# ABSTRACT: Class representing fatal errors

package Dancer::Core::Error;
{
    $Dancer::Core::Error::VERSION = '2.0000_01';
}
use Moo;
use Carp;
use Dancer::Core::Types;
use Data::Dumper;
use Dancer::FileUtils 'path';

with 'Dancer::Core::Role::Hookable';


my %error_title = (
    400 => "Bad Request",
    401 => "Unauthorized",
    402 => "Payment Required",
    403 => "Forbidden",
    404 => "Not Found",
    405 => "Method Not Allowed",
    406 => "Not Acceptable",
    407 => "Proxy Authentication Required",
    408 => "Request Timeout",
    409 => "Conflict",
    410 => "Gone",
    411 => "Length Required",
    412 => "Precondition Failed",
    413 => "Request Entity Too Large",
    414 => "Request-URI Too Long",
    415 => "Unsupported Media Type",
    416 => "Requested Range Not Satisfiable",
    417 => "Expectation Failed",
    418 => "I'm a teapot",
    420 => "Enhance Your Calm",
    422 => "Unprocessable Entity",
    423 => "Locked",
    424 => "Failed Dependency",
    424 => "Method Failure",
    425 => "Unordered Collection",
    426 => "Upgrade Required",
    428 => "Precondition Required",
    429 => "Too Many Requests",
    431 => "Request Header Fields Too Large",
    444 => "No Response",
    449 => "Retry With",
    450 => "Blocked by Windows Parental Controls ",
    451 => "Unavailable For Legal Reasons ",
    451 => "Redirect",
    494 => "Request Header Too Large ",
    495 => "Cert Error",
    496 => "No Cert ",
    497 => "HTTP to HTTPS",
    499 => "Client Closed Request",
    500 => "Internal Server Error",
    501 => "Not Implemented",
    502 => "Bad Gateway",
    503 => "Service Unavailable",
    504 => "Gateway Timeout",
    505 => "HTTP Version Not Supported",
    506 => "Variant Also Negotiates ",
    507 => "Insufficient Storage ",
    508 => "Loop Detected ",
    509 => "Bandwidth Limit Exceeded ",
    510 => "Not Extended",
    511 => "Network Authentication Required ",
    598 => "Network read timeout error ",
    599 => "Network connect timeout error ",
);


sub supported_hooks {
    qw/
      core.error.before
      core.error.after
      core.error.init
      /;
}


has show_errors => (
    is  => 'ro',
    isa => Bool,
);


has charset => (
    is      => 'ro',
    isa     => Str,
    default => sub {'UTF-8'},
);


has type => (
    is      => 'ro',
    isa     => Str,
    default => sub {'Runtime Error'},
);


has title => (
    is      => 'rw',
    isa     => Str,
    lazy    => 1,
    builder => '_build_title',
);

sub _build_title {
    my ($self) = @_;
    my $title = 'Error ' . $self->status;
    $title .= ' - ' . $error_title{$self->status}
      if $error_title{$self->status};

    return $title;
}

has template => (
    is => 'ro',

#    isa => sub { ref($_[0]) eq 'SCALAR' || ReadableFilePath->(@_) },
    lazy    => 1,
    builder => '_build_error_template',
);

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

    # look for a template named after the status number.
    # E.g.: views/404.tt  for a TT template
    return $self->status
      if -f $self->context->app->engine('template')->view($self->status);

    return undef;
}

has static_page => (
    is      => 'ro',
    lazy    => 1,
    builder => '_build_static_page',
);

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

    # TODO there must be a better way to get it
    my $public_dir = $ENV{DANCER_PUBLIC}
      || ($self->has_context
        && path($self->context->app->config_location, 'public'));

    my $filename = sprintf "%s/%d.html", $public_dir, $self->status;

    open my $fh, $filename or return undef;

    local $/ = undef;    # slurp time

    return <$fh>;
}


sub default_error_page {
    my $self = shift;

    require Template::Tiny;

    my $opts = {
        title   => $self->title,
        charset => $self->charset,
        content => $self->message,
        version => Dancer->VERSION,
    };

    Template::Tiny->new->process(\<<"END_TEMPLATE", $opts, \my $output);
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>[% title %]</title>
<link rel="stylesheet" href="/css/error.css" />
<meta http-equiv="Content-type" content="text/html; charset='[% charset %]'" />
</head>
<body>
<h1>[% title %]</h1>
<div id="content">
[% content %]
</div>
<div id="footer">
Powered by <a href="http://perldancer.org/">Dancer</a> [% version %]
</div>
</body>
</html>
END_TEMPLATE

    return $output;
}


has status => (
    is      => 'ro',
    default => sub {500},
    isa     => Num,
);


has message => (
    is  => 'rw',
    isa => Str,
);

sub full_message {
    my ($self) = @_;
    my $html_output = "<h2>" . $self->type . "</h2>";
    $html_output .= $self->backtrace;
    $html_output .= $self->environment;
    return $html_output;
}

has serializer => (
    is  => 'ro',
    isa => ConsumerOf ['Dancer::Core::Role::Serializer'],
);

has session => (
    is  => 'ro',
    isa => ConsumerOf ['Dancer::Core::Role::Session'],
);

has context => (
    is        => 'ro',
    isa       => InstanceOf ['Dancer::Core::Context'],
    predicate => 1,
);

sub BUILD {
    my ($self) = @_;
    $self->execute_hook('core.error.init', $self);
}

has exception => (
    is  => 'rw',
    isa => Str,
);

has response => (
    is      => 'rw',
    lazy    => 1,
    default => sub {
        $_[0]->has_context
          ? $_[0]->context->response
          : Dancer::Core::Response->new;
    },
);

has content_type => (
    is      => 'ro',
    default => sub {'text/html'},
);

has content => (
    is      => 'ro',
    lazy    => 1,
    default => sub {
        my $self = shift;

        # we check for a template, for a static file and,
        # if all else fail, the default error page

        if ($self->has_context and $self->template) {
            return $self->context->app->template(
                $self->template,
                {   title   => $self->title,
                    content => $self->message,
                    status  => $self->status,
                }
            );
        }

        if (my $content = $self->static_page) {
            return $content;
        }

        return $self->default_error_page;
    },
);


sub throw {
    my $self = shift;
    $self->response(shift) if @_;

    croak "error has no response to throw at" unless $self->response;

    $self->execute_hook('core.error.before', $self);

    $self->response->status($self->status);
    $self->response->header($self->content_type);
    $self->response->content($self->content);
    $self->response->halt(1);

    $self->execute_hook('core.error.after', $self->response);

    return $self->response;
}


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

    my $message =
      qq|<pre class="error">| . _html_encode($self->message) . "</pre>";

    # the default perl warning/error pattern
    my ($file, $line) = ($message =~ /at (\S+) line (\d+)/);

    # the Devel::SimpleTrace pattern
    ($file, $line) = ($message =~ /at.*\((\S+):(\d+)\)/)
      unless $file and $line;

    # no file/line found, cannot open a file for context
    return $message unless ($file and $line);

    # file and line are located, let's read the source Luke!
    my $fh = open_file('<', $file) or return $message;
    my @lines = <$fh>;
    close $fh;

    my $backtrace = $message;

    $backtrace
      .= qq|<div class="title">| . "$file around line $line" . "</div>";

    $backtrace .= qq|<pre class="content">|;

    $line--;
    my $start = (($line - 3) >= 0)             ? ($line - 3) : 0;
    my $stop  = (($line + 3) < scalar(@lines)) ? ($line + 3) : scalar(@lines);

    for (my $l = $start; $l <= $stop; $l++) {
        chomp $lines[$l];

        if ($l == $line) {
            $backtrace
              .= qq|<span class="nu">|
              . tabulate($l + 1, $stop + 1)
              . qq|</span> <span style="color: red;">|
              . _html_encode($lines[$l])
              . "</span>\n";
        }
        else {
            $backtrace
              .= qq|<span class="nu">|
              . tabulate($l + 1, $stop + 1)
              . "</span> "
              . _html_encode($lines[$l]) . "\n";
        }
    }
    $backtrace .= "</pre>";


    return $backtrace;
}


sub tabulate {
    my ($number, $max) = @_;
    my $len = length($max);
    return $number if length($number) == $len;
    return " $number";
}


sub dumper {
    my $obj = shift;

    # Take a copy of the data, so we can mask sensitive-looking stuff:
    my %data     = %$obj;
    my $censored = _censor(\%data);

    #use Data::Dumper;
    my $dd = Data::Dumper->new([\%data]);
    $dd->Terse(1)->Quotekeys(0)->Indent(1);
    my $content = $dd->Dump();
    $content =~ s{(\s*)(\S+)(\s*)=>}{$1<span class="key">$2</span>$3 =&gt;}g;
    if ($censored) {
        $content
          .= "\n\nNote: Values of $censored sensitive-looking keys hidden\n";
    }
    return $content;
}


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

    my $request = $self->has_context ? $self->context->request : 'TODO';
    my $r_env = {};
    $r_env = $request->env if defined $request;

    my $env =
        qq|<div class="title">Environment</div><pre class="content">|
      . dumper($r_env)
      . "</pre>";
    my $settings =
        qq|<div class="title">Settings</div><pre class="content">|
      . dumper($self->app->settings)
      . "</pre>";
    my $source =
        qq|<div class="title">Stack</div><pre class="content">|
      . $self->get_caller
      . "</pre>";
    my $session = "";

    if ($self->session) {
        $session =
            qq[<div class="title">Session</div><pre class="content">]
          . dumper($self->session->data)
          . "</pre>";
    }
    return "$source $settings $session $env";
}


sub get_caller {
    my ($self) = @_;
    my @stack;

    my $deepness = 0;
    while (my ($package, $file, $line) = caller($deepness++)) {
        push @stack, "$package in $file l. $line";
    }

    return join("\n", reverse(@stack));
}

# private

# Given a hashref, censor anything that looks sensitive.  Returns number of
# items which were "censored".


sub _censor {
    my $hash = shift;
    if (!$hash || ref $hash ne 'HASH') {
        carp "_censor given incorrect input: $hash";
        return;
    }

    my $censored = 0;
    for my $key (keys %$hash) {
        if (ref $hash->{$key} eq 'HASH') {
            $censored += _censor($hash->{$key});
        }
        elsif ($key =~ /(pass|card?num|pan|secret)/i) {
            $hash->{$key} = "Hidden (looks potentially sensitive)";
            $censored++;
        }
    }

    return $censored;
}


# Replaces the entities that are illegal in (X)HTML.
sub _html_encode {
    my $value = shift;

    $value =~ s/&/&amp;/g;
    $value =~ s/</&lt;/g;
    $value =~ s/>/&gt;/g;
    $value =~ s/'/&#39;/g;
    $value =~ s/"/&quot;/g;

    return $value;
}

sub _render_html {
    my $self = shift;

    # error_template defaults to something, always
    my $template_name = $self->error_template;

    my $ops = {
        title   => $self->title,
        content => $self->message,
        status  => $self->status,
        defined $self->exception ? (exception => $self->exception) : (),
    };
    my $content = $self->template->apply_renderer($template_name, $ops);
    $self->response->status($self->status);
    $self->response->header('Content-Type' => 'text/html');
    return $content;
}

1;

__END__

=pod

=head1 NAME

Dancer::Core::Error - Class representing fatal errors

=head1 VERSION

version 2.0000_01

=head1 SYNOPSIS

    # taken from send_file:
    use Dancer::Error;

    my $error = Dancer::Error->new(
        status    => 404,
        message => "No such file: `$path'"
    );

    Dancer::Response->set($error->render);

=head1 DESCRIPTION

With Dancer::Error you can throw reasonable-looking errors to the user instead
of crashing the application and filling up the logs.

This is usually used in debugging environments, and it's what Dancer uses as
well under debugging to catch errors and show them on screen.

=head1 ATTRIBUTES

=head2 show_errors

=head2 charset

=head2 type

The error type.

=head2 title

The title of the error page.

This is only an attribute getter, you'll have to set it at C<new>.

=head2 status

The status that caused the error.

This is only an attribute getter, you'll have to set it at C<new>.

=head2 message

The message of the error page.

=head1 METHODS

=head2 my $error=new Dancer::Core::Error(status    => 404, message => "No such file: `$path'");

Create a new Dancer::Error object. For available arguments see ATTRIBUTES.

=head2 supported_hooks ();

=head2 throw($response)

Populates the content of the response with the error's information.
If I<$response> is not given, acts on the I<context> 
attribute's response.

=head2 backtrace

Create a backtrace of the code where the error is caused.

This method tries to find out where the error appeared according to the actual
error message (using the C<message> attribute) and tries to parse it (supporting
the regular/default Perl warning or error pattern and the L<Devel::SimpleTrace>
output) and then returns an error-higlighted C<message>.

=head2 tabulate

Small subroutine to help output nicer.

=head2 environment

A main function to render environment information: the caller (using
C<get_caller>), the settings and environment (using C<dumper>) and more.

=head2 get_caller

Creates a strack trace of callers.

=head1 FUNCTIONS

=head2 _censor

An private function that tries to censor out content which should be protected.

C<dumper> calls this method to censor things like passwords and such.

=head2 my $string=_html_encode ($string);

Private function that replaces illegal entities in (X)HTML with their
escaped representations. 

html_encode() doesn't do any UTF black magic.

=head2 dumper

This uses L<Data::Dumper> to create nice content output with a few predefined
options.

=head1 AUTHOR

Dancer Core Developers

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2012 by Alexis Sukrieh.

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
