package HTML::Form;

use strict;
use URI;
use Carp ();

use vars qw($VERSION);

$VERSION='1.00';

my %form_tags = map {$_ => 1} qw(input textarea button select option);

my %type2class = (
 text     => "TextInput",
 password => "TextInput",
 hidden   => "TextInput",
 textarea => "TextInput",

 button   => "IgnoreInput",
 "reset"  => "IgnoreInput",

 radio    => "ListInput",
 checkbox => "ListInput",
 option   => "ListInput",

 submit   => "SubmitInput",
 image    => "ImageInput",
 file     => "FileInput",
);

=head1 NAME

HTML::Form - Class that represents an HTML form element

=head1 SYNOPSIS

 use HTML::Form;
 $form = HTML::Form->parse($html, $base_uri);
 $form->value(query => "Perl");

 use LWP::UserAgent;
 $ua = LWP::UserAgent->new;
 $response = $ua->request($form->click);

=head1 DESCRIPTION

Objects of the C<HTML::Form> class represents a single HTML
C<E<lt>formE<gt> ... E<lt>/formE<gt>> instance.  A form consist of a
sequence of inputs that usually have names, and which can take on
various values.  The state of a form can be tweaked and it can then be
asked to provide HTTP::Request objects that can be passed to LWP.

The following constructor methods are available:

=over 4

=item @forms = HTML::Form->parse( $html_document, $base_uri )

The parse() class method will parse an HTML document and build up
C<HTML::Form> objects for each <form> element found.  If called in scalar
context only returns the first <form>.  Returns an empty list if there
are no forms to be found.

The $base_uri is (usually) the URI used to retrieve the $html_document.
It is needed to resolve relative action URIs.  For LWP this parameter
is obtained from the $response->base() method.

=cut

sub parse
{
    my($class, $html, $base_uri) = @_;
    require HTML::TokeParser;
    my $p = HTML::TokeParser->new(\$html);
    eval {
	# optimization
	$p->report_tags(qw(form input textarea select optgroup option));
    };

    my @forms;
    my $f;  # current form

    while (my $t = $p->get_tag) {
	my($tag,$attr) = @$t;
	if ($tag eq "form") {
	    my $action = delete $attr->{'action'};
	    $action = "" unless defined $action;
	    $action = URI->new_abs($action, $base_uri);
	    $f = $class->new($attr->{'method'},
			     $action,
			     $attr->{'enctype'});
	    $f->{attr} = $attr;
	    push(@forms, $f);
	    while (my $t = $p->get_tag) {
		my($tag, $attr) = @$t;
		last if $tag eq "/form";
		if ($tag eq "input") {
		    my $type = delete $attr->{type} || "text";
		    $f->push_input($type, $attr);
		} elsif ($tag eq "textarea") {
		    $attr->{textarea_value} = $attr->{value}
		        if exists $attr->{value};
		    my $text = $p->get_text("/textarea");
		    $attr->{value} = $text;
		    $f->push_input("textarea", $attr);
		} elsif ($tag eq "select") {
		    $attr->{select_value} = $attr->{value}
		        if exists $attr->{value};
		    while ($t = $p->get_tag) {
			my $tag = shift @$t;
			last if $tag eq "/select";
			next if $tag =~ m,/?optgroup,;
			next if $tag eq "/option";
			if ($tag eq "option") {
			    my %a = (%$attr, %{$t->[0]});
			    $a{value} = $p->get_trimmed_text
				unless defined $a{value};
			    $f->push_input("option", \%a);
			} else {
			    Carp::carp("Bad <select> tag '$tag'") if $^W;
			}
		    }
		}
	    }
	} elsif ($form_tags{$tag}) {
	    Carp::carp("<$tag> outside <form>") if $^W;
	}
    }
    for (@forms) {
	$_->fixup;
    }

    wantarray ? @forms : $forms[0];
}

=item $form = HTML::Form->new( $method, $action_uri, $enctype )

This constructs a new empty HTML::Form object.  The arguments are the
initial value for which method the form should use to invoke a
request, which URI to apply the method to, and what encoding type to
use for the form data.

The $method defaults to "GET" if not provided.  The $enctype defaults
to "application/x-www-form-urlencoded" if not provided.

You will normally use HTML::Form->parse() to create new HTML::Form
objects.

=cut

sub new {
    my $class = shift;
    my $self = bless {}, $class;
    $self->{method} = uc(shift  || "GET");
    $self->{action} = shift  || Carp::croak("No action defined");
    $self->{enctype} = lc(shift || "application/x-www-form-urlencoded");
    $self->{inputs} = [@_];
    $self;
}


sub push_input
{
    my($self, $type, $attr) = @_;
    $type = lc $type;
    my $class = $type2class{$type};
    unless ($class) {
	Carp::carp("Unknown input type '$type'") if $^W;
	$class = "IgnoreInput";
    }
    $class = "IgnoreInput" if exists $attr->{disabled};
    $class = "HTML::Form::$class";

    my $input = $class->new(type => $type, %$attr);
    $input->add_to_form($self);
}


=back

The following instance methods are available on C<HTML::Form> objects:

=over 4

=item $method = $form->method

=item $form->method( $new_method )

This method is gets/sets the I<method> used to for the
C<HTTP::Request> generated.  It is a string like "GET" or "POST".

=item $action = $form->action

=item $form->action( $new_action )

This method gets/sets the URI which we want to apply the request
I<method> to.

=item $enctype = $form->enctype

=item $form->enctype( $new_enctype )

This method gets/sets the encoding type for the form data.  It is a
string like "application/x-www-form-urlencoded" or "multipart/form-data".

=cut

BEGIN {
    # Set up some accesor
    for (qw(method action enctype)) {
	my $m = $_;
	no strict 'refs';
	*{$m} = sub {
	    my $self = shift;
	    my $old = $self->{$m};
	    $self->{$m} = shift if @_;
	    $old;
	};
    }
    *uri = \&action;  # alias
}

=item $value = $form->attr( $name )

=item $form->attr( $name, $new_value )

This method give access to the original HTML attributes of the <form> tag.
The $name should always be passed in lower case.

Example:

   @f = HTML::Form->parse( $html, $foo );
   @f = grep $_->attr("id") == "foo", @f;
   die "No form named 'foo' found" unless @f;
   $foo = shift @f;

=cut

sub attr {
    my $self = shift;
    my $name = shift;
    return undef unless defined $name;

    my $old = $self->{attr}{$name};
    $self->{attr}{$name} = shift if @_;
    return $old;
}

=item @inputs = $form->inputs

This method returns the list of inputs in the form.  If called in
scalar context it returns the number of inputs contained in the form.

=cut

sub inputs
{
    my $self = shift;
    @{$self->{'inputs'}};
}


=item $input = $form->find_input($name, $type, $index)

This method is used to locate some specific input within the form.  At
least one of the arguments must be defined.  If no matching input is
found, C<undef> is returned.

If $name is specified, then the input must have the indicated name.

If $type is specified then the input must have the specified type.
The following type names are used: "text", "password", "hidden",
"textarea", "file", "image", "submit", "radio", "checkbox" and "option".

The $index is the sequence number of the input matched where 1 is the
first.  If combined with $name and/or $type then it select the I<n>th
input with the given name and/or type.

=cut

sub find_input
{
    my($self, $name, $type, $no) = @_;
    $no ||= 1;
    for (@{$self->{'inputs'}}) {
	if (defined $name) {
	    next unless exists $_->{name};
	    next if $name ne $_->{name};
	}
	next if $type && $type ne $_->{type};
	next if --$no;
	return $_;
    }
    return undef;
}

sub fixup
{
    my $self = shift;
    for (@{$self->{'inputs'}}) {
	$_->fixup;
    }
}


=item $value = $form->value( $name )

=item $form->value( $name, $new_value )

The value() method can be used to get/set the value of some input.  If
no input have the indicated name, then this method will croak.

If multiple inputs has the same name, only the first one will be
affected.

The call:

    $form->value('foo')

is a short-hand for:

    $form->find_value('foo')->value;

=cut

sub value
{
    my $self = shift;
    my $key  = shift;
    my $input = $self->find_input($key);
    Carp::croak("No such field '$key'") unless $input;
    local $Carp::CarpLevel = 1;
    $input->value(@_);
}


=item $form->try_others( \&callback )

This method will iterate over all permutations of unvisited enumerated
values (<select>, <radio>, <checkbox>) and invoke the callback for
each.  The callback is passed the $form as argument.  The return value
from the callback is ignored and the try_others() method itself does
not return anything.

=cut

sub try_others
{
    my($self, $cb) = @_;
    my @try;
    for (@{$self->{'inputs'}}) {
	my @not_tried_yet = $_->other_possible_values;
	next unless @not_tried_yet;
	push(@try, [\@not_tried_yet, $_]);
    }
    return unless @try;
    $self->_try($cb, \@try, 0);
}

sub _try
{
    my($self, $cb, $try, $i) = @_;
    for (@{$try->[$i][0]}) {
	$try->[$i][1]->value($_);
	&$cb($self);
	$self->_try($cb, $try, $i+1) if $i+1 < @$try;
    }
}


=item $request = $form->make_request

Will return an C<HTTP::Request> object that reflects the current setting
of the form.  You might want to use the click() method instead.

=cut

sub make_request
{
    my $self = shift;
    my $method  = uc $self->{'method'};
    my $uri     = $self->{'action'};
    my $enctype = $self->{'enctype'};
    my @form    = $self->form;

    if ($method eq "GET") {
	require HTTP::Request;
	$uri = URI->new($uri, "http");
	$uri->query_form(@form);
	return HTTP::Request->new(GET => $uri);
    } elsif ($method eq "POST") {
	require HTTP::Request::Common;
	return HTTP::Request::Common::POST($uri, \@form,
					   Content_Type => $enctype);
    } else {
	Carp::croak("Unknown method '$method'");
    }
}


=item $request = $form->click

=item $request = $form->click( $name )

=item $request = $form->click( $x, $y )

=item $request = $form->click( $name, $x, $y )

Will "click" on the first clickable input (which will be of type
C<submit> or C<image>).  The result of clicking is an C<HTTP::Request>
object that can then be passed to C<LWP::UserAgent> if you want to
obtain the server response.

If a $name is specified we will click on the first clickable input
with the given name, and the method will croak if no clickable input
with the given name is found.  If $name is I<not> specified, then it
is ok if the form contains no clickable inputs.  In this case the
click() method returns the same request as the make_request() method
would do.

If there is multiple clickable inputs with the same name, then there
is no way to get the click() method of the C<HTML::Form> to click on
any but the first.  If you need this you would have to locate the
input with find_input() and invoke the click() method on the given
input yourself.

A click coordinate pair can also be provided, but this only makes a
difference if you clicked on an image.  The default coordinate is
(1,1).  The upper-left corner of the image is (0,0), but some badly
coded CGI scripts are known to not recognize this so (1,1) was
selectes as a safer default.

=cut

sub click
{
    my $self = shift;
    my $name;
    $name = shift if (@_ % 2) == 1;  # odd number of arguments

    # try to find first submit button to activate
    for (@{$self->{'inputs'}}) {
        next unless $_->can("click");
        next if $name && $_->name ne $name;
	return $_->click($self, @_);
    }
    Carp::croak("No clickable input with name $name") if $name;
    $self->make_request;
}


=item @kw = $form->form

Returns the current setting as a sequence of key/value pairs.  Note
that keys might be repeated which means that some values might be lost
if the return values are assigned to a hash.

In scalar context this method returns the number of key/value pairs
generated.

=cut

sub form
{
    my $self = shift;
    map { $_->form_name_value($self) } @{$self->{'inputs'}};
}


=item $form->dump

Returns a textual representation of current state of the form.  Mainly
useful for debugging.  If called in void context, then the dump is
printed on STDERR.

=cut

sub dump
{
    my $self = shift;
    my $method  = $self->{'method'};
    my $uri     = $self->{'action'};
    my $enctype = $self->{'enctype'};
    my $dump = "$method $uri";
    $dump .= " ($enctype)"
	if $enctype ne "application/x-www-form-urlencoded";
    $dump .= "\n";
    for ($self->inputs) {
	$dump .= "  " . $_->dump . "\n";
    }
    print STDERR $dump unless defined wantarray;
    $dump;
}


#---------------------------------------------------
package HTML::Form::Input;

=back

=head1 INPUTS

An C<HTML::Form> contains a sequence of inputs.  References to the
inputs can be obtained with the $form->inputs or $form->find_input
methods.  Once you have such a reference, then one of the following
methods can be used on it:

=over 4

=cut

sub new
{
    my $class = shift;
    my $self = bless {@_}, $class;
    $self;
}

sub add_to_form
{
    my($self, $form) = @_;
    push(@{$form->{'inputs'}}, $self);
    $self;
}

sub fixup {}


=item $input->type

Returns the type of this input.  The type is one of the following
strings: "text", "password", "hidden", "textarea", "file", "image", "submit",
"radio", "checkbox" or "option".

=cut

sub type
{
    shift->{type};
}

=item $name = $input->name

=item $input->name( $new_name )

This method can be used to get/set the current name of the input.

=item $value = $input->value

=item $input->value( $new_value )

This method can be used to get/set the current value of an
input.

If the input only can take an enumerated list of values, then it is an
error to try to set it to something else and the method will croak if
you try.  A croak will also be triggered if you try to set the value
of a read-only input.

=cut

sub name
{
    my $self = shift;
    my $old = $self->{name};
    $self->{name} = shift if @_;
    $old;
}

sub value
{
    my $self = shift;
    my $old = $self->{value};
    $self->{value} = shift if @_;
    $old;
}

=item $input->possible_values

Returns a list of all values that and input can take.  For inputs that
does not have discrete values this returns an empty list.

=cut

sub possible_values
{
    return;
}

=item $input->other_possible_values

Returns a list of all values not tried yet.

=cut

sub other_possible_values
{
    return;
}

=item $input->form_name_value

Returns a (possible empty) list of key/value pairs that should be
incorporated in the form value from this input.

=cut

sub form_name_value
{
    my $self = shift;
    my $name = $self->{'name'};
    return unless defined $name;
    my $value = $self->value;
    return unless defined $value;
    return ($name => $value);
}

sub dump
{
    my $self = shift;
    my $name = $self->name;
    $name = "<NONAME>" unless defined $name;
    my $value = $self->value;
    $value = "<UNDEF>" unless defined $value;
    my $dump = "$name=$value";

    my $type = $self->type;
    return $dump if $type eq "text";

    $type = ($type eq "text") ? "" : " ($type)";
    my $menu = $self->{menu} || "";
    if ($menu) {
	my @menu;
	for (0 .. @$menu-1) {
	    my $opt = $menu->[$_];
	    $opt = "<UNDEF>" unless defined $opt;
	    substr($opt,0,0) = "*" if $self->{seen}[$_];
	    push(@menu, $opt);
	}
	$menu = "[" . join("|", @menu) . "]";
    }
    sprintf "%-30s %-10s %s", $dump, $type, $menu;
}


#---------------------------------------------------
package HTML::Form::TextInput;
@HTML::Form::TextInput::ISA=qw(HTML::Form::Input);

#input/text
#input/password
#input/hidden
#textarea

sub value
{
    my $self = shift;
    my $old = $self->{value};
    $old = "" unless defined $old;
    if (@_) {
	if (exists($self->{readonly}) || $self->{type} eq "hidden") {
	    Carp::carp("Input '$self->{name}' is readonly") if $^W;
	}
	$self->{value} = shift;
    }
    $old;
}

#---------------------------------------------------
package HTML::Form::IgnoreInput;
@HTML::Form::IgnoreInput::ISA=qw(HTML::Form::Input);

#input/button
#input/reset

sub value { return }


#---------------------------------------------------
package HTML::Form::ListInput;
@HTML::Form::ListInput::ISA=qw(HTML::Form::Input);

#select/option   (val1, val2, ....)
#input/radio     (undef, val1, val2,...)
#input/checkbox  (undef, value)

sub new
{
    my $class = shift;
    my $self = $class->SUPER::new(@_);
    if ($self->type eq "checkbox") {
	my $value = delete $self->{value};
	$value = "on" unless defined $value;
	$self->{menu} = [undef, $value];
	$self->{current} = (exists $self->{checked}) ? 1 : 0;
	delete $self->{checked};
    } else {
	$self->{menu} = [delete $self->{value}];
	my $checked = exists $self->{checked} || exists $self->{selected};
	delete $self->{checked};
	delete $self->{selected};
	if (exists $self->{multiple}) {
	    unshift(@{$self->{menu}}, undef);
	    $self->{current} = $checked ? 1 : 0;
	} else {
	    $self->{current} = 0 if $checked;
	}
    }
    $self;
}

sub add_to_form
{
    my($self, $form) = @_;
    my $type = $self->type;
    return $self->SUPER::add_to_form($form)
	if $type eq "checkbox" ||
	   ($type eq "option" && exists $self->{multiple});

    my $prev = $form->find_input($self->{name}, $self->{type});
    return $self->SUPER::add_to_form($form) unless $prev;

    # merge menues
    push(@{$prev->{menu}}, @{$self->{menu}});
    $prev->{current} = @{$prev->{menu}} - 1 if exists $self->{current};
}

sub fixup
{
    my $self = shift;
    if ($self->{type} eq "option" && !(exists $self->{current})) {
	$self->{current} = 0;
    }
    $self->{seen} = [(0) x @{$self->{menu}}];
    $self->{seen}[$self->{current}] = 1 if exists $self->{current};
}

sub value
{
    my $self = shift;
    my $old;
    $old = $self->{menu}[$self->{current}] if exists $self->{current};
    if (@_) {
	my $i = 0;
	my $val = shift;
	my $cur;
	for (@{$self->{menu}}) {
	    if ((defined($val) && defined($_) && $val eq $_) ||
		(!defined($val) && !defined($_))
	       )
	    {
		$cur = $i;
		last;
	    }
	    $i++;
	}
	Carp::croak("Illegal value '$val'") unless defined $cur;
	$self->{current} = $cur;
	$self->{seen}[$cur] = 1;
    }
    $old;
}

sub possible_values
{
    my $self = shift;
    @{$self->{menu}};
}

sub other_possible_values
{
    my $self = shift;
    map { $self->{menu}[$_] }
        grep {!$self->{seen}[$_]}
             0 .. (@{$self->{seen}} - 1);
}


#---------------------------------------------------
package HTML::Form::SubmitInput;
@HTML::Form::SubmitInput::ISA=qw(HTML::Form::Input);

#input/image
#input/submit

=item $input->click($form, $x, $y)

Some input types (currently "sumbit" buttons and "images") can be
clicked to submit the form.  The click() method returns the
corrsponding C<HTTP::Request> object.

=cut

sub click
{
    my($self,$form,$x,$y) = @_;
    for ($x, $y) { $_ = 1 unless defined; }
    local($self->{clicked}) = [$x,$y];
    return $form->make_request;
}

sub form_name_value
{
    my $self = shift;
    return unless $self->{clicked};
    return $self->SUPER::form_name_value(@_);
}


#---------------------------------------------------
package HTML::Form::ImageInput;
@HTML::Form::ImageInput::ISA=qw(HTML::Form::SubmitInput);

sub form_name_value
{
    my $self = shift;
    my $clicked = $self->{clicked};
    return unless $clicked;
    my $name = $self->{name};
    return unless defined $name;
    return ("$name.x" => $clicked->[0],
	    "$name.y" => $clicked->[1]
	   );
}

#---------------------------------------------------
package HTML::Form::FileInput;
@HTML::Form::FileInput::ISA=qw(HTML::Form::TextInput);

=back

If the input is of type C<file>, then it has these additional methods:

=over 4

=item $input->file

This is just an alias for the value() method.  It sets the filename to
read data from.

=cut

sub file {
    my $self = shift;
    $self->value(@_);
}

=item $filename = $input->filename

=item $input->filename( $new_filename )

This get/sets the filename reported to the server during file upload.
This attribute defaults to the value reported by the file() method.

=cut

sub filename {
    my $self = shift;
    my $old = $self->{filename};
    $self->{filename} = shift if @_;
    $old = $self->file unless defined $old;
    $old;
}

=item $content = $input->content

=item $input->content( $new_content )

This get/sets the file content provided to the server during file
upload.  This method can be used if you do not want the content to be
uploaded to be provided from an actual file.

=cut

sub content {
    my $self = shift;
    my $old = $self->{content};
    $self->{content} = shift if @_;
    $old;
}

=item @headers = $input->headers

=item input->headers($key => $value, .... )

This get/set additional header fields describing the file uploaded.
This can for instance be used to set the C<Content-Type> reported for
the file.

=cut

sub headers {
    my $self = shift;
    my $old = $self->{headers} || [];
    $self->{headers} = [@_] if @_;
    @$old;
}

sub form_name_value {
    my($self, $form) = @_;
    return $self->SUPER::form_name_value($form)
	if $form->method ne "POST" ||
	   $form->enctype ne "multipart/form-data";

    my $name = $self->name;
    return unless defined $name;

    my $file = $self->file;
    my $filename = $self->filename;
    my @headers = $self->headers;
    my $content = $self->content;
    if (defined $content) {
	$filename = $file unless defined $filename;
	$file = undef;
	unshift(@headers, "Content" => $content);
    }
    elsif (!defined($file) || length($file) == 0) {
	return;
    }

    # legacy (this used to be the way to do it)
    if (ref($file) eq "ARRAY") {
	my $f = shift @$file;
	my $fn = shift @$file;
	push(@headers, @$file);
	$file = $f;
	$filename = $fn unless defined $filename;
    }

    return ($name => [$file, $filename, @headers]);
}

1;

__END__

=back

=head1 SEE ALSO

L<LWP>, L<HTML::Parser>

=head1 COPYRIGHT

Copyright 1998-2002 Gisle Aas.

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

=cut