<?php
/**
 * Front end: add <track> elements to videos and render transcripts.
 *
 * @package Captionwright
 */

namespace Captionwright;

defined( 'ABSPATH' ) || exit;

/**
 * Insert caption tracks into a <video> element's HTML.
 *
 * @param string $html HTML containing a video element.
 * @param int    $id   Attachment ID.
 * @return string
 */
function inject_tracks( $html, $id ) {
	$tracks = get_tracks( $id );
	if ( ! $tracks || false === stripos( $html, '</video>' ) ) {
		return $html;
	}
	$default = (bool) settings()['default_on'] && false === stripos( $html, ' default' );
	$add     = '';
	foreach ( $tracks as $lang => $t ) {
		if ( preg_match( '/srclang=["\']' . preg_quote( $lang, '/' ) . '["\']/i', $html ) ) {
			continue;
		}
		$add    .= sprintf(
			'<track kind="captions" src="%1$s" srclang="%2$s" label="%3$s"%4$s>',
			esc_url( $t['url'] ),
			esc_attr( $lang ),
			esc_attr( $t['label'] ),
			$default ? ' default' : ''
		);
		$default = false;
	}
	if ( '' === $add ) {
		return $html;
	}
	$pos = strripos( $html, '</video>' );
	return substr( $html, 0, $pos ) . $add . substr( $html, $pos );
}

add_filter(
	'render_block_core/video',
	function ( $html, $block ) {
		$id = isset( $block['attrs']['id'] ) ? (int) $block['attrs']['id'] : 0;
		if ( ! $id ) {
			return $html;
		}
		$html = inject_tracks( $html, $id );
		if ( settings()['auto_transcript'] && get_tracks( $id ) ) {
			$html .= render_transcript( array( 'attachmentId' => $id ) );
		}
		return $html;
	},
	10,
	2
);

add_filter(
	'wp_video_shortcode',
	function ( $output, $atts ) {
		foreach ( array( 'src', 'mp4', 'webm', 'm4v', 'ogv', 'mov' ) as $key ) {
			if ( ! empty( $atts[ $key ] ) ) {
				$id = attachment_url_to_postid( $atts[ $key ] );
				if ( $id ) {
					return inject_tracks( $output, $id );
				}
			}
		}
		return $output;
	},
	10,
	2
);

/**
 * Format seconds as m:ss or h:mm:ss.
 *
 * @param float $s Seconds.
 * @return string
 */
function clock( $s ) {
	$s = (int) floor( $s );
	return $s >= 3600
		? sprintf( '%d:%02d:%02d', intdiv( $s, 3600 ), intdiv( $s % 3600, 60 ), $s % 60 )
		: sprintf( '%d:%02d', intdiv( $s, 60 ), $s % 60 );
}

/**
 * Transcript HTML for an attachment.
 *
 * @param array<string, mixed> $atts attachmentId, lang, collapsed, showTimes.
 * @param string               $wrapper Extra wrapper attributes (from blocks).
 * @return string
 */
function render_transcript( $atts, $wrapper = '' ) {
	$id     = isset( $atts['attachmentId'] ) ? (int) $atts['attachmentId'] : 0;
	$tracks = $id ? get_tracks( $id ) : array();
	if ( ! $tracks ) {
		return '';
	}
	$lang = isset( $atts['lang'] ) && isset( $tracks[ $atts['lang'] ] ) ? $atts['lang'] : (string) array_key_first( $tracks );
	$cues = parse_vtt( read_track( $id, $lang ) );
	if ( ! $cues ) {
		return '';
	}
	$collapsed = ! isset( $atts['collapsed'] ) || (bool) $atts['collapsed'];
	$times     = ! isset( $atts['showTimes'] ) || (bool) $atts['showTimes'];

	wp_enqueue_style( 'captionwright-transcript' );
	wp_enqueue_script( 'captionwright-transcript-view' );

	// Join cues into readable paragraphs: break after a long pause, or at the end of a
	// sentence once the paragraph has some length.
	$paras = array();
	$cur   = array();
	$chars = 0;
	$prev  = null;
	foreach ( $cues as $c ) {
		$sentence_end = $cur && preg_match( '/[.!?…]["\'”’)]*$/u', end( $cur )['text'] );
		if ( $cur && ( ( null !== $prev && $c['start'] - $prev > 2.5 ) || ( $sentence_end && $chars > 280 ) ) ) {
			$paras[] = $cur;
			$cur     = array();
			$chars   = 0;
		}
		$cur[]  = $c;
		$chars += strlen( $c['text'] );
		$prev   = $c['end'];
	}
	if ( $cur ) {
		$paras[] = $cur;
	}

	$body = '';
	foreach ( $paras as $p ) {
		$body .= '<p>';
		if ( $times ) {
			$body .= sprintf(
				'<button type="button" class="captionwright-transcript__time" data-start="%1$s" aria-label="%2$s">%3$s</button> ',
				esc_attr( (string) $p[0]['start'] ),
				/* translators: %s: timestamp such as 1:05 */
				esc_attr( sprintf( __( 'Play from %s', 'captionwright' ), clock( $p[0]['start'] ) ) ),
				esc_html( clock( $p[0]['start'] ) )
			);
		}
		foreach ( $p as $c ) {
			$body .= sprintf( '<span data-start="%1$s" data-end="%2$s">%3$s</span> ', esc_attr( (string) $c['start'] ), esc_attr( (string) $c['end'] ), esc_html( $c['text'] ) );
		}
		$body .= '</p>';
	}

	$title = sprintf(
		/* translators: %s: media title */
		__( 'Transcript: %s', 'captionwright' ),
		get_the_title( $id )
	);
	/**
	 * Filters the media URL the transcript is linked to (used to find the player).
	 *
	 * @param string $url Attachment URL.
	 * @param int    $id  Post ID holding the tracks.
	 */
	$url = (string) apply_filters( 'captionwright_media_url', (string) wp_get_attachment_url( $id ), $id );

	return sprintf(
		'<div %1$s data-media="%2$s" lang="%3$s"><details%4$s><summary>%5$s</summary><div class="captionwright-transcript__body">%6$s</div></details></div>',
		'' !== $wrapper ? $wrapper : 'class="captionwright-transcript"',
		esc_url( $url ),
		esc_attr( $lang ),
		$collapsed ? '' : ' open',
		esc_html( $title ),
		$body
	);
}

add_action(
	'init',
	function () {
		wp_register_style( 'captionwright-transcript', CAPTIONWRIGHT_URL . 'blocks/transcript/style.css', array(), CAPTIONWRIGHT_VERSION . '.' . filemtime( CAPTIONWRIGHT_DIR . 'blocks/transcript/style.css' ) );
		wp_register_script(
			'captionwright-transcript-view',
			CAPTIONWRIGHT_URL . 'blocks/transcript/view.js',
			array(),
			CAPTIONWRIGHT_VERSION . '.' . filemtime( CAPTIONWRIGHT_DIR . 'blocks/transcript/view.js' ),
			array(
				'in_footer' => true,
				'strategy'  => 'defer',
			)
		);
		register_block_type( CAPTIONWRIGHT_DIR . 'blocks/transcript' );
		add_shortcode(
			'captionwright_transcript',
			function ( $atts ) {
				$atts = shortcode_atts(
					array(
						'id'        => 0,
						'lang'      => '',
						'collapsed' => 'yes',
						'times'     => 'yes',
					),
					$atts,
					'captionwright_transcript'
				);
				return render_transcript(
					array(
						'attachmentId' => (int) $atts['id'],
						'lang'         => sanitize_key( $atts['lang'] ),
						'collapsed'    => 'no' !== $atts['collapsed'],
						'showTimes'    => 'no' !== $atts['times'],
					)
				);
			}
		);
	}
);