroy
    );
  }

  sub CLONE {
    # As per DBI's recommendation, DBIO disconnects all handles as
    # soon as possible (DBIO will reconnect only on demand from within
    # the thread)
    my @instances = grep { defined $_ } values %seek_and_destroy;
    %seek_and_destroy = ();

    for (@instances) {
      $_->_dbh(undef);

      $_->transaction_depth(0);
      $_->savepoints([]);

      # properly renumber existing refs
      $_->_arm_global_destructor
    }
  }
}

sub DESTROY {
  $_[0]->_verify_pid unless is_windows();
  # some databases spew warnings on implicit disconnect
  local $SIG{__WARN__} = sub {};
  $_[0]->_dbh(undef);

  # this op is necessary, since the very last perl runtime statement
  # triggers a global destruction shootout, and the $SIG localization
  # may very well be destroyed before perl actually gets to do the
  # $dbh undef
  1;
}

# handle pid changes correctly - do not destroy parent's connection
sub _verify_pid {

  my $pid = $_[0]->_conn_pid;

  if( defined $pid and $pid != $$ and my $dbh = $_[0]->_dbh ) {
    $dbh->{InactiveDestroy} = 1;
    $_[0]->_dbh(undef);
    $_[0]->transaction_depth(0);
    $_[0]->savepoints([]);
  }

  return;
}


sub connect_info {
  my ($self, $info) = @_;

  return $self->_connect_info if !$info;

  $self->_connect_info($info); # copy for _connect_info

  if ($self->_is_access_broker_connect_info($info)) {
    $self->set_access_broker($info->[0], 'write');
    my $broker_info = $self->_current_dbi_connect_info($self->access_broker_mode);
    # Broker may return hashref or arrayref depending on implementation
    $broker_info = [$broker_info] if ref $broker_info eq 'HASH';
    $info = $self->_normalize_connect_info($broker_info);
  }
  else {
    $self->clear_access_broker;
    $info = $self->_normalize_connect_info($info)
      if ref $info eq 'ARRAY';
  }

  my %attrs = (
    %{ $self->_default_dbi_connect_attributes || {} },
    %{ $info->{attributes} || {} },
  );

  my @args = @{ $info->{arguments} };

  if (keys %attrs and ref $args[0] ne 'CODE') {
    carp_unique (
        'You provided explicit AutoCommit => 0 in your connection_info. '
      . 'This is almost universally a bad idea (see the footnotes of '
      . 'DBIO::Storage::DBI for more info). If you still want to '
      . 'do this you can set $ENV{DBIO_UNSAFE_AUTOCOMMIT_OK} to disable '
      . 'this warning.'
    ) if ! $attrs{AutoCommit} and ! $ENV{DBIO_UNSAFE_AUTOCOMMIT_OK};

    # Strip DBIO-private attrs before passing to DBI->connect.
    # ignore_version is consumed by the DeploymentHandler version-storage
    # component (DBIO::DeploymentHandler::VersionStorage::Standard::Component),
    # not by the DBD.
    my %dbi_attrs = %attrs;
    delete @dbi_attrs{qw( ignore_version )};

    push @args, \%dbi_attrs if keys %dbi_attrs;
  }

  # this is the authoritative "always an arrayref" thing fed to DBI->connect
  # OR a single-element coderef-based $dbh factory
  $self->_dbi_connect_info(\@args);

  # extract the individual storage options
  for my $storage_opt (keys %{ $info->{storage_options} }) {
    my $value = $info->{storage_options}{$storage_opt};

    $self->$storage_opt($value);
  }

  # ADR 0030: the async execution mode is chosen per connection via
  # { async => 'MODE' } in the connect attributes, and is fixed for the life of
  # this instance. Absent => sync (the *_async methods croak). Reset the
  # resolved-backend cache so a fresh connect_info re-resolves the mode.
  $self->_async_mode($info->{async_mode});
  delete $self->{_async_storage_obj};

  # Extract the individual sqlmaker options
  #
  # Kill sql_maker/_sql_maker_opts, so we get a fresh one with only
  #  the new set of options
  $self->_sql_maker(undef);
  $self->_sql_maker_opts({});

  for my $sql_maker_opt (keys %{ $info->{sql_maker_options} }) {
    my $value = $info->{sql_maker_options}{$sql_maker_opt};

    $self->_sql_maker_opts->{$sql_maker_opt} = $value;
  }

  # FIXME - dirty:
  # save attributes in a separate accessor so they are always
  # introspectable, even in case of a CODE $dbhmaker
  $self->_dbio_connect_attributes (\%attrs);

  return $self->_connect_info;
}


sub _dbi_connect_info {
  my $self = shift;

  return $self->{_dbi_connect_info} = $_[0]
    if @_;

  my $conninfo = $self->{_dbi_connect_info} || [];

  # last ditch effort to grab a DSN
  if ( ! defined $conninfo->[0] and $ENV{DBI_DSN} ) {
    my @new_conninfo = @$conninfo;
    $new_conninfo[0] = $ENV{DBI_DSN};
    $conninfo = \@new_conninfo;
  }

  return $conninfo;
}


sub _normalize_connect_info {
  my ($self, $info_arg) = @_;
  my %info;

  my @args = @$info_arg;  # take a shallow copy for further mutilation

  # combine/pre-parse arguments depending on invocation style

  my %attrs;
  if (ref $args[0] eq 'CODE') {     # coderef with optional \%extra_attributes
    %attrs = %{ $args[1] || {} };
    @args = $args[0];
  }
  elsif (ref $args[0] eq 'HASH') { # single hashref (i.e. Catalyst config)
    %attrs = %{$args[0]};
    @args = ();
    if (my $code = delete $attrs{dbh_maker}) {
      @args = $code;

      my @ignored = grep { delete $attrs{$_} } (qw/dsn user password/);
      if (@ignored) {
        carp sprintf (
            'Attribute(s) %s in connect_info were ignored, as they can not be applied '
          . "to the result of 'dbh_maker'",

          join (', ', map { "'$_'" } (@ignored) ),
        );
      }
    }
    else {
      # Handle a dbname-only hash (e.g. from a hashref-shaped AccessBroker
      # such as DBIO::AccessBroker::Static): convert dbname to dsn if dsn
      # is missing.
      if (!exists $attrs{dsn} && exists $attrs{dbname}) {
        $attrs{dsn} = delete $attrs{dbname};
        # Prepend 'dbi:' if not already a full DSN
        $attrs{dsn} = "dbi:SQLite:dbname=$attrs{dsn}" unless $attrs{dsn} =~ /^dbi:/i;
      }
      @args = delete @attrs{qw/dsn user password/};
    }
  }
  else {                # otherwise assume dsn/user/password + \%attrs + \%extra_attrs
    %attrs = (
      % { $args[3] || {} },
      % { $args[4] || {} },
    );
    @args = @args[0,1,2];
  }

  $info{arguments} = \@args;

  my @storage_opts = grep exists $attrs{$_},
    @storage_options, 'cursor_class';

  @{ $info{storage_options} }{@storage_opts} =
    delete @attrs{@storage_opts} if @storage_opts;

  # ADR 0030: the async mode is a DBIO-private connect attribute, not a DBI one.
  # Pull it out of %attrs (so it never reaches DBI->connect) and surface it
  # separately for connect_info to set on the instance.
  $info{async_mode} = delete $attrs{async}
    if exists $attrs{async};

  my @sql_maker_opts = grep exists $attrs{$_},
    $self->_dbio_sql_maker_option_names;

  @{ $info{sql_maker_options} }{@sql_maker_opts} =
    delete @attrs{@sql_maker_opts} if @sql_maker_opts;

  $info{attributes} = \%attrs if %attrs;

  return \%info;
}

sub _default_dbi_connect_attributes () {
  +{
    AutoCommit => 1,
    PrintError => 0,
    RaiseError => 1,
    ShowErrorStatement => 1,
  };
}



sub _parse_connect_do {
  my ($self, $type) = @_;

  my $val = $self->$type;
  return () if not defined $val;

  my @res;

  if (not ref($val)) {
    push @res, [ 'do_sql', $val ];
  } elsif (ref($val) eq 'CODE') {
    push @res, $val;
  } elsif (ref($val) eq 'ARRAY') {
    push @res, map { [ 'do_sql', $_ ] } @$val;
  } else {
    $self->throw_exception("Invalid type for $type: ".ref($val));
  }

  return \@res;
}


sub dbh_do {
  my $self = shift;
  my $run_target = shift; # either a coderef or a method name

  # short circuit when we know there is no need for a runner
  #
  # FIXME - assumption may be wrong
  # the rationale for the txn_depth check is that if this block is a part
  # of a larger transaction, everything up to that point is screwed anyway
  return $self->$run_target($self->_get_dbh, @_)
    if $self->{_in_do_block} or $self->transaction_depth;

  # take a ref instead of a copy, to preserve @_ aliasing
  # semantics within the coderef, but only if needed
  # (pseudoforking doesn't like this trick much)
  my $args = @_ ? \@_ : [];

  DBIO::Storage::BlockRunner->new(
    storage => $self,
    wrap_txn => 0,
    retry_handler => sub {
      $_[0]->failed_attempt_count == 1
        and
      ! $_[0]->storage->connected
    },
  )->run(sub {
    $self->$run_target ($self->_get_dbh, @$args )
  });
}

sub txn_do {
  $_[0]->_get_dbh; # connects or reconnects on pid change, necessary to grab correct txn_depth
  shift->next::method(@_);
}


sub register_async_mode {
  my ($class, $mode, $backend_class) = @_;
  $_async_mode_registry{$class}{$mode} = $backend_class;
}

# The class whose linearised ISA the async transport/mode resolution walks.
# Async transport (mode) resolution is a property of the DRIVER, never of the
# storage LAYERS composed on top of it (karr #70): a composed instance's class
# (DBIO::Storage::Composed::<layer>__<driver>) has the sync layer packages
# more-specific than the driver in its MRO, and a sync layer's plain ::Async
# mixin (the WP2 async-mirror target -- NOT a DBIO::Storage::Async transport)
# would otherwise be probed before the driver's real transport adapter. So we
# resolve the walk against the composition BASE (the concrete driver storage),
# not ref($self). A non-composed instance has no registry entry -> base is just
# ref($self), i.e. behaviour identical to before composition existed. Class-
# method callers (e.g. DBIO::Storage::DBI->_resolve_async_mode_class) keep the
# ref($self) || $self fallback.
sub _async_resolution_class {
  my $self  = shift;
  my $class = ref($self) || $self;
  my $comp  = DBIO::Storage::Composed->composition_of($class);
  return $comp ? $comp->{base} : $class;
}

# Walk the instance's MRO and return the backend class registered for $mode
# (driver registrations shadow/extend generic ones), or undef if no class in
# the linearised ISA registered that mode. With exclude => $pkg, that one class
# is skipped in the walk -- used by future_io (karr #65) to honour an explicit
# per-driver registration while ignoring any GENERIC base-class one. The walk
# is over the composition BASE (see _async_resolution_class), so storage layers
# never shadow the driver's transport registrations (karr #70).
sub _resolve_async_mode_class {
  my ($self, $mode, %opt) = @_;
  my $exclude = $opt{exclude};
  for my $pkg (@{ mro::get_linear_isa($self->_async_resolution_class) }) {
    next if defined $exclude and $pkg eq $exclude;
    return $_async_mode_registry{$pkg}{$mode}
      if exists $_async_mode_registry{$pkg}
      && exists $_async_mode_registry{$pkg}{$mode};
  }
  return undef;
}

# Resolve an OPTIONAL async class candidate to the three-way outcome that
# load_optional_class alone cannot express: LOADED / genuinely-ABSENT /
# PRESENT-but-UNLOADABLE. load_optional_class returns 0 only when the
# candidate's OWN .pm is missing from @INC; when the file EXISTS but its
# compilation fails -- e.g. its own dependency is not installed (the driver
# ships <pkg>::Async, but the separate async dist providing its base class,
# such as DBIO::Async, is absent), or a genuine bug in the adapter -- it
# instead THROWS the raw compile error. We reproduce the distinction and, on
# the unloadable case, fail loud with a clear, correctly-attributed message
# (ADR 0030 §3: a broken adapter fails loud, never silently degrading to a
# parent's). Naming the missing MODULE is only claimed when Perl actually
# reports one -- a syntax error in an installed adapter is surfaced honestly,
# never misreported as a missing dependency.
# Returns 1 if loaded, 0 if genuinely absent; throws otherwise.
sub _try_load_async_class {
  my ($self, $candidate, $what) = @_;
  $what //= 'async class';

  my $loaded = eval { $self->load_optional_class($candidate) };
  return $loaded if defined $loaded;   # 1 = loaded, 0 = genuinely absent

  my $err = $@;   # load_optional_class threw: file exists, compilation failed

  # A not-installed dependency shows up in one of two shapes: the require's
  # own "Can't locate X.pm in @INC", or use base/parent's "Base class
  # package "X" is empty" (base.pm suppresses the inner Can't-locate and
  # reports the empty base instead).
  my $missing;
  if ($err =~ /\bCan't locate (\S+?)\.pm in \@INC/) {
    ($missing = $1) =~ s{/}{::}g;
  }
  elsif ($err =~ /\bBase class package "([\w:]+)" is empty/) {
    $missing = $1;
  }

  $self->throw_exception(
    (defined $missing && $missing ne $candidate)
      ? "$what '$candidate' is present but cannot be loaded -- it requires "
      . "'$missing', which is not installed. Install the distribution that "
      . "provides '$missing' and retry.\n\nUnderlying error: $err"
      : "$what '$candidate' is present but failed to load.\n\n"
      . "Underlying error: $err"
  );
}

# Resolve (and cache) the embedded async backend for this instance's chosen
# mode, or undef. undef means one of two very different things, disambiguated
# by _async_mode: no mode chosen (sync -- *_async croaks) vs. the 'immediate'
# in-process mode (no event loop, no backend -- *_async degrades). A bad/absent
# mode croaks loudly here (ADR 0030: explicit or it croaks). The resolved value
# is cached in {_async_storage_obj}; disconnect/connect_info delete the slot.
sub _async_storage {
  my $self = shift;

  return $self->{_async_storage_obj}
    if exists $self->{_async_storage_obj};

  my $mode = $self->_async_mode;

  # No async mode chosen -> sync instance, no backend. The *_async dispatch
  # turns this into a loud croak; we never touch the driver/registry here.
  return $self->{_async_storage_obj} = undef
    if !defined $mode;

  # The native 'ev' mapping is declared on the concrete driver storage class,
  # and future_io's adapter is derived by convention FROM that class (below);
  # both only work once the storage is reblessed into its driver storage. Force
  # driver determination so the registry walk sees the driver's registrations
  # and ref($self) is the concrete driver storage class.
  $self->_determine_driver;

  my $backend_class;

  if ($mode eq 'future_io') {
    # --- ADR 0030 refinement (karr #65 + #67): future_io class-by-CONVENTION -
    # future_io's transport adapter is discovered off the concrete,
    # driver-determined storage class: <pkg> . '::Async' -- parallel to the
    # sync driver storage (DBIO::X::Storage -> DBIO::X::Storage::Async). Because
    # a storage is always driver-specific, every driver's adapter is thus
    # deterministic with no registry entry at all. Precedence:
    #   1. An EXPLICIT register_async_mode(future_io => ...) on a concrete
    #      driver storage class still wins, as a backward-compatible override.
    #      A GENERIC base-class (DBIO::Storage::DBI) registration is deliberately
    #      NOT honoured -- so merely loading an async dist can no longer globally
    #      "claim" future_io for every driver and then die deep in an abstract
    #      base's _submit_query seam. That is exactly what this replaces.
    #   2. Otherwise WALK the linearised ISA (ADR 0030 second refinement, karr
    #      #67), most-specific first, probing <pkg>::Async at each rung and
    #      STOPPING strictly BEFORE the generic DBIO::Storage::DBI base (a
    #      generic ::Async claiming every driver is the hole #65 banned; the
    #      walk must not reopen it). The first candidate that LOADS wins; one
    #      that loads but is NOT a DBIO::Storage::Async croaks AT ONCE naming
    #      it -- a broken extension adapter fails loud, never silently degrading
    #      to a parent's adapter. This mirrors the registry walk
    #      (_resolve_async_mode_class) so extension storage_type subclasses
    #      (AGE/PostGIS) inherit the nearest parent adapter, just like sync
    #      storage inheritance.
    # The MODE stays explicit (ADR 0030: the caller still writes
    # { async => 'future_io' }); only the CLASS is resolved by convention. This
    # is NOT the banned ADR 0029 mode auto-fallback.
    $backend_class = $self->_resolve_async_mode_class($mode, exclude => __PACKAGE__);

    if (defined $backend_class) {
      $self->throw_exception(
        "async mode '$mode' is not available -- install $backend_class"
      ) unless $self->load_optional_class($backend_class);
    }
    else {
      # Walk the composition BASE, not ref($self): the transport adapter is a
      # property of the concrete DRIVER, and a composed instance's storage
      # layers (with their plain ::Async mixins) sit more-specific than the
      # driver in ref($self)'s MRO -- probing those would find a layer's async
      # mixin (not a DBIO::Storage::Async) before the driver's real adapter and
      # croak. For a non-composed instance the base IS ref($self) (karr #70).
      my $class = $self->_async_resolution_class;
      my @tried;
      for my $pkg (@{ mro::get_linear_isa($class) }) {
        last if $pkg eq __PACKAGE__;   # stop strictly BEFORE the generic base
        my $adapter = $pkg . '::Async';
        push @tried, $adapter;
        # Genuinely absent -> keep walking; present-but-unloadable (its own
        # async dependency missing, or broken) -> fail loud with the cause.
        next unless $self->_try_load_async_class($adapter, 'future_io adapter');

        # Loaded -- it MUST be a proper backend or we fail loud, naming it;
        # never silently skip past it to a parent's adapter (ADR 0030 §3).
        $self->throw_exception(
          "driver $class does not support future_io -- "
          . "$adapter loaded but is not a DBIO::Storage::Async"
        ) unless $adapter->isa('DBIO::Storage::Async');

        $backend_class = $adapter;
        last;
      }

      $self->throw_exception(
        "driver $class does not support future_io -- no ${class}::Async adapter "
        . "found on it or any parent (tried: @{[ join ', ', @tried ]})"
      ) unless defined $backend_class;
    }
  }
  else {
    $backend_class = $self->_resolve_async_mode_class($mode);

    $self->throw_exception(
      "async mode '$mode' is not available -- no driver or add-on registers it"
    ) if !defined $backend_class;

    $self->throw_exception(
      "async mode '$mode' is not available -- install $backend_class"
    ) unless $self->load_optional_class($backend_class);
  }

  # A non-DBIO::Storage::Async target (the 'immediate' Future class) is the
  # in-process degrade mode: no embedded backend is built.
  return $self->{_async_storage_obj} = undef
    unless $backend_class->isa('DBIO::Storage::Async');

  # --- WP2 (karr #70): async mirror composition. The transport class is now
  # resolved; mirror each registered SYNC storage layer onto its ASYNC
  # counterpart and compose them over the transport, so an extension's async
  # behaviour rides every transport just as its sync behaviour rides every
  # driver (one behaviour, one transport). Per sync layer L, in registration
  # order:
  #   * L->async_layer_class($mode) if L defines it -- a package (must load, or
  #     croak) or undef (fall back to convention);
  #   * otherwise the convention sibling "${L}::Async" via load_optional_class;
  #   * absent -> skip L silently (a sync-only extension, e.g. PostGIS).
  # This does NOT touch the transport resolution above (ADR 0030: the mode
  # stays explicit; only the layer CLASSES are added by composition).
  # A storage with no live schema (weakened ref already gone) can carry no
  # registered layers, so there is nothing to mirror.
  my $schema = $self->schema;
  my @async_layers;
  for my $sync_layer ($schema ? @{ $schema->storage_layers } : ()) {
    my $async_layer;

    if ($sync_layer->can('async_layer_class')) {
      $async_layer = $sync_layer->async_layer_class($mode);
      if (defined $async_layer) {
        # An explicitly declared class MUST load: genuinely absent -> the
        # "could not be loaded" croak; present-but-unloadable -> _try_load's
        # cause-naming croak (never a raw compile stack).
        $self->throw_exception(
          "async layer class '$async_layer' for storage layer '$sync_layer' "
        . "(async mode '$mode') could not be loaded"
        ) unless $self->_try_load_async_class(
          $async_layer, "async layer class for storage layer '$sync_layer'"
        );
      }
    }

    if (!defined $async_layer) {
      my $candidate = "${sync_layer}::Async";
      # Convention sibling: genuinely absent -> skip L silently (sync-only
      # extension, e.g. PostGIS); present-but-unloadable -> fail loud naming
      # the cause, never a silent feature loss nor a raw compile stack.
      $async_layer = $candidate
        if $self->_try_load_async_class($candidate, 'async layer');
    }

    push @async_layers, $async_layer if defined $async_layer;
  }

  if (@async_layers) {
    # Capability gate: an async layer may only compose over a transport that
    # provides every capability it declares as required. A shortfall croaks
    # naming the layer, the missing capabilities and the transport -- a
    # transport gap becomes that transport's ticket, never a silent feature loss.
    my %have = map { $_ => 1 } $backend_class->transport_capabilities;
    for my $async_layer (@async_layers) {
      next unless $async_layer->can('required_transport_capabilities');
      my @missing = grep { !$have{$_} }
        $async_layer->required_transport_capabilities;
      next unless @missing;
      $self->throw_exception(
        "async layer '$async_layer' requires transport "
      . (@missing == 1 ? 'capability' : 'capabilities') . " '"
      . join("', '", @missing) . "' which transport '$backend_class' does not "
      . "provide -- upgrade the transport '$backend_class' (or its "
      . "distribution) or choose another async mode"
      );
    }

    $backend_class =
      DBIO::Storage::Composed->compose($backend_class, \@async_layers);
  }

  # Build the embedded backend (ADR 0028 mechanism): ->new($schema) fed this
  # storage's DBI-form connect_info.
  my $async = $backend_class->new($self->schema);
  $async->connect_info($self->_connect_info);

  # karr #68: give the async backend a weak back-reference to THIS owning sync
  # storage, so its pool can resolve on_connect_call/on_connect_do (and their
  # connect_call_* methods) on the class that actually defines them, and replay
  # them against each freshly-spawned pool connection.
  $async->_owner_storage($self) if $async->can('_owner_storage');

  return $self->{_async_storage_obj} = $async;
}


sub async {
  my $self = shift;
  return $self->_async_storage;
}


sub disconnect {

  if( my $dbh = $_[0]->_dbh ) {

    $_[0]->_do_connection_actions(disconnect_call_ => $_) for (
      ( $_[0]->on_disconnect_call || () ),
      $_[0]->_parse_connect_do ('on_disconnect_do')
    );

    # stops the "implicit rollback on disconnect" warning
    $_[0]->_exec_txn_rollback unless $_[0]->_dbh_autocommit;

    %{ $dbh->{CachedKids} } = ();
    $dbh->disconnect;
    $_[0]->_dbh(undef);
    $_[0]->deferred_rollback(undef);
  }

  # Tear down the embedded async backend, if one was built. Outside the _dbh
  # guard so it runs even when no sync dbh was ever opened. delete invalidates
  # the _async_storage cache so a later *_async call rebuilds.
  if (my $async = delete $_[0]->{_async_storage_obj}) {
    $async->disconnect;
  }
}


# Storage subclasses should override this
sub with_deferred_fk_checks {
  #my ($self, $sub) = @_;
  $_[1]->();
}


sub connected {
  return 0 unless $_[0]->_seems_connected;

  #be on the safe side
  local $_[0]->_dbh->{RaiseError} = 1;

  return $_[0]->_ping;
}

sub _seems_connected {
  $_[0]->_verify_pid unless is_windows();

  ($_[0]->_dbh || return 0)->FETCH('Active');
}

sub _ping {
  ($_[0]->_dbh || return 0)->ping;
}

sub ensure_connected {
  $_[0]->connected || ( $_[0]->_populate_dbh && 1 );
}


sub dbh {
  # maybe save a ping call
  $_[0]->_dbh
    ? ( $_[0]->ensure_connected and $_[0]->_dbh )
    : $_[0]->_populate_dbh
  ;
}

# this is the internal "get dbh or connect (don't check)" method
sub _get_dbh {
  $_[0]->_verify_pid unless is_windows();
  $_[0]->_dbh || $_[0]->_populate_dbh;
}

# *DELIBERATELY* not a setter (for the time being)
# Too intertwined with everything else for any kind of sanity
sub sql_maker {
  my $self = shift;

  $self->throw_exception('sql_maker() is not a setter method') if @_;

  unless ($self->_sql_maker) {
    my $sql_maker_class = $self->sql_maker_class;

    my %opts = %{$self->_sql_maker_opts||{}};

    my ($quote_char, $name_sep);

    # Identifier quoting defaults to ON (security hardening, Codeberg
    # dbio/dbio#2). Quote unless the user explicitly passed a false
    # quote_names in their connect_info.
    if (!exists $opts{quote_names} || $opts{quote_names}) {
      # An explicitly supplied quote_char is always respected, including an
      # empty string (which means "no quoting" and must win over the class
      # default) -- hence exists(), not truthiness.
      $quote_char = exists $opts{quote_char}
        ? delete $opts{quote_char}
        : $self->sql_quote_char || do {
          my $s_class = (ref $self) || $self;
          carp_unique (<<"__EOW__");
You requested 'quote_names' but your storage class ($s_class) does
not explicitly define a default sql_quote_char and you have not
supplied a quote_char as part of your connection_info. DBIO will
default to the ANSI SQL standard quote '"', which works most of
the time. Please file a Codeberg issue against '$s_class' at
https://codeberg.org/dbio/dbio/issues
__EOW__

          '"'; # RV
        };

      $name_sep = (delete $opts{name_sep}) || $self->sql_name_sep;
    }

    $self->_sql_maker($sql_maker_class->new(
      bindtype=>'columns',
      array_datatypes => 1,
      ($quote_char ? (quote_char => $quote_char) : ()),
      name_sep => ($name_sep || '.'),
      %opts,
    ));
  }
  return $self->_sql_maker;
}

# nothing to do by default
sub _rebless {}
sub _init {}

sub _populate_dbh {

  $_[0]->_dbh(undef); # in case ->connected failed we might get sent here

  $_[0]->_dbh_details({}); # reset everything we know

  # FIXME - this needs reenabling with the proper "no reset on same DSN" check
  #$_[0]->_sql_maker(undef); # this may also end up being different

  $_[0]->_dbh($_[0]->_connect);

  $_[0]->_conn_pid($$) unless is_windows(); # on win32 these are in fact threads

  $_[0]->_determine_driver;

  # Always set the transaction depth on connect, since
  #  there is no transaction in progress by definition
  $_[0]->{transaction_depth} = $_[0]->_dbh_autocommit ? 0 : 1;
  $_[0]->deferred_rollback(undef);

  $_[0]->_run_connection_actions unless $_[0]->{_in_determine_driver};

  $_[0]->_dbh;
}

sub _run_connection_actions {
  # there are pathological cases in the CI where this can loop
  # did not investigae in depth, but in either case this makes
  # sense to guard like this
  return if $_[0]->{_running_connections_actions};

  local $_[0]->{_running_connections_actions} = 1;

  $_[0]->_do_connection_actions(connect_call_ => $_) for (
    ( $_[0]->on_connect_call || () ),
    $_[0]->_parse_connect_do ('on_connect_do'),
  );

  my $sqlac_like;
  if(
    is_dev_release
      and
    ($ENV{DBIODEVREL_SWAPOUT_SQLAC_WITH} || $ENV{DBICDEVREL_SWAPOUT_SQLAC_WITH})
      and
    ( $sqlac_like ) = ($ENV{DBIODEVREL_SWAPOUT_SQLAC_WITH} || $ENV{DBICDEVREL_SWAPOUT_SQLAC_WITH}) =~ /(.+)/
      and
    # delay calling ->sql_maker as long as we can
    # ensure_class_loaded returns undef or throws
    ( Class::C3::Componentised->ensure_class_loaded( $sqlac_like ), 1 )
      and
    ( ref $_[0]->sql_maker ) !~ /__REBASED__/
  ) {

    require DBIO::SQLMaker::ClassicExtensions;
    require SQL::Abstract;

    Class::C3::Componentised->inject_base(
      'DBICDevRel::SQLAC::SwapOut',
      'DBIO::SQLMaker::ClassicExtensions',
      $sqlac_like,
      'SQL::Abstract',
    );

    $_[0]->_do_connection_actions(connect_call_ => [[ rebase_sqlmaker => 'DBICDevRel::SQLAC::SwapOut' ]]);
  }
}

# karr #68: replay THIS storage's configured on_connect actions against a freshly
# spawned async pool connection. Called from the embedded async backend's
# _setup_pool_connection with $runner, a coderef that runs one statement on the
# pool connection. We reuse the exact sync dispatch (_do_connection_actions +
# _parse_connect_do, in the same order _run_connection_actions uses) so that
# connect_call_* resolve on this (owning) storage identically to sync -- but the
# statements they emit via _do_query are redirected onto the pool connection by
# localising _pool_connect_runner (honoured in _do_query). This is the
# convention-friendly dispatch (ticket #68 option a): resolve on the sync
# storage, execute against the pool handle.
sub _run_pool_connect_actions {
  my ($self, $runner) = @_;

  local $self->{_pool_connect_runner} = $runner;

  $self->_do_connection_actions(connect_call_ => $_) for (
    ( $self->on_connect_call || () ),
    $self->_parse_connect_do('on_connect_do'),
  );

  return $self;
}

# Symmetric counterpart for disconnect: same dispatch machinery, run against the
# pool connection while it is still live (from the pool's shutdown path).
sub _run_pool_disconnect_actions {
  my ($self, $runner) = @_;

  local $self->{_pool_connect_runner} = $runner;

  $self->_do_connection_actions(disconnect_call_ => $_) for (
    ( $self->on_disconnect_call || () ),
    $self->_parse_connect_do('on_disconnect_do'),
  );

  return $self;
}



sub _server_info {
  my $self = shift;

  my $info;
  unless ($info = $self->_dbh_details->{info}) {

    $info = {};
    # this guarantees that problematic conninfo won't be hidden
    # by the try{} below
    $self->ensure_connected;

    my $server_version = try {
      $self->_get_server_version
    } catch {
      # driver determination *may* use this codepath
      # in which case we must rethrow
      $self->throw_exception($_) if $self->{_in_determine_driver};

      # $server_version on failure
      undef;
    };

    if (defined $server_version) {
      $info->{dbms_version} = $server_version;

      my ($numeric_version) = $server_version =~ /^([\d\.]+)/;
      my @verparts = split (/\./, $numeric_version);
      if (
        @verparts
          &&
        $verparts[0] <= 999
      ) {
        # consider only up to 3 version parts, iff not more than 3 digits
        my @use_parts;
        while (@verparts && @use_parts < 3) {
          my $p = shift @verparts;
          last if $p > 999;
          push @use_parts, $p;
        }
        push @use_parts, 0 while @use_parts < 3;

        $info->{normalized_dbms_version} = sprintf "%d.%03d%03d", @use_parts;
      }
    }

    $self->_dbh_details->{info} = $info;
  }

  return $info;
}

sub _get_server_version {
  shift->_dbh_get_info('SQL_DBMS_VER');
}

sub _dbh_get_info {
  my ($self, $info) = @_;

  if ($info =~ /[^0-9]/) {
    require DBI::Const::GetInfoType;
    $info = $DBI::Const::GetInfoType::GetInfoType{$info};
    $self->throw_exception("Info type '$_[1]' not provided by DBI::Const::GetInfoType")
      unless defined $info;
  }

  $self->_get_dbh->get_info($info);
}

sub _describe_connection {
  require DBI::Const::GetInfoReturn;

  my $self = shift;

  my $drv;
  try {
    $drv = $self->_extract_driver_from_connect_info;
    $self->ensure_connected;
  };

  $drv = "DBD::$drv" if $drv;

  my $res = do {
    local $SIG{__WARN__} = sigwarn_silencer(qr/Argument .+? isn't numeric in subroutine entry/);
    {
      DBIO_DSN => $self->_dbi_connect_info->[0],
      DBI_VER => DBI->VERSION,
      DBIO_VER => DBIO->VERSION,
      DBIO_DRIVER => ref $self,
      $drv ? (
        DBD => $drv,
        DBD_VER => try { $drv->VERSION },
      ) : (),
    }
  };

  # try to grab data even if we never managed to connect
  # will cover us in cases of an oddly broken half-connect
  for my $inf (
    #keys %DBI::Const::GetInfoType::GetInfoType,
    qw/
      SQL_CURSOR_COMMIT_BEHAVIOR
      SQL_CURSOR_ROLLBACK_BEHAVIOR
      SQL_CURSOR_SENSITIVITY
      SQL_DATA_SOURCE_NAME
      SQL_DBMS_NAME
      SQL_DBMS_VER
      SQL_DEFAULT_TXN_ISOLATION
      SQL_DM_VER
      SQL_DRIVER_NAME
      SQL_DRIVER_ODBC_VER
      SQL_DRIVER_VER
      SQL_EXPRESSIONS_IN_ORDERBY
      SQL_GROUP_BY
      SQL_IDENTIFIER_CASE
      SQL_IDENTIFIER_QUOTE_CHAR
      SQL_MAX_CATALOG_NAME_LEN
      SQL_MAX_COLUMN_NAME_LEN
      SQL_MAX_IDENTIFIER_LEN
      SQL_MAX_TABLE_NAME_LEN
      SQL_MULTIPLE_ACTIVE_TXN
      SQL_MULT_RESULT_SETS
      SQL_NEED_LONG_DATA_LEN
      SQL_NON_NULLABLE_COLUMNS
      SQL_ODBC_VER
      SQL_QUALIFIER_NAME_SEPARATOR
      SQL_QUOTED_IDENTIFIER_CASE
      SQL_TXN_CAPABLE
      SQL_TXN_ISOLATION_OPTION
    /
  ) {
    # some drivers barf on things they do not know about instead
    # of returning undef
    my $v = try { $self->_dbh_get_info($inf) };
    next unless defined $v;

    #my $key = sprintf( '%s(%s)', $inf, $DBI::Const::GetInfoType::GetInfoType{$inf} );
    my $expl = DBI::Const::GetInfoReturn::Explain($inf, $v);
    $res->{$inf} = DBI::Const::GetInfoReturn::Format($inf, $v) . ( $expl ? " ($expl)" : '' );
  }

  $res;
}

# Driver registry: maps DBD driver names to DBIO Storage classes.
# External DBIO::* distributions register themselves here via
# register_driver(), or are discovered via the default mapping below.
my %_driver_registry = (
  Pg        => 'DBIO::PostgreSQL::Storage',
  mysql     => 'DBIO::MySQL::Storage',
  MariaDB   => 'DBIO::MySQL::Storage::MariaDB',
  SQLite    => 'DBIO::SQLite::Storage',
  Oracle    => 'DBIO::Oracle::Storage',
  Sybase    => 'DBIO::Sybase::Storage',
  Firebird  => 'DBIO::Firebird::Storage',
  InterBase => 'DBIO::Firebird::Storage::InterBase',
  Informix  => 'DBIO::Informix::Storage',
  DB2       => 'DBIO::DB2::Storage',
  ODBC      => 'DBIO::Storage::DBI::ODBC',
);

# Connector registry: maps SQL_DBMS_NAME values (via ODBC/ADO) to
# DBIO Storage classes for secondary driver detection.
my %_connector_registry = (
  'Microsoft_SQL_Server' => 'DBIO::MSSQL::Storage::ODBC',
  'Firebird'             => 'DBIO::Firebird::Storage',
);



sub register_driver {
  my ($class, $driver_name, $storage_class) = @_;
  $_driver_registry{$driver_name} = $storage_class;
}

sub driver_storage_class {
  my ($class, $driver_name) = @_;
  return $_driver_registry{$driver_name};
}



sub register_connector_driver {
  my ($class, $dbms_name, $storage_class) = @_;
  $_connector_registry{$dbms_name} = $storage_class;
}

# Standard SQL type registrations for DBIO::Cake.
# Driver subclasses add or override entries for their own types.
__PACKAGE__->register_type('json', {
  cake_options => [qw(inflate_json)],
  components   => ['InflateColumn::Serializer'],
  col_attrs    => { serializer_class => 'JSON' },
});

for my $dt (qw(date datetime timestamp time timetz timestamptz interval)) {
  __PACKAGE__->register_type($dt, {
    cake_options => ['inflate_datetime'],
    components   => ['InflateColumn::DateTime'],
  });
}

sub _determine_driver {
  my ($self) = @_;

  if ((not $self->_driver_determined) && (not $self->{_in_determine_driver})) {
    my $started_connected = 0;
    local $self->{_in_determine_driver} = 1;

    # A composed storage class (DBIO::Storage::Composed over the generic base)
    # must enter driver determination too: its BASE is __PACKAGE__, so the bare
    # ref() equality would skip it and the driver would never get composed in.
    # Recover its composition; when its base is the generic __PACKAGE__ treat it
    # exactly like a bare generic storage, and re-compose the same layers over
    # the concrete driver class as the rebless target. A non-composed instance
    # has no registry entry and behaves exactly as before.
    my $composition = DBIO::Storage::Composed->composition_of(ref $self);
    my $is_generic = ref($self) eq __PACKAGE__
      || ($composition && $composition->{base} eq __PACKAGE__);

    if ($is_generic) {
      my $driver;
      if ($self->_dbh) { # we are connected
        $driver = $self->_dbh->{Driver}{Name};
        $started_connected = 1;
      }
      else {
        $driver = $self->_extract_driver_from_connect_info;
      }

      if ($driver) {
        my $storage_class = $_driver_registry{$driver};

        if ($storage_class && $self->load_optional_class($storage_class)) {
          mro::set_mro($storage_class, 'c3');

          # Re-compose the instance's layers over the driver class, or rebless
          # straight to the driver when it was never composed.
          my $target = $composition
            ? DBIO::Storage::Composed->recompose(ref $self, $storage_class)
            : $storage_class;
          bless $self, $target;
          $self->_rebless();

          # Expose this driver's bundled agent skills (see DBIO::Skills).
          DBIO::Skills->register_class($storage_class);
        }
        elsif ($storage_class) {
          $self->throw_exception(
            "The DBIO driver '$storage_class' for DBD driver '$driver' could not be loaded. "
          . "Install the corresponding distribution (e.g. cpanm DBIO::PostgreSQL for dbi:Pg)."
          );
        }
        else {
          $self->throw_exception(
            "No DBIO driver registered for DBD driver '$driver'. "
          . "Install the appropriate DBIO::* distribution for your database, "
          . "or register a custom driver via DBIO::Storage::DBI->register_driver."
          );
        }
      }
      else {
        $self->_warn_undetermined_driver(
          'Unable to extract a driver name from connect info.'
        );
      }
    }

    $self->_driver_determined(1);

    Class::C3->reinitialize() if old_mro();

    $self->_init; # run driver-specific initializations

    $self->_run_connection_actions
        if !$started_connected && defined $self->_dbh;
  }
}

sub _extract_driver_from_connect_info {
  my $self = shift;

  my $drv;

  # if connect_info is a CODEREF, we have no choice but to connect
  if (
    ref $self->_dbi_connect_info->[0]
      and
    reftype $self->_dbi_connect_info->[0] eq 'CODE'
  ) {
    $self->_populate_dbh;
    $drv = $self->_dbh->{Driver}{Name};
  }
  else {
    # try to use dsn to not require being connected, the driver may still
    # force a connection later in _rebless to determine version
    # (dsn may not be supplied at all if all we do is make a mock-schema)
    #
    # Use the same regex as the one used by DBI itself (even if the use of
    # \w is odd given unicode):
    # https://metacpan.org/source/TIMB/DBI-1.634/DBI.pm#L621
    #
    # DO NOT use https://metacpan.org/source/TIMB/DBI-1.634/DBI.pm#L559-566
    # as there is a long-standing precedent of not loading DBI.pm until the
    # very moment we are actually connecting
    #
    ($drv) = ($self->_dbi_connect_info->[0] || '') =~ /^dbi:(\w*)/i;
    $drv ||= $ENV{DBI_DRIVER};
  }

  return $drv;
}

sub _determine_connector_driver {
  my ($self, $conn) = @_;

  my $dbtype = $self->_dbh_get_info('SQL_DBMS_NAME');

  if (not $dbtype) {
    $self->_warn_undetermined_driver(
      'Unable to retrieve RDBMS type (SQL_DBMS_NAME) of the engine behind your '
    . "$conn connector - this should not have happened."
    );
    return;
  }

  $dbtype =~ s/\W/_/gi;

  my $subclass = $_connector_registry{$dbtype};

  if ($subclass) {
    return if $self->isa($subclass);

    if ($self->load_optional_class($subclass)) {
      # Keep the instance's layers when reblessing onto the connector subclass
      # (mirrors the driver rebless above); rebless straight to the subclass
      # when it was never composed.
      my $composition = DBIO::Storage::Composed->composition_of(ref $self);
      my $target = $composition
        ? DBIO::Storage::Composed->recompose(ref $self, $subclass)
        : $subclass;
      bless $self, $target;
      $self->_rebless;
    }
    else {
      $self->throw_exception(
        "The DBIO driver '$subclass' for $conn/$dbtype could not be loaded. "
      . "Install the corresponding distribution."
      );
    }
  }
  else {
    $self->throw_exception(
      "No DBIO driver registered for connector '$conn/$dbtype'. "
    . "Install the appropriate DBIO::* distribution for your database, "
    . "or register via DBIO::Storage::DBI->register_connector_driver."
    );
  }
}

sub _warn_undetermined_driver {
  my ($self, $msg) = @_;

  carp_once ($msg . ' While we will attempt to continue anyway, the results '
  . 'are likely to be underwhelming. Please upgrade DBIO, and if this message '
  . "does not go away, file a bugreport including the following info:\n"
  . dump_value($self->_describe_connection)
  );
}

sub _do_connection_actions {
  my ($self, $method_prefix, $call, @args) = @_;

  try {
    if (not ref($call)) {
      my $method = $method_prefix . $call;
      $self->$method(@args);
    }
    elsif (ref($call) eq 'CODE') {
      $self->$call(@args);
    }
    elsif (ref($call) eq 'ARRAY') {
      if (ref($call->[0]) ne 'ARRAY') {
        $self->_do_connection_actions($method_prefix, $_) for @$call;
      }
      else {
        $self->_do_connection_actions($method_prefix, @$_) for @$call;
      }
    }
    else {
      $self->throw_exception (sprintf ("Don't know how to process conection actions of type '%s'", ref($call)) );
    }
  }
  catch {
    if ( $method_prefix =~ /^connect/ ) {
      # this is an on_connect cycle - we can't just throw while leaving
      # a handle in an undefined state in our storage object
      # kill it with fire and rethrow
      $self->_dbh(undef);
      $self->throw_exception( $_[0] );
    }
    else {
      carp "Disconnect action failed: $_[0]";
    }
  };

  return $self;
}

sub connect_call_do_sql {
  my $self = shift;
  $self->_do_query(@_);
}

sub disconnect_call_do_sql {
  my $self = shift;
  $self->_do_query(@_);
}


sub connect_call_datetime_setup { 1 }

sub _do_query {
  my ($self, $action) = @_;

  if (ref $action eq 'CODE') {
    $action = $action->($self);
    $self->_do_query($_) foreach @$action;
  }
  else {
    # Most debuggers expect ($sql, @bind), so we need to exclude
    # the attribute hash which is the second argument to $dbh->do
    # furthermore the bind values are usually to be presented
    # as named arrayref pairs, so wrap those here too
    my @do_args = (ref $action eq 'ARRAY') ? (@$action) : ($action);
    my $sql = shift @do_args;
    my $attrs = shift @do_args;
    my @bind = map { [ undef, $_ ] } @do_args;

    # karr #68: when replaying this storage's connection actions against a
    # freshly-spawned async pool connection (_run_pool_connect_actions), the
    # statement must execute on THAT pool connection, not on this sync storage's
    # own dbh. The runner (installed by the async backend's
    # _setup_pool_connection) does the blocking do on the pool handle. Only ever
    # set inside that dynamic scope, so the normal sync path is untouched.
    if (my $runner = $self->{_pool_connect_runner}) {
      $runner->($sql, $attrs, @do_args);
      return $self;
    }

    $self->dbh_do(sub {
      $_[0]->_query_start($sql, \@bind);
      $_[1]->do($sql, $attrs, @do_args);
      $_[0]->_query_end($sql, \@bind);
    });
  }

  return $self;
}


sub connect_call_rebase_sqlmaker {
  my( $self, $requested_base_class ) = @_;

  $self->throw_exception(
    "The on_connect callee 'rebase_sqlmaker' expects a single plain string argument: the name of the target base class"
  ) if (
    @_ != 2
      or
    ! length( $requested_base_class )
  );

  my $old_class = ref( $self->sql_maker );

  # nothing to do!
  return if $old_class->isa( $requested_base_class );

  my $synthetic_class = "${old_class}__REBASED_ON__${requested_base_class}";

  {
    no strict 'refs';

    # skip if we already made that class
    unless( @{"${synthetic_class}::ISA"} ) {

      $self->ensure_class_loaded( $requested_base_class );

      $self->throw_exception(
        "The 'rebase_sqlmaker' target class '$requested_base_class' is not inheriting from 'DBIO::SQLMaker::ClassicExtensions', this can not work"
      ) unless $requested_base_class->isa( 'DBIO::SQLMaker::ClassicExtensions' );

      $self->throw_exception(
        "The 'rebase_sqlmaker' target class '$requested_base_class' must inherit from SQL::Abstract or SQL::Abstract::Classic"
      ) unless $requested_base_class->isa( 'SQL::Abstract' )
            or $requested_base_class->isa( 'SQL::Abstract::Classic' );

      $self->inject_base( $synthetic_class, $old_class, $requested_base_class );

      Class::C3->reinitialize
        if old_mro();
    }
  }

  # force re-build on next access for this particular $storage instance
  $self->sql_maker_class( $synthetic_class );
  $self->_sql_maker( undef );
}

sub _connect {
  my $self = shift;

  if ($self->access_broker) {
    my $broker_info = $self->_current_dbi_connect_info($self->access_broker_mode);
    # Broker returns HASHREF; normalize to ARRAYREF for _normalize_connect_info
    $broker_info = [$broker_info] if ref $broker_info eq 'HASH';
    my $info = $self->_normalize_connect_info($broker_info);

    my %attrs = (
      %{ $self->_default_dbi_connect_attributes || {} },
      %{ $info->{attributes} || {} },
    );

    my @args = @{ $info->{arguments} };

    # _dbio_connect_attributes keeps the full set (including DBIO-private
    # keys like ignore_version) for introspection by upper layers.
    # _dbi_connect_info must only contain attrs that DBI/DBD understands.
    my %dbi_attrs = %attrs;
    delete @dbi_attrs{qw( ignore_version )};

    push @args, \%dbi_attrs if keys %dbi_attrs and ref $args[0] ne 'CODE';

    $self->_dbi_connect_info(\@args);
    $self->_dbio_connect_attributes(\%attrs);
  }

  my $info = $self->_dbi_connect_info;

  $self->throw_exception("You did not provide any connection_info")
    unless defined $info->[0];

  my ($old_connect_via, $dbh);

  local $DBI::connect_via = 'connect' if $INC{'Apache/DBI.pm'} && $ENV{MOD_PERL};

  # this odd anonymous coderef dereference is in fact really
  # necessary to avoid the unwanted effect described in perl5
  # RT#75792
  #
  # in addition the coderef itself can't reside inside the try{} block below
  # as it somehow triggers a leak under perl -d
  my $dbh_error_handler_installer = sub {
    weaken (my $weak_self = $_[0]);

    # the coderef is blessed so we can distinguish it from externally
    # supplied handles (which must be preserved)
    $_[1]->{HandleError} = bless sub {
      if ($weak_self) {
        $weak_self->throw_exception("DBI Exception: $_[0]");
      }
      else {
        # the handler may be invoked by something totally out of
        # the scope of DBIO
        DBIO::Exception->throw("DBI Exception (unhandled by DBIO, ::Schema GCed): $_[0]");
      }
    }, '__DBIO__DBH__ERROR__HANDLER__';
  };

  try {
    if(ref $info->[0] eq 'CODE') {
      $dbh = $info->[0]->();
    }
    else {
      require DBI;
      $dbh = DBI->connect(@$info);
    }

    die $DBI::errstr unless $dbh;

    die sprintf ("%s fresh DBI handle with a *false* 'Active' attribute. "
      . 'This handle is disconnected as far as DBIO is concerned, and we can '
      . 'not continue',
      ref $info->[0] eq 'CODE'
        ? "Connection coderef $info->[0] returned a"
        : 'DBI->connect($schema->storage->connect_info) resulted in a'
    ) unless $dbh->FETCH('Active');

    # sanity checks unless asked otherwise
    unless ($self->unsafe) {

      $self->throw_exception(
        'Refusing clobbering of {HandleError} installed on externally supplied '
       ."DBI handle $dbh. Either remove the handler or use the 'unsafe' attribute."
      ) if $dbh->{HandleError} and ref $dbh->{HandleError} ne '__DBIO__DBH__ERROR__HANDLER__';

      # Default via _default_dbi_connect_attributes is 1, hence it was an explicit
      # request, or an external handle. Complain and set anyway
      unless ($dbh->{RaiseError}) {
        carp( ref $info->[0] eq 'CODE'

          ? "The 'RaiseError' of the externally supplied DBI handle is set to false. "
           ."DBIO will toggle it back to true, unless the 'unsafe' connect "
           .'attribute has been supplied'

          : 'RaiseError => 0 supplied in your connection_info, without an explicit '
           .'unsafe => 1. Toggling RaiseError back to true'
        );

        $dbh->{RaiseError} = 1;
      }

      $dbh_error_handler_installer->($self, $dbh);
    }
  }
  catch {
    $self->throw_exception("DBI Connection failed: $_")
  };

  $self->_dbh_autocommit($dbh->{AutoCommit});
  return $dbh;
}

sub txn_begin {
  $_[0]->_assert_transaction_safe_access_broker;
  local $_[0]->{_access_broker_txn_safety_checked} = 1;

  # this means we have not yet connected and do not know the AC status
  # (e.g. coderef $dbh), need a full-fledged connection check
  if (! defined $_[0]->_dbh_autocommit) {
    $_[0]->ensure_connected;
  }
  # Otherwise simply connect or re-connect on pid changes
  else {
    $_[0]->_get_dbh;
  }

  shift->next::method(@_);
}

sub _exec_txn_begin {
  my $self = shift;

  # if the user is utilizing txn_do - good for him, otherwise we need to
  # ensure that the $dbh is healthy on BEGIN.
  # We do this via ->dbh_do instead of ->dbh, so that the ->dbh "ping"
  # will be replaced by a failure of begin_work itself (which will be
  # then retried on reconnect)
  if ($self->{_in_do_block}) {
    $self->_dbh->begin_work;
  } else {
    $self->dbh_do(sub { $_[1]->begin_work });
  }
}

sub txn_commit {
  my $self = shift;

  $self->throw_exception("Unable to txn_commit() on a disconnected storage")
    unless $self->_seems_connected;

  # esoteric case for folks using external $dbh handles
  if (! $self->transaction_depth and ! $self->_dbh->FETCH('AutoCommit') ) {
    carp "Storage transaction_depth 0 does not match "
        ."false AutoCommit of $self->{_dbh}, attempting COMMIT anyway";
    $self->transaction_depth(1);
  }

  $self->next::method(@_);

  # if AutoCommit is disabled txn_depth never goes to 0
  # as a new txn is started immediately on commit
  $self->transaction_depth(1) if (
    !$self->transaction_depth
      and
    defined $self->_dbh_autocommit
      and
    ! $self->_dbh_autocommit
  );
}

sub _exec_txn_commit {
  shift->_dbh->commit;
}

sub txn_rollback {
  my $self = shift;

  $self->throw_exception("Unable to txn_rollback() on a disconnected storage")
    unless $self->_seems_connected;

  # esoteric case for folks using external $dbh handles
  if (! $self->transaction_depth and ! $self->_dbh->FETCH('AutoCommit') ) {
    carp "Storage transaction_depth 0 does not match "
        ."false AutoCommit of $self->{_dbh}, attempting ROLLBACK anyway";
    $self->transaction_depth(1);
  }

  $self->next::method(@_);

  # if AutoCommit is disabled txn_depth never goes to 0
  # as a new txn is started immediately on commit
  $self->transaction_depth(1) if (
    !$self->transaction_depth
      and
    defined $self->_dbh_autocommit
      and
    ! $self->_dbh_autocommit
  );
}

sub _exec_txn_rollback {
  shift->_dbh->rollback;
}

# generate the DBI-specific stubs, which then fallback to ::Storage proper
quote_sub __PACKAGE__ . "::$_" => sprintf (<<'EOS', $_) for qw(svp_begin svp_release svp_rollback);
  $_[0]->throw_exception('Unable to %s() on a disconnected storage')
    unless $_[0]->_seems_connected;
  shift->next::method(@_);
EOS

# This used to be the top-half of _execute.  It was split out to make it
#  easier to override in NoBindVars without duping the rest.  It takes up
#  all of _execute's args, and emits $sql, @bind.
sub _prep_for_execute {
  #my ($self, $op, $ident, $args) = @_;
  return shift->_gen_sql_bind(@_)
}

sub _gen_sql_bind {
  my ($self, $op, $ident, $args) = @_;

  my ($colinfos, $from);
  if ( blessed($ident) ) {
    $from = $ident->from;
    $colinfos = $ident->columns_info;
  }

  my ($sql, $bind);
  ($sql, @$bind) = $self->sql_maker->$op( ($from || $ident), @$args );

  $bind = $self->_resolve_bindattrs(
    $ident, [ @{$args->[2]{bind}||[]}, @$bind ], $colinfos
  );

  if (
    ! $ENV{DBIO_DT_SEARCH_OK}
      and
    $op eq 'select'
      and
    grep {
      length ref $_->[1]
        and
      blessed($_->[1])
        and
      $_->[1]->isa('DateTime')
    } @$bind
  ) {
    carp_unique 'DateTime objects passed to search() are not supported '
      . 'properly (InflateColumn::DateTime formats and settings are not '
      . 'respected.) See ".. format a DateTime object for searching?" in '
      . 'DBIO::Manual::FAQ. To disable this warning for good '
      . 'set $ENV{DBIO_DT_SEARCH_OK} to true'
  }

  return( $sql, $bind );
}

sub _resolve_bindattrs {
  my ($self, $ident, $bind, $colinfos) = @_;

  my $resolve_bindinfo = sub {
    #my $infohash = shift;

    $colinfos ||= { %{ $self->_resolve_column_info($ident) } };

    my $ret;
    if (my $col = $_[0]->{dbic_colname}) {
      $ret = { %{$_[0]} };

      $ret->{sqlt_datatype} ||= $colinfos->{$col}{data_type}
        if $colinfos->{$col}{data_type};

      $ret->{sqlt_size} ||= $colinfos->{$col}{size}
        if $colinfos->{$col}{size};
    }

    $ret || $_[0];
  };

  return [ map {
      ( ref $_ ne 'ARRAY' or @$_ != 2 ) ? [ {}, $_ ]
    : ( ! defined $_->[0] )             ? [ {}, $_->[1] ]
    : (ref $_->[0] eq 'HASH')           ? [(
                                            ! keys %{$_->[0]}
                                              or
                                            exists $_->[0]{dbd_attrs}
                                              or
                                            $_->[0]{sqlt_datatype}
                                           ) ? $_->[0]
                                             : $resolve_bindinfo->($_->[0])
                                           , $_->[1]
                                          ]
    : (ref $_->[0] eq 'SCALAR')         ? [ { sqlt_datatype => ${$_->[0]} }, $_->[1] ]
    :                                     [ $resolve_bindinfo->(
                                              { dbic_colname => $_->[0] }
                                            ), $_->[1] ]
  } @$bind ];
}

sub _format_for_trace {
  my $self = $_[0];

  ### Turn @bind from something like this:
  ###   ( [ "artist", 1 ], [ \%attrs, 3 ] )
  ### to this:
  ###   ( "'1'", "'3'" )
  ###
  ### Bind values are run through the L</redact_bind_value> hook before
  ### interpolation so that credential / PII columns do not leak into the
  ### trace sink. The hook receives the column name (or undef if no
  ### column metadata is attached to the bind slot) and the raw value,
  ### and must return the value to interpolate.

  my $redact = $self->redact_bind_value;

  map {
    my $val = $_ && $_->[1];
    if (defined $val) {
      my $colname = ( ref( $_->[0] ) eq 'HASH' )
        ? $_->[0]{dbic_colname}
        : undef;
      my $shown = $redact->( $colname, $val );
      qq{'$shown'};
    }
    else {
      q{NULL};
    }
  } @{$_[1] || []};
}



sub _query_start {
  my ( $self, $sql, $bind ) = @_;

  if ($self->debug) {
    my @trace = $self->_format_for_trace($bind);
    # Always pass at least one element when debug is on so that
    # Statistics::query_start produces output even for no-bind queries
    $self->debugobj->query_start($sql, @trace ? @trace : '');
  } else {
    $self->debugobj->query_start($sql);
  }
}

sub _query_end {
  my ( $self, $sql, $bind ) = @_;

  $self->debugobj->query_end(
    $sql,
    $self->debug ? $self->_format_for_trace($bind) : (),
  );
}

sub _dbi_attrs_for_bind {
  my ($self, $ident, $bind) = @_;

  my @attrs;

  for (map { $_->[0] } @$bind) {
    push @attrs, do {
      if (exists $_->{dbd_attrs}) {
        $_->{dbd_attrs}
      }
      elsif($_->{sqlt_datatype}) {
        # cache the result in the dbh_details hash, as it can not change unless
        # we connect to something else
        my $cache = $self->_dbh_details->{_datatype_map_cache} ||= {};
        if (not exists $cache->{$_->{sqlt_datatype}}) {
          $cache->{$_->{sqlt_datatype}} = $self->bind_attribute_by_data_type($_->{sqlt_datatype}) || undef;
        }
        $cache->{$_->{sqlt_datatype}};
      }
      else {
        undef;  # always push something at this position
      }
    }
  }

  return \@attrs;
}

sub _execute {
  my ($self, $op, $ident, @args) = @_;

  my ($sql, $bind) = $self->_prep_for_execute($op, $ident, \@args);

  # not even a PID check - we do not care about the state of the _dbh.
  # All we need is to get the appropriate drivers loaded if they aren't
  # already so that the assumption in ad7c50fc26e holds
  $self->_populate_dbh unless $self->_dbh;

  $self->dbh_do( _dbh_execute =>     # retry over disconnects
    $sql,
    $bind,
    $self->_dbi_attrs_for_bind($ident, $bind),
  );
}

sub _dbh_execute {
  my ($self, $dbh, $sql, $bind, $bind_attrs) = @_;

  $self->_query_start( $sql, $bind );

  my $sth = $self->_bind_sth_params(
    $self->_prepare_sth($dbh, $sql),
    $bind,
    $bind_attrs,
  );

  # Can this fail without throwing an exception anyways???
  my $rv = $sth->execute();
  $self->throw_exception(
    $sth->errstr || $sth->err || 'Unknown error: execute() returned false, but error flags were not set...'
  ) if !$rv;

  $self->_query_end( $sql, $bind );

  return (wantarray ? ($rv, $sth, @$bind) : $rv);
}

sub _prepare_sth {
  my ($self, $dbh, $sql) = @_;

  # 3 is the if_active parameter which avoids active sth re-use
  my $sth = $self->disable_sth_caching
    ? $dbh->prepare($sql)
    : $dbh->prepare_cached($sql, {}, 3);

  # XXX You would think RaiseError would make this impossible,
  #  but apparently that's not true :(
  $self->throw_exception(
    $dbh->errstr
      ||
    sprintf( "\$dbh->prepare() of '%s' through %s failed *silently* without "
            .'an exception and/or setting $dbh->errstr',
      length ($sql) > 20
        ? substr($sql, 0, 20) . '...'
        : $sql
      ,
      'DBD::' . $dbh->{Driver}{Name},
    )
  ) if !$sth;

  $sth;
}

sub _bind_sth_params {
  my ($self, $sth, $bind, $bind_attrs) = @_;

  for my $i (0 .. $#$bind) {
    if (ref $bind->[$i][1] eq 'SCALAR') {  # any scalarrefs are assumed to be bind_inouts
      $sth->bind_param_inout(
        $i + 1, # bind params counts are 1-based
        $bind->[$i][1],
        $bind->[$i][0]{dbd_size} || $self->_max_column_bytesize($bind->[$i][0]), # size
        $bind_attrs->[$i],
      );
    }
    else {
      # FIXME SUBOPTIMAL - DBI needs fixing to always stringify regardless of DBD
      my $v = ( length ref $bind->[$i][1] and is_plain_value $bind->[$i][1] )
        ? "$bind->[$i][1]"
        : $bind->[$i][1]
      ;

      $sth->bind_param(
        $i + 1,
        # The temp-var is CRUCIAL - DO NOT REMOVE IT, breaks older DBD::SQLite RT#79576
        $v,
        $bind_attrs->[$i],
      );
    }
  }

  $sth;
}

sub _prefetch_autovalues {
  my ($self, $source, $colinfo, $to_insert) = @_;

  my %values;
  for my $col (keys %$colinfo) {
    if (
      $colinfo->{$col}{auto_nextval}
        and
      (
        ! exists $to_insert->{$col}
          or
        is_literal_value($to_insert->{$col})
      )
    ) {
      $values{$col} = $self->_sequence_fetch(
        'NEXTVAL',
        ( $colinfo->{$col}{sequence} ||=
            $self->_dbh_get_autoinc_seq($self->_get_dbh, $source, $col)
        ),
      );
    }
  }

  \%values;
}

sub insert {
  my ($self, $source, $to_insert) = @_;

  my $col_infos = $source->columns_info;

  my $prefetched_values = $self->_prefetch_autovalues($source, $col_infos, $to_insert);

  # fuse the values, but keep a separate list of prefetched_values so that
  # they can be fused once again with the final return
  $to_insert = { %$to_insert, %$prefetched_values };

  my %pcols = map { $_ => 1 } $source->primary_columns;

  my (%retrieve_cols, $autoinc_supplied, $retrieve_autoinc_col, $pk_supplied);

  for my $col ($source->columns) {

    # first autoinc wins - this is why ->columns() in-order iteration is important
    #
    # FIXME - there ought to be a sanity-check for multiple is_auto_increment settings
    # or something...
    #
    if ($col_infos->{$col}{is_auto_increment}) {

      # FIXME - we seem to assume undef values as non-supplied.
      # This is wrong.
      # Investigate what does it take to s/defined/exists/
      # ( fails t/cdbi/copy.t amoong other things )
      $autoinc_supplied ||= 1 if defined $to_insert->{$col};

      $retrieve_autoinc_col ||= $col unless $autoinc_supplied;
    }

    # Track if any primary key column has a supplied value (including scalar references)
    if ($pcols{$col}) {
      $pk_supplied ||= 1 if (
        defined $to_insert->{$col}
          and
        (
          # not a ref - cheaper to check before a call to is_literal_value()
          ! length ref $to_insert->{$col}
            or
          # is a literal value (like scalar references for database functions)
          is_literal_value( $to_insert->{$col} )
        )
      );
    }

    # nothing to retrieve when explicit values are supplied
    next if (
      # FIXME - we seem to assume undef values as non-supplied.
      # This is wrong.
      # Investigate what does it take to s/defined/exists/
      # ( fails t/cdbi/copy.t amoong other things )
      defined $to_insert->{$col}
        and
      (
        # not a ref - cheaper to check before a call to is_literal_value()
        ! length ref $to_insert->{$col}
          or
        # not a literal we *MAY* need to pull out ( see check below )
        ! is_literal_value( $to_insert->{$col} )
      )
    );

    # the 'scalar keys' is a trick to preserve the ->columns declaration order
    $retrieve_cols{$col} = scalar keys %retrieve_cols if (
      $pcols{$col}
        or
      $col_infos->{$col}{retrieve_on_insert}
    );
  };

  # corner case of a non-supplied PK which is *not* declared as autoinc
  if (
    ! $autoinc_supplied
      and
    ! defined $retrieve_autoinc_col
      and
    ! $pk_supplied
      and
    # FIXME - first come-first serve, suboptimal...
    ($retrieve_autoinc_col) = ( grep
      {
        $pcols{$_}
          and
        ! $col_infos->{$_}{retrieve_on_insert}
          and
        ! defined $col_infos->{$_}{is_auto_increment}
      }
      sort
        { $retrieve_cols{$a} <=> $retrieve_cols{$b} }
        keys %retrieve_cols
    )
  ) {
    carp_unique(
      "Missing value for primary key column '$retrieve_autoinc_col' on "
    . "@{[ $source->source_name ]} - perhaps you forgot to set its "
    . "'is_auto_increment' attribute during add_columns()? Treating "
    . "'$retrieve_autoinc_col' implicitly as an autoinc, and attempting "
    . 'value retrieval'
    );
  }

  local $self->{_autoinc_supplied_for_op} = $autoinc_supplied;
  local $self->{_perform_autoinc_retrieval} = $retrieve_autoinc_col;

  my ($sqla_opts, @ir_container);
  if (%retrieve_cols and $self->_use_insert_returning) {
    $sqla_opts->{returning_container} = \@ir_container
      if $self->_use_insert_returning_bound;

    $sqla_opts->{returning} = [
      sort { $retrieve_cols{$a} <=> $retrieve_cols{$b} } keys %retrieve_cols
    ];
  }

  my ($rv, $sth) = $self->_execute('insert', $source, $to_insert, $sqla_opts);

  my %returned_cols = %$to_insert;
  if (my $retlist = $sqla_opts->{returning}) {  # if IR is supported - we will get everything in one set

    unless( @ir_container ) {
      try {

        # FIXME - need to investigate why Caelum silenced this in 4d4dc518
        local $SIG{__WARN__} = sub {};

        @ir_container = $sth->fetchrow_array;
        $sth->finish;

      } catch {
        # Evict the $sth from the cache in case we got here, since the finish()
        # is crucial, at least on older Firebirds, possibly on other engines too
        #
        # It would be too complex to make this a proper subclass override,
        # and besides we already take the try{} penalty, adding a catch that
        # triggers infrequently is a no-brainer
        #
        if( my $kids = $self->_dbh->{CachedKids} ) {
          $kids->{$_} == $sth and delete $kids->{$_}
            for keys %$kids
        }
      };
    }

    @returned_cols{@$retlist} = @ir_container if @ir_container;
  }
  else {
    # pull in PK if needed and then everything else
    if (my @missing_pri = grep { $pcols{$_} } keys %retrieve_cols) {

      $self->throw_exception( "Missing primary key but Storage doesn't support last_insert_id" )
        unless $self->can('last_insert_id');

      my @pri_values = $self->last_insert_id($source, @missing_pri);

      $self->throw_exception( "Can't get last insert id" )
        unless (@pri_values == @missing_pri);

      @returned_cols{@missing_pri} = @pri_values;
      delete @retrieve_cols{@missing_pri};
    }

    # if there is more left to pull
    if (%retrieve_cols) {
      $self->throw_exception(
        'Unable to retrieve additional columns without a Primary Key on ' . $source->source_name
      ) unless %pcols;

      my @left_to_fetch = sort { $retrieve_cols{$a} <=> $retrieve_cols{$b} } keys %retrieve_cols;

      my $cur = DBIO::ResultSet->new($source, {
        where => { map { $_ => $returned_cols{$_} } (keys %pcols) },
        select => \@left_to_fetch,
      })->cursor;

      @returned_cols{@left_to_fetch} = $cur->next;

      $self->throw_exception('Duplicate row returned for PK-search after fresh insert')
        if scalar $cur->next;
    }
  }

  return { %$prefetched_values, %returned_cols };
}

sub insert_bulk {
  carp_unique(
    'insert_bulk() should have never been exposed as a public method and '
  . 'calling it is depecated as of Aug 2014. If you believe having a genuine '
  . 'use for this method please contact the development team via '
  . help_url()
  );

  return '0E0' unless @{$_[3]||[]};

  shift->_insert_bulk(@_);
}

sub _insert_bulk {
  my ($self, $source, $cols, $data) = @_;

  $self->throw_exception('Calling _insert_bulk without a dataset to process makes no sense')
    unless @{$data||[]};

  my $colinfos = $source->columns_info($cols);

  local $self->{_autoinc_supplied_for_op} =
    (grep { $_->{is_auto_increment} } values %$colinfos)
      ? 1
      : 0
  ;

  # get a slice type index based on first row of data
  # a "column" in this context may refer to more than one bind value
  # e.g. \[ '?, ?', [...], [...] ]
  #
  # construct the value type index - a description of values types for every
  # per-column slice of $data:
  #
  # nonexistent - nonbind literal
  # 0 - regular value
  # [] of bindattrs - resolved attribute(s) of bind(s) passed via literal+bind \[] combo
  #
  # also construct the column hash to pass to the SQL generator. For plain
  # (non literal) values - convert the members of the first row into a
  # literal+bind combo, with extra positional info in the bind attr hashref.
  # This will allow us to match the order properly, and is so contrived
  # because a user-supplied literal/bind (or something else specific to a
  # resultsource and/or storage driver) can inject extra binds along the
  # way, so one can't rely on "shift positions" ordering at all. Also we
  # can't just hand SQLMaker a set of some known "values" (e.g. hashrefs that
  # can be later matched up by address), because we want to supply a real
  # value on which perhaps e.g. datatype checks will be performed
  my ($proto_data, $serialized_bind_type_by_col_idx);
  for my $col_idx (0..$#$cols) {
    my $colname = $cols->[$col_idx];
    if (ref $data->[0][$col_idx] eq 'SCALAR') {
      # no bind value at all - no type

      $proto_data->{$colname} = $data->[0][$col_idx];
    }
    elsif (ref $data->[0][$col_idx] eq 'REF' and ref ${$data->[0][$col_idx]} eq 'ARRAY' ) {
      # repack, so we don't end up mangling the original \[]
      my ($sql, @bind) = @${$data->[0][$col_idx]};

      # normalization of user supplied stuff
      my $resolved_bind = $self->_resolve_bindattrs(
        $source, \@bind, $colinfos,
      );

      # store value-less (attrs only) bind info - we will be comparing all
      # supplied binds against this for sanity
      $serialized_bind_type_by_col_idx->{$col_idx} = serialize [ map { $_->[0] } @$resolved_bind ];

      $proto_data->{$colname} = \[ $sql, map { [
        # inject slice order to use for $proto_bind construction
          { %{$resolved_bind->[$_][0]}, _bind_data_slice_idx => $col_idx, _literal_bind_subindex => $_+1 }
            =>
          $resolved_bind->[$_][1]
        ] } (0 .. $#bind)
      ];
    }
    else {
      $serialized_bind_type_by_col_idx->{$col_idx} = undef;

      $proto_data->{$colname} = \[ '?', [
        { dbic_colname => $colname, _bind_data_slice_idx => $col_idx }
          =>
        $data->[0][$col_idx]
      ] ];
    }
  }

  my ($sql, $proto_bind) = $self->_prep_for_execute (
    'insert',
    $source,
    [ $proto_data ],
  );

  if (! @$proto_bind and keys %$serialized_bind_type_by_col_idx) {
    # if the bindlist is empty and we had some dynamic binds, this means the
    # storage ate them away (e.g. the NoBindVars component) and interpolated
    # them directly into the SQL. This obviously can't be good for multi-inserts
    $self->throw_exception('Unable to invoke fast-path insert without storage placeholder support');
  }

  # sanity checks
  # FIXME - devise a flag "no babysitting" or somesuch to shut this off
  #
  # use an error reporting closure for convenience (less to pass)
  my $bad_slice_report_cref = sub {
    my ($msg, $r_idx, $c_idx) = @_;
    $self->throw_exception(sprintf "%s for column '%s' in populate slice:\n%s",
      $msg,
      $cols->[$c_idx],
      do {
        require Data::Dumper;
        local $Data::Dumper::Indent = 1;
        local $Data::Dumper::Terse = 1;
        local $Data::Dumper::Sortkeys = 1;
        local $Data::Dumper::Maxdepth = 5;
        Data::Dumper::Dumper ({
          map { $cols->[$_] =>
            $data->[$r_idx][$_]
          } 0..$#$cols
        }),
      }
    );
  };

  for my $col_idx (0..$#$cols) {
    my $reference_val = $data->[0][$col_idx];

    for my $row_idx (1..$#$data) {  # we are comparing against what we got from [0] above, hence start from 1
      my $val = $data->[$row_idx][$col_idx];

      if (! exists $serialized_bind_type_by_col_idx->{$col_idx}) { # literal no binds
        if (ref $val ne 'SCALAR') {
          $bad_slice_report_cref->(
            "Incorrect value (expecting SCALAR-ref \\'$$reference_val')",
            $row_idx,
            $col_idx,
          );
        }
        elsif ($$val ne $$reference_val) {
          $bad_slice_report_cref->(
            "Inconsistent literal SQL value (expecting \\'$$reference_val')",
            $row_idx,
            $col_idx,
          );
        }
      }
      elsif (! defined $serialized_bind_type_by_col_idx->{$col_idx} ) {  # regular non-literal value
        if (is_literal_value($val)) {
          $bad_slice_report_cref->("Literal SQL found where a plain bind value is expected", $row_idx, $col_idx);
        }
      }
      else {  # binds from a \[], compare type and attrs
        if (ref $val ne 'REF' or ref $$val ne 'ARRAY') {
          $bad_slice_report_cref->(
            "Incorrect value (expecting ARRAYREF-ref \\['${$reference_val}->[0]', ... ])",
            $row_idx,
            $col_idx,
          );
        }
        # start drilling down and bail out early on identical refs
        elsif (
          $reference_val != $val
            or
          $$reference_val != $$val
        ) {
          if (${$val}->[0] ne ${$reference_val}->[0]) {
            $bad_slice_report_cref->(
              "Inconsistent literal/bind SQL (expecting \\['${$reference_val}->[0]', ... ])",
              $row_idx,
              $col_idx,
            );
          }
          # need to check the bind attrs - a bind will happen only once for
          # the entire dataset, so any changes further down will be ignored.
          elsif (
            $serialized_bind_type_by_col_idx->{$col_idx}
              ne
            serialize [
              map
              { $_->[0] }
              @{$self->_resolve_bindattrs(
                $source, [ @{$$val}[1 .. $#$$val] ], $colinfos,
              )}
            ]
          ) {
            $bad_slice_report_cref->(
              'Differing bind attributes on literal/bind values not supported',
              $row_idx,
              $col_idx,
            );
          }
        }
      }
    }
  }

  # neither _dbh_execute_for_fetch, nor _dbh_execute_inserts_with_no_binds
  # are atomic (even if execute_for_fetch is a single call). Thus a safety
  # scope guard
  my $guard = $self->txn_scope_guard;

  $self->_query_start( $sql, @$proto_bind ? [[undef => '__BULK_INSERT__' ]] : () );
  my $sth = $self->_prepare_sth($self->_dbh, $sql);
  my $rv = do {
    if (@$proto_bind) {
      # proto bind contains the information on which pieces of $data to pull
      # $cols is passed in only for prettier error-reporting
      $self->_dbh_execute_for_fetch( $source, $sth, $proto_bind, $cols, $data );
    }
    else {
      # bind_param_array doesn't work if there are no binds
      $self->_dbh_execute_inserts_with_no_binds( $sth, scalar @$data );
    }
  };

  $self->_query_end( $sql, @$proto_bind ? [[ undef => '__BULK_INSERT__' ]] : () );

  $guard->commit;

  return wantarray ? ($rv, $sth, @$proto_bind) : $rv;
}

# execute_for_fetch is capable of returning data just fine (it means it
# can be used for INSERT...RETURNING and UPDATE...RETURNING. Since this
# is the void-populate fast-path we will just ignore this altogether
# for the time being.
sub _dbh_execute_for_fetch {
  my ($self, $source, $sth, $proto_bind, $cols, $data) = @_;

  # If we have any bind attributes to take care of, we will bind the
  # proto-bind data (which will never be used by execute_for_fetch)
  # However since column bindtypes are "sticky", this is sufficient
  # to get the DBD to apply the bindtype to all values later on
  my $bind_attrs = $self->_dbi_attrs_for_bind($source, $proto_bind);

  for my $i (0 .. $#$proto_bind) {
    $sth->bind_param (
      $i+1, # DBI bind indexes are 1-based
      $proto_bind->[$i][1],
      $bind_attrs->[$i],
    ) if defined $bind_attrs->[$i];
  }

  # At this point $data slots named in the _bind_data_slice_idx of
  # each piece of $proto_bind are either \[]s or plain values to be
  # passed in. Construct the dispensing coderef. *NOTE* the order
  # of $data will differ from this of the ?s in the SQL (due to
  # alphabetical ordering by colname). We actually do want to
  # preserve this behavior so that prepare_cached has a better
  # chance of matching on unrelated calls

  my $fetch_row_idx = -1; # saner loop this way
  my $fetch_tuple = sub {
    return undef if ++$fetch_row_idx > $#$data;

    return [ map {
      my $v = ! defined $_->{_literal_bind_subindex}

        ? $data->[ $fetch_row_idx ]->[ $_->{_bind_data_slice_idx} ]

        # There are no attributes to resolve here - we already did everything
        # when we constructed proto_bind. However we still want to sanity-check
        # what the user supplied, so pass stuff through to the resolver *anyway*
        : $self->_resolve_bindattrs (
            undef,  # a fake rsrc
            [ ${ $data->[ $fetch_row_idx ]->[ $_->{_bind_data_slice_idx} ]}->[ $_->{_literal_bind_subindex} ] ],
            {},     # a fake column_info bag
          )->[0][1]
      ;

      # FIXME SUBOPTIMAL - DBI needs fixing to always stringify regardless of DBD
      # For the time being forcibly stringify whatever is stringifiable
      (length ref $v and is_plain_value $v)
        ? "$v"
        : $v
      ;
    } map { $_->[0] } @$proto_bind ];
  };

  my $tuple_status = [];
  my ($rv, $err);
  try {
    $rv = $sth->execute_for_fetch(
      $fetch_tuple,
      $tuple_status,
    );
  }
  catch {
    $err = shift;
  };

  # Not all DBDs are create equal. Some throw on error, some return
  # an undef $rv, and some set $sth->err - try whatever we can
  $err = ($sth->errstr || 'UNKNOWN ERROR ($sth->errstr is unset)') if (
    ! defined $err
      and
    ( !defined $rv or $sth->err )
  );

  # Statement must finish even if there was an exception.
  try {
    $sth->finish
  }
  catch {
    $err = shift unless defined $err
  };

  if (defined $err) {
    my $i = 0;
    ++$i while $i <= $#$tuple_status && !ref $tuple_status->[$i];

    $self->throw_exception("Unexpected populate error: $err")
      if ($i > $#$tuple_status);

    $self->throw_exception(sprintf "execute_for_fetch() aborted with '%s' at populate slice:\n%s",
      ($tuple_status->[$i][1] || $err),
      dump_value( { map { $cols->[$_] => $data->[$i][$_] } (0 .. $#$cols) } ),
    );
  }

  return $rv;
}

sub _dbh_execute_inserts_with_no_binds {
  my ($self, $sth, $count) = @_;

  my $err;
  try {
    my $dbh = $self->_get_dbh;
    local $dbh->{RaiseError} = 1;
    local $dbh->{PrintError} = 0;

    $sth->execute foreach 1..$count;
  }
  catch {
    $err = shift;
  };

  # Make sure statement is finished even if there was an exception.
  try {
    $sth->finish
  }
  catch {
    $err = shift unless defined $err;
  };

  $self->throw_exception($err) if defined $err;

  return $count;
}

sub update {
  #my ($self, $source, @args) = @_;
  shift->_execute('update', @_);
}


sub delete {
  #my ($self, $source, @args) = @_;
  shift->_execute('delete', @_);
}

sub _select {
  my $self = shift;
  $self->_execute($self->_select_args(@_));
}

sub _select_args_to_query {
  my $self = shift;

  $self->throw_exception(
    "Unable to generate limited query representation with 'software_limit' enabled"
  ) if ($_[3]->{software_limit} and ($_[3]->{offset} or $_[3]->{rows}) );

  # my ($op, $ident, $select, $cond, $rs_attrs, $rows, $offset)
  #  = $self->_select_args($ident, $select, $cond, $attrs);
  my ($op, $ident, @args) =
    $self->_select_args(@_);

  # my ($sql, $prepared_bind) = $self->_gen_sql_bind($op, $ident, [ $select, $cond, $rs_attrs, $rows, $offset ]);
  my ($sql, $bind) = $self->_gen_sql_bind($op, $ident, \@args);

  # reuse the bind arrayref
  unshift @{$bind}, "($sql)";
  \$bind;
}

sub _select_args {
  my ($self, $ident, $select, $where, $orig_attrs) = @_;

  # FIXME - that kind of caching would be nice to have
  # however currently we *may* pass the same $orig_attrs
  # with different ident/select/where
  # the whole interface needs to be rethought, since it
  # was centered around the flawed SQLMaker API. We can do
  # soooooo much better now. But that is also another
  # battle...
  #return (
  #  'select', $orig_attrs->{!args_as_stored_at_the_end_of_this_method!}
  #) if $orig_attrs->{!args_as_stored_at_the_end_of_this_method!};

  my $sql_maker = $self->sql_maker;

  my $attrs = {
    %$orig_attrs,
    select => $select,
    from => $ident,
    where => $where,
  };

  # Sanity check the attributes (SQLMaker does it too, but
  # in case of a software_limit we'll never reach there)
  if (defined $attrs->{offset}) {
    $self->throw_exception('A supplied offset attribute must be a non-negative integer')
      if ( $attrs->{offset} =~ /\D/ or $attrs->{offset} < 0 );
  }

  if (defined $attrs->{rows}) {
    $self->throw_exception("The rows attribute must be a positive integer if present")
      if ( $attrs->{rows} =~ /\D/ or $attrs->{rows} <= 0 );
  }
  elsif ($attrs->{offset}) {
    # MySQL actually recommends this approach.  I cringe.
    $attrs->{rows} = $sql_maker->__max_int;
  }

  # see if we will need to tear the prefetch apart to satisfy group_by == select
  # this is *extremely tricky* to get right, I am still not sure I did
  #
  my ($prefetch_needs_subquery, @limit_args);

  if ( $attrs->{_grouped_by_distinct} and $attrs->{collapse} ) {
    # we already know there is a valid group_by (we made it) and we know it is
    # intended to be based *only* on non-multi stuff
    # short circuit the group_by parsing below
    $prefetch_needs_subquery = 1;
  }
  elsif (
    # The rationale is that even if we do *not* have collapse, we still
    # need to wrap the core grouped select/group_by in a subquery
    # so that databases that care about group_by/select equivalence
    # are happy (this includes MySQL in strict_mode)
    # If any of the other joined tables are referenced in the group_by
    # however - the user is on their own
    ( $prefetch_needs_subquery or ! $attrs->{_simple_passthrough_construction} )
      and
    $attrs->{group_by}
      and
    @{$attrs->{group_by}}
      and
    my $grp_aliases = try { # try{} because $attrs->{from} may be unreadable
      $self->_resolve_aliastypes_from_select_args({ from => $attrs->{from}, group_by => $attrs->{group_by} })
    }
  ) {
    # no aliases other than our own in group_by
    # if there are - do not allow subquery even if limit is present
    $prefetch_needs_subquery = ! scalar grep { $_ ne $attrs->{alias} } keys %{ $grp_aliases->{grouping} || {} };
  }
  elsif ( $attrs->{rows} && $attrs->{collapse} ) {
    # active collapse with a limit - that one is a no-brainer unless
    # overruled by a group_by above
    $prefetch_needs_subquery = 1;
  }

  if ($prefetch_needs_subquery) {
    $attrs = $self->_adjust_select_args_for_complex_prefetch ($attrs);
  }
  elsif (! $attrs->{software_limit} ) {
    push @limit_args, (
      $attrs->{rows} || (),
      $attrs->{offset} || (),
    );
  }

  # try to simplify the joinmap further (prune unreferenced type-single joins)
  if (
    ! $prefetch_needs_subquery  # already pruned
      and
    ref $attrs->{from}
      and
    reftype $attrs->{from} eq 'ARRAY'
      and
    @{$attrs->{from}} != 1
  ) {
    ($attrs->{from}, $attrs->{_aliastypes}) = $self->_prune_unused_joins ($attrs);
  }

  # FIXME this is a gross, inefficient, largely incorrect and fragile hack
  # during the result inflation stage we *need* to know what was the aliastype
  # map as sqla saw it when the final pieces of SQL were being assembled
  # Originally we simply carried around the entirety of $attrs, but this
  # resulted in resultsets that are being reused growing continuously, as
  # the hash in question grew deeper and deeper.
  # Instead hand-pick what to take with us here (we actually don't need much
  # at this point just the map itself)
  $orig_attrs->{_last_sqlmaker_alias_map} = $attrs->{_aliastypes};

###
  #   my $alias2source = $self->_resolve_ident_sources ($ident);
  #
  # This would be the point to deflate anything found in $attrs->{where}
  # (and leave $attrs->{bind} intact). Problem is - inflators historically
  # expect a result object. And all we have is a resultsource (it is trivial
  # to extract deflator coderefs via $alias2source above).
  #
  # I don't see a way forward other than changing the way deflators are
  # invoked, and that's just bad...
###

  return ( 'select', @{$attrs}{qw(from select where)}, $attrs, @limit_args );
}

# Returns a counting SELECT for a simple count
# query. Abstracted so that a storage could override
# this to { count => 'firstcol' } or whatever makes
# sense as a performance optimization
sub _count_select {
  #my ($self, $source, $rs_attrs) = @_;
  return { count => '*' };
}


sub select {
  my $self = shift;
  my ($ident, $select, $condition, $attrs) = @_;
  return $self->cursor_class->new($self, \@_, $attrs);
}

sub select_single {
  my $self = shift;
  my ($rv, $sth, @bind) = $self->_select(@_);
  my @row = $sth->fetchrow_array;
  my @nextrow = $sth->fetchrow_array if @row;
  if(@row && @nextrow) {
    carp "Query returned more than one row.  SQL that returns multiple rows is DEPRECATED for ->find and ->single";
  }
  # Need to call finish() to work round broken DBDs
  $sth->finish();
  return @row;
}

sub _dbh_columns_info_for {
  my ($self, $dbh, $table) = @_;

  if ($dbh->can('column_info')) {
    my %result;
    my $caught;
    try {
      my ($schema,$tab) = $table =~ /^(.+?)\.(.+)$/ ? ($1,$2) : (undef,$table);
      my $sth = $dbh->column_info( undef,$schema, $tab, '%' );
      $sth->execute();
      while ( my $info = $sth->fetchrow_hashref() ){
        my %column_info;
        $column_info{data_type}   = $info->{TYPE_NAME};
        $column_info{size}      = $info->{COLUMN_SIZE};
        $column_info{is_nullable}   = $info->{NULLABLE} ? 1 : 0;
        $column_info{default_value} = $info->{COLUMN_DEF};
        my $col_name = $info->{COLUMN_NAME};
        $col_name =~ s/^\"(.*)\"$/$1/;

        $result{$col_name} = \%column_info;
      }
    } catch {
      $caught = 1;
    };
    return \%result if !$caught && scalar keys %result;
  }

  my %result;
  my $sth = $dbh->prepare($self->sql_maker->select($table, undef, \'1 = 0'));
  $sth->execute;
  my @columns = @{$sth->{NAME_lc}};
  for my $i ( 0 .. $#columns ){
    my %column_info;
    $column_info{data_type} = $sth->{TYPE}->[$i];
    $column_info{size} = $sth->{PRECISION}->[$i];
    $column_info{is_nullable} = $sth->{NULLABLE}->[$i] ? 1 : 0;

    if ($column_info{data_type} =~ m/^(.*?)\((.*?)\)$/) {
      $column_info{data_type} = $1;
      $column_info{size}    = $2;
    }

    $result{$columns[$i]} = \%column_info;
  }
  $sth->finish;

  foreach my $col (keys %result) {
    my $colinfo = $result{$col};
    my $type_num = $colinfo->{data_type};
    my $type_name;
    if(defined $type_num && $dbh->can('type_info')) {
      my $type_info = $dbh->type_info($type_num);
      $type_name = $type_info->{TYPE_NAME} if $type_info;
      $colinfo->{data_type} = $type_name if $type_name;
    }
  }

  return \%result;
}

sub columns_info_for {
  my ($self, $table) = @_;
  $self->_dbh_columns_info_for ($self->_get_dbh, $table);
}


sub _dbh_last_insert_id {
    my ($self, $dbh, $source, $col) = @_;

    my $id = try { $dbh->last_insert_id (undef, undef, $source->name, $col) };

    return $id if defined $id;

    my $class = ref $self;
    $self->throw_exception ("No storage specific _dbh_last_insert_id() method implemented in $class, and the generic DBI::last_insert_id() failed");
}


sub last_insert_id {
  my $self = shift;
  $self->_dbh_last_insert_id ($self->_dbh, @_);
}

# Override in DB-specific subclasses for the correct RANDOM() function
sub _random_function { 'RANDOM()' }

# Override in DB-specific subclasses for the correct EXPLAIN syntax
sub _explain_sql { "EXPLAIN $_[1]" }

# Check if placeholders are supported at all
sub _determine_supports_placeholders {
  my $self = shift;
  my $dbh  = $self->_get_dbh;

  # some drivers provide a $dbh attribute (e.g. Sybase and $dbh->{syb_dynamic_supported})
  # but it is inaccurate more often than not
  return try {
    local $dbh->{PrintError} = 0;
    local $dbh->{RaiseError} = 1;
    $dbh->do('select ?', {}, 1);
    1;
  }
  catch {
    0;
  };
}

# Check if placeholders bound to non-string types throw exceptions
#
sub _determine_supports_typeless_placeholders {
  my $self = shift;
  my $dbh  = $self->_get_dbh;

  return try {
    local $dbh->{PrintError} = 0;
    local $dbh->{RaiseError} = 1;
    # this specifically tests a bind that is NOT a string
    $dbh->do('select 1 where 1 = ?', {}, 1);
    1;
  }
  catch {
    0;
  };
}


sub sqlt_type {
  shift->_get_dbh->{Driver}->{Name};
}


sub bind_attribute_by_data_type {
    return;
}


sub is_datatype_numeric {
  #my ($self, $dt) = @_;

  return 0 unless $_[1];

  $_[1] =~ /^ (?:
    numeric | int(?:eger)? | (?:tiny|small|medium|big)int | dec(?:imal)? | real | float | double (?: \s+ precision)? | (?:big)?serial
  ) $/ix;
}



sub create_ddl_dir {
  my ($self, $schema, $databases, $version, $dir, $preversion, $sqltargs) = @_;
  $self->throw_exception("create_ddl_dir() is deprecated. "
    . "Use the native Deploy class on your storage instead.");
}


sub deployment_statements {
  my ($self, $schema, $type, $version, $dir, $sqltargs) = @_;
  $type ||= $self->sqlt_type;
  $version ||= $schema->schema_version || '1.x';
  $dir ||= './';
  my $filename = $schema->ddl_filename($type, $version, $dir);
  if(-f $filename)
  {
      # FIXME replace this block when a proper sane sql parser is available
      my $file;
      open($file, "<$filename")
        or $self->throw_exception("Can't open $filename ($!)");
      my @rows = <$file>;
      close($file);
      return join('', @rows);
  }

  $self->throw_exception("deployment_statements() requires a pre-existing DDL file; "
    . "native Deploy classes handle SQL generation. "
    . "Use L<DBIO::Schema/deploy> with a storage that provides a native Deploy class.");
}


sub deploy_defaults { () }


sub deploy_setup { }

# FIXME deploy() currently does not accurately report sql errors
# Will always return true while errors are warned
sub deploy {
  my ($self, $schema, $type, $sqltargs, $dir) = @_;
  my $deploy = sub {
    my $line = shift;
    return if(!$line);
    return if($line =~ /^--/);
    # next if($line =~ /^DROP/m);
    return if($line =~ /^BEGIN TRANSACTION/m);
    return if($line =~ /^COMMIT/m);
    return if $line =~ /^\s+$/; # skip whitespace only
    $self->_query_start($line);
    try {
      # do a dbh_do cycle here, as we need some error checking in
      # place (even though we will ignore errors)
      $self->dbh_do (sub { $_[1]->do($line) });
    } catch {
      carp qq{$_ (running "${line}")};
    };
    $self->_query_end($line);
  };
  my @statements = $schema->deployment_statements($type, undef, $dir, { %{ $sqltargs || {} }, no_comments => 1 } );
  if (@statements > 1) {
    foreach my $statement (@statements) {
      $deploy->( $statement );
    }
  }
  elsif (@statements == 1) {
    # split on single line comments and end of statements
    foreach my $line ( split(/\s*--.*\n|;\n/, $statements[0])) {
      $deploy->( $line );
    }
  }
}


sub datetime_parser {
  my $self = shift;
  return $self->{datetime_parser} ||= do {
    $self->build_datetime_parser(@_);
  };
}


sub build_datetime_parser {
  my $self = shift;
  my $type = $self->datetime_parser_type(@_);
  return $type;
}



sub is_replicating {
    return;

}


sub lag_behind_master {
    return;
}


sub relname_to_table_alias {
  my ($self, $relname, $join_count) = @_;

  my $alias = ($join_count && $join_count > 1 ?
    join('_', $relname, $join_count) : $relname);

  return $alias;
}

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

DBIO::Storage::DBI - DBI storage handler

=head1 VERSION

version 0.900001

=head1 SYNOPSIS

  my $schema = MySchema->connect('dbi:SQLite:my.db');

  $schema->storage->debug(1);

  my @stuff = $schema->storage->dbh_do(
    sub {
      my ($storage, $dbh, @args) = @_;
      $dbh->do("DROP TABLE authors");
    },
    @column_list
  );

  $schema->resultset('Book')->search({
     written_on => $schema->storage->datetime_parser->format_datetime(DateTime->now)
  });

See F<t/test/04_query_capture.t> for a runnable example.

=head1 DESCRIPTION

This is DBIO's common storage backend for L<DBI>-based databases. It owns the
live database handle, transaction state, SQL maker integration, and the driver
detection path that later reblesses into database-specific storage subclasses
such as L<DBIO::PostgreSQL::Storage>, L<DBIO::MySQL::Storage>, or
L<DBIO::SQLite::Storage>.

See L<DBIO::Storage> for the storage API shared across all backends. This POD
focuses on the DBI-specific layer, including connection handling, capability
checks, and the hooks that driver subclasses build on.

=head1 METHODS

=head2 connect_info

This method is normally called by L<DBIO::Schema/connection>, which
encapsulates its argument list in an arrayref before passing them here.

The argument list may contain:

=over

=item *

The same 4-element argument set one would normally pass to
L<DBI/connect>, optionally followed by
L<extra attributes|/DBIO specific connection attributes>
recognized by DBIO:

  $connect_info_args = [ $dsn, $user, $password, \%dbi_attributes?, \%extra_attributes? ];

=item *

A single code reference which returns a connected
L<DBI database handle|DBI/connect> optionally followed by
L<extra attributes|/DBIO specific connection attributes> recognized
by DBIO:

  $connect_info_args = [ sub { DBI->connect (...) }, \%extra_attributes? ];

=item *

A single hashref with all the attributes and the dsn/user/password
mixed together:

  $connect_info_args = [{
    dsn => $dsn,
    user => $user,
    password => $pass,
    %dbi_attributes,
    %extra_attributes,
  }];

  $connect_info_args = [{
    dbh_maker => sub { DBI->connect (...) },
    %dbi_attributes,
    %extra_attributes,
  }];

This is particularly useful for L<Catalyst> based applications, allowing the
following config (L<Config::General> style):

  <Model::DB>
    schema_class   App::DB
    <connect_info>
      dsn          dbi:mysql:database=test
      user         testuser
      password     TestPass
      AutoCommit   1
    </connect_info>
  </Model::DB>

The C<dsn>/C<user>/C<password> combination can be substituted by the
C<dbh_maker> key whose value is a coderef that returns a connected
L<DBI database handle|DBI/connect>

=back

Please note that the L<DBI> docs recommend that you always explicitly
set C<AutoCommit> to either I<0> or I<1>.  L<DBIO> further
recommends that it be set to I<1>, and that you perform transactions
via our L<DBIO::Schema/txn_do> method.  L<DBIO> will set it
to I<1> if you do not do explicitly set it to zero.  This is the default
for most DBDs. See L</DBIO and AutoCommit> for details.

=head3 DBIO specific connection attributes

In addition to the standard L<DBI|DBI/ATTRIBUTES COMMON TO ALL HANDLES>
L<connection|DBI/Database Handle Attributes> attributes, DBIO recognizes
the following connection options. These options can be mixed in with your other
L<DBI> connection attributes, or placed in a separate hashref
(C<\%extra_attributes>) as shown above.

Every time C<connect_info> is invoked, any previous settings for
these options will be cleared before setting the new ones, regardless of
whether any options are specified in the new C<connect_info>.

=over

=item on_connect_do

Specifies things to do immediately after connecting or re-connecting to
the database.  Its value may contain:

=over

=item a scalar

This contains one SQL statement to execute.

=item an array reference

This contains SQL statements to execute in order.  Each element contains
a string or a code reference that returns a string.

=item a code reference

This contains some code to execute.  Unlike code references within an
array reference, its return value is ignored.

=back

=item on_disconnect_do

Takes arguments in the same form as L</on_connect_do> and executes them
immediately before disconnecting from the database.

Note, this only runs if you explicitly call L</disconnect> on the
storage object.

=item on_connect_call

A more generalized form of L</on_connect_do> that calls the specified
C<connect_call_METHOD> methods in your storage driver.

  on_connect_do => 'select 1'

is equivalent to:

  on_connect_call => [ [ do_sql => 'select 1' ] ]

Its values may contain:

=over

=item a scalar

Will call the C<connect_call_METHOD> method.

=item a code reference

Will execute C<< $code->($storage) >>

=item an array reference

Each value can be a method name or code reference.

=item an array of arrays

For each array, the first item is taken to be the C<connect_call_> method name
or code reference, and the rest are parameters to it.

=back

Some predefined storage methods you may use:

=over

=item do_sql

Executes a SQL string or a code reference that returns a SQL string. This is
what L</on_connect_do> and L</on_disconnect_do> use.

It can take:

=over

=item a scalar

Will execute the scalar as SQL.

=item an arrayref

Taken to be arguments to L<DBI/do>, the SQL string optionally followed by the
attributes hashref and bind values.

=item a code reference

Will execute C<< $code->($storage) >> and execute the return array refs as
above.

=back

=item datetime_setup

Execute any statements necessary to initialize the database session to return
and accept datetime/timestamp values used with
L<DBIO::InflateColumn::DateTime>.

Only necessary for some databases, see your specific storage driver for
implementation details.

=back

=item on_disconnect_call

Takes arguments in the same form as L</on_connect_call> and executes them
immediately before disconnecting from the database.

Calls the C<disconnect_call_METHOD> methods as opposed to the
C<connect_call_METHOD> methods called by L</on_connect_call>.

Note, this only runs if you explicitly call L</disconnect> on the
storage object.

=item disable_sth_caching

If set to a true value, this option will disable the caching of
statement handles via L<DBI/prepare_cached>.

=item quote_names

B<On by default in DBIO> (unlike upstream DBIx::Class, where it defaults off).
Automatically sets L</quote_char> and L</name_sep> to the characters appropriate
for your particular RDBMS, so generated SQL always quotes table and column
identifiers. This is a security-hardening default: it makes reserved words and
unusual identifiers safe and removes a class of SQL-injection footguns. This
option is preferred over specifying L</quote_char> directly.

Pass C<< quote_names => 0 >> in your connect_info to opt out and emit unquoted
identifiers. An explicitly supplied L</quote_char> / L</name_sep> is always
respected.

=item quote_char

Specifies what characters to use to quote table and column names.

C<quote_char> expects either a single character, in which case is it
is placed on either side of the table/column name, or an arrayref of length
2 in which case the table/column name is placed between the elements.

For example under MySQL you should use C<< quote_char => '`' >>, and for
SQL Server you should use C<< quote_char => [qw/[ ]/] >>.

=item name_sep

This parameter is only useful in conjunction with C<quote_char>, and is used to
specify the character that separates elements (schemas, tables, columns) from
each other. If unspecified it defaults to the most commonly used C<.>.

=item unsafe

This Storage driver normally installs its own C<HandleError>, sets
C<RaiseError> and C<ShowErrorStatement> on, and sets C<PrintError> off on
all database handles, including those supplied by a coderef.  It does this
so that it can have consistent and useful error behavior.

If you set this option to a true value, Storage will not do its usual
modifications to the database handle's attributes, and instead relies on
the settings in your connect_info DBI options (or the values you set in
your connection coderef, in the case that you are connecting via coderef).

Note that your custom settings can cause Storage to malfunction,
especially if you set a C<HandleError> handler that suppresses exceptions
and/or disable C<RaiseError>.

=item auto_savepoint

If this option is true, L<DBIO> will use savepoints when nesting
transactions, making it possible to recover from failure in the inner
transaction without having to abort all outer transactions.

=item cursor_class

Use this argument to supply a cursor class other than the default
L<DBIO::Storage::DBI::Cursor>.

=back

Some real-life examples of arguments to L</connect_info> and
L<DBIO::Schema/connect>

  # Simple SQLite connection
  ->connect_info([ 'dbi:SQLite:./foo.db' ]);

  # Connect via subref
  ->connect_info([ sub { DBI->connect(...) } ]);

  # Connect via subref in hashref
  ->connect_info([{
    dbh_maker => sub { DBI->connect(...) },
    on_connect_do => 'alter session ...',
  }]);

  # A bit more complicated
  ->connect_info(
    [
      'dbi:Pg:dbname=foo',
      'postgres',
      'my_pg_password',
      { AutoCommit => 1 },
      { quote_char => q{"} },
    ]
  );

  # Equivalent to the previous example
  ->connect_info(
    [
      'dbi:Pg:dbname=foo',
      'postgres',
      'my_pg_password',
      { AutoCommit => 1, quote_char => q{"}, name_sep => q{.} },
    ]
  );

  # Same, but with hashref as argument
  # See parse_connect_info for explanation
  ->connect_info(
    [{
      dsn         => 'dbi:Pg:dbname=foo',
      user        => 'postgres',
      password    => 'my_pg_password',
      AutoCommit  => 1,
      quote_char  => q{"},
      name_sep    => q{.},
    }]
  );

  # Subref + DBIO-specific connection options
  ->connect_info(
    [
      sub { DBI->connect(...) },
      {
          quote_char => q{`},
          name_sep => q{@},
          on_connect_do => ['SET search_path TO myschema,otherschema,public'],
          disable_sth_caching => 1,
      },
    ]
  );

=head2 on_connect_do

This method is deprecated in favour of setting via L</connect_info>.

=head2 on_disconnect_do

This method is deprecated in favour of setting via L</connect_info>.

=head2 dbh_do

Arguments: ($subref | $method_name), @extra_coderef_args?

Execute the given $subref or $method_name using the new exception-based
connection management.

The first two arguments will be the storage object that C<dbh_do> was called
on and a database handle to use.  Any additional arguments will be passed
verbatim to the called subref as arguments 2 and onwards.

Using this (instead of $self->_dbh or $self->dbh) ensures correct
exception handling and reconnection (or failover in future subclasses).

Your subref should have no side-effects outside of the database, as
there is the potential for your subref to be partially double-executed
if the database connection was stale/dysfunctional.

Example:

  my @stuff = $schema->storage->dbh_do(
    sub {
      my ($storage, $dbh, @cols) = @_;
      my $cols = join(q{, }, @cols);
      $dbh->selectrow_array("SELECT $cols FROM foo");
    },
    @column_list
  );

=head2 register_async_mode

  DBIO::Storage::DBI->register_async_mode( forked    => 'DBIO::Forked::Storage' );
  DBIO::PostgreSQL::Storage->register_async_mode( ev   => 'DBIO::PostgreSQL::EV::Storage' );

Registers an async I<mode> name against the embedded backend class that answers
the C<*_async> methods for a connection opened with C<< { async => $mode } >>.
Generic modes register on a base storage class (inherited by every driver);
native modes register on a concrete driver storage class, so the same logical
mode name (e.g. C<ev>) resolves to a DB-specific backend. See L<ADR 0030>.

The C<future_io> mode is the exception: it is resolved B<by convention>, not
from this registry. Rather than a registered class, its transport adapter is
found by walking the concrete storage's linearised ISA most-specific first and
taking the first C<< <class>::Async >> that loads (stopping before the generic
C<DBIO::Storage::DBI> base), so an extension C<storage_type> subclass without
its own adapter inherits the nearest parent driver's one. An explicit
C<< register_async_mode(future_io => ...) >> on a concrete class still wins over
the walk; a same-named adapter that loads but is not a L<DBIO::Storage::Async>
croaks rather than degrading to a parent. See L<ADR 0030> (karr #65, #67).

=head2 register_driver

Registers a DBD driver-name to DBIO storage-class mapping.

=head2 register_connector_driver

Registers an ODBC/ADO C<SQL_DBMS_NAME> to DBIO storage-class mapping.

=head2 redact_bind_value

=head2 last_insert_id

Returns autoincrement values for the columns requested by insert codepaths.

=head2 deploy_defaults

Returns a hash of default arguments merged into every C<< $schema->deploy() >>
call made by L<DBIO::Test>.  The base implementation returns an empty list;
drivers override this to declare their requirements without hard-coding driver
names in test infrastructure.

  # DBIO::MySQL::Storage
  sub deploy_defaults { return (add_drop_table => 1) }

=head2 deploy_setup

  $storage->deploy_setup($schema);

Called by L<DBIO::Test> immediately before C<< $schema->deploy() >>.  The
default implementation is a no-op.  Drivers override this to perform any
one-time database-level setup that must happen before the schema is installed
(for example, stripping incompatible C<sql_mode> flags on MySQL).

=head2 async

Returns the embedded async backend storage (a L<DBIO::Storage::Async>) for an
instance connected with an event-loop async mode (C<< { async => 'forked' } >>,
C<'future_io'>, C<'ev'>, ...), or C<undef> for a sync or C<immediate>-mode
instance. It is a thin public alias over the lazy C<_async_storage> resolver
that also feeds the six CRUD C<*_async> methods, so it shares their backend
discovery and caching. An unavailable mode croaks (see L</register_async_mode>
and ADR 0030). For C<future_io> the backend class is resolved by convention:
the concrete storage's linearised ISA is walked most-specific first for a
C<< <class>::Async >> adapter, stopping before the generic C<DBIO::Storage::DBI>
base, so extension C<storage_type> subclasses (AGE, PostGIS) reach async CRUD
through the nearest parent driver's adapter (karr #67).

Use it to reach async-only driver features that are not covered by the CRUD
C<*_async> methods -- for example PostgreSQL's C<listen>/C<notify>,
C<pipeline>, and C<copy_in> -- on the very same schema that serves your
synchronous queries:

  $schema->storage->async->listen('channel');

=head2 disconnect

Our C<disconnect> method also performs a rollback first if the
database is not in C<AutoCommit> mode.

=head2 with_deferred_fk_checks

=over 4

=item Arguments: C<$coderef>

=item Return Value: The return value of $coderef

=back

Storage specific method to run the code ref with FK checks deferred or
in MySQL's case disabled entirely.

=head2 connected

=over

=item Arguments: none

=item Return Value: 1|0

=back

Verifies that the current database handle is active and ready to execute
an SQL statement (e.g. the connection did not get stale, server is still
answering, etc.) This method is used internally by L</dbh>.

=head2 dbh

Returns a C<$dbh> - a data base handle of class L<DBI>. The returned handle
is guaranteed to be healthy by implicitly calling L</connected>, and if
necessary performing a reconnection before returning. Keep in mind that this
is very B<expensive> on some database engines. Consider using L</dbh_do>
instead.

=head2 register_driver

=over 4

=item Arguments: $dbd_driver_name, $storage_class

=item Return value: none

=back

Registers a mapping from a DBI driver name (for example C<Pg>, C<mysql>,
C<SQLite>) to a DBIO storage class.

This is primarily used by external DBIO driver distributions, so
L<DBIO::Storage::DBI> can rebless itself into the correct storage subclass
during driver detection.

Example:

  __PACKAGE__->register_driver('Pg' => 'DBIO::PostgreSQL::Storage');

=head2 register_connector_driver

=over 4

=item Arguments: $sql_dbms_name, $storage_class

=item Return value: none

=back

Registers a mapping from C<SQL_DBMS_NAME> values (as reported by ODBC/ADO
connectors) to a DBIO storage class. This is used by connector-based
secondary driver detection in L</_determine_connector_driver>.

Example:

  __PACKAGE__->register_connector_driver(
    'Microsoft_SQL_Server' => 'DBIO::MSSQL::Storage::ODBC',
  );

=head2 connect_call_datetime_setup

A no-op stub method, provided so that one can always safely supply the
L<connection option|/DBIO specific connection attributes>

 on_connect_call => 'datetime_setup'

This way one does not need to know in advance whether the underlying
storage requires any sort of hand-holding when dealing with calendar
data.

=head2 connect_call_rebase_sqlmaker

This on-connect call takes as a single argument the name of a class to "rebase"
the SQLMaker inheritance hierarchy upon. For this to work properly the target
class B<MUST> inherit from L<DBIO::SQLMaker::ClassicExtensions> and
either L<SQL::Abstract> or L<SQL::Abstract::Classic> as shown below.

This infrastructure is provided to aid recent activity around experimental new
aproaches to SQL generation within DBIO. You can (and are encouraged to)
mix and match old and new within the same codebase as follows:

  package DBIO::Awesomer::SQLMaker;
  # you MUST inherit in this order to get the composition right
  # you are free to override-without-next::method any part you need
  use base qw(
    DBIO::SQLMaker::ClassicExtensions
    << OPTIONAL::AWESOME::Class::Implementing::ExtraRainbowSauce >>
    SQL::Abstract
  );
  << your new code goes here >>


  ... and then ...


  my $experimental_schema = $original_schema->connect(
    sub {
      $original_schema->storage->dbh
    },
    {
      # the nested arrayref is important, as per
      # https://metacpan.org/pod/DBIO::Storage::DBI#on_connect_call
      on_connect_call => [ [ rebase_sqlmaker => 'DBIO::Awesomer::SQLMaker' ] ],
    },
  );

=head2 redact_bind_value

Class-level accessor for a coderef that decides how each bind value appears
in the trace output. The coderef is invoked as

  $redactor->($column_name, $value)

where C<$column_name> is the column name attached to the bind slot by the
SQL generator (or C<undef> for binds that carry no column metadata, such as
positional placeholders in raw SQL passed to L</do_query>). The coderef
returns the value to interpolate into the trace string. The raw bind value
sent to the database is not modified - only its representation in the trace
sink is.

The default redactor is the identity function, which preserves the
historical plaintext trace behavior. Install a custom redactor to scrub
credential or PII columns, e.g.:

  DBIO::Storage::DBI->redact_bind_value(sub {
      my ($colname, $value) = @_;
      return $colname eq 'password' ? '***' : $value;
  });

The redactor is a single class-level slot; setting it on a subclass does
not affect the parent or sibling classes. If you need per-instance
behavior, install a closure that consults C<$self> on the storage object
(via a dispatcher closure captured at connect time).

=head2 select

=over 4

=item Arguments: $ident, $select, $condition, $attrs

=back

Handle a SQL select statement.

=head2 last_insert_id

Return the row id of the last insert.

=head2 sqlt_type

Returns the database driver name.

=head2 bind_attribute_by_data_type

Given a datatype from column info, returns a database specific bind
attribute for C<< $dbh->bind_param($val,$attribute) >> or nothing if we will
let the database planner just handle it.

This method is always called after the driver has been determined and a DBI
connection has been established. Therefore you can refer to C<DBI::$constant>
and/or C<DBD::$driver::$constant> directly, without worrying about loading
the correct modules.

=head2 is_datatype_numeric

Given a datatype from column_info, returns a boolean value indicating if
the current RDBMS considers it a numeric value. This controls how
L<DBIO::Row/set_column> decides whether to mark the column as
dirty - when the datatype is deemed numeric a C<< != >> comparison will
be performed instead of the usual C<eq>.

=head2 create_ddl_dir

=over 4

=item Arguments: $schema, \@databases, $version, $directory, $preversion, \%sqlt_args

=back

B<DEPRECATED:> This method is deprecated and will throw an
exception if called. Use the native Deploy class on your storage instead
(see L<DBIO::Schema/deploy>).

Historically this created SQL DDL files for each requested database engine,
plus C<ALTER TABLE> upgrade scripts between schema versions, via
L<SQL::Translator>. Core no longer generates SQL on the fly; the native Deploy
classes (e.g. L<DBIO::PostgreSQL::Deploy>) handle introspection, diff and
deployment. The original signature is retained only for the deprecation throw.

=head2 deployment_statements

=over 4

=item Arguments: $schema, $type, $version, $directory, $sqlt_args

=back

Returns the SQL statements for deploying the schema.

If a DDL file exists in the directory (from a prior L</create_ddl_dir>
call), reads and returns its contents. Otherwise, throws an exception.
There is no on-the-fly SQL generation without a Deploy class.

For deployments, use L<DBIO::Schema/deploy> instead, which routes to the
storage's native Deploy class if available.

=head2 datetime_parser

Returns the datetime parser class

=head2 datetime_parser_type

Defines the datetime parser class - currently defaults to L<DateTime::Format::MySQL>

=head2 build_datetime_parser

See L</datetime_parser>

=head2 is_replicating

A boolean that reports if a particular L<DBIO::Storage::DBI> is set to
replicate from a master database.  Default is undef, which is the result
returned by databases that don't support replication.

=head2 lag_behind_master

Returns a number that represents a certain amount of lag behind a master db
when a given storage is replicating.  The number is database dependent, but
starts at zero and increases with the amount of lag. Default in undef

=head2 relname_to_table_alias

=over 4

=item Arguments: $relname, $join_count

=item Return Value: $alias

=back

L<DBIO> uses L<DBIO::Relationship> names as table aliases in
queries.

This hook is to allow specific L<DBIO::Storage> drivers to change the
way these aliases are named.

The default behavior is C<< "$relname_$join_count" if $join_count > 1 >>,
otherwise C<"$relname">.

=head1 USAGE NOTES

=head2 DBIO and AutoCommit

DBIO can do some wonderful magic with handling exceptions,
disconnections, and transactions when you use C<< AutoCommit => 1 >>
(the default) combined with L<txn_do|DBIO::Storage/txn_do> for
transaction support.

If you set C<< AutoCommit => 0 >> in your connect info, then you are always
in an assumed transaction between commits, and you're telling us you'd
like to manage that manually.  A lot of the magic protections offered by
this module will go away.  We can't protect you from exceptions due to database
disconnects because we don't know anything about how to restart your
transactions.  You're on your own for handling all sorts of exceptional
cases if you choose the C<< AutoCommit => 0 >> path, just as you would
be with raw DBI.

=head1 AUTHOR

DBIO & DBIx::Class Authors

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2026 DBIO Authors
Portions Copyright (C) 2005-2025 DBIx::Class Authors
Based on DBIx::Class, heavily modified.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut
