<?php

namespace Glovario\Cache;

defined( 'ABSPATH' ) || exit;

/**
 * Purges page caches after variables or rules change.
 *
 * A cached page would otherwise keep showing the previous value until the
 * cache expired. Changes are collected during the request and purged once, at
 * shutdown, so an import or a batch of edits causes a single purge.
 */
final class ContentChangePurge {
	private $keys = array();

	public function register() {
		add_action( 'glovario_after_variable_saved', array( $this, 'variable_changed' ) );
		add_action( 'glovario_variable_deleted', array( $this, 'variable_changed' ) );
		add_action( 'glovario_rules_changed', array( $this, 'rules_changed' ) );
		add_action( 'shutdown', array( $this, 'flush' ) );
	}

	public function variable_changed( $variable ) {
		$this->keys[] = is_array( $variable ) ? (string) ( $variable['variable_key'] ?? '' ) : '';
	}

	public function rules_changed( $variable_id ) {
		$this->keys[] = 'variable:' . absint( $variable_id );
	}

	/**
	 * Whether a purge is waiting for the end of the request.
	 *
	 * @return bool
	 */
	public function pending() {
		return (bool) $this->keys;
	}

	public function flush() {
		if ( ! $this->keys ) {
			return;
		}
		$keys       = array_values( array_unique( array_filter( $this->keys ) ) );
		$this->keys = array();
		PageCachePurger::purge( 'content_changed', array( 'changed' => $keys ) );
	}
}