Flickr::API - Perl interface to the Flickr API

  use Flickr::API;

  my $api = new Flickr::API({'key'    => 'your_api_key',
                             'secret' => 'your_app_secret'});

  my $response = $api->execute_method('flickr.test.echo', {
		'foo' => 'bar',
		'baz' => 'quux',
	});

  use Flickr::API;
  use Flickr::API::Request;

  my $api = new Flickr::API({'key' => 'your_api_key'});

  my $request = new Flickr::API::Request({
		'method' => 'flickr.test.echo',
		'args' => {},
	});

  my $response = $api->execute_request($request);

package Flickr::API;

use strict;
use warnings;
use LWP::UserAgent;
use XML::Parser::Lite::Tree;
use Flickr::API::Request;
use Flickr::API::Response;
use Digest::MD5 qw(md5_hex);

our @ISA = qw(LWP::UserAgent);

our $VERSION = '1.04';

sub new {
	my $class = shift;
	my $options = shift;
	my $self = new LWP::UserAgent;
	$self->{api_key}	= $options->{key};
	$self->{api_secret}	= $options->{secret};
	$self->{rest_uri}	= $options->{rest_uri} || 'http://www.flickr.com/services/rest/';
	$self->{auth_uri}	= $options->{auth_uri} || 'http://www.flickr.com/services/auth/';

	eval {
		require Compress::Zlib;

		$self->default_header('Accept-Encoding' => 'gzip');
	};

	warn "You must pass an API key to the constructor" unless defined $self->{api_key};

	bless $self, $class;
	return $self;
}

sub sign_args {
	my $self = shift;
	my $args = shift;

	my $sig  = $self->{api_secret};

	foreach my $key (sort {$a cmp $b} keys %{$args}) {

		my $value = (defined($args->{$key})) ? $args->{$key} : "";
		$sig .= $key . $value;
	}

	return md5_hex($sig);
}

sub request_auth_url {
	my $self  = shift;
	my $perms = shift;
	my $frob  = shift;

	return undef unless defined $self->{api_secret} && length $self->{api_secret};

	my %args = (
		'api_key' => $self->{api_key},
		'perms'   => $perms
	);

	if ($frob) {
		$args{frob} = $frob;
	}

	my $sig = $self->sign_args(\%args);
	$args{api_sig} = $sig;

	my $uri = URI->new($self->{auth_uri});
	$uri->query_form(%args);

	return $uri;
}

sub execute_method {
	my ($self, $method, $args) = @_;

	my $request = new Flickr::API::Request({'method' => $method, 'args' => $args, rest_uri => $self->{rest_uri}});

	$self->execute_request($request);
}

sub execute_request {
	my ($self, $request) = @_;

	$request->{api_args}->{method}  = $request->{api_method};
	$request->{api_args}->{api_key} = $self->{api_key};

	if (defined($self->{api_secret}) && length($self->{api_secret})){

		$request->{api_args}->{api_sig} = $self->sign_args($request->{api_args});
	}

	$request->encode_args();


	my $response = $self->request($request);
	bless $response, 'Flickr::API::Response';
	$response->init_flickr();

	if ($response->{_rc} != 200){
		$response->set_fail(0, "API returned a non-200 status code ($response->{_rc})");
		return $response;
	}

	my $content = $response->decoded_content();
	$content = $response->content() unless defined $content;

	my $tree = XML::Parser::Lite::Tree::instance()->parse($content);

	my $rsp_node = $self->_find_tag($tree->{children});

	if ($rsp_node->{name} ne 'rsp'){
		$response->set_fail(0, "API returned an invalid response");
		return $response;
	}

	if ($rsp_node->{attributes}->{stat} eq 'fail'){
		my $fail_node = $self->_find_tag($rsp_node->{children});
		if ($fail_node->{name} eq 'err'){
			$response->set_fail($fail_node->{attributes}->{code}, $fail_node->{attributes}->{msg});
		}else{
			$response->set_fail(0, "Method failed but returned no error code");
		}
		return $response;
	}

	if ($rsp_node->{attributes}->{stat} eq 'ok'){
		$response->set_ok($rsp_node);
		return $response;
	}

	$response->set_fail(0, "API returned an invalid status code");
	return $response;
}

sub _find_tag {
	my ($self, $children) = @_;
	for my $child(@{$children}){
		return $child if $child->{type} eq 'element';
	}
	return {};
}

1;
__END__