<?php
/**
 * Remove Class Filter Without Access to Class Object
 *
 * In order to use the core WordPress remove_filter() on a filter added with the callback
 * to a class, you either have to have access to that class object, or it has to be a call
 * to a static method.  This method allows you to remove filters with a callback to a class
 * you don't have access to.
 *
 * Works with WordPress 1.2+
 *
 * Supported for WordPress 4.7+ added on September 19, 2016
 *
 *
 * @param string $tag         Filter to remove
 * @param string $class_name  Class name for the filter's callback
 * @param string $method_name Method name for the filter's callback
 * @param int    $priority    Priority of the filter (default 10)
 *
 * @return bool Whether the function is removed.
 */
function remove_class_filter( $tag, $class_name = '', $method_name = '', $priority = 10 ) {

	global $wp_filter;

	// Check that filter actually exists first
	if ( ! isset( $wp_filter[ $tag ] ) ) return FALSE;

	/**
	 * If filter config is an object, means we're using WordPress 4.7+ and the config is no longer
	 * a simple array, rather it is an object that implements the ArrayAccess interface.
	 *
	 * To be backwards compatible, we set $callbacks equal to the correct array as a reference (so $wp_filter is updated)
	 *
	 * @see https://make.wordpress.org/core/2016/09/08/wp_hook-next-generation-actions-and-filters/
	 */
	if ( is_object( $wp_filter[ $tag ] ) && isset( $wp_filter[ $tag ]->callbacks ) ) {
		$callbacks = &$wp_filter[ $tag ]->callbacks;
	} else {
		$callbacks = &$wp_filter[ $tag ];
	}

	// Exit if there aren't any callbacks for specified priority
	if ( ! isset( $callbacks[ $priority ] ) || empty( $callbacks[ $priority ] ) ) return FALSE;

	// Loop through each filter for the specified priority, looking for our class & method
	foreach( (array) $callbacks[ $priority ] as $filter_id => $filter ) {

		// Filter should always be an array - array( $this, 'method' ), if not goto next
		if ( ! isset( $filter[ 'function' ] ) || ! is_array( $filter[ 'function' ] ) ) continue;

		// If first value in array is not an object, it can't be a class
		if ( ! is_object( $filter[ 'function' ][ 0 ] ) ) continue;

		// Method doesn't match the one we're looking for, goto next
		if ( $filter[ 'function' ][ 1 ] !== $method_name ) continue;

		// Method matched, now let's check the Class
		if ( get_class( $filter[ 'function' ][ 0 ] ) === $class_name ) {

			// Now let's remove it from the array
			unset( $callbacks[ $priority ][ $filter_id ] );

			// and if it was the only filter in that priority, unset that priority
			if ( empty( $callbacks[ $priority ] ) ) unset( $callbacks[ $priority ] );

			// and if the only filter for that tag, set the tag to an empty array
			if ( empty( $callbacks ) ) $callbacks = array();

			// If using WordPress older than 4.7
			if ( ! is_object( $wp_filter[ $tag ] ) ) {
				// Remove this filter from merged_filters, which specifies if filters have been sorted
				unset( $GLOBALS[ 'merged_filters' ][ $tag ] );
			}

			return TRUE;
		}
	}

	return FALSE;
}

/**
 * Remove Class Action Without Access to Class Object
 *
 * In order to use the core WordPress remove_action() on an action added with the callback
 * to a class, you either have to have access to that class object, or it has to be a call
 * to a static method.  This method allows you to remove actions with a callback to a class
 * you don't have access to.
 *
 * Works with WordPress 1.2+
 *
 * Supported for WordPress 4.7+ added on September 19, 2016
 *
 *
 * @param string $tag         Action to remove
 * @param string $class_name  Class name for the action's callback
 * @param string $method_name Method name for the action's callback
 * @param int    $priority    Priority of the action (default 10)
 *
 * @return bool               Whether the function is removed.
 */
function remove_class_action( $tag, $class_name = '', $method_name = '', $priority = 10 ) {
	remove_class_filter( $tag, $class_name, $method_name, $priority );
}