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

declare(strict_types=1);

namespace Postlinkly\Keywords\Sources;

/**
 * Reads the focus keyword set by Squirrly SEO for a post.
 *
 * Squirrly stores its SEO data in `_sq_post_keyword` post meta as a
 * serialised array. The keyword phrase lives at `$data['keyword']`.
 *
 * Availability is determined by checking for the `SQ_Classes_Helpers_Tools`
 * class, which is present whenever Squirrly SEO is active.
 *
 * @since 1.0.0
 */
final class SquirrlySource implements KeywordSourceInterface {

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

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

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

	/**
	 * @since 1.0.0
	 */
	public function is_available(): bool {
		return class_exists( 'SQ_Classes_Helpers_Tools', 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, '_sq_post_keyword', true );
		if ( empty( $raw ) ) {
			return array();
		}

		if ( is_string( $raw ) ) {
			$data = maybe_unserialize( $raw );
		} else {
			$data = $raw;
		}

		if ( ! is_array( $data ) ) {
			return array();
		}

		$kw = trim( (string) ( $data['keyword'] ?? '' ) );
		return '' !== $kw ? array( $kw ) : array();
	}
}