<?php
/**
 * Article summaries: data model, validation and the summary card.
 *
 * @package KarmaDocs
 */

namespace KarmaDocs;

use KarmaDocs\Search\Index;

defined( 'ABSPATH' ) || exit;

/**
 * A summary is stored in the `_kdocs_summary` post meta:
 *
 *     {
 *       points: string[2–4], steps: string[], minutes: int,
 *       status: generated|edited|approved, locked: bool,
 *       model, content_hash, generated_at, approved_by, approved_at
 *     }
 *
 * Pro generates it with AI; the free "Key points" block renders the same card
 * from points written by hand. A summary is "outdated" when the article text
 * changed after it was generated or reviewed.
 */
class Summary {

	/**
	 * Meta key.
	 */
	const META = '_kdocs_summary';

	/**
	 * Meta key: hide the summary on this article.
	 */
	const HIDE_META = '_kdocs_summary_hide';

	/**
	 * Most key points.
	 */
	const MAX_POINTS = 4;

	/**
	 * Longest key point (characters).
	 */
	const MAX_POINT = 160;

	/**
	 * Hooks.
	 */
	public function register() {
		add_action( 'init', array( $this, 'register_meta' ) );
	}

	/**
	 * Meta fields (revisions keep a copy of the summary).
	 */
	public function register_meta() {
		register_post_meta(
			PostTypes::ARTICLE,
			self::META,
			array(
				'type'              => 'object',
				'single'            => true,
				'show_in_rest'      => false,
				'revisions_enabled' => true,
				'auth_callback'     => static fn( $allowed, $key, $post_id ) => current_user_can( 'edit_post', $post_id ),
			)
		);
		register_post_meta(
			PostTypes::ARTICLE,
			self::HIDE_META,
			array(
				'type'          => 'boolean',
				'single'        => true,
				'default'       => false,
				'show_in_rest'  => true,
				'auth_callback' => static fn( $allowed, $key, $post_id ) => current_user_can( 'edit_post', $post_id ),
			)
		);
	}

	/**
	 * Stored summary.
	 *
	 * @param int $post_id Article.
	 * @return array|null
	 */
	public static function get( $post_id ) {
		$data = get_post_meta( (int) $post_id, self::META, true );
		return is_array( $data ) && ! empty( $data['points'] ) ? $data : null;
	}

	/**
	 * Saves a summary (validated; extra fields kept as given).
	 *
	 * @param int   $post_id Article.
	 * @param array $data    Summary.
	 * @return array|\WP_Error Saved summary.
	 */
	public static function save( $post_id, array $data ) {
		$clean = self::validate( $data );
		if ( is_wp_error( $clean ) ) {
			return $clean;
		}
		$data = array_merge( $data, $clean );
		update_post_meta( (int) $post_id, self::META, $data );
		return $data;
	}

	/**
	 * Validates points, steps and minutes.
	 *
	 * @param array $data Raw summary (also an AI response).
	 * @param int   $min  Fewest points.
	 * @return array{points:string[],steps:string[],minutes:int}|\WP_Error
	 */
	public static function validate( array $data, $min = 1 ) {
		$line   = static function ( $text, $max ) {
			$text = trim( preg_replace( '/\s+/u', ' ', wp_strip_all_tags( (string) $text ) ) );
			$text = ltrim( $text, "-•*· \t" );
			return mb_strlen( $text ) > $max ? rtrim( mb_substr( $text, 0, $max - 1 ) ) . '…' : $text;
		};
		$points = array_values( array_filter( array_map( static fn( $p ) => $line( $p, self::MAX_POINT ), (array) ( $data['points'] ?? array() ) ) ) );
		$steps  = array_values( array_filter( array_map( static fn( $s ) => $line( $s, 120 ), (array) ( $data['steps'] ?? array() ) ) ) );
		if ( count( $points ) < $min ) {
			return new \WP_Error( 'kdocs_invalid_summary', __( 'A summary needs at least one key point.', 'karma-docs' ), array( 'status' => 400 ) );
		}
		return array(
			'points'  => array_slice( $points, 0, self::MAX_POINTS ),
			'steps'   => array_slice( $steps, 0, 8 ),
			'minutes' => max( 0, min( 600, (int) ( $data['minutes'] ?? 0 ) ) ),
		);
	}

	/**
	 * Plain text of an article for summarizing: headings kept as "## …" lines,
	 * long code blocks shortened.
	 *
	 * @param \WP_Post $post Article.
	 * @return string
	 */
	public static function text( $post ) {
		$copy               = clone $post;
		$copy->post_content = preg_replace_callback(
			'#(<pre[^>]*>)(.*?)(</pre>)#is',
			static fn( $m ) => $m[1] . ( strlen( $m[2] ) > 600 ? substr( $m[2], 0, 600 ) . "\n…" : $m[2] ) . $m[3],
			(string) $post->post_content
		);
		$out                = array();
		foreach ( Index::sections( $copy ) as $section ) {
			$out[] = ( $section['heading'] ? '## ' . $section['heading'] . "\n" : '' ) . $section['text'];
		}
		return trim( implode( "\n\n", $out ) );
	}

	/**
	 * Fingerprint of the article text a summary was made from.
	 *
	 * @param \WP_Post $post Article.
	 * @return string
	 */
	public static function hash( $post ) {
		return md5( get_the_title( $post ) . "\n" . self::text( $post ) );
	}

	/**
	 * Word count of the article.
	 *
	 * @param \WP_Post $post Article.
	 * @return int
	 */
	public static function words( $post ) {
		return count( Index::words( wp_strip_all_tags( strip_shortcodes( (string) $post->post_content ) ) ) );
	}

	/**
	 * Status: none, generated, edited, approved or outdated.
	 *
	 * @param \WP_Post|int $post Article.
	 * @return string
	 */
	public static function status( $post ) {
		$post = get_post( $post );
		$data = $post ? self::get( $post->ID ) : null;
		if ( ! $data ) {
			return 'none';
		}
		if ( ! empty( $data['content_hash'] ) && self::hash( $post ) !== $data['content_hash'] ) {
			return 'outdated';
		}
		return in_array( $data['status'] ?? '', array( 'edited', 'approved' ), true ) ? $data['status'] : 'generated';
	}

	/**
	 * The AI summary card for an article, when it should be shown.
	 *
	 * @param \WP_Post $post Article.
	 * @return string HTML.
	 */
	public static function render( $post ) {
		$data = self::get( $post->ID );
		if ( ! $data || ! Features::is_pro() || ! Settings::get( 'summary_show', true ) || get_post_meta( $post->ID, self::HIDE_META, true ) ) {
			return '';
		}
		if ( Settings::get( 'summary_approved_only', false ) && 'approved' !== ( $data['status'] ?? '' ) ) {
			return '';
		}
		if ( self::words( $post ) < (int) Settings::get( 'summary_min_words', 250 ) ) {
			return '';
		}
		/**
		 * Whether to show the AI summary on an article (Pro: per knowledge base setting).
		 *
		 * @param bool     $show Show.
		 * @param \WP_Post $post Article.
		 */
		if ( ! apply_filters( 'kdocs_show_summary', true, $post ) ) {
			return '';
		}
		return self::card(
			$data,
			array(
				'ai'       => true,
				'article'  => $post->ID,
				'approved' => 'approved' === ( $data['status'] ?? '' ),
				'open'     => (bool) Settings::get( 'summary_open', true ),
			)
		);
	}

	/**
	 * Summary card markup (AI summary and the "Key points" block).
	 *
	 * @param array $data Summary: points, steps, minutes.
	 * @param array $args ai (label + rating), article, approved, open, title.
	 * @return string HTML.
	 */
	public static function card( array $data, array $args = array() ) {
		$args  = wp_parse_args(
			$args,
			array(
				'ai'       => false,
				'article'  => 0,
				'approved' => false,
				'open'     => true,
				'title'    => '',
			)
		);
		$title = $args['title'] ? $args['title'] : ( $args['ai'] ? __( 'Summary', 'karma-docs' ) : __( 'Key points', 'karma-docs' ) );
		$note  = $args['approved']
			? __( 'Generated from this article and reviewed by our team.', 'karma-docs' )
			: __( 'Generated from this article by AI. Check the article for details.', 'karma-docs' );

		ob_start();
		?>
		<section class="kdocs-summary<?php echo $args['ai'] ? ' is-ai' : ''; ?>" aria-label="<?php echo esc_attr( $title ); ?>"<?php echo $args['ai'] ? ' data-kdocs-summary="' . (int) $args['article'] . '"' : ''; ?>>
			<details<?php echo $args['open'] ? ' open' : ''; ?>>
				<summary class="kdocs-summary-head">
					<span class="kdocs-summary-title"><?php echo esc_html( $title ); ?></span>
					<?php if ( $args['ai'] ) : ?>
						<span class="kdocs-summary-label" title="<?php echo esc_attr( $note ); ?>">
							<?php echo esc_html( $args['approved'] ? __( 'AI-generated · reviewed', 'karma-docs' ) : __( 'AI-generated', 'karma-docs' ) ); ?>
						</span>
					<?php endif; ?>
				</summary>
				<div class="kdocs-summary-body">
					<ul class="kdocs-summary-points">
						<?php foreach ( (array) $data['points'] as $point ) : ?>
							<li><?php echo esc_html( $point ); ?></li>
						<?php endforeach; ?>
					</ul>
					<?php if ( ! empty( $data['steps'] ) ) : ?>
						<p class="kdocs-summary-sub"><?php esc_html_e( 'Steps at a glance', 'karma-docs' ); ?></p>
						<ol class="kdocs-summary-steps">
							<?php foreach ( (array) $data['steps'] as $step ) : ?>
								<li><?php echo esc_html( $step ); ?></li>
							<?php endforeach; ?>
						</ol>
					<?php endif; ?>
					<?php if ( ! empty( $data['minutes'] ) || $args['ai'] ) : ?>
						<div class="kdocs-summary-foot">
							<?php if ( ! empty( $data['minutes'] ) ) : ?>
								<span class="kdocs-summary-time">
									<?php
									/* translators: %d: minutes */
									echo esc_html( sprintf( _n( 'About %d minute to complete', 'About %d minutes to complete', (int) $data['minutes'], 'karma-docs' ), (int) $data['minutes'] ) );
									?>
								</span>
							<?php endif; ?>
							<?php if ( $args['ai'] ) : ?>
								<span class="kdocs-summary-rate" data-kdocs-summary-rate>
									<span><?php esc_html_e( 'Was this summary useful?', 'karma-docs' ); ?></span>
									<button type="button" data-vote="yes" aria-label="<?php esc_attr_e( 'Yes', 'karma-docs' ); ?>">👍</button>
									<button type="button" data-vote="no" aria-label="<?php esc_attr_e( 'No', 'karma-docs' ); ?>">👎</button>
								</span>
							<?php endif; ?>
						</div>
					<?php endif; ?>
				</div>
			</details>
		</section>
		<?php
		return trim( (string) ob_get_clean() );
	}

	/**
	 * Meta description for an article: the SEO description, else the excerpt,
	 * else the approved summary, else the start of the text.
	 *
	 * @param \WP_Post $post Article.
	 * @return string
	 */
	public static function description( $post ) {
		$custom = trim( (string) get_post_meta( $post->ID, '_kdocs_seo_description', true ) );
		if ( '' !== $custom ) {
			return $custom;
		}
		if ( '' !== trim( (string) $post->post_excerpt ) ) {
			return wp_trim_words( wp_strip_all_tags( $post->post_excerpt ), 30, '…' );
		}
		$data = self::get( $post->ID );
		if ( $data && 'approved' === ( $data['status'] ?? '' ) && Features::is_pro() ) {
			$text = implode( ' ', $data['points'] );
			return mb_strlen( $text ) > 158 ? rtrim( mb_substr( $text, 0, 157 ) ) . '…' : $text;
		}
		return wp_trim_words( wp_strip_all_tags( strip_shortcodes( excerpt_remove_blocks( (string) $post->post_content ) ) ), 30, '…' );
	}
}