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[catagits/Catalyst-Runtime.git] / lib / Catalyst.pm

package Catalyst;

use strict;
use base 'Catalyst::Component';
use bytes;
use Catalyst::Exception;
use Catalyst::Log;
use Catalyst::Request;
use Catalyst::Request::Upload;
use Catalyst::Response;
use Catalyst::Utils;
use Catalyst::Controller;
use Devel::InnerPackage ();
use File::stat;
use Module::Pluggable::Object ();
use NEXT;
use Text::SimpleTable ();
use Path::Class::Dir ();
use Path::Class::File ();
use Time::HiRes qw/gettimeofday tv_interval/;
use URI ();
use URI::http;
use URI::https;
use Scalar::Util qw/weaken blessed/;
use Tree::Simple qw/use_weak_refs/;
use Tree::Simple::Visitor::FindByUID;
use attributes;
use utf8;
use Carp qw/croak carp/;

BEGIN { require 5.008001; }

__PACKAGE__->mk_accessors(
    qw/counter request response state action stack namespace stats/
);

attributes->import( __PACKAGE__, \&namespace, 'lvalue' );

sub depth { scalar @{ shift->stack || [] }; }

# Laziness++
*comp = \&component;
*req  = \&request;
*res  = \&response;

# For backwards compatibility
*finalize_output = \&finalize_body;

# For statistics
our $COUNT     = 1;
our $START     = time;
our $RECURSION = 1000;
our $DETACH    = "catalyst_detach\n";

__PACKAGE__->mk_classdata($_)
  for qw/components arguments dispatcher engine log dispatcher_class
  engine_class context_class request_class response_class stats_class 
  setup_finished/;

__PACKAGE__->dispatcher_class('Catalyst::Dispatcher');
__PACKAGE__->engine_class('Catalyst::Engine::CGI');
__PACKAGE__->request_class('Catalyst::Request');
__PACKAGE__->response_class('Catalyst::Response');
__PACKAGE__->stats_class('Catalyst::Stats');

# Remember to update this in Catalyst::Runtime as well!

our $VERSION = '5.7011';

sub import {
    my ( $class, @arguments ) = @_;

    # We have to limit $class to Catalyst to avoid pushing Catalyst upon every
    # callers @ISA.
    return unless $class eq 'Catalyst';

    my $caller = caller(0);

    unless ( $caller->isa('Catalyst') ) {
        no strict 'refs';
        push @{"$caller\::ISA"}, $class, 'Catalyst::Controller';
    }

    $caller->arguments( [@arguments] );
    $caller->setup_home;
}

=head1 NAME

Catalyst - The Elegant MVC Web Application Framework

=head1 SYNOPSIS

See the L<Catalyst::Manual> distribution for comprehensive
documentation and tutorials.

    # Install Catalyst::Devel for helpers and other development tools
    # use the helper to create a new application
    catalyst.pl MyApp

    # add models, views, controllers
    script/myapp_create.pl model MyDatabase DBIC::Schema create=dynamic dbi:SQLite:/path/to/db
    script/myapp_create.pl view MyTemplate TT
    script/myapp_create.pl controller Search

    # built in testserver -- use -r to restart automatically on changes
    # --help to see all available options
    script/myapp_server.pl

    # command line testing interface
    script/myapp_test.pl /yada

    ### in lib/MyApp.pm
    use Catalyst qw/-Debug/; # include plugins here as well
    
    ### In lib/MyApp/Controller/Root.pm (autocreated)
    sub foo : Global { # called for /foo, /foo/1, /foo/1/2, etc.
        my ( $self, $c, @args ) = @_; # args are qw/1 2/ for /foo/1/2
        $c->stash->{template} = 'foo.tt'; # set the template
        # lookup something from db -- stash vars are passed to TT
        $c->stash->{data} = 
          $c->model('Database::Foo')->search( { country => $args[0] } );
        if ( $c->req->params->{bar} ) { # access GET or POST parameters
            $c->forward( 'bar' ); # process another action
            # do something else after forward returns            
        }
    }
    
    # The foo.tt TT template can use the stash data from the database
    [% WHILE (item = data.next) %]
        [% item.foo %]
    [% END %]
    
    # called for /bar/of/soap, /bar/of/soap/10, etc.
    sub bar : Path('/bar/of/soap') { ... }

    # called for all actions, from the top-most controller downwards
    sub auto : Private { 
        my ( $self, $c ) = @_;
        if ( !$c->user_exists ) { # Catalyst::Plugin::Authentication
            $c->res->redirect( '/login' ); # require login
            return 0; # abort request and go immediately to end()
        }
        return 1; # success; carry on to next action
    }
    
    # called after all actions are finished
    sub end : Private { 
        my ( $self, $c ) = @_;
        if ( scalar @{ $c->error } ) { ... } # handle errors
        return if $c->res->body; # already have a response
        $c->forward( 'MyApp::View::TT' ); # render template
    }

    ### in MyApp/Controller/Foo.pm
    # called for /foo/bar
    sub bar : Local { ... }
    
    # called for /blargle
    sub blargle : Global { ... }
    
    # an index action matches /foo, but not /foo/1, etc.
    sub index : Private { ... }
    
    ### in MyApp/Controller/Foo/Bar.pm
    # called for /foo/bar/baz
    sub baz : Local { ... }
    
    # first Root auto is called, then Foo auto, then this
    sub auto : Private { ... }
    
    # powerful regular expression paths are also possible
    sub details : Regex('^product/(\w+)/details$') {
        my ( $self, $c ) = @_;
        # extract the (\w+) from the URI
        my $product = $c->req->captures->[0];
    }

See L<Catalyst::Manual::Intro> for additional information.

=head1 DESCRIPTION

Catalyst is a modern framework for making web applications without the
pain usually associated with this process. This document is a reference
to the main Catalyst application. If you are a new user, we suggest you
start with L<Catalyst::Manual::Tutorial> or L<Catalyst::Manual::Intro>.

See L<Catalyst::Manual> for more documentation.

Catalyst plugins can be loaded by naming them as arguments to the "use
Catalyst" statement. Omit the C<Catalyst::Plugin::> prefix from the
plugin name, i.e., C<Catalyst::Plugin::My::Module> becomes
C<My::Module>.

    use Catalyst qw/My::Module/;

If your plugin starts with a name other than C<Catalyst::Plugin::>, you can
fully qualify the name by using a unary plus:

    use Catalyst qw/
        My::Module
        +Fully::Qualified::Plugin::Name
    /;

Special flags like C<-Debug> and C<-Engine> can also be specified as
arguments when Catalyst is loaded:

    use Catalyst qw/-Debug My::Module/;

The position of plugins and flags in the chain is important, because
they are loaded in the order in which they appear.

The following flags are supported:

=head2 -Debug

Enables debug output. You can also force this setting from the system
environment with CATALYST_DEBUG or <MYAPP>_DEBUG. The environment
settings override the application, with <MYAPP>_DEBUG having the highest
priority.

=head2 -Engine

Forces Catalyst to use a specific engine. Omit the
C<Catalyst::Engine::> prefix of the engine name, i.e.:

    use Catalyst qw/-Engine=CGI/;

=head2 -Home

Forces Catalyst to use a specific home directory, e.g.:

    use Catalyst qw[-Home=/usr/mst];

This can also be done in the shell environment by setting either the
C<CATALYST_HOME> environment variable or C<MYAPP_HOME>; where C<MYAPP>
is replaced with the uppercased name of your application, any "::" in
the name will be replaced with underscores, e.g. MyApp::Web should use
MYAPP_WEB_HOME. If both variables are set, the MYAPP_HOME one will be used.

=head2 -Log

Specifies log level.

=head2 -Stats

Enables statistics collection and reporting. You can also force this setting
from the system environment with CATALYST_STATS or <MYAPP>_STATS. The
environment settings override the application, with <MYAPP>_STATS having the
highest priority.

e.g. 

   use Catalyst qw/-Stats=1/

=head1 METHODS

=head2 INFORMATION ABOUT THE CURRENT REQUEST

=head2 $c->action

Returns a L<Catalyst::Action> object for the current action, which
stringifies to the action name. See L<Catalyst::Action>.

=head2 $c->namespace

Returns the namespace of the current action, i.e., the URI prefix
corresponding to the controller of the current action. For example:

    # in Controller::Foo::Bar
    $c->namespace; # returns 'foo/bar';

=head2 $c->request

=head2 $c->req

Returns the current L<Catalyst::Request> object, giving access to
information about the current client request (including parameters,
cookies, HTTP headers, etc.). See L<Catalyst::Request>.

=head2 REQUEST FLOW HANDLING

=head2 $c->forward( $action [, \@arguments ] )

=head2 $c->forward( $class, $method, [, \@arguments ] )

Forwards processing to another action, by its private name. If you give a
class name but no method, C<process()> is called. You may also optionally
pass arguments in an arrayref. The action will receive the arguments in
C<@_> and C<< $c->req->args >>. Upon returning from the function,
C<< $c->req->args >> will be restored to the previous values.

Any data C<return>ed from the action forwarded to, will be returned by the
call to forward.

    my $foodata = $c->forward('/foo');
    $c->forward('index');
    $c->forward(qw/MyApp::Model::DBIC::Foo do_stuff/);
    $c->forward('MyApp::View::TT');

Note that forward implies an C<<eval { }>> around the call (actually
C<execute> does), thus de-fatalizing all 'dies' within the called
action. If you want C<die> to propagate you need to do something like:

    $c->forward('foo');
    die $c->error if $c->error;

Or make sure to always return true values from your actions and write
your code like this:

    $c->forward('foo') || return;

=cut

sub forward { my $c = shift; $c->dispatcher->forward( $c, @_ ) }

=head2 $c->detach( $action [, \@arguments ] )

=head2 $c->detach( $class, $method, [, \@arguments ] )

=head2 $c->detach()

The same as C<forward>, but doesn't return to the previous action when 
processing is finished. 

When called with no arguments it escapes the processing chain entirely.

=cut

sub detach { my $c = shift; $c->dispatcher->detach( $c, @_ ) }

=head2 $c->response

=head2 $c->res

Returns the current L<Catalyst::Response> object, see there for details.

=head2 $c->stash

Returns a hashref to the stash, which may be used to store data and pass
it between components during a request. You can also set hash keys by
passing arguments. The stash is automatically sent to the view. The
stash is cleared at the end of a request; it cannot be used for
persistent storage (for this you must use a session; see
L<Catalyst::Plugin::Session> for a complete system integrated with
Catalyst).

    $c->stash->{foo} = $bar;
    $c->stash( { moose => 'majestic', qux => 0 } );
    $c->stash( bar => 1, gorch => 2 ); # equivalent to passing a hashref
    
    # stash is automatically passed to the view for use in a template
    $c->forward( 'MyApp::View::TT' );

=cut

sub stash {
    my $c = shift;
    if (@_) {
        my $stash = @_ > 1 ? {@_} : $_[0];
        croak('stash takes a hash or hashref') unless ref $stash;
        foreach my $key ( keys %$stash ) {
            $c->{stash}->{$key} = $stash->{$key};
        }
    }
    return $c->{stash};
}

=head2 $c->error

=head2 $c->error($error, ...)

=head2 $c->error($arrayref)

Returns an arrayref containing error messages.  If Catalyst encounters an
error while processing a request, it stores the error in $c->error.  This
method should only be used to store fatal error messages.

    my @error = @{ $c->error };

Add a new error.

    $c->error('Something bad happened');

=cut

sub error {
    my $c = shift;
    if ( $_[0] ) {
        my $error = ref $_[0] eq 'ARRAY' ? $_[0] : [@_];
        croak @$error unless ref $c;
        push @{ $c->{error} }, @$error;
    }
    elsif ( defined $_[0] ) { $c->{error} = undef }
    return $c->{error} || [];
}


=head2 $c->state

Contains the return value of the last executed action.

=head2 $c->clear_errors

Clear errors.  You probably don't want to clear the errors unless you are
implementing a custom error screen.

This is equivalent to running

    $c->error(0);

=cut

sub clear_errors {
    my $c = shift;
    $c->error(0);
}


# search via regex
sub _comp_search {
    my ( $c, @names ) = @_;

    foreach my $name (@names) {
        foreach my $component ( keys %{ $c->components } ) {
            return $c->components->{$component} if $component =~ /$name/i;
        }
    }

    return undef;
}

# try explicit component names
sub _comp_explicit {
    my ( $c, @names ) = @_;

    foreach my $try (@names) {
        return $c->components->{$try} if ( exists $c->components->{$try} );
    }

    return undef;
}

# like component, but try just these prefixes before regex searching,
#  and do not try to return "sort keys %{ $c->components }"
sub _comp_prefixes {
    my ( $c, $name, @prefixes ) = @_;

    my $appclass = ref $c || $c;

    my @names = map { "${appclass}::${_}::${name}" } @prefixes;

    my $comp = $c->_comp_explicit(@names);
    return $comp if defined($comp);
    $comp = $c->_comp_search($name);
    return $comp;
}

# Find possible names for a prefix 

sub _comp_names {
    my ( $c, @prefixes ) = @_;

    my $appclass = ref $c || $c;

    my @pre = map { "${appclass}::${_}::" } @prefixes;

    my @names;

    COMPONENT: foreach my $comp ($c->component) {
        foreach my $p (@pre) {
            if ($comp =~ s/^$p//) {
                push(@names, $comp);
                next COMPONENT;
            }
        }
    }

    return @names;
}

# Return a component if only one matches.
sub _comp_singular {
    my ( $c, @prefixes ) = @_;

    my $appclass = ref $c || $c;

    my ( $comp, $rest ) =
      map { $c->_comp_search("^${appclass}::${_}::") } @prefixes;
    return $comp unless $rest;
}

# Filter a component before returning by calling ACCEPT_CONTEXT if available
sub _filter_component {
    my ( $c, $comp, @args ) = @_;
    if ( eval { $comp->can('ACCEPT_CONTEXT'); } ) {
        return $comp->ACCEPT_CONTEXT( $c, @args );
    }
    else { return $comp }
}

=head2 COMPONENT ACCESSORS

=head2 $c->controller($name)

Gets a L<Catalyst::Controller> instance by name.

    $c->controller('Foo')->do_stuff;

If the name is omitted, will return the controller for the dispatched
action.

=cut

sub controller {
    my ( $c, $name, @args ) = @_;
    return $c->_filter_component( $c->_comp_prefixes( $name, qw/Controller C/ ),
        @args )
      if ($name);
    return $c->component( $c->action->class );
}

=head2 $c->model($name)

Gets a L<Catalyst::Model> instance by name.

    $c->model('Foo')->do_stuff;

Any extra arguments are directly passed to ACCEPT_CONTEXT.

If the name is omitted, it will look for 
 - a model object in $c->stash{current_model_instance}, then
 - a model name in $c->stash->{current_model}, then
 - a config setting 'default_model', or
 - check if there is only one model, and return it if that's the case.

=cut

sub model {
    my ( $c, $name, @args ) = @_;
    return $c->_filter_component( $c->_comp_prefixes( $name, qw/Model M/ ),
        @args )
      if $name;
    if (ref $c) {
        return $c->stash->{current_model_instance} 
          if $c->stash->{current_model_instance};
        return $c->model( $c->stash->{current_model} )
          if $c->stash->{current_model};
    }
    return $c->model( $c->config->{default_model} )
      if $c->config->{default_model};
    return $c->_filter_component( $c->_comp_singular(qw/Model M/) );

}

=head2 $c->controllers

Returns the available names which can be passed to $c->controller

=cut

sub controllers {
    my ( $c ) = @_;
    return $c->_comp_names(qw/Controller C/);
}


=head2 $c->view($name)

Gets a L<Catalyst::View> instance by name.

    $c->view('Foo')->do_stuff;

Any extra arguments are directly passed to ACCEPT_CONTEXT.

If the name is omitted, it will look for 
 - a view object in $c->stash{current_view_instance}, then
 - a view name in $c->stash->{current_view}, then
 - a config setting 'default_view', or
 - check if there is only one view, and return it if that's the case.

=cut

sub view {
    my ( $c, $name, @args ) = @_;
    return $c->_filter_component( $c->_comp_prefixes( $name, qw/View V/ ),
        @args )
      if $name;
    if (ref $c) {
        return $c->stash->{current_view_instance} 
          if $c->stash->{current_view_instance};
        return $c->view( $c->stash->{current_view} )
          if $c->stash->{current_view};
    }
    return $c->view( $c->config->{default_view} )
      if $c->config->{default_view};
    return $c->_filter_component( $c->_comp_singular(qw/View V/) );
}

=head2 $c->models

Returns the available names which can be passed to $c->model

=cut

sub models {
    my ( $c ) = @_;
    return $c->_comp_names(qw/Model M/);
}


=head2 $c->views

Returns the available names which can be passed to $c->view

=cut

sub views {
    my ( $c ) = @_;
    return $c->_comp_names(qw/View V/);
}

=head2 $c->comp($name)

=head2 $c->component($name)

Gets a component object by name. This method is not recommended,
unless you want to get a specific component by full
class. C<< $c->controller >>, C<< $c->model >>, and C<< $c->view >>
should be used instead.

=cut

sub component {
    my $c = shift;

    if (@_) {

        my $name = shift;

        my $appclass = ref $c || $c;

        my @names = (
            $name, "${appclass}::${name}",
            map { "${appclass}::${_}::${name}" }
              qw/Model M Controller C View V/
        );

        my $comp = $c->_comp_explicit(@names);
        return $c->_filter_component( $comp, @_ ) if defined($comp);

        $comp = $c->_comp_search($name);
        return $c->_filter_component( $comp, @_ ) if defined($comp);
    }

    return sort keys %{ $c->components };
}



=head2 CLASS DATA AND HELPER CLASSES

=head2 $c->config

Returns or takes a hashref containing the application's configuration.

    __PACKAGE__->config( { db => 'dsn:SQLite:foo.db' } );

You can also use a C<YAML>, C<XML> or C<Config::General> config file
like myapp.yml in your applications home directory. See
L<Catalyst::Plugin::ConfigLoader>.

    ---
    db: dsn:SQLite:foo.db


=cut

sub config {
    my $c = shift;

    $c->log->warn("Setting config after setup has been run is not a good idea.")
      if ( @_ and $c->setup_finished );

    $c->NEXT::config(@_);
}

=head2 $c->log

Returns the logging object instance. Unless it is already set, Catalyst
sets this up with a L<Catalyst::Log> object. To use your own log class,
set the logger with the C<< __PACKAGE__->log >> method prior to calling
C<< __PACKAGE__->setup >>.

 __PACKAGE__->log( MyLogger->new );
 __PACKAGE__->setup;

And later:

    $c->log->info( 'Now logging with my own logger!' );

Your log class should implement the methods described in
L<Catalyst::Log>.


=head2 $c->debug

Overload to enable debug messages (same as -Debug option).

Note that this is a static method, not an accessor and should be overloaded
by declaring "sub debug { 1 }" in your MyApp.pm, not by calling $c->debug(1).

=cut

sub debug { 0 }

=head2 $c->dispatcher

Returns the dispatcher instance. Stringifies to class name. See
L<Catalyst::Dispatcher>.

=head2 $c->engine

Returns the engine instance. Stringifies to the class name. See
L<Catalyst::Engine>.


=head2 UTILITY METHODS

=head2 $c->path_to(@path)

Merges C<@path> with C<< $c->config->{home} >> and returns a
L<Path::Class::Dir> object.

For example:

    $c->path_to( 'db', 'sqlite.db' );

=cut

sub path_to {
    my ( $c, @path ) = @_;
    my $path = Path::Class::Dir->new( $c->config->{home}, @path );
    if ( -d $path ) { return $path }
    else { return Path::Class::File->new( $c->config->{home}, @path ) }
}

=head2 $c->plugin( $name, $class, @args )

Helper method for plugins. It creates a classdata accessor/mutator and
loads and instantiates the given class.

    MyApp->plugin( 'prototype', 'HTML::Prototype' );

    $c->prototype->define_javascript_functions;

=cut

sub plugin {
    my ( $class, $name, $plugin, @args ) = @_;
    $class->_register_plugin( $plugin, 1 );

    eval { $plugin->import };
    $class->mk_classdata($name);
    my $obj;
    eval { $obj = $plugin->new(@args) };

    if ($@) {
        Catalyst::Exception->throw( message =>
              qq/Couldn't instantiate instant plugin "$plugin", "$@"/ );
    }

    $class->$name($obj);
    $class->log->debug(qq/Initialized instant plugin "$plugin" as "$name"/)
      if $class->debug;
}

=head2 MyApp->setup

Initializes the dispatcher and engine, loads any plugins, and loads the
model, view, and controller components. You may also specify an array
of plugins to load here, if you choose to not load them in the C<use
Catalyst> line.

    MyApp->setup;
    MyApp->setup( qw/-Debug/ );

=cut

sub setup {
    my ( $class, @arguments ) = @_;

    $class->log->warn("Running setup twice is not a good idea.")
      if ( $class->setup_finished );

    unless ( $class->isa('Catalyst') ) {

        Catalyst::Exception->throw(
            message => qq/'$class' does not inherit from Catalyst/ );
    }

    if ( $class->arguments ) {
        @arguments = ( @arguments, @{ $class->arguments } );
    }

    # Process options
    my $flags = {};

    foreach (@arguments) {

        if (/^-Debug$/) {
            $flags->{log} =
              ( $flags->{log} ) ? 'debug,' . $flags->{log} : 'debug';
        }
        elsif (/^-(\w+)=?(.*)$/) {
            $flags->{ lc $1 } = $2;
        }
        else {
            push @{ $flags->{plugins} }, $_;
        }
    }

    $class->setup_home( delete $flags->{home} );

    $class->setup_log( delete $flags->{log} );
    $class->setup_plugins( delete $flags->{plugins} );
    $class->setup_dispatcher( delete $flags->{dispatcher} );
    $class->setup_engine( delete $flags->{engine} );
    $class->setup_stats( delete $flags->{stats} );

    for my $flag ( sort keys %{$flags} ) {

        if ( my $code = $class->can( 'setup_' . $flag ) ) {
            &$code( $class, delete $flags->{$flag} );
        }
        else {
            $class->log->warn(qq/Unknown flag "$flag"/);
        }
    }

    eval { require Catalyst::Devel; };
    if( !$@ && $ENV{CATALYST_SCRIPT_GEN} && ( $ENV{CATALYST_SCRIPT_GEN} < $Catalyst::Devel::CATALYST_SCRIPT_GEN ) ) {
        $class->log->warn(<<"EOF");
You are running an old script!

  Please update by running (this will overwrite existing files):
    catalyst.pl -force -scripts $class

  or (this will not overwrite existing files):
    catalyst.pl -scripts $class

EOF
    }
    
    if ( $class->debug ) {
        my @plugins = map { "$_  " . ( $_->VERSION || '' ) } $class->registered_plugins;

        if (@plugins) {
            my $t = Text::SimpleTable->new(74);
            $t->row($_) for @plugins;
            $class->log->debug( "Loaded plugins:\n" . $t->draw . "\n" );
        }

        my $dispatcher = $class->dispatcher;
        my $engine     = $class->engine;
        my $home       = $class->config->{home};

        $class->log->debug(qq/Loaded dispatcher "$dispatcher"/);
        $class->log->debug(qq/Loaded engine "$engine"/);

        $home
          ? ( -d $home )
          ? $class->log->debug(qq/Found home "$home"/)
          : $class->log->debug(qq/Home "$home" doesn't exist/)
          : $class->log->debug(q/Couldn't find home/);
    }

    # Call plugins setup
    {
        no warnings qw/redefine/;
        local *setup = sub { };
        $class->setup;
    }

    # Initialize our data structure
    $class->components( {} );

    $class->setup_components;

    if ( $class->debug ) {
        my $t = Text::SimpleTable->new( [ 63, 'Class' ], [ 8, 'Type' ] );
        for my $comp ( sort keys %{ $class->components } ) {
            my $type = ref $class->components->{$comp} ? 'instance' : 'class';
            $t->row( $comp, $type );
        }
        $class->log->debug( "Loaded components:\n" . $t->draw . "\n" )
          if ( keys %{ $class->components } );
    }

    # Add our self to components, since we are also a component
    $class->components->{$class} = $class;

    $class->setup_actions;

    if ( $class->debug ) {
        my $name = $class->config->{name} || 'Application';
        $class->log->info("$name powered by Catalyst $Catalyst::VERSION");
    }
    $class->log->_flush() if $class->log->can('_flush');

    $class->setup_finished(1);
}

=head2 $c->uri_for( $path, @args?, \%query_values? )

Merges path with C<< $c->request->base >> for absolute URIs and with
C<< $c->namespace >> for relative URIs, then returns a normalized L<URI>
object. If any args are passed, they are added at the end of the path.
If the last argument to C<uri_for> is a hash reference, it is assumed to
contain GET parameter key/value pairs, which will be appended to the URI
in standard fashion.

Instead of C<$path>, you can also optionally pass a C<$action> object
which will be resolved to a path using
C<< $c->dispatcher->uri_for_action >>; if the first element of
C<@args> is an arrayref it is treated as a list of captures to be passed
to C<uri_for_action>.

=cut

sub uri_for {
    my ( $c, $path, @args ) = @_;

    if ( Scalar::Util::blessed($path) ) { # action object
        my $captures = ( scalar @args && ref $args[0] eq 'ARRAY'
                         ? shift(@args)
                         : [] );
        $path = $c->dispatcher->uri_for_action($path, $captures);
        return undef unless defined($path);
        $path = '/' if $path eq '';
    }

    undef($path) if (defined $path && $path eq '');

    my $params =
      ( scalar @args && ref $args[$#args] eq 'HASH' ? pop @args : {} );

    carp "uri_for called with undef argument" if grep { ! defined $_ } @args;
    s/([^$URI::uric])/$URI::Escape::escapes{$1}/go for @args;

    unshift(@args, $path);

    unless (defined $path && $path =~ s!^/!!) { # in-place strip
        my $namespace = $c->namespace;
        if (defined $path) { # cheesy hack to handle path '../foo'
           $namespace =~ s{(?:^|/)[^/]+$}{} while $args[0] =~ s{^\.\./}{};
        }
        unshift(@args, $namespace || '');
    }
    
    # join args with '/', or a blank string
    my $args = join('/', grep { defined($_) } @args);
    $args =~ s/\?/%3F/g; # STUPID STUPID SPECIAL CASE
    $args =~ s!^/!!;
    my $base = $c->req->base;
    my $class = ref($base);
    $base =~ s{(?<!/)$}{/};

    my $query = '';

    if (my @keys = keys %$params) {
      # somewhat lifted from URI::_query's query_form
      $query = '?'.join('&', map {
          s/([;\/?:@&=+,\$\[\]%])/$URI::Escape::escapes{$1}/go;
          s/ /+/g;
          my $key = $_;
          my $val = $params->{$_};
          $val = '' unless defined $val;
          (map {
              $_ = "$_";
              utf8::encode( $_ );
              # using the URI::Escape pattern here so utf8 chars survive
              s/([^A-Za-z0-9\-_.!~*'() ])/$URI::Escape::escapes{$1}/go;
              s/ /+/g;
              "${key}=$_"; } ( ref $val eq 'ARRAY' ? @$val : $val ));
      } @keys);
    }

    my $res = bless(\"${base}${args}${query}", $class);
    $res;
}

=head2 $c->welcome_message

Returns the Catalyst welcome HTML page.

=cut

sub welcome_message {
    my $c      = shift;
    my $name   = $c->config->{name};
    my $logo   = $c->uri_for('/static/images/catalyst_logo.png');
    my $prefix = Catalyst::Utils::appprefix( ref $c );
    $c->response->content_type('text/html; charset=utf-8');
    return <<"EOF";
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
    <meta http-equiv="Content-Language" content="en" />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>$name on Catalyst $VERSION</title>
        <style type="text/css">
            body {
                color: #000;
                background-color: #eee;
            }
            div#content {
                width: 640px;
                margin-left: auto;
                margin-right: auto;
                margin-top: 10px;
                margin-bottom: 10px;
                text-align: left;
                background-color: #ccc;
                border: 1px solid #aaa;
            }
            p, h1, h2 {
                margin-left: 20px;
                margin-right: 20px;
                font-family: verdana, tahoma, sans-serif;
            }
            a {
                font-family: verdana, tahoma, sans-serif;
            }
            :link, :visited {
                    text-decoration: none;
                    color: #b00;
                    border-bottom: 1px dotted #bbb;
            }
            :link:hover, :visited:hover {
                    color: #555;
            }
            div#topbar {
                margin: 0px;
            }
            pre {
                margin: 10px;
                padding: 8px;
            }
            div#answers {
                padding: 8px;
                margin: 10px;
                background-color: #fff;
                border: 1px solid #aaa;
            }
            h1 {
                font-size: 0.9em;
                font-weight: normal;
                text-align: center;
            }
            h2 {
                font-size: 1.0em;
            }
            p {
                font-size: 0.9em;
            }
            p img {
                float: right;
                margin-left: 10px;
            }
            span#appname {
                font-weight: bold;
                font-size: 1.6em;
            }
        </style>
    </head>
    <body>
        <div id="content">
            <div id="topbar">
                <h1><span id="appname">$name</span> on <a href="http://catalyst.perl.org">Catalyst</a>
                    $VERSION</h1>
             </div>
             <div id="answers">
                 <p>
                 <img src="$logo" alt="Catalyst Logo" />
                 </p>
                 <p>Welcome to the  world of Catalyst.
                    This <a href="http://en.wikipedia.org/wiki/MVC">MVC</a>
                    framework will make web development something you had
                    never expected it to be: Fun, rewarding, and quick.</p>
                 <h2>What to do now?</h2>
                 <p>That really depends  on what <b>you</b> want to do.
                    We do, however, provide you with a few starting points.</p>
                 <p>If you want to jump right into web development with Catalyst
                    you might want want to start with a tutorial.</p>
<pre>perldoc <a href="http://cpansearch.perl.org/dist/Catalyst-Manual/lib/Catalyst/Manual/Tutorial.pod">Catalyst::Manual::Tutorial</a></code>
</pre>
<p>Afterwards you can go on to check out a more complete look at our features.</p>
<pre>
<code>perldoc <a href="http://cpansearch.perl.org/dist/Catalyst-Manual/lib/Catalyst/Manual/Intro.pod">Catalyst::Manual::Intro</a>
<!-- Something else should go here, but the Catalyst::Manual link seems unhelpful -->
</code></pre>
                 <h2>What to do next?</h2>
                 <p>Next it's time to write an actual application. Use the
                    helper scripts to generate <a href="http://cpansearch.perl.org/search?query=Catalyst%3A%3AController%3A%3A&amp;mode=all">controllers</a>,
                    <a href="http://cpansearch.perl.org/search?query=Catalyst%3A%3AModel%3A%3A&amp;mode=all">models</a>, and
                    <a href="http://cpansearch.perl.org/search?query=Catalyst%3A%3AView%3A%3A&amp;mode=all">views</a>;
                    they can save you a lot of work.</p>
                    <pre><code>script/${prefix}_create.pl -help</code></pre>
                    <p>Also, be sure to check out the vast and growing
                    collection of <a href="http://cpansearch.perl.org/search?query=Catalyst%3A%3APlugin%3A%3A&amp;mode=all">plugins for Catalyst on CPAN</a>;
                    you are likely to find what you need there.
                    </p>

                 <h2>Need help?</h2>
                 <p>Catalyst has a very active community. Here are the main places to
                    get in touch with us.</p>
                 <ul>
                     <li>
                         <a href="http://dev.catalyst.perl.org">Wiki</a>
                     </li>
                     <li>
                         <a href="http://lists.rawmode.org/mailman/listinfo/catalyst">Mailing-List</a>
                     </li>
                     <li>
                         <a href="irc://irc.perl.org/catalyst">IRC channel #catalyst on irc.perl.org</a>
                     </li>
                 </ul>
                 <h2>In conclusion</h2>
                 <p>The Catalyst team hopes you will enjoy using Catalyst as much 
                    as we enjoyed making it. Please contact us if you have ideas
                    for improvement or other feedback.</p>
             </div>
         </div>
    </body>
</html>
EOF
}

=head1 INTERNAL METHODS

These methods are not meant to be used by end users.

=head2 $c->components

Returns a hash of components.

=head2 $c->context_class

Returns or sets the context class.

=head2 $c->counter

Returns a hashref containing coderefs and execution counts (needed for
deep recursion detection).

=head2 $c->depth

Returns the number of actions on the current internal execution stack.

=head2 $c->dispatch

Dispatches a request to actions.

=cut

sub dispatch { my $c = shift; $c->dispatcher->dispatch( $c, @_ ) }

=head2 $c->dispatcher_class

Returns or sets the dispatcher class.

=head2 $c->dump_these

Returns a list of 2-element array references (name, structure) pairs
that will be dumped on the error page in debug mode.

=cut

sub dump_these {
    my $c = shift;
    [ Request => $c->req ], 
    [ Response => $c->res ], 
    [ Stash => $c->stash ],
    [ Config => $c->config ];
}

=head2 $c->engine_class

Returns or sets the engine class.

=head2 $c->execute( $class, $coderef )

Execute a coderef in given class and catch exceptions. Errors are available
via $c->error.

=cut

sub execute {
    my ( $c, $class, $code ) = @_;
    $class = $c->component($class) || $class;
    $c->state(0);

    if ( $c->depth >= $RECURSION ) {
        my $action = "$code";
        $action = "/$action" unless $action =~ /->/;
        my $error = qq/Deep recursion detected calling "$action"/;
        $c->log->error($error);
        $c->error($error);
        $c->state(0);
        return $c->state;
    }

    my $stats_info = $c->_stats_start_execute( $code ) if $c->use_stats;

    push( @{ $c->stack }, $code );
    
    eval { $c->state( &$code( $class, $c, @{ $c->req->args } ) || 0 ) };

    $c->_stats_finish_execute( $stats_info ) if $c->use_stats and $stats_info;
    
    my $last = pop( @{ $c->stack } );

    if ( my $error = $@ ) {
        if ( !ref($error) and $error eq $DETACH ) { die $DETACH if $c->depth > 1 }
        else {
            unless ( ref $error ) {
                no warnings 'uninitialized';
                chomp $error;
                my $class = $last->class;
                my $name  = $last->name;
                $error = qq/Caught exception in $class->$name "$error"/;
            }
            $c->error($error);
            $c->state(0);
        }
    }
    return $c->state;
}

sub _stats_start_execute {
    my ( $c, $code ) = @_;

    return if ( ( $code->name =~ /^_.*/ )
        && ( !$c->config->{show_internal_actions} ) );

    $c->counter->{"$code"}++;

    my $action = "$code";
    $action = "/$action" unless $action =~ /->/;

    # determine if the call was the result of a forward
    # this is done by walking up the call stack and looking for a calling
    # sub of Catalyst::forward before the eval
    my $callsub = q{};
    for my $index ( 2 .. 11 ) {
        last
        if ( ( caller($index) )[0] eq 'Catalyst'
            && ( caller($index) )[3] eq '(eval)' );

        if ( ( caller($index) )[3] =~ /forward$/ ) {
            $callsub = ( caller($index) )[3];
            $action  = "-> $action";
            last;
        }
    }

    my $uid = "$code" . $c->counter->{"$code"};

    # is this a root-level call or a forwarded call?
    if ( $callsub =~ /forward$/ ) {

        # forward, locate the caller
        if ( my $parent = $c->stack->[-1] ) {
            $c->stats->profile(begin => $action, 
                               parent => "$parent" . $c->counter->{"$parent"},
			       uid => $uid);
        }
        else {

            # forward with no caller may come from a plugin
            $c->stats->profile(begin => $action,
			       uid => $uid);
        }
    }
    else {
        
        # root-level call
        $c->stats->profile(begin => $action,
			   uid => $uid);
    }
    return $action;

}

sub _stats_finish_execute {
    my ( $c, $info ) = @_;
    $c->stats->profile(end => $info);
}

=head2 $c->_localize_fields( sub { }, \%keys );

=cut

sub _localize_fields {
    my ( $c, $localized, $code ) = ( @_ );

    my $request = delete $localized->{request} || {};
    my $response = delete $localized->{response} || {};
    
    local @{ $c }{ keys %$localized } = values %$localized;
    local @{ $c->request }{ keys %$request } = values %$request;
    local @{ $c->response }{ keys %$response } = values %$response;

    $code->();
}

=head2 $c->finalize

Finalizes the request.

=cut

sub finalize {
    my $c = shift;

    for my $error ( @{ $c->error } ) {
        $c->log->error($error);
    }

    # Allow engine to handle finalize flow (for POE)
    if ( $c->engine->can('finalize') ) {
        $c->engine->finalize($c);
    }
    else {

        $c->finalize_uploads;

        # Error
        if ( $#{ $c->error } >= 0 ) {
            $c->finalize_error;
        }

        $c->finalize_headers;

        # HEAD request
        if ( $c->request->method eq 'HEAD' ) {
            $c->response->body('');
        }

        $c->finalize_body;
    }
    
    if ($c->use_stats) {        
        my $elapsed = sprintf '%f', $c->stats->elapsed;
        my $av = $elapsed == 0 ? '??' : sprintf '%.3f', 1 / $elapsed;
        $c->log->info(
            "Request took ${elapsed}s ($av/s)\n" . $c->stats->report . "\n" );        
    }

    return $c->response->status;
}

=head2 $c->finalize_body

Finalizes body.

=cut

sub finalize_body { my $c = shift; $c->engine->finalize_body( $c, @_ ) }

=head2 $c->finalize_cookies

Finalizes cookies.

=cut

sub finalize_cookies { my $c = shift; $c->engine->finalize_cookies( $c, @_ ) }

=head2 $c->finalize_error

Finalizes error.

=cut

sub finalize_error { my $c = shift; $c->engine->finalize_error( $c, @_ ) }

=head2 $c->finalize_headers

Finalizes headers.

=cut

sub finalize_headers {
    my $c = shift;

    # Check if we already finalized headers
    return if $c->response->{_finalized_headers};

    # Handle redirects
    if ( my $location = $c->response->redirect ) {
        $c->log->debug(qq/Redirecting to "$location"/) if $c->debug;
        $c->response->header( Location => $location );
        
        if ( !$c->response->body ) {
            # Add a default body if none is already present
            $c->response->body(
                qq{<html><body><p>This item has moved <a href="$location">here</a>.</p></body></html>}
            );
        }
    }

    # Content-Length
    if ( $c->response->body && !$c->response->content_length ) {

        # get the length from a filehandle
        if ( blessed( $c->response->body ) && $c->response->body->can('read') )
        {
            my $stat = stat $c->response->body;
            if ( $stat && $stat->size > 0 ) {
                $c->response->content_length( $stat->size );
            }
            else {
                $c->log->warn('Serving filehandle without a content-length');
            }
        }
        else {
            $c->response->content_length( bytes::length( $c->response->body ) );
        }
    }

    # Errors
    if ( $c->response->status =~ /^(1\d\d|[23]04)$/ ) {
        $c->response->headers->remove_header("Content-Length");
        $c->response->body('');
    }

    $c->finalize_cookies;

    $c->engine->finalize_headers( $c, @_ );

    # Done
    $c->response->{_finalized_headers} = 1;
}

=head2 $c->finalize_output

An alias for finalize_body.

=head2 $c->finalize_read

Finalizes the input after reading is complete.

=cut

sub finalize_read { my $c = shift; $c->engine->finalize_read( $c, @_ ) }

=head2 $c->finalize_uploads

Finalizes uploads. Cleans up any temporary files.

=cut

sub finalize_uploads { my $c = shift; $c->engine->finalize_uploads( $c, @_ ) }

=head2 $c->get_action( $action, $namespace )

Gets an action in a given namespace.

=cut

sub get_action { my $c = shift; $c->dispatcher->get_action(@_) }

=head2 $c->get_actions( $action, $namespace )

Gets all actions of a given name in a namespace and all parent
namespaces.

=cut

sub get_actions { my $c = shift; $c->dispatcher->get_actions( $c, @_ ) }

=head2 $c->handle_request( $class, @arguments )

Called to handle each HTTP request.

=cut

sub handle_request {
    my ( $class, @arguments ) = @_;

    # Always expect worst case!
    my $status = -1;
    eval {
        if ($class->debug) {
            my $secs = time - $START || 1;
            my $av = sprintf '%.3f', $COUNT / $secs;
            my $time = localtime time;
            $class->log->info("*** Request $COUNT ($av/s) [$$] [$time] ***");
        }

        my $c = $class->prepare(@arguments);
        $c->dispatch;
        $status = $c->finalize;   
    };

    if ( my $error = $@ ) {
        chomp $error;
        $class->log->error(qq/Caught exception in engine "$error"/);
    }

    $COUNT++;
    $class->log->_flush() if $class->log->can('_flush');
    return $status;
}

=head2 $c->prepare( @arguments )

Creates a Catalyst context from an engine-specific request (Apache, CGI,
etc.).

=cut

sub prepare {
    my ( $class, @arguments ) = @_;

    $class->context_class( ref $class || $class ) unless $class->context_class;
    my $c = $class->context_class->new(
        {
            counter => {},
            stack   => [],
            request => $class->request_class->new(
                {
                    arguments        => [],
                    body_parameters  => {},
                    cookies          => {},
                    headers          => HTTP::Headers->new,
                    parameters       => {},
                    query_parameters => {},
                    secure           => 0,
                    captures         => [],
                    uploads          => {}
                }
            ),
            response => $class->response_class->new(
                {
                    body    => '',
                    cookies => {},
                    headers => HTTP::Headers->new(),
                    status  => 200
                }
            ),
            stash => {},
            state => 0
        }
    );

    $c->stats($class->stats_class->new)->enable($c->use_stats);
    if ( $c->debug ) {
        $c->res->headers->header( 'X-Catalyst' => $Catalyst::VERSION );            
    }

    # For on-demand data
    $c->request->{_context}  = $c;
    $c->response->{_context} = $c;
    weaken( $c->request->{_context} );
    weaken( $c->response->{_context} );

    # Allow engine to direct the prepare flow (for POE)
    if ( $c->engine->can('prepare') ) {
        $c->engine->prepare( $c, @arguments );
    }
    else {
        $c->prepare_request(@arguments);
        $c->prepare_connection;
        $c->prepare_query_parameters;
        $c->prepare_headers;
        $c->prepare_cookies;
        $c->prepare_path;

        # Prepare the body for reading, either by prepare_body
        # or the user, if they are using $c->read
        $c->prepare_read;
        
        # Parse the body unless the user wants it on-demand
        unless ( $c->config->{parse_on_demand} ) {
            $c->prepare_body;
        }
    }

    my $method  = $c->req->method  || '';
    my $path    = $c->req->path    || '/';
    my $address = $c->req->address || '';

    $c->log->debug(qq/"$method" request for "$path" from "$address"/)
      if $c->debug;

    $c->prepare_action;

    return $c;
}

=head2 $c->prepare_action

Prepares action. See L<Catalyst::Dispatcher>.

=cut

sub prepare_action { my $c = shift; $c->dispatcher->prepare_action( $c, @_ ) }

=head2 $c->prepare_body

Prepares message body.

=cut

sub prepare_body {
    my $c = shift;

    # Do we run for the first time?
    return if defined $c->request->{_body};

    # Initialize on-demand data
    $c->engine->prepare_body( $c, @_ );
    $c->prepare_parameters;
    $c->prepare_uploads;

    if ( $c->debug && keys %{ $c->req->body_parameters } ) {
        my $t = Text::SimpleTable->new( [ 35, 'Parameter' ], [ 36, 'Value' ] );
        for my $key ( sort keys %{ $c->req->body_parameters } ) {
            my $param = $c->req->body_parameters->{$key};
            my $value = defined($param) ? $param : '';
            $t->row( $key,
                ref $value eq 'ARRAY' ? ( join ', ', @$value ) : $value );
        }
        $c->log->debug( "Body Parameters are:\n" . $t->draw );
    }
}

=head2 $c->prepare_body_chunk( $chunk )

Prepares a chunk of data before sending it to L<HTTP::Body>.

See L<Catalyst::Engine>.

=cut

sub prepare_body_chunk {
    my $c = shift;
    $c->engine->prepare_body_chunk( $c, @_ );
}

=head2 $c->prepare_body_parameters

Prepares body parameters.

=cut

sub prepare_body_parameters {
    my $c = shift;
    $c->engine->prepare_body_parameters( $c, @_ );
}

=head2 $c->prepare_connection

Prepares connection.

=cut

sub prepare_connection {
    my $c = shift;
    $c->engine->prepare_connection( $c, @_ );
}

=head2 $c->prepare_cookies

Prepares cookies.

=cut

sub prepare_cookies { my $c = shift; $c->engine->prepare_cookies( $c, @_ ) }

=head2 $c->prepare_headers

Prepares headers.

=cut

sub prepare_headers { my $c = shift; $c->engine->prepare_headers( $c, @_ ) }

=head2 $c->prepare_parameters

Prepares parameters.

=cut

sub prepare_parameters {
    my $c = shift;
    $c->prepare_body_parameters;
    $c->engine->prepare_parameters( $c, @_ );
}

=head2 $c->prepare_path

Prepares path and base.

=cut

sub prepare_path { my $c = shift; $c->engine->prepare_path( $c, @_ ) }

=head2 $c->prepare_query_parameters

Prepares query parameters.

=cut

sub prepare_query_parameters {
    my $c = shift;

    $c->engine->prepare_query_parameters( $c, @_ );

    if ( $c->debug && keys %{ $c->request->query_parameters } ) {
        my $t = Text::SimpleTable->new( [ 35, 'Parameter' ], [ 36, 'Value' ] );
        for my $key ( sort keys %{ $c->req->query_parameters } ) {
            my $param = $c->req->query_parameters->{$key};
            my $value = defined($param) ? $param : '';
            $t->row( $key,
                ref $value eq 'ARRAY' ? ( join ', ', @$value ) : $value );
        }
        $c->log->debug( "Query Parameters are:\n" . $t->draw );
    }
}

=head2 $c->prepare_read

Prepares the input for reading.

=cut

sub prepare_read { my $c = shift; $c->engine->prepare_read( $c, @_ ) }

=head2 $c->prepare_request

Prepares the engine request.

=cut

sub prepare_request { my $c = shift; $c->engine->prepare_request( $c, @_ ) }

=head2 $c->prepare_uploads

Prepares uploads.

=cut

sub prepare_uploads {
    my $c = shift;

    $c->engine->prepare_uploads( $c, @_ );

    if ( $c->debug && keys %{ $c->request->uploads } ) {
        my $t = Text::SimpleTable->new(
            [ 12, 'Parameter' ],
            [ 26, 'Filename' ],
            [ 18, 'Type' ],
            [ 9,  'Size' ]
        );
        for my $key ( sort keys %{ $c->request->uploads } ) {
            my $upload = $c->request->uploads->{$key};
            for my $u ( ref $upload eq 'ARRAY' ? @{$upload} : ($upload) ) {
                $t->row( $key, $u->filename, $u->type, $u->size );
            }
        }
        $c->log->debug( "File Uploads are:\n" . $t->draw );
    }
}

=head2 $c->prepare_write

Prepares the output for writing.

=cut

sub prepare_write { my $c = shift; $c->engine->prepare_write( $c, @_ ) }

=head2 $c->request_class

Returns or sets the request class.

=head2 $c->response_class

Returns or sets the response class.

=head2 $c->read( [$maxlength] )

Reads a chunk of data from the request body. This method is designed to
be used in a while loop, reading C<$maxlength> bytes on every call.
C<$maxlength> defaults to the size of the request if not specified.

You have to set C<< MyApp->config->{parse_on_demand} >> to use this
directly.

Warning: If you use read(), Catalyst will not process the body,
so you will not be able to access POST parameters or file uploads via
$c->request.  You must handle all body parsing yourself.

=cut

sub read { my $c = shift; return $c->engine->read( $c, @_ ) }

=head2 $c->run

Starts the engine.

=cut

sub run { my $c = shift; return $c->engine->run( $c, @_ ) }

=head2 $c->set_action( $action, $code, $namespace, $attrs )

Sets an action in a given namespace.

=cut

sub set_action { my $c = shift; $c->dispatcher->set_action( $c, @_ ) }

=head2 $c->setup_actions($component)

Sets up actions for a component.

=cut

sub setup_actions { my $c = shift; $c->dispatcher->setup_actions( $c, @_ ) }

=head2 $c->setup_components

Sets up components. Specify a C<setup_components> config option to pass
additional options directly to L<Module::Pluggable>. To add additional
search paths, specify a key named C<search_extra> as an array
reference. Items in the array beginning with C<::> will have the
application class name prepended to them.

=cut

sub setup_components {
    my $class = shift;

    my @paths   = qw( ::Controller ::C ::Model ::M ::View ::V );
    my $config  = $class->config->{ setup_components };
    my $extra   = delete $config->{ search_extra } || [];
    
    push @paths, @$extra;
        
    my $locator = Module::Pluggable::Object->new(
        search_path => [ map { s/^(?=::)/$class/; $_; } @paths ],
        %$config
    );

    my @comps = sort { length $a <=> length $b } $locator->plugins;
    my %comps = map { $_ => 1 } @comps;
    
    for my $component ( @comps ) {

        # We pass ignore_loaded here so that overlay files for (e.g.)
        # Model::DBI::Schema sub-classes are loaded - if it's in @comps
        # we know M::P::O found a file on disk so this is safe

        Catalyst::Utils::ensure_class_loaded( $component, { ignore_loaded => 1 } );

        my $module  = $class->setup_component( $component );
        my %modules = (
            $component => $module,
            map {
                $_ => $class->setup_component( $_ )
            } grep { 
              not exists $comps{$_}
            } Devel::InnerPackage::list_packages( $component )
        );
        
        for my $key ( keys %modules ) {
            $class->components->{ $key } = $modules{ $key };
        }
    }
}

=head2 $c->setup_component

=cut

sub setup_component {
    my( $class, $component ) = @_;

    unless ( $component->can( 'COMPONENT' ) ) {
        return $component;
    }

    my $suffix = Catalyst::Utils::class2classsuffix( $component );
    my $config = $class->config->{ $suffix } || {};

    my $instance = eval { $component->COMPONENT( $class, $config ); };

    if ( my $error = $@ ) {
        chomp $error;
        Catalyst::Exception->throw(
            message => qq/Couldn't instantiate component "$component", "$error"/
        );
    }

    Catalyst::Exception->throw(
        message =>
        qq/Couldn't instantiate component "$component", "COMPONENT() didn't return an object-like value"/
    ) unless eval { $instance->can( 'can' ) };

    return $instance;
}

=head2 $c->setup_dispatcher

Sets up dispatcher.

=cut

sub setup_dispatcher {
    my ( $class, $dispatcher ) = @_;

    if ($dispatcher) {
        $dispatcher = 'Catalyst::Dispatcher::' . $dispatcher;
    }

    if ( my $env = Catalyst::Utils::env_value( $class, 'DISPATCHER' ) ) {
        $dispatcher = 'Catalyst::Dispatcher::' . $env;
    }

    unless ($dispatcher) {
        $dispatcher = $class->dispatcher_class;
    }

    unless (Class::Inspector->loaded($dispatcher)) {
        require Class::Inspector->filename($dispatcher);
    }

    # dispatcher instance
    $class->dispatcher( $dispatcher->new );
}

=head2 $c->setup_engine

Sets up engine.

=cut

sub setup_engine {
    my ( $class, $engine ) = @_;

    if ($engine) {
        $engine = 'Catalyst::Engine::' . $engine;
    }

    if ( my $env = Catalyst::Utils::env_value( $class, 'ENGINE' ) ) {
        $engine = 'Catalyst::Engine::' . $env;
    }

    if ( $ENV{MOD_PERL} ) {

        # create the apache method
        {
            no strict 'refs';
            *{"$class\::apache"} = sub { shift->engine->apache };
        }

        my ( $software, $version ) =
          $ENV{MOD_PERL} =~ /^(\S+)\/(\d+(?:[\.\_]\d+)+)/;

        $version =~ s/_//g;
        $version =~ s/(\.[^.]+)\./$1/g;

        if ( $software eq 'mod_perl' ) {

            if ( !$engine ) {

                if ( $version >= 1.99922 ) {
                    $engine = 'Catalyst::Engine::Apache2::MP20';
                }

                elsif ( $version >= 1.9901 ) {
                    $engine = 'Catalyst::Engine::Apache2::MP19';
                }

                elsif ( $version >= 1.24 ) {
                    $engine = 'Catalyst::Engine::Apache::MP13';
                }

                else {
                    Catalyst::Exception->throw( message =>
                          qq/Unsupported mod_perl version: $ENV{MOD_PERL}/ );
                }

            }

            # install the correct mod_perl handler
            if ( $version >= 1.9901 ) {
                *handler = sub  : method {
                    shift->handle_request(@_);
                };
            }
            else {
                *handler = sub ($$) { shift->handle_request(@_) };
            }

        }

        elsif ( $software eq 'Zeus-Perl' ) {
            $engine = 'Catalyst::Engine::Zeus';
        }

        else {
            Catalyst::Exception->throw(
                message => qq/Unsupported mod_perl: $ENV{MOD_PERL}/ );
        }
    }

    unless ($engine) {
        $engine = $class->engine_class;
    }

    unless (Class::Inspector->loaded($engine)) {
        require Class::Inspector->filename($engine);
    }

    # check for old engines that are no longer compatible
    my $old_engine;
    if ( $engine->isa('Catalyst::Engine::Apache')
        && !Catalyst::Engine::Apache->VERSION )
    {
        $old_engine = 1;
    }

    elsif ( $engine->isa('Catalyst::Engine::Server::Base')
        && Catalyst::Engine::Server->VERSION le '0.02' )
    {
        $old_engine = 1;
    }

    elsif ($engine->isa('Catalyst::Engine::HTTP::POE')
        && $engine->VERSION eq '0.01' )
    {
        $old_engine = 1;
    }

    elsif ($engine->isa('Catalyst::Engine::Zeus')
        && $engine->VERSION eq '0.01' )
    {
        $old_engine = 1;
    }

    if ($old_engine) {
        Catalyst::Exception->throw( message =>
              qq/Engine "$engine" is not supported by this version of Catalyst/
        );
    }

    # engine instance
    $class->engine( $engine->new );
}

=head2 $c->setup_home

Sets up the home directory.

=cut

sub setup_home {
    my ( $class, $home ) = @_;

    if ( my $env = Catalyst::Utils::env_value( $class, 'HOME' ) ) {
        $home = $env;
    }

    unless ($home) {
        $home = Catalyst::Utils::home($class);
    }

    if ($home) {
        $class->config->{home} ||= $home;
        $class->config->{root} ||= Path::Class::Dir->new($home)->subdir('root');
    }
}

=head2 $c->setup_log

Sets up log.

=cut

sub setup_log {
    my ( $class, $debug ) = @_;

    unless ( $class->log ) {
        $class->log( Catalyst::Log->new );
    }

    my $env_debug = Catalyst::Utils::env_value( $class, 'DEBUG' );
    if ( defined($env_debug) ? $env_debug : $debug ) {
        no strict 'refs';
        *{"$class\::debug"} = sub { 1 };
        $class->log->debug('Debug messages enabled');
    }
}

=head2 $c->setup_plugins

Sets up plugins.

=cut

=head2 $c->setup_stats

Sets up timing statistics class.

=cut

sub setup_stats {
    my ( $class, $stats ) = @_;

    Catalyst::Utils::ensure_class_loaded($class->stats_class);

    my $env = Catalyst::Utils::env_value( $class, 'STATS' );
    if ( defined($env) ? $env : ($stats || $class->debug ) ) {
        no strict 'refs';
        *{"$class\::use_stats"} = sub { 1 };
        $class->log->debug('Statistics enabled');
    }
}


=head2 $c->registered_plugins 

Returns a sorted list of the plugins which have either been stated in the
import list or which have been added via C<< MyApp->plugin(@args); >>.

If passed a given plugin name, it will report a boolean value indicating
whether or not that plugin is loaded.  A fully qualified name is required if
the plugin name does not begin with C<Catalyst::Plugin::>.

 if ($c->registered_plugins('Some::Plugin')) {
     ...
 }

=cut

{

    sub registered_plugins {
        my $proto = shift;
        return sort keys %{ $proto->_plugins } unless @_;
        my $plugin = shift;
        return 1 if exists $proto->_plugins->{$plugin};
        return exists $proto->_plugins->{"Catalyst::Plugin::$plugin"};
    }

    sub _register_plugin {
        my ( $proto, $plugin, $instant ) = @_;
        my $class = ref $proto || $proto;

        # no ignore_loaded here, the plugin may already have been
        # defined in memory and we don't want to error on "no file" if so

        Catalyst::Utils::ensure_class_loaded( $plugin );

        $proto->_plugins->{$plugin} = 1;
        unless ($instant) {
            no strict 'refs';
            unshift @{"$class\::ISA"}, $plugin;
        }
        return $class;
    }

    sub setup_plugins {
        my ( $class, $plugins ) = @_;

        $class->_plugins( {} ) unless $class->_plugins;
        $plugins ||= [];
        for my $plugin ( reverse @$plugins ) {

            unless ( $plugin =~ s/\A\+// ) {
                $plugin = "Catalyst::Plugin::$plugin";
            }

            $class->_register_plugin($plugin);
        }
    }
}

=head2 $c->stack

Returns an arrayref of the internal execution stack (actions that are
currently executing).

=head2 $c->stats_class

Returns or sets the stats (timing statistics) class.

=head2 $c->use_stats

Returns 1 when stats collection is enabled.  Stats collection is enabled
when the -Stats options is set, debug is on or when the <MYAPP>_STATS
environment variable is set.

Note that this is a static method, not an accessor and should be overloaded
by declaring "sub use_stats { 1 }" in your MyApp.pm, not by calling $c->use_stats(1).

=cut

sub use_stats { 0 }


=head2 $c->write( $data )

Writes $data to the output stream. When using this method directly, you
will need to manually set the C<Content-Length> header to the length of
your output data, if known.

=cut

sub write {
    my $c = shift;

    # Finalize headers if someone manually writes output
    $c->finalize_headers;

    return $c->engine->write( $c, @_ );
}

=head2 version

Returns the Catalyst version number. Mostly useful for "powered by"
messages in template systems.

=cut

sub version { return $Catalyst::VERSION }

=head1 INTERNAL ACTIONS

Catalyst uses internal actions like C<_DISPATCH>, C<_BEGIN>, C<_AUTO>,
C<_ACTION>, and C<_END>. These are by default not shown in the private
action table, but you can make them visible with a config parameter.

    MyApp->config->{show_internal_actions} = 1;

=head1 CASE SENSITIVITY

By default Catalyst is not case sensitive, so C<MyApp::C::FOO::Bar> is
mapped to C</foo/bar>. You can activate case sensitivity with a config
parameter.

    MyApp->config->{case_sensitive} = 1;

This causes C<MyApp::C::Foo::Bar> to map to C</Foo/Bar>.

=head1 ON-DEMAND PARSER

The request body is usually parsed at the beginning of a request,
but if you want to handle input yourself, you can enable on-demand
parsing with a config parameter.

    MyApp->config->{parse_on_demand} = 1;
    
=head1 PROXY SUPPORT

Many production servers operate using the common double-server approach,
with a lightweight frontend web server passing requests to a larger
backend server. An application running on the backend server must deal
with two problems: the remote user always appears to be C<127.0.0.1> and
the server's hostname will appear to be C<localhost> regardless of the
virtual host that the user connected through.

Catalyst will automatically detect this situation when you are running
the frontend and backend servers on the same machine. The following
changes are made to the request.

    $c->req->address is set to the user's real IP address, as read from 
    the HTTP X-Forwarded-For header.
    
    The host value for $c->req->base and $c->req->uri is set to the real
    host, as read from the HTTP X-Forwarded-Host header.

Obviously, your web server must support these headers for this to work.

In a more complex server farm environment where you may have your
frontend proxy server(s) on different machines, you will need to set a
configuration option to tell Catalyst to read the proxied data from the
headers.

    MyApp->config->{using_frontend_proxy} = 1;
    
If you do not wish to use the proxy support at all, you may set:

    MyApp->config->{ignore_frontend_proxy} = 1;

=head1 THREAD SAFETY

Catalyst has been tested under Apache 2's threading C<mpm_worker>,
C<mpm_winnt>, and the standalone forking HTTP server on Windows. We
believe the Catalyst core to be thread-safe.

If you plan to operate in a threaded environment, remember that all other
modules you are using must also be thread-safe. Some modules, most notably
L<DBD::SQLite>, are not thread-safe.

=head1 SUPPORT

IRC:

    Join #catalyst on irc.perl.org.

Mailing Lists:

    http://lists.rawmode.org/mailman/listinfo/catalyst
    http://lists.rawmode.org/mailman/listinfo/catalyst-dev

Web:

    http://catalyst.perl.org

Wiki:

    http://dev.catalyst.perl.org

=head1 SEE ALSO

=head2 L<Task::Catalyst> - All you need to start with Catalyst

=head2 L<Catalyst::Manual> - The Catalyst Manual

=head2 L<Catalyst::Component>, L<Catalyst::Base> - Base classes for components

=head2 L<Catalyst::Engine> - Core engine

=head2 L<Catalyst::Log> - Log class.

=head2 L<Catalyst::Request> - Request object

=head2 L<Catalyst::Response> - Response object

=head2 L<Catalyst::Test> - The test suite.

=head1 CREDITS

Andy Grundman

Andy Wardley

Andreas Marienborg

Andrew Bramble

Andrew Ford

Andrew Ruthven

Arthur Bergman

Autrijus Tang

Brian Cassidy

Carl Franks

Christian Hansen

Christopher Hicks

Dan Sully

Danijel Milicevic

David Kamholz

David Naughton

Drew Taylor

Gary Ashton Jones

Geoff Richards

Jesse Sheidlower

Jesse Vincent

Jody Belka

Johan Lindstrom

Juan Camacho

Leon Brocard

Marcus Ramberg

Matt S Trout

Robert Sedlacek

Sam Vilain

Sascha Kiefer

Sebastian Willert

Tatsuhiko Miyagawa

Ulf Edvinsson

Yuval Kogman

=head1 AUTHOR

Sebastian Riedel, C<sri@oook.de>

=head1 LICENSE

This library is free software, you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut

1;