package SQL::Translator::Parser::DBI;

# -------------------------------------------------------------------
# $Id: DBI.pm,v 1.6 2004/09/24 14:06:46 kycl4rk Exp $
# -------------------------------------------------------------------
# Copyright (C) 2002-4 SQLFairy Authors
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; version 2.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
# 02111-1307  USA
# -------------------------------------------------------------------

=head1 NAME

SQL::Translator::Parser::DBI - "parser" for DBI handles

=head1 SYNOPSIS

  use DBI;
  use SQL::Translator;

  my $dbh = DBI->connect('dsn', 'user', 'pass', 
      {
          RaiseError       => 1,
          FetchHashKeyName => 'NAME_lc',
      }
  );

  my $translator  =  SQL::Translator->new(
      parser      => 'DBI',
      dbh         => $dbh,
  );

Or:

  use SQL::Translator;

  my $translator      =  SQL::Translator->new(
      parser          => 'DBI',
      parser_args     => {
          dsn         => 'dbi:mysql:FOO',
          db_user     => 'guest',
          db_password => 'password',
    }
  );

=head1 DESCRIPTION

This parser accepts an open database handle (or the arguments to create 
one) and queries the database directly for the information.  

The following are acceptable arguments:

=over 4

=item * dbh

An open DBI database handle.  NB:  Be sure to create the database with the 
"FetchHashKeyName => 'NAME_lc'" option as all the DBI parsers expect 
lowercased column names.

=item * dsn

The DSN to use for connecting to a database.

=item * db_user

The user name to use for connecting to a database.

=item * db_password

The password to use for connecting to a database.

=back

There is no need to specify which type of database you are querying as
this is determined automatically by inspecting $dbh->{'Driver'}{'Name'}.
If a parser exists for your database, it will be used automatically;
if not, the code will fail automatically (and you can write the parser
and contribute it to the project!).  

Currently parsers exist for the following databases:

=over 4

=item * MySQL

=item * SQLite

=item * Sybase

=item * PostgreSQL (still experimental)

=back

Most of these parsers are able to query the database directly for the
structure rather than parsing a text file.  For large schemas, this is
probably orders of magnitude faster than traditional parsing (which
uses Parse::RecDescent, an amazing module but really quite slow).

Though no Oracle parser currently exists, it would be fairly easy to
query an Oracle database directly by using DDL::Oracle to generate a
DDL for the schema and then using the normal Oracle parser on this.
Perhaps future versions of SQL::Translator will include the ability to
query Oracle directly and skip the parsing of a text file, too.

=cut

# -------------------------------------------------------------------

use strict;
use DBI;
use vars qw($VERSION @EXPORT);
$VERSION = sprintf "%d.%02d", q$Revision: 1.6 $ =~ /(\d+)\.(\d+)/;

use constant DRIVERS => {
    mysql            => 'MySQL',
    sqlite           => 'SQLite',
    sybase           => 'Sybase',
    pg               => 'PostgreSQL',
};

use Exporter;

use SQL::Translator::Utils qw(debug);

use SQL::Translator::Parser::DBI::MySQL;
use SQL::Translator::Parser::DBI::SQLite;
use SQL::Translator::Parser::DBI::Sybase;
use SQL::Translator::Parser::DBI::PostgreSQL;

use base qw(Exporter);
@EXPORT = qw(parse);

#
# Passed a SQL::Translator instance and a string containing the data
#
sub parse {
    my ( $tr, $data ) = @_;

    my $args          = $tr->parser_args;
    my $dbh           = $args->{'dbh'};
    my $dsn           = $args->{'dsn'};
    my $db_user       = $args->{'db_user'};
    my $db_password   = $args->{'db_password'};

    unless ( $dbh ) {
        die 'No DSN' unless $dsn;
        $dbh = DBI->connect( $dsn, $db_user, $db_password, 
            {
                FetchHashKeyName => 'NAME_lc',
                LongReadLen      => 3000,
                LongTruncOk      => 1,
                RaiseError       => 1,
            } 
        );
    }

    die 'No database handle' unless defined $dbh;

    my $db_type = $dbh->{'Driver'}{'Name'} or die 'Cannot determine DBI type';
    my $driver  = DRIVERS->{ lc $db_type } or die "$db_type not supported";
    my $pkg     = "SQL::Translator::Parser::DBI::$driver";
    my $sub     = $pkg.'::parse';

    #
    # I can't get this to work.  I seem to have to have the "use"
    # statements above.
    #
#    $tr->load( $pkg );

    eval {
        no strict 'refs';
        &{ $sub }( $tr, $dbh ) or die "No result from $pkg";
    };

    $dbh->disconnect if defined $dbh;

    die $@ if $@;

    return 1;
}

1;

# -------------------------------------------------------------------
=pod

=head1 AUTHOR

Ken Y. Clark E<lt>kclark@cpan.orgE<gt>.

=head1 SEE ALSO

DBI, SQL::Translator.

=cut
