<?php
/**
 * PlugeTune YouTube API handler.
 *
 * Provides the YouTube Data API integration used by the plugin.
 * All styling is applied via classes defined in assets/css/plugetune_admin.css.
 *
 * @package PlugeTune
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * YouTube API handler.
 */
class PlugeTune_YouTube_API {

	/**
	 * Singleton instance.
	 *
	 * @var PlugeTune_YouTube_API|null
	 */
	private static $instance = null;

	/**
	 * Retrieve the singleton instance.
	 *
	 * @return PlugeTune_YouTube_API
	 */
	public static function get_instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Constructor.
	 */
	private function __construct() {}

	/**
	 * Retrieve the stored YouTube API key.
	 *
	 * @return string
	 */
	public static function get_api_key() {
		return get_option( 'plugetune_api_key', '' );
	}

	/**
	 * Retrieve the stored channel IDs string.
	 *
	 * @return string
	 */
	public static function get_channel_ids() {
		return get_option( 'plugetune_allowed_channel_ids', '' );
	}

	/**
	 * Determine whether both the API key and channel IDs are configured.
	 *
	 * @return bool
	 */
	public static function is_configured() {
		$api_key     = self::get_api_key();
		$channel_ids = self::get_channel_ids();
		return ! empty( $api_key ) && ! empty( $channel_ids );
	}

	/**
	 * Retrieve the plugin settings page URL.
	 *
	 * @return string
	 */
	public static function get_settings_url() {
		return admin_url( 'edit.php?post_type=plugetune_video&page=plugetune-settings' );
	}

	/**
	 * Validate a YouTube API key against the YouTube Data API.
	 *
	 * @param string $api_key API key to validate.
	 * @return array { @type bool $success @type string $message }
	 */
	public function test_api_key( $api_key ) {
		if ( empty( $api_key ) ) {
			return array(
				'success' => false,
				'message' => 'Please enter an API key first.',
			);
		}

		$test_url = "https://www.googleapis.com/youtube/v3/videos?part=snippet&id=dQw4w9WgXcQ&key={$api_key}";
		$response = wp_remote_get(
			$test_url,
			array(
				'timeout'   => 45,
				'headers'   => array(
					'Accept'     => 'application/json',
					'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
				),
				'sslverify' => true,
			)
		);

		if ( is_wp_error( $response ) ) {
			return array(
				'success' => false,
				'message' => 'Connection failed: ' . $response->get_error_message(),
			);
		}

		$data = json_decode( wp_remote_retrieve_body( $response ) );

		if ( isset( $data->error ) ) {
			$error_message = '';
			if ( isset( $data->error->errors[0]->reason ) ) {
				switch ( $data->error->errors[0]->reason ) {
					case 'keyInvalid':
						$error_message = 'Your API key is invalid. Please check your key and try again.';
						break;
					case 'keyExpired':
						$error_message = 'Your API key has expired. Please generate a new key.';
						break;
					case 'accessNotConfigured':
						$error_message = 'YouTube Data API v3 is not enabled for this project. Please enable it in Google Cloud Console.';
						break;
					case 'quotaExceeded':
						$error_message = 'API quota exceeded. Please try again later or upgrade your quota.';
						break;
					default:
						$error_message = isset( $data->error->errors[0]->message ) ? $data->error->errors[0]->message : 'Invalid API key.';
				}
			} else {
				$error_message = isset( $data->error->message ) ? $data->error->message : 'Invalid API key.';
			}
			return array(
				'success' => false,
				'message' => $error_message,
			);
		}

		return array(
			'success' => true,
			'message' => 'API key is valid and working correctly!',
		);
	}

	/**
	 * Fetch all playlists belonging to the provided channels.
	 *
	 * @param string $api_key           YouTube API key.
	 * @param string $channel_ids_input Comma-separated channel IDs.
	 * @return array Playlist data.
	 */
	public function fetch_playlists( $api_key, $channel_ids_input ) {
		if ( empty( $api_key ) ) {
			return array(
				'success' => false,
				'message' => 'API key is required.',
			);
		}

		if ( empty( $channel_ids_input ) ) {
			return array(
				'success' => false,
				'message' => 'Channel ID(s) are required.',
			);
		}

		$channel_ids = array_map( 'trim', explode( ',', $channel_ids_input ) );
		$channel_ids = array_filter( $channel_ids );

		if ( empty( $channel_ids ) ) {
			return array(
				'success' => false,
				'message' => 'No valid Channel IDs provided.',
			);
		}

		$all_playlists = array();

		foreach ( $channel_ids as $channel_id ) {
			$page_token = '';

			do {
				$playlist_url = "https://www.googleapis.com/youtube/v3/playlists?part=snippet,contentDetails&channelId={$channel_id}&maxResults=50&key={$api_key}";
				if ( ! empty( $page_token ) ) {
					$playlist_url .= "&pageToken={$page_token}";
				}

				$playlist_response = wp_remote_get(
					$playlist_url,
					array(
						'timeout'   => 30,
						'headers'   => array(
							'Accept'     => 'application/json',
							'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
						),
						'sslverify' => true,
					)
				);

				if ( is_wp_error( $playlist_response ) ) {
					break;
				}

				$playlist_data = json_decode( wp_remote_retrieve_body( $playlist_response ) );

				if ( isset( $playlist_data->error ) ) {
					return array(
						'success' => false,
						'message' => 'YouTube API error: ' . ( isset( $playlist_data->error->message ) ? $playlist_data->error->message : 'Unknown error' ),
					);
				}

				if ( ! empty( $playlist_data->items ) ) {
					foreach ( $playlist_data->items as $item ) {
						$all_playlists[] = array(
							'id'           => $item->id,
							'title'        => $item->snippet->title,
							'description'  => isset( $item->snippet->description ) ? substr( wp_strip_all_tags( $item->snippet->description ), 0, 100 ) : '',
							'itemCount'    => $item->contentDetails->itemCount,
							'channelId'    => $item->snippet->channelId,
							'channelTitle' => $item->snippet->channelTitle,
							'publishedAt'  => $item->snippet->publishedAt,
							'thumbnails'   => isset( $item->snippet->thumbnails ) ? $item->snippet->thumbnails : null,
						);
					}
				}

				$page_token = isset( $playlist_data->nextPageToken ) ? $playlist_data->nextPageToken : '';
			} while ( ! empty( $page_token ) );
		}

		usort(
			$all_playlists,
			function ( $a, $b ) {
				return strcmp( strtolower( $a['title'] ), strtolower( $b['title'] ) );
			}
		);

		return array(
			'success'   => true,
			'playlists' => $all_playlists,
			'total'     => count( $all_playlists ),
		);
	}

	/**
	 * Fetch videos from the uploads playlist of the provided channels.
	 *
	 * @param string $api_key           YouTube API key.
	 * @param string $channel_ids_input Comma-separated channel IDs.
	 * @param string $page_token        Optional YouTube page token.
	 * @return array Video data.
	 */
	public function fetch_videos( $api_key, $channel_ids_input, $page_token = '' ) {
		if ( empty( $api_key ) ) {
			return array(
				'success' => false,
				'message' => 'API key is required.',
			);
		}

		if ( empty( $channel_ids_input ) ) {
			return array(
				'success' => false,
				'message' => 'Channel ID(s) are required.',
			);
		}

		$channel_ids = array_map( 'trim', explode( ',', $channel_ids_input ) );
		$channel_ids = array_filter( $channel_ids );

		if ( empty( $channel_ids ) ) {
			return array(
				'success' => false,
				'message' => 'No valid Channel IDs provided.',
			);
		}

		global $wpdb;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$imported_video_ids = $wpdb->get_col(
			$wpdb->prepare(
				"SELECT meta_value FROM {$wpdb->postmeta}
				WHERE meta_key = %s
				AND meta_value != ''",
				PlugeTune_Free_Feature::META_VIDEO
			)
		);
		$imported_video_ids = array_map( 'trim', $imported_video_ids );

		$all_videos      = array();
		$next_page_token = '';

		foreach ( $channel_ids as $channel_id ) {
			$channel_url      = "https://www.googleapis.com/youtube/v3/channels?part=contentDetails&id={$channel_id}&key={$api_key}";
			$channel_response = wp_remote_get(
				$channel_url,
				array(
					'timeout'   => 30,
					'headers'   => array(
						'Accept'     => 'application/json',
						'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
					),
					'sslverify' => true,
				)
			);

			if ( is_wp_error( $channel_response ) ) {
				continue;
			}

			$channel_data = json_decode( wp_remote_retrieve_body( $channel_response ) );

			if ( empty( $channel_data->items ) ) {
				continue;
			}

			$uploads_playlist_id = $channel_data->items[0]->contentDetails->relatedPlaylists->uploads;

			$videos_url = "https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&maxResults=50&playlistId={$uploads_playlist_id}&key={$api_key}";
			if ( ! empty( $page_token ) ) {
				$videos_url .= "&pageToken={$page_token}";
			}

			$videos_response = wp_remote_get(
				$videos_url,
				array(
					'timeout'   => 30,
					'headers'   => array(
						'Accept'     => 'application/json',
						'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
					),
					'sslverify' => true,
				)
			);

			if ( is_wp_error( $videos_response ) ) {
				return array(
					'success' => false,
					'message' => 'Failed to fetch videos: ' . $videos_response->get_error_message(),
				);
			}

			$videos_data = json_decode( wp_remote_retrieve_body( $videos_response ) );

			if ( isset( $videos_data->error ) ) {
				return array(
					'success' => false,
					'message' => 'YouTube API error: ' . ( isset( $videos_data->error->message ) ? $videos_data->error->message : 'Unknown error' ),
				);
			}

			if ( ! empty( $videos_data->items ) ) {
				foreach ( $videos_data->items as $item ) {
					$video_id    = $item->snippet->resourceId->videoId;
					$is_imported = in_array( $video_id, $imported_video_ids, true );

					$all_videos[] = array(
						'id'          => $video_id,
						'title'       => $item->snippet->title,
						'description' => isset( $item->snippet->description ) ? substr( wp_strip_all_tags( $item->snippet->description ), 0, 100 ) : '',
						'publishedAt' => $item->snippet->publishedAt,
						'thumbnails'  => isset( $item->snippet->thumbnails ) ? $item->snippet->thumbnails : null,
						'is_imported' => $is_imported,
					);
				}
			}

			$next_page_token = isset( $videos_data->nextPageToken ) ? $videos_data->nextPageToken : '';
		}

		return array(
			'success'       => true,
			'videos'        => $all_videos,
			'total'         => count( $all_videos ),
			'nextPageToken' => $next_page_token,
		);
	}

	/**
	 * Validate that a playlist belongs to one of the allowed channels.
	 *
	 * @param string $playlist_id         YouTube playlist ID.
	 * @param string $api_key             YouTube API key.
	 * @param array  $allowed_channel_ids Allowed channel IDs.
	 * @return array|false Playlist ownership data or false.
	 */
	public function validate_playlist_ownership( $playlist_id, $api_key, $allowed_channel_ids ) {
		$playlist_url      = "https://www.googleapis.com/youtube/v3/playlists?part=snippet,status&id={$playlist_id}&key={$api_key}";
		$playlist_response = wp_remote_get(
			$playlist_url,
			array(
				'timeout'   => 45,
				'headers'   => array(
					'Accept'     => 'application/json',
					'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
				),
				'sslverify' => true,
			)
		);

		if ( is_wp_error( $playlist_response ) ) {
			$this->log_error( $playlist_id, 'API request failed: ' . $playlist_response->get_error_message() );
			return false;
		}

		$playlist_data = json_decode( wp_remote_retrieve_body( $playlist_response ) );

		if ( isset( $playlist_data->error ) ) {
			$this->log_error( $playlist_id, 'API error: ' . wp_json_encode( $playlist_data->error ) );
			return false;
		}

		if ( empty( $playlist_data->items ) ) {
			$this->log_error( $playlist_id, 'Playlist not found or not accessible' );
			return false;
		}

		$playlist            = $playlist_data->items[0];
		$playlist_channel_id = $playlist->snippet->channelId;
		$playlist_title      = $playlist->snippet->title;

		$playlist_channel_clean = trim( $playlist_channel_id );
		$is_authorized          = false;

		foreach ( $allowed_channel_ids as $allowed_id ) {
			$allowed_clean = trim( $allowed_id );
			if ( strtolower( $allowed_clean ) === strtolower( $playlist_channel_clean ) ) {
				$is_authorized = true;
				break;
			}
		}

		if ( $is_authorized ) {
			return array(
				'owner_channel_id' => $playlist_channel_id,
				'playlist_title'   => $playlist_title,
			);
		}

		$this->log_error(
			$playlist_id,
			'Ownership validation failed. Playlist owner: ' . $playlist_channel_id . ', Allowed channels: ' . implode( ', ', $allowed_channel_ids )
		);

		return false;
	}

	/**
	 * Extract the YouTube video ID from a URL.
	 *
	 * @param string $url YouTube URL.
	 * @return string Video ID, or an empty string when not matched.
	 */
	public function extract_youtube_id_from_url( $url ) {
		$patterns = array(
			'/(?:youtube\.com\/watch\?v=)([a-zA-Z0-9_-]{11})/',
			'/(?:youtu\.be\/)([a-zA-Z0-9_-]{11})/',
			'/(?:youtube\.com\/shorts\/)([a-zA-Z0-9_-]{11})/',
			'/(?:youtube\.com\/embed\/)([a-zA-Z0-9_-]{11})/',
			'/(?:v=)([a-zA-Z0-9_-]{11})/',
		);

		foreach ( $patterns as $pattern ) {
			if ( preg_match( $pattern, $url, $matches ) ) {
				return $matches[1];
			}
		}
		return '';
	}

	/**
	 * Log a debug message when WP_DEBUG is enabled.
	 *
	 * @param string $playlist_id Playlist ID associated with the message.
	 * @param string $message     Message to log.
	 * @return void
	 */
	private function log_error( $playlist_id, $message ) {
		if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
			// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
			error_log(
				sprintf(
					'[PlugeTune YouTube API] Playlist ID: %s - %s',
					$playlist_id,
					$message
				)
			);
		}
	}

	/**
	 * Render the YouTube API settings UI on the plugin settings page.
	 *
	 * All styling is applied via classes defined in assets/css/plugetune_admin.css.
	 *
	 * @return void
	 */
	public static function render_settings() {
		?>
		<div class="settings-card plugetune-settings-card">
			<div class="settings-card-header">
				<i class="fab fa-youtube"></i>
				<h3><?php esc_html_e( 'YouTube API Settings', 'plugetune' ); ?></h3>
			</div>
			<div class="settings-card-body">
				<div class="setting-field">
					<label><?php esc_html_e( 'YouTube API Key', 'plugetune' ); ?></label>
					<div class="field-wrapper">
						<input type="password" name="plugetune_api_key" id="plugetune_api_key" value="<?php echo esc_attr( get_option( 'plugetune_api_key' ) ); ?>" class="modern-input plugetune-input-full" autocomplete="new-password" data-lpignore="true" data-1p-ignore="true" />
						<button type="button" class="button small-btn test-api-btn plugetune-btn-test-api">
							<i class="fas fa-vial"></i> <?php esc_html_e( 'Test API Key', 'plugetune' ); ?>
						</button>
						<div id="api-test-message" class="plugetune-api-test-msg"></div>
						<p class="description">
							<a href="https://youtu.be/tw-htZ-Es90" class="plugetune-video-link" data-plugetune-video="tw-htZ-Es90" target="_blank" rel="noopener noreferrer">
								<?php esc_html_e( 'How to get your Free YouTube API key', 'plugetune' ); ?>
							</a>
						</p>
					</div>
				</div>
				<div class="setting-field">
					<label><?php esc_html_e( 'Channel ID(s)', 'plugetune' ); ?></label>
					<div class="field-wrapper">
						<input type="text" name="plugetune_allowed_channel_ids" id="plugetune_allowed_channel_ids" value="<?php echo esc_attr( get_option( 'plugetune_allowed_channel_ids' ) ); ?>" class="modern-input plugetune-input-full" />
						<p class="description">
							<a href="https://youtu.be/rotP4xKBiTI" class="plugetune-video-link" data-plugetune-video="rotP4xKBiTI" target="_blank" rel="noopener noreferrer">
								<?php esc_html_e( 'How to find your YouTube Channel ID', 'plugetune' ); ?>
							</a>
						</p>
					</div>
				</div>
			</div>
		</div>
		<?php
	}
}

PlugeTune_YouTube_API::get_instance();