<?php
/**
 * Functions for retrieving and manipulating metadata of various GlotPress object types.
 *
 * @package GlotPress
 * @subpackage Meta
 */

/**
 * Sanitizes a key name to be used to store meta data in to the database.
 *
 * @since 1.0.0
 *
 * @param string $key Metadata key.
 *
 * @return string
 */
function gp_sanitize_meta_key( $key ) {
	return preg_replace( '|[^a-z0-9_]|i', '', $key );
}


/**
 * Retrieves and returns a meta value from the database.
 *
 * @since 1.0.0
 *
 * @param string      $object_type The object type.
 * @param int         $object_id   ID of the object metadata is for.
 * @param string|null $meta_key    Optional. Metadata key. Default null.
 *
 * @return mixed|false Metadata or false.
 */
function gp_get_meta( $object_type, $object_id, $meta_key = null ) {
	global $wpdb;
	$meta_key = gp_sanitize_meta_key( $meta_key );

	if ( ! $object_type ) {
		return false;
	}

	if ( ! is_numeric( $object_id ) || empty( $object_id ) ) {
		return false;
	}
	$object_id = (int) $object_id;

	$object_meta = wp_cache_get( $object_id, $object_type );

	if ( false === $object_meta ) {
		$db_object_meta = $wpdb->get_results( $wpdb->prepare( "SELECT `meta_key`, `meta_value` FROM `$wpdb->gp_meta` WHERE `object_type` = %s AND `object_id` = %d", $object_type, $object_id ) );

		$object_meta = array();
		foreach ( $db_object_meta as $meta ) {
			$object_meta[ $meta->meta_key ] = maybe_unserialize( $meta->meta_value );
		}

		wp_cache_add( $object_id, $object_meta, $object_type );
	}

	if ( $meta_key && isset( $object_meta[ $meta_key ] ) ) {
		return $object_meta[ $meta_key ];
	} elseif ( ! $meta_key ) {
		return $object_meta;
	} else {
		return false;
	}
}

/**
 * Adds and updates meta data in the database
 *
 * @since 1.0.0
 *
 * @param int    $object_id  ID of the object metadata is for.
 * @param string $meta_key   Metadata key.
 * @param mixed  $meta_value The value to store.
 * @param string $type       The object type.
 * @param bool   $global     Overrides the requirement of $object_id to be a number OR not empty.
 *
 * @return bool|int True if meta updated, false if there is an error and the id of the inserted row otherwise.
 */
function gp_update_meta( $object_id = 0, $meta_key, $meta_value, $type, $global = false ) {
	global $wpdb;

	if ( ! is_numeric( $object_id ) || empty( $object_id ) && ! $global ) {
		return false;
	}

	$cache_object_id = $object_id = (int) $object_id;
	$object_type     = $type;
	$meta_key        = gp_sanitize_meta_key( $meta_key );

	$meta_tuple = compact( 'object_type', 'object_id', 'meta_key', 'meta_value', 'type' );

	/**
	 * Filter the meta data before it gets updated.
	 *
	 * @since 1.0.0
	 *
	 * @param array $meta_tuple Key value pairs of database columns and their values according
	 *                          to update meta values from the database.
	 */
	$meta_tuple = apply_filters( 'gp_update_meta', $meta_tuple );
	extract( $meta_tuple, EXTR_OVERWRITE );

	$meta_value = $_meta_value = maybe_serialize( $meta_value );
	$meta_value = maybe_unserialize( $meta_value );

	$cur = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM `$wpdb->gp_meta` WHERE `object_type` = %s AND `object_id` = %d AND `meta_key` = %s", $object_type, $object_id, $meta_key ) );

	// Setup a default return value, if any error happens we will abort immediately and return false so it won't be used.
	// Otherwise we'll default to true, but this may be changed to the id of the inserted row later.
	$ret = true;

	// If no rows are returned we need to insert the meta data instead of updating it.
	if ( null === $cur ) {
		$result = $wpdb->insert(
			$wpdb->gp_meta,
			array(
				'object_type' => $object_type,
				'object_id'   => $object_id,
				'meta_key'    => $meta_key,
				'meta_value'  => $_meta_value,
			)
		);

		// If the insert failed, return false, otherwise return the id of the inserted row.
		if ( false === $result ) {
			return false;
		} else {
			$ret = $wpdb->insert_id;
		}
	} elseif ( $cur->meta_value !== $meta_value ) {
		$result = $wpdb->update(
			$wpdb->gp_meta,
			array( 'meta_value' => $_meta_value ),
			array(
				'object_type' => $object_type,
				'object_id'   => $object_id,
				'meta_key'    => $meta_key,
			)
		);

		// If the update failed, return false.
		if ( false === $result ) {
			return false;
		}
	}

	wp_cache_delete( $cache_object_id, $object_type );

	return $ret;
}

/**
 * Deletes meta data from the database.
 *
 * @since 1.0.0
 *
 * @param int    $object_id  ID of the object metadata is for.
 * @param string $meta_key   Metadata key.
 * @param mixed  $meta_value The value to store.
 * @param string $type       The object type.
 * @param bool   $global     Overrides the requirement of $object_id to be a number OR not empty.
 *
 * @return bool
 */
function gp_delete_meta( $object_id = 0, $meta_key, $meta_value, $type, $global = false ) {
	global $wpdb;

	if ( ! is_numeric( $object_id ) || empty( $object_id ) && ! $global ) {
		return false;
	}

	$cache_object_id = $object_id = (int) $object_id;
	$object_type     = $type;
	$meta_key        = gp_sanitize_meta_key( $meta_key );

	$meta_tuple = compact( 'object_type', 'object_id', 'meta_key', 'meta_value', 'type' );

	/**
	 * Filter the meta data before it gets deleted.
	 *
	 * @since 1.0.0
	 *
	 * @param array $meta_tuple Key value pairs of database columns and their values according to delete meta values from the database.
	 */
	$meta_tuple = apply_filters( 'gp_delete_meta', $meta_tuple );
	extract( $meta_tuple, EXTR_OVERWRITE );

	$meta_value = maybe_serialize( $meta_value );

	if ( empty( $meta_value ) ) {
		$meta_sql = $wpdb->prepare( "SELECT `meta_id` FROM `$wpdb->gp_meta` WHERE `object_type` = %s AND `object_id` = %d AND `meta_key` = %s", $object_type, $object_id, $meta_key );
	} else {
		$meta_sql = $wpdb->prepare( "SELECT `meta_id` FROM `$wpdb->gp_meta` WHERE `object_type` = %s AND `object_id` = %d AND `meta_key` = %s AND `meta_value` = %s", $object_type, $object_id, $meta_key, $meta_value );
	}

	if ( ! $meta_id = $wpdb->get_var( $meta_sql ) ) { // WPCS: unprepared SQL ok.
		return false;
	}

	$wpdb->query( $wpdb->prepare( "DELETE FROM `$wpdb->gp_meta` WHERE `meta_id` = %d", $meta_id ) );

	wp_cache_delete( $cache_object_id, $object_type );

	return true;
}