<?php
/**
 * WP Ajax Abstract Class.
 *
 * @package   WPS_Core
 * @author    Travis Smith <t@wpsmith.net>
 * @copyright 2014 Travis Smith
 * @license   GPL-2.0+
 */

/**
 * WPS_Ajax class.
 *
 * @package WPS_Core
 * @author  Travis Smith <t@wpsmith.net>
 */
class WPS_Ajax {

	/**
	 * WP Nounce
	 *
	 * @var string
	 */
	protected $nonce = '';

	/**
	 * WP AJAX Name
	 *
	 * @var string
	 */
	protected $name = '';

	/**
	 * Whether to hook AJAX callback into front-end.
	 *
	 * @var string
	 */
	protected $nopriv = false;

	/**
	 * Hook for scripts.
	 * Could be: wp_enqueue_scripts or login_enqueue_scripts or admin_enqueue_scripts
	 *
	 * @var string
	 */
	protected $script_hook = 'admin_enqueue_scripts';

	/**
	 * Whether to keep the WP Heartbeat script.
	 *
	 * @var string
	 */
	protected $heartbeat = true;

	/**
	 * AJAX callback function name.
	 *
	 * @var string
	 */
	 protected $callback;

	/**
	 * Constructor
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @param string $name   Name (lower-case, without spaces, use underscore) of the WP Action
	 * @param array  $script Array of script information: url, src (path), data (localized info).

	 * @return void.
	 */
	public function __construct( $name, $script = array(), $callback ) {
		$this->name = str_replace( ' ', '_', strtolower( $name ) );

		// if not doing ajax, load script
		if ( ( defined( 'DOING_AJAX' ) && !DOING_AJAX ) || !defined( 'DOING_AJAX' ) ) {
			$this->maybe_do_action( 'plugins_loaded', 'script' );
		}

		// Hook up AJAX Action
		$this->maybe_do_action( 'plugins_loaded', 'init' );

		// Hook into secured callback
		add_action( "{$this->name}_wp_ajax_action", $callback );
	}

	/**
	 * Sets object parameters.
	 *   Available parameters: nopriv, script_hook, callback
	 *
	 * @since 1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @param string $param Parameter name.
	 * @param mixed  $value Value of parameter.
	 * @return void.
	 */
	public function set( $param, $value ) {
		switch ( $param ) {
			case 'nopriv':
				$this->nopriv = (bool) $value;
				break;
			case 'heartbeat':
				$this->heartbeat = (bool) $value;
				break;
			case 'script_hook':
				$hooks = array(
					'wp_enqueue_scripts',
					'login_enqueue_scripts',
					'admin_enqueue_scripts',
				);
				if ( in_array( $value, $hooks ) ) {
					$this->script_hook = strtolower( $value );
				}
				break;
			case 'callback':
				if ( is_callable( $value ) ) {
					$this->callback = $value;
				}
				break;
		}
	}

	/**
	 * Gets object parameter.
	 *   Available parameters: nopriv, script_hook, callback
	 *
	 * @since 1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @param string $param Parameter name.
	 * @return mixed        Value of parameter.
	 */
	public function get( $param ) {
		switch ( $param ) {
			case 'nopriv':
				return (bool)$this->nopriv;
			case 'heartbeat':
				return (bool)$this->heartbeat;
			case 'script_hook':
				return (string)$this->script_hook;
			case 'callback':
				return (string)$this->callback;
			default:
				return null;
		}
	}

	/**
	 * Hooks up AJAX Action
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	protected function init() {
		add_action( "wp_ajax_{$this->name}_action", array( $this, 'callback' ) );
		if ( $this->nopriv ) {
			add_action( "wp_ajax_nopriv_{$this->name}_action", array( $this, 'callback' ) );
		}
	}

	/**
	 * Hooks action or executes action.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @param string       WordPress action to be checked with did_action().
	 * @param string|array Function name/array to be called.
	 * @return void.
	 */
	private function maybe_do_action( $hook, $action ) {
		if ( !did_action( $hook ) ) {
			add_action( $hook, array( $this, $action ) );
		} elseif ( is_callable( $action ) ) {
			call_user_func( $action );
		}
	}

	/**
	 * Performs script operations: register, localize, and enqueue.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	public function script() {
		// Register Script
		add_action( 'wp_loaded', array( $this, 'register' ) );

		// Make sure we hook scripts in proper place & prevent user error.
		if ( $this->nopriv && 'admin_enqueue_scripts' === $this->script_hook ) {
			$this->script_hook = 'wp_enqueue_scripts';
		}

		// Go SCRIPT!
		add_action( $this->script_hook, array( $this, 'localize' ) );
		add_action( $this->script_hook, array( $this, 'enqueue' ) );

		if ( !$this->heartbeat ) {
			add_action( 'admin_enqueue_scripts', array( $this, 'no_heartbeat' ) );
		}
	}

	/**
	 * Properly Registers AJAX script.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	public function register() {
		wp_register_script(
			$this->name,
			$this->script['url'],
			$this->script['deps'],
			filemtime( $this->script['src'] ),
			true
		);
	}

	/**
	 * Properly Enqueues AJAX script.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	public function enqueue()	{
		wp_enqueue_script( $this->name );
	}

	/**
	 * Properly provides localized data for the action.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	public function localize() {
		// Get JS object name
		$object = isset( $this->script['data_object'] ) ? $this->script['data_object'] : $this->name;
		$this->nonce = wp_create_nonce( "{$this->name}_nonce" );
		$data = wp_parse_args( $this->script['data'], array(
			'ajaxurl'          => admin_url( 'admin-ajax.php' ),
			'_ajax_nonce'      => $this->nonce,
			'action'           => "{$this->name}_action",
			'screen_id'        => get_current_screen()->id,
		));
		wp_localize_script( $this->name, "$object", $data );
	}

	public function no_heartbeat() {
		wp_deregister_script('heartbeat');
		wp_register_script('heartbeat', false);
	}

	/**
	 * Does proper AJAX security check & then calls "{$this->name}_wp_ajax_action" action.
	 *
	 * @since  1.0.0
	 * @author Travis Smith <t@wpsmith.net>
	 *
	 * @return void.
	 */
	public function _callback() {
		$data = array_map( 'esc_attr', $_GET );
		! check_ajax_referer( $data['action'], "_ajax_nonce", false )
			AND wp_send_json_error();

		do_action( "{$this->name}_wp_ajax_action", $data );
	}

}