<?php
/**
 * Rank Math SEO target keyword source.
 *
 * @package Postlinkly
 * @since   1.0.0
 */

declare(strict_types=1);

namespace Postlinkly\Keywords\Sources;

/**
 * Reads the focus keyword set by Rank Math SEO for a post.
 *
 * Rank Math stores the primary focus keyword in `rank_math_focus_keyword`
 * as a comma-separated string (multiple keywords are comma-delimited).
 *
 * Availability is determined by checking for the `RankMath` class, which
 * is present whenever Rank Math Free or Pro is active.
 *
 * @since 1.0.0
 */
final class RankMathSource implements KeywordSourceInterface {

	/**
	 * Source identifier.
	 */
	public const SOURCE_ID = 'rankmath';

	/**
	 * @since 1.0.0
	 */
	public function get_id(): string {
		return self::SOURCE_ID;
	}

	/**
	 * @since 1.0.0
	 */
	public function get_label(): string {
		return __( 'Rank Math SEO', 'postlinkly' );
	}

	/**
	 * @since 1.0.0
	 */
	public function is_available(): bool {
		return class_exists( 'RankMath', false );
	}

	/**
	 * @since 1.0.0
	 *
	 * @param int    $post_id   Post identifier.
	 * @param string $post_type Item type. Default `post`.
	 *
	 * @return array<int, string>
	 */
	public function get_keywords_for( int $post_id, string $post_type = 'post' ): array {
		if ( $post_id <= 0 || 'post' !== $post_type || ! function_exists( 'get_post_meta' ) ) {
			return array();
		}

		$raw = get_post_meta( $post_id, 'rank_math_focus_keyword', true );
		if ( ! is_string( $raw ) || '' === trim( $raw ) ) {
			return array();
		}

		// Rank Math separates multiple keywords with commas.
		$parts = explode( ',', $raw );
		$out   = array();
		foreach ( $parts as $part ) {
			$kw = trim( $part );
			if ( '' !== $kw ) {
				$out[] = $kw;
			}
		}
		return $out;
	}
}