<?php
namespace BavarianRankEngine\Helpers;

class FallbackMeta {
	private const MIN = 150;
	private const MAX = 160;

	/**
	 * Extract a clean 150–160 char meta description from post content.
	 * Ends on a complete sentence or word boundary. No HTML.
	 *
	 * @param object $post Object with post_content property (WP_Post compatible)
	 */
	public static function extract( object $post ): string {
		$text = wp_strip_all_tags( $post->post_content ?? '' );
		$text = preg_replace( '/\s+/', ' ', $text );
		$text = trim( $text );

		if ( $text === '' ) {
			return '';
		}

		if ( mb_strlen( $text ) <= self::MAX ) {
			return $text;
		}

		// Try to end on a sentence boundary within MAX chars
		$candidate     = mb_substr( $text, 0, self::MAX );
		$last_period   = mb_strrpos( $candidate, '. ' );
		$last_exclaim  = mb_strrpos( $candidate, '! ' );
		$last_question = mb_strrpos( $candidate, '? ' );

		$last_sentence = max(
			$last_period === false ? -1 : $last_period,
			$last_exclaim === false ? -1 : $last_exclaim,
			$last_question === false ? -1 : $last_question
		);

		if ( $last_sentence >= 0 && $last_sentence >= self::MIN - 1 ) {
			return mb_substr( $text, 0, $last_sentence + 1 );
		}

		// Fall back to last word boundary within MAX
		$last_space = mb_strrpos( $candidate, ' ' );
		if ( $last_space !== false && $last_space >= self::MIN - 20 ) {
			return mb_substr( $text, 0, $last_space ) . '…';
		}

		// Last resort: hard cut with ellipsis
		return mb_substr( $text, 0, self::MAX - 1 ) . '…';
	}
}