package WWW::FairViewer::Channels;

use utf8;
use 5.014;
use warnings;

=head1 NAME

WWW::FairViewer::Channels - Channels interface.

=head1 SYNOPSIS

    use WWW::FairViewer;
    my $obj = WWW::FairViewer->new(%opts);
    my $videos = $obj->channels_from_categoryID($category_id);

=head1 SUBROUTINES/METHODS

=cut

sub _make_channels_url {
    my ($self, %opts) = @_;
    return $self->_make_feed_url('channels', %opts);
}

sub videos_from_channel_id {
    my ($self, $channel_id) = @_;
    return $self->_get_results($self->_make_feed_url("channels/$channel_id/videos"));
}

sub videos_from_username {
    my ($self, $channel_id) = @_;
    return $self->_get_results($self->_make_feed_url("channels/$channel_id/videos"));
}

=head2 popular_videos($channel_id)

Get the most popular videos for a given channel ID.

=cut

sub popular_videos {
    my ($self, $channel_id) = @_;
    return $self->_get_results($self->_make_feed_url("channels/$channel_id/videos", sort_by => 'popular'));
}

=head2 channels_from_categoryID($category_id)

Return the YouTube channels associated with the specified category.

=head2 channels_info($channel_id)

Return information for the comma-separated list of the YouTube channel ID(s).

=head1 Channel details

For all functions, C<$channels->{results}{items}> contains:

=cut

{
    no strict 'refs';

    foreach my $method (
                        {
                         key  => 'categoryId',
                         name => 'channels_from_guide_category',
                        },
                        {
                         key  => 'id',
                         name => 'channels_info',
                        },
                        {
                         key  => 'forUsername',
                         name => 'channels_from_username',
                        },
      ) {
        *{__PACKAGE__ . '::' . $method->{name}} = sub {
            my ($self, $channel_id) = @_;
            return $self->_get_results($self->_make_channels_url($method->{key} => $channel_id));
        };
    }

    foreach my $part (qw(id contentDetails statistics topicDetails)) {
        *{__PACKAGE__ . '::' . 'channels_' . $part} = sub {
            my ($self, $id) = @_;
            return $self->_get_results($self->_make_channels_url(id => $id, part => $part));
        };
    }
}

=head2 my_channel()

Returns info about the channel of the current authenticated user.

=cut

sub my_channel {
    my ($self) = @_;
    $self->get_access_token() // return;
    return $self->_get_results($self->_make_channels_url(part => 'snippet', mine => 'true'));
}

=head2 my_channel_id()

Returns the channel ID of the current authenticated user.

=cut

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

    state $cache = {};

    if (exists $cache->{id}) {
        return $cache->{id};
    }

    $cache->{id} = undef;
    my $channel = $self->my_channel() // return;
    $cache->{id} = $channel->{results}{items}[0]{id} // return;
}

=head2 channels_my_subscribers()

Retrieve a list of channels that subscribed to the authenticated user's channel.

=cut

sub channels_my_subscribers {
    my ($self) = @_;
    $self->get_access_token() // return;
    return $self->_get_results($self->_make_channels_url(mySubscribers => 'true'));
}

=head2 channel_id_from_username($username)

Return the channel ID for an username.

=cut

sub channel_id_from_username {
    my ($self, $username) = @_;

    # A channel's username (if it doesn't include spaces) is also valid in place of ucid.
    if ($username =~ /\w/ and not $username =~ /\s/) {
        return $username;
    }

    # TODO: resolve channel name to channel ID
    return $username;
}

=head2 channel_title_from_id($channel_id)

Return the channel title for a given channel ID.

=cut

sub channel_title_from_id {
    my ($self, $channel_id) = @_;

    if ($channel_id eq 'mine') {
        $channel_id = $self->my_channel_id();
    }

    my $info = $self->channels_info($channel_id // return) // return;

    (    ref($info) eq 'HASH'
     and ref($info->{results}) eq 'HASH'
     and ref($info->{results}{items}) eq 'ARRAY'
     and ref($info->{results}{items}[0]) eq 'HASH')
      ? $info->{results}{items}[0]{snippet}{title}
      : ();
}

=head2 channels_contentDetails($channelID)

=head2 channels_statistics($channelID);

=head2 channels_topicDetails($channelID)

=cut

=head1 AUTHOR

Trizen, C<< <echo dHJpemVuQHByb3Rvbm1haWwuY29tCg== | base64 -d> >>

Jesus, C<< <echo aGVja3llbEBoeXBlcmJvbGEuaW5mbw== | base64 -d> >>


=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc WWW::FairViewer::Channels


=head1 LICENSE AND COPYRIGHT

Copyright 2013-2015 Trizen.

Copyright 2020 Jesus E.

This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.

See L<http://dev.perl.org/licenses/> for more information.

=cut

1;    # End of WWW::FairViewer::Channels