<?php
/**
 * Pods: relationship and file fields, and the Pods structure (pods, groups, fields).
 *
 * @package WonderfulSync
 */

namespace WonderfulPlugins\WonderfulSync;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * What Wonderful Sync needs to know about Pods.
 *
 * Content: relationship and file fields keep IDs of posts, media and terms in the
 * field's meta, in "_pods_<field>" (the order) and in the wp_podsrel table. The IDs
 * travel as tokens; after a write, Pods' own API writes meta and wp_podsrel again.
 *
 * Structure: pods, groups and fields are posts of the types _pods_pod, _pods_group
 * and _pods_field. They travel as layouts unless switched off in the settings; a
 * field removed on staging moves to the trash on live, its data stays.
 */
class Pods {

	/**
	 * Post types that hold the Pods structure.
	 */
	const STRUCTURE = array( '_pods_pod', '_pods_group', '_pods_field' );

	/**
	 * Meta keys of the structure that hold IDs of other structure posts.
	 */
	const STRUCTURE_REFS = array( 'group', 'parent', 'sister_id' );

	/**
	 * Option: '0' keeps the Pods structure out of transfers.
	 */
	const OPTION = 'wonderful_sync_pods_structure';

	/**
	 * Reference fields per pod (request cache).
	 *
	 * @var array<string, array>
	 */
	private static $fields = array();

	/**
	 * Whether Pods runs on this site.
	 */
	public static function active(): bool {
		return function_exists( 'pods_api' );
	}

	/**
	 * Whether the Pods structure travels.
	 */
	public static function structure_enabled(): bool {
		return '0' !== (string) get_option( self::OPTION, '1' );
	}

	/**
	 * Relationship and file fields of the pod behind a post type or taxonomy.
	 *
	 * @param string $object  'post' or 'term'.
	 * @param string $subtype Post type or taxonomy.
	 * @return array<string, array{kind: string, field: array, pod: array}> Field name => what its IDs are.
	 */
	public static function ref_fields( string $object, string $subtype ): array {
		$cache = $object . ':' . $subtype;
		if ( isset( self::$fields[ $cache ] ) ) {
			return self::$fields[ $cache ];
		}
		self::$fields[ $cache ] = array();
		if ( ! self::active() || '' === $subtype || in_array( $subtype, self::STRUCTURE, true ) ) {
			return array();
		}
		try {
			$pod = pods_api()->load_pod( array( 'name' => $subtype ), false );
		} catch ( \Throwable $e ) {
			return array();
		}
		$types = 'post' === $object ? array( 'post_type', 'media' ) : array( 'taxonomy' );
		if ( empty( $pod ) || ! in_array( (string) ( $pod['type'] ?? '' ), $types, true ) || 'meta' !== (string) ( $pod['storage'] ?? 'meta' ) ) {
			return array();
		}
		foreach ( (array) ( $pod['fields'] ?? array() ) as $name => $field ) {
			$kind = self::field_kind( $field );
			if ( '' !== $kind ) {
				self::$fields[ $cache ][ (string) ( $field['name'] ?? $name ) ] = array(
					'kind'  => $kind,
					'field' => $field,
					'pod'   => $pod,
				);
			}
		}

		return self::$fields[ $cache ];
	}

	/**
	 * What the IDs of a field point to: 'post', 'term' or '' (no IDs, or users).
	 *
	 * @param array|\ArrayAccess $field Pods field.
	 */
	private static function field_kind( $field ): string {
		$type = (string) ( $field['type'] ?? '' );
		if ( 'file' === $type ) {
			return 'post';
		}
		if ( 'pick' !== $type ) {
			return '';
		}
		$object = (string) ( $field['pick_object'] ?? '' );
		if ( in_array( $object, array( 'post_type', 'media' ), true ) ) {
			return 'post';
		}
		if ( in_array( $object, array( 'taxonomy', 'nav_menu' ), true ) ) {
			return 'term';
		}
		// Pods of type post_type or taxonomy are named by "pod" with the pod in pick_val.
		if ( 'pod' === $object ) {
			try {
				$related = pods_api()->load_pod( array( 'name' => (string) ( $field['pick_val'] ?? '' ) ), false );
			} catch ( \Throwable $e ) {
				return '';
			}
			$related_type = (string) ( $related['type'] ?? '' );
			if ( 'meta' === (string) ( $related['storage'] ?? 'meta' ) ) {
				return in_array( $related_type, array( 'post_type', 'media' ), true ) ? 'post' : ( 'taxonomy' === $related_type ? 'term' : '' );
			}
		}

		return '';
	}

	/**
	 * Lets Pods write meta and wp_podsrel of the reference fields again from the IDs that
	 * were just written ("_pods_<field>" keeps their order). Pods' API only adds and
	 * updates rows; relationships that are gone are deleted here, on both sides of a
	 * two-way field.
	 *
	 * @param string $object  'post' or 'term'.
	 * @param int    $id      Object ID.
	 * @param string $subtype Post type or taxonomy.
	 * @return string[] Fields whose relationship table could not be updated.
	 */
	public static function sync_relationships( string $object, int $id, string $subtype ): array {
		global $wpdb;
		$failed = array();
		$table  = $wpdb->prefix . 'podsrel';
		foreach ( self::ref_fields( $object, $subtype ) as $name => $info ) {
			$ordered = get_metadata( $object, $id, '_pods_' . $name, true );
			$ids     = is_array( $ordered ) && $ordered ? $ordered : get_metadata( $object, $id, $name, false );
			$ids     = array_values( array_unique( array_filter( array_map( 'intval', (array) $ids ) ) ) );
			$pod_id  = (int) ( $info['pod']['id'] ?? 0 );
			$fid     = (int) ( $info['field']['id'] ?? 0 );
			$rel     = function_exists( 'pods_podsrel_enabled' ) ? pods_podsrel_enabled( $info['field'], 'save' ) : false;
			$old     = $rel ? array_map( 'intval', (array) $wpdb->get_col( $wpdb->prepare( 'SELECT related_item_id FROM %i WHERE pod_id = %d AND field_id = %d AND item_id = %d', $table, $pod_id, $fid, $id ) ) ) : array(); // phpcs:ignore WordPress.DB.DirectDatabaseQuery -- Pods' own table, read right before it is rewritten.
			try {
				pods_api()->save_relationships( $id, $ids, $info['pod'], $info['field'] );
				$gone = array_diff( $old, $ids );
				if ( $gone ) {
					$gone  = array_values( array_map( 'intval', $gone ) );
					$marks = implode( ',', array_fill( 0, count( $gone ), '%d' ) );
					$wpdb->query( $wpdb->prepare( "DELETE FROM %i WHERE pod_id = %d AND field_id = %d AND item_id = %d AND related_item_id IN ({$marks})", array_merge( array( $table, $pod_id, $fid, $id ), $gone ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber -- one %d per ID.
					$sister = (int) ( $info['field']['sister_id'] ?? 0 );
					if ( $sister ) {
						$wpdb->query( $wpdb->prepare( "DELETE FROM %i WHERE field_id = %d AND related_item_id = %d AND item_id IN ({$marks})", array_merge( array( $table, $sister, $id ), $gone ) ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber -- one %d per ID.
					}
				}
			} catch ( \Throwable $e ) {
				$failed[] = $name;
			}
		}

		return $failed;
	}

	/**
	 * Pods caches its structure; after a transfer it reads it again.
	 */
	public static function flush(): void {
		self::$fields = array();
		if ( self::active() ) {
			try {
				pods_api()->cache_flush_pods( null, false );
				// New pods may bring post types with their own permalinks: rebuilt on demand.
				delete_option( 'rewrite_rules' );
			} catch ( \Throwable $e ) {
				return;
			}
		}
	}
}