<?php
/*
 * Plugin Name: WP Crontrol
 * Plugin URI:  https://wordpress.org/plugins/wp-crontrol/
 * Description: WP Crontrol lets you view and control what's happening in the WP-Cron system.
 * Author:      <a href="https://johnblackbourn.com/">John Blackbourn</a> & <a href="http://www.scompt.com/">Edward Dale</a>
 * Version:     1.3.1
 * Text Domain: wp-crontrol
 * Domain Path: /languages/
 * License:     GPL v2 or later
 */

/**
 * WP Crontrol lets you view and control what's happening in the WP-Cron system.
 *
 * LICENSE
 * This file is part of WP Crontrol.
 *
 * WP Crontrol is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * @package    WP Crontrol
 * @author     Edward Dale <scompt@scompt.com> & John Blackbourn <john@johnblackbourn.com>
 * @copyright  Copyright 2013 Edward Dale & John Blackbourn
 * @license    http://www.gnu.org/licenses/gpl.txt GPL 2.0
 * @link       https://wordpress.org/plugins/wp-crontrol/
 * @since      0.2
 */

defined( 'ABSPATH' ) or die();

class Crontrol {

	/**
	 * Hook onto all of the actions and filters needed by the plugin.
	 */
	protected function __construct() {

		$plugin_file = plugin_basename( __FILE__ );

		add_action( 'init',                               array( $this, 'action_init' ) );
		add_action( 'init',                               array( $this, 'action_handle_posts' ) );
		add_action( 'admin_menu',                         array( $this, 'action_admin_menu' ) );
		add_filter( "plugin_action_links_{$plugin_file}", array( $this, 'plugin_action_links' ), 10, 4 );

		register_activation_hook( __FILE__, array( $this, 'action_activate' ) );

		add_filter( 'cron_schedules',    array( $this, 'filter_cron_schedules' ) );
		add_action( 'crontrol_cron_job', array( $this, 'action_php_cron_event' ) );
	}

	/**
	 * Evaluates the provided code using eval.
	 */
	public function action_php_cron_event( $code ) {
		eval( $code );
	}

	/**
	 * Run using the 'init' action.
	 */
	public function action_init() {
		load_plugin_textdomain( 'wp-crontrol', false, dirname( plugin_basename( __FILE__ ) ) . '/gettext' );
	}

	/**
	 * Handles any POSTs made by the plugin. Run using the 'init' action.
	 */
	public function action_handle_posts() {
		if ( isset( $_POST['new_cron'] ) ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to add new cron events.', 'wp-crontrol' ) );
			}
			check_admin_referer( 'new-cron' );
			extract( wp_unslash( $_POST ), EXTR_PREFIX_ALL, 'in' );
			$in_args = json_decode( $in_args, true );
			$this->add_cron( $in_next_run, $in_schedule, $in_hookname, $in_args );
			$redirect = array(
				'page'             => 'crontrol_admin_manage_page',
				'crontrol_message' => '5',
				'crontrol_name'    => urlencode( $in_hookname ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
			exit;

		} else if ( isset( $_POST['new_php_cron'] ) ) {
			if ( ! current_user_can( 'edit_files' ) ) {
				wp_die( esc_html__( 'You are not allowed to add new PHP cron events.', 'wp-crontrol' ) );
			}
			check_admin_referer( 'new-cron' );
			extract( wp_unslash( $_POST ), EXTR_PREFIX_ALL, 'in' );
			$args = array( 'code' => $in_hookcode );
			$this->add_cron( $in_next_run, $in_schedule, 'crontrol_cron_job', $args );
			$redirect = array(
				'page'             => 'crontrol_admin_manage_page',
				'crontrol_message' => '5',
				'crontrol_name'    => urlencode( $in_hookname ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
			exit;

		} else if ( isset( $_POST['edit_cron'] ) ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to edit cron events.', 'wp-crontrol' ) );
			}

			extract( wp_unslash( $_POST ), EXTR_PREFIX_ALL, 'in' );
			check_admin_referer( "edit-cron_{$in_original_hookname}_{$in_original_sig}_{$in_original_next_run}" );
			$in_args = json_decode( $in_args, true );
			$i = $this->delete_cron( $in_original_hookname, $in_original_sig, $in_original_next_run );
			$i = $this->add_cron( $in_next_run, $in_schedule, $in_hookname, $in_args );
			$redirect = array(
				'page'             => 'crontrol_admin_manage_page',
				'crontrol_message' => '4',
				'crontrol_name'    => urlencode( $in_hookname ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
			exit;

		} else if ( isset( $_POST['edit_php_cron'] ) ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to edit cron events.', 'wp-crontrol' ) );
			}

			extract( wp_unslash( $_POST ), EXTR_PREFIX_ALL, 'in' );
			check_admin_referer( "edit-cron_{$in_original_hookname}_{$in_original_sig}_{$in_original_next_run}" );
			$args['code'] = $in_hookcode;
			$args = array( 'code' => $in_hookcode );
			$i = $this->delete_cron( $in_original_hookname, $in_original_sig, $in_original_next_run );
			$i = $this->add_cron( $in_next_run, $in_schedule, 'crontrol_cron_job', $args );
			$redirect = array(
				'page'             => 'crontrol_admin_manage_page',
				'crontrol_message' => '4',
				'crontrol_name'    => urlencode( $in_hookname ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
			exit;

		} else if ( isset( $_POST['new_schedule'] ) ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to add new cron schedules.', 'wp-crontrol' ) );
			}
			check_admin_referer( 'new-sched' );
			$name = wp_unslash( $_POST['internal_name'] );
			$interval = wp_unslash( $_POST['interval'] );
			$display = wp_unslash( $_POST['display_name'] );

			// The user entered something that wasn't a number.
			// Try to convert it with strtotime
			if ( ! is_numeric( $interval ) ) {
				$now = time();
				$future = strtotime( $interval, $now );
				if ( false === $future || -1 == $future || $now > $future ) {
					$redirect = array(
						'page'             => 'crontrol_admin_options_page',
						'crontrol_message' => '7',
						'crontrol_name'    => urlencode( $interval ),
					);
					wp_redirect( add_query_arg( $redirect, admin_url( 'options-general.php' ) ) );
					exit;
				}
				$interval = $future - $now;
			} else if ( $interval <= 0 ) {
				$redirect = array(
					'page'             => 'crontrol_admin_options_page',
					'crontrol_message' => '7',
					'crontrol_name'    => urlencode( $interval ),
				);
				wp_redirect( add_query_arg( $redirect, admin_url( 'options-general.php' ) ) );
				exit;
			}

			$this->add_schedule( $name, $interval, $display );
			$redirect = array(
				'page'             => 'crontrol_admin_options_page',
				'crontrol_message' => '3',
				'crontrol_name'    => urlencode( $name ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'options-general.php' ) ) );
			exit;

		} else if ( isset( $_GET['action'] ) && 'delete-sched' == $_GET['action'] ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to delete cron schedules.', 'wp-crontrol' ) );
			}
			$id = wp_unslash( $_GET['id'] );
			check_admin_referer( "delete-sched_{$id}" );
			$this->delete_schedule( $id );
			$redirect = array(
				'page'             => 'crontrol_admin_options_page',
				'crontrol_message' => '2',
				'crontrol_name'    => urlencode( $id ),
			);
			wp_redirect( add_query_arg( $redirect, admin_url( 'options-general.php' ) ) );
			exit;

		} else if ( isset( $_GET['action'] ) && 'delete-cron' == $_GET['action'] ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to delete cron events.', 'wp-crontrol' ) );
			}
			$id = wp_unslash( $_GET['id'] );
			$sig = wp_unslash( $_GET['sig'] );
			$next_run = $_GET['next_run'];
			check_admin_referer( "delete-cron_{$id}_{$sig}_{$next_run}" );
			if ( $this->delete_cron( $id, $sig, $next_run ) ) {
				$redirect = array(
					'page'             => 'crontrol_admin_manage_page',
					'crontrol_message' => '6',
					'crontrol_name'    => urlencode( $id ),
				);
				wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
				exit;
			} else {
				$redirect = array(
					'page'             => 'crontrol_admin_manage_page',
					'crontrol_message' => '7',
					'crontrol_name'    => urlencode( $id ),
				);
				wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
				exit;

			};

		} else if ( isset( $_GET['action'] ) && 'run-cron' == $_GET['action'] ) {
			if ( ! current_user_can( 'manage_options' ) ) {
				wp_die( esc_html__( 'You are not allowed to run cron events.', 'wp-crontrol' ) );
			}
			$id = wp_unslash( $_GET['id'] );
			$sig = wp_unslash( $_GET['sig'] );
			check_admin_referer( "run-cron_{$id}_{$sig}" );
			if ( $this->run_cron( $id, $sig ) ) {
				$redirect = array(
					'page'             => 'crontrol_admin_manage_page',
					'crontrol_message' => '1',
					'crontrol_name'    => urlencode( $id ),
				);
				wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
				exit;
			} else {
				$redirect = array(
					'page'             => 'crontrol_admin_manage_page',
					'crontrol_message' => '8',
					'crontrol_name'    => urlencode( $id ),
				);
				wp_redirect( add_query_arg( $redirect, admin_url( 'tools.php' ) ) );
				exit;
			}
		}
	}

	/**
	 * Executes a cron event immediately.
	 *
	 * Executes an event by scheduling a new single event with the same arguments.
	 *
	 * @param string $hookname The hookname of the cron event to run
	 */
	public function run_cron( $hookname, $sig ) {
		$crons = _get_cron_array();
		foreach ( $crons as $time => $cron ) {
			if ( isset( $cron[ $hookname ][ $sig ] ) ) {
				$args = $cron[ $hookname ][ $sig ]['args'];
				delete_transient( 'doing_cron' );
				wp_schedule_single_event( time() - 1, $hookname, $args );
				spawn_cron();
				return true;
			}
		}
		return false;
	}

	/**
	 * Adds a new cron event.
	 *
	 * @param string $next_run A human-readable (strtotime) time that the event should be run at
	 * @param string $schedule The recurrence of the cron event
	 * @param string $hookname The name of the hook to execute
	 * @param array $args Arguments to add to the cron event
	 */
	public function add_cron( $next_run, $schedule, $hookname, $args ) {
		$next_run = strtotime( $next_run );
		if ( false === $next_run || -1 == $next_run ) {
			$next_run = time();
		}
		if ( ! is_array( $args ) ) {
			$args = array();
		}
		if ( '_oneoff' == $schedule ) {
			return wp_schedule_single_event( $next_run, $hookname, $args ) === null;
		} else {
			return wp_schedule_event( $next_run, $schedule, $hookname, $args ) === null;
		}
	}

	/**
	 * Deletes a cron event.
	 *
	 * @param string $name The hookname of the event to delete.
	 */
	public function delete_cron( $to_delete, $sig, $next_run ) {
		$crons = _get_cron_array();
		if ( isset( $crons[ $next_run ][ $to_delete ][ $sig ] ) ) {
			$args = $crons[ $next_run ][ $to_delete ][ $sig ]['args'];
			wp_unschedule_event( $next_run, $to_delete, $args );
			return true;
		}
		return false;
	}

	/**
	 * Adds a new custom cron schedule.
	 *
	 * @param string $name     The internal name of the schedule
	 * @param int    $interval The interval between executions of the new schedule
	 * @param string $display  The display name of the schedule
	 */
	public function add_schedule( $name, $interval, $display ) {
		$old_scheds = get_option( 'crontrol_schedules', array() );
		$old_scheds[ $name ] = array( 'interval' => $interval, 'display' => $display );
		update_option( 'crontrol_schedules', $old_scheds );
	}

	/**
	 * Deletes a custom cron schedule.
	 *
	 * @param string $name The internal_name of the schedule to delete.
	 */
	public function delete_schedule( $name ) {
		$scheds = get_option( 'crontrol_schedules', array() );
		unset( $scheds[ $name ] );
		update_option( 'crontrol_schedules', $scheds );
	}

	/**
	 * Sets up the plugin environment upon first activation.
	 *
	 * Run using the 'activate_' action.
	 */
	public function action_activate() {
		add_option( 'crontrol_schedules', array() );

		// if there's never been a cron event, _get_cron_array will return false
		if ( _get_cron_array() === false ) {
			_set_cron_array( array() );
		}
	}

	/**
	 * Adds options & management pages to the admin menu.
	 *
	 * Run using the 'admin_menu' action.
	 */
	public function action_admin_menu() {
		add_options_page( esc_html__( 'Cron Schedules', 'wp-crontrol' ), esc_html__( 'Cron Schedules', 'wp-crontrol' ), 'manage_options', 'crontrol_admin_options_page', array( $this, 'admin_options_page' ) );
		add_management_page( esc_html__( 'Cron Events', 'wp-crontrol' ), esc_html__( 'Cron Events', 'wp-crontrol' ), 'manage_options', 'crontrol_admin_manage_page', array( $this, 'admin_manage_page' ) );
	}

	public function plugin_action_links( $actions, $plugin_file, $plugin_data, $context ) {
		$actions['crontrol-events'] = sprintf(
			'<a href="%s">%s</a>',
			admin_url( 'tools.php?page=crontrol_admin_manage_page' ),
			esc_html__( 'Cron Events', 'wp-crontrol' )
		);
		$actions['crontrol-schedules'] = sprintf(
			'<a href="%s">%s</a>',
			admin_url( 'options-general.php?page=crontrol_admin_options_page' ),
			esc_html__( 'Cron Schedules', 'wp-crontrol' )
		);
		return $actions;
	}

	/**
	 * Gives WordPress the plugin's set of cron schedules.
	 *
	 * Called by the 'cron_schedules' filter.
	 *
	 * @param array $scheds The current cron schedules. Usually an empty array.
	 * @return array The existing cron schedules along with the plugin's schedules.
	 */
	public function filter_cron_schedules( $scheds ) {
		$new_scheds = get_option( 'crontrol_schedules', array() );
		return array_merge( $new_scheds, $scheds );
	}

	/**
	 * Displays the options page for the plugin.
	 */
	public function admin_options_page() {
		$schedules = $this->get_schedules();
		$custom_schedules = get_option( 'crontrol_schedules', array() );
		$custom_keys = array_keys( $custom_schedules );

		$messages = array(
			'2' => __( 'Successfully deleted the cron schedule %s.', 'wp-crontrol' ),
			'3' => __( 'Successfully added the cron schedule %s.', 'wp-crontrol' ),
			'7' => __( 'Cron schedule not added because there was a problem parsing %s.', 'wp-crontrol' ),
		);
		if ( isset( $_GET['crontrol_message'] ) && isset( $_GET['crontrol_name'] ) && isset( $messages[ $_GET['crontrol_message'] ] ) ) {
			$hook = wp_unslash( $_GET['crontrol_name'] );
			$msg  = sprintf( esc_html( $messages[ $_GET['crontrol_message'] ] ), '<strong>' . esc_html( $hook ) . '</strong>' );

			printf( '<div id="message" class="updated notice is-dismissible"><p>%s</p></div>', $msg ); // WPCS:: XSS ok.
		}

		?>
		<div class="wrap">
		<h1><?php esc_html_e( 'WP-Cron Schedules', 'wp-crontrol' ); ?></h1>
		<p><?php esc_html_e( 'WP-Cron schedules are the time intervals that are available for scheduling events. You can only delete custom schedules.', 'wp-crontrol' ); ?></p>
		<table class="widefat striped">
		<thead>
			<tr>
				<th scope="col"><?php esc_html_e( 'Name', 'wp-crontrol' ); ?></th>
				<th scope="col"><?php esc_html_e( 'Interval', 'wp-crontrol' ); ?></th>
				<th scope="col"><?php esc_html_e( 'Display Name', 'wp-crontrol' ); ?></th>
				<th>&nbsp;</th>
			</tr>
		</thead>
		<tbody>
		<?php
		if ( empty( $schedules ) ) {
			?>
			<tr colspan="4"><td><?php esc_html_e( 'You currently have no schedules. Add one below.', 'wp-crontrol' ); ?></td></tr>
			<?php
		} else {
			foreach ( $schedules as $name => $data ) {
				printf( '<tr id="sched-%s">',
					esc_attr( $name )
				);
				printf( '<td>%s</td>',
					esc_html( $name )
				);
				printf( '<td>%s (%s)</td>',
					esc_html( $data['interval'] ),
					esc_html( $this->interval( $data['interval'] ) )
				);
				printf( '<td>%s</td>',
					esc_html( $data['display'] )
				);
				if ( in_array( $name, $custom_keys ) ) {
					$url = add_query_arg( array(
						'page'   => 'crontrol_admin_options_page',
						'action' => 'delete-sched',
						'id'     => urlencode( $name ),
					), admin_url( 'options-general.php' ) );
					$url = wp_nonce_url( $url, 'delete-sched_' . $name );
					printf( '<td><a href="%s" class="delete">%s</a></td>',
						esc_url( $url ),
						esc_html__( 'Delete', 'wp-crontrol' )
					);
				} else {
					echo '<td>&nbsp;</td>';
				}
				echo '</tr>';
			}
		}
		?>
		</tbody>
		</table>
		</div>
		<div class="wrap narrow">
			<h2 class="title"><?php esc_html_e( 'Add new cron schedule', 'wp-crontrol' ); ?></h2>
			<p><?php esc_html_e( 'Adding a new cron schedule will allow you to schedule events that re-occur at the given interval.', 'wp-crontrol' ); ?></p>
			<form method="post" action="options-general.php?page=crontrol_admin_options_page">
				<table class="form-table">
					<tbody>
					<tr>
						<th valign="top" scope="row"><label for="cron_internal_name"><?php esc_html_e( 'Internal name', 'wp-crontrol' ); ?>:</label></th>
						<td><input type="text" class="regular-text" value="" id="cron_internal_name" name="internal_name"/></td>
					</tr>
					<tr>
						<th valign="top" scope="row"><label for="cron_interval"><?php esc_html_e( 'Interval (seconds)', 'wp-crontrol' ); ?>:</label></th>
						<td><input type="text" class="regular-text" value="" id="cron_interval" name="interval"/></td>
					</tr>
					<tr>
						<th valign="top" scope="row"><label for="cron_display_name"><?php esc_html_e( 'Display name', 'wp-crontrol' ); ?>:</label></th>
						<td><input type="text" class="regular-text" value="" id="cron_display_name" name="display_name"/></td>
					</tr>
				</tbody></table>
				<p class="submit"><input id="schedadd-submit" type="submit" class="button-primary" value="<?php esc_attr_e( 'Add Cron Schedule', 'wp-crontrol' ); ?>" name="new_schedule"/></p>
				<?php wp_nonce_field( 'new-sched' ); ?>
			</form>
		</div>
		<?php
	}

	/**
	 * Gets a sorted (according to interval) list of the cron schedules
	 */
	public function get_schedules() {
		$schedules = wp_get_schedules();
		uasort( $schedules, create_function( '$a, $b', 'return $a["interval"] - $b["interval"];' ) );
		return $schedules;
	}

	/**
	 * Displays a dropdown filled with the possible schedules, including non-repeating.
	 *
	 * @param boolean $current The currently selected schedule
	 */
	public function schedules_dropdown( $current = false ) {
		$schedules = $this->get_schedules();
		?>
		<select class="postform" name="schedule" id="schedule">
		<option <?php selected( $current, '_oneoff' ); ?> value="_oneoff"><?php esc_html_e( 'Non-repeating', 'wp-crontrol' ); ?></option>
		<?php foreach ( $schedules as $sched_name => $sched_data ) { ?>
			<option <?php selected( $current, $sched_name ); ?> value="<?php echo esc_attr( $sched_name ); ?>">
				<?php
				printf(
					'%s (%s)',
					esc_html( $sched_data['display'] ),
					esc_html( $this->interval( $sched_data['interval'] ) )
				);
				?>
			</option>
		<?php } ?>
		</select>
		<?php
	}

	/**
	 * Gets the status of WP-Cron functionality on the site by performing a test spawn. Cached for one hour when all is well.
	 *
	 */
	public function test_cron_spawn( $cache = true ) {
		global $wp_version;

		if ( defined( 'DISABLE_WP_CRON' ) && DISABLE_WP_CRON ) {
			return new WP_Error( 'crontrol_info', sprintf( __( 'The %s constant is set to true. WP-Cron spawning is disabled.', 'wp-crontrol' ), 'DISABLE_WP_CRON' ) );
		}

		if ( defined( 'ALTERNATE_WP_CRON' ) && ALTERNATE_WP_CRON ) {
			return new WP_Error( 'crontrol_info', sprintf( __( 'The %s constant is set to true.', 'wp-crontrol' ), 'ALTERNATE_WP_CRON' ) );
		}

		$cached_status = get_transient( 'wp-cron-test-ok' );

		if ( $cache && $cached_status ) {
			return true;
		}

		$sslverify     = version_compare( $wp_version, 4.0, '<' );
		$doing_wp_cron = sprintf( '%.22F', microtime( true ) );

		$cron_request = apply_filters( 'cron_request', array(
			'url'  => site_url( 'wp-cron.php?doing_wp_cron=' . $doing_wp_cron ),
			'key'  => $doing_wp_cron,
			'args' => array(
				'timeout'   => 3,
				'blocking'  => true,
				'sslverify' => apply_filters( 'https_local_ssl_verify', $sslverify ),
			),
		) );

		$cron_request['args']['blocking'] = true;

		$result = wp_remote_post( $cron_request['url'], $cron_request['args'] );

		if ( is_wp_error( $result ) ) {
			return $result;
		} else if ( wp_remote_retrieve_response_code( $result ) >= 300 ) {
			return new WP_Error( 'unexpected_http_response_code', sprintf(
				__( 'Unexpected HTTP response code: %s', 'wp-crontrol' ),
				intval( wp_remote_retrieve_response_code( $result ) )
			) );
		} else {
			set_transient( 'wp-cron-test-ok', 1, 3600 );
			return true;
		}

	}

	/**
	 * Shows the status of WP-Cron functionality on the site. Only displays a message when there's a problem.
	 *
	 */
	public function show_cron_status() {

		$status = $this->test_cron_spawn();

		if ( is_wp_error( $status ) ) {
			if (  'crontrol_info' === $status->get_error_code() ) {
				?>
				<div id="cron-status-notice" class="notice notice-info">
					<p><?php echo esc_html( $status->get_error_message() ); ?></p>
				</div>
				<?php
			} else {
				?>
				<div id="cron-status-error" class="error">
					<p><?php printf( esc_html__( 'There was a problem spawning a call to the WP-Cron system on your site. This means WP-Cron events on your site may not work. The problem was: %s', 'wp-crontrol' ), '<br><strong>' . esc_html( $status->get_error_message() ) . '</strong>' ); ?></p>
				</div>
				<?php
			}
		}

	}

	/**
	 * Shows the form used to add/edit cron events.
	 *
	 * @param boolean $is_php Whether this is a PHP cron event
	 * @param mixed $existing An array of existing values for the cron event, or null
	 */
	public function show_cron_form( $is_php, $existing ) {
		$new_tabs = array(
			'cron'     => __( 'Add Cron Event', 'wp-crontrol' ),
			'php-cron' => __( 'Add PHP Cron Event', 'wp-crontrol' ),
		);
		$modify_tabs = array(
			'cron'     => __( 'Modify Cron Event', 'wp-crontrol' ),
			'php-cron' => __( 'Modify PHP Cron Event', 'wp-crontrol' ),
		);
		$new_links = array(
			'cron'     => admin_url( 'tools.php?page=crontrol_admin_manage_page&action=new-cron' ) . '#crontrol_form',
			'php-cron' => admin_url( 'tools.php?page=crontrol_admin_manage_page&action=new-php-cron' ) . '#crontrol_form',
		);
		if ( $is_php ) {
			$helper_text = esc_html__( 'Cron events trigger actions in your code. Using the form below, you can enter the schedule of the action, as well as the PHP code for the action itself.', 'wp-crontrol' );
		} else {
			$helper_text = sprintf(
				esc_html__( 'Cron events trigger actions in your code. A cron event added using the form below needs a corresponding action hook somewhere in code, perhaps the %1$s file in your theme.', 'wp-crontrol' ),
				'<code>functions.php</code>'
			);
		}
		if ( is_array( $existing ) ) {
			$other_fields  = wp_nonce_field( "edit-cron_{$existing['hookname']}_{$existing['sig']}_{$existing['next_run']}", '_wpnonce', true, false );
			$other_fields .= sprintf( '<input name="original_hookname" type="hidden" value="%s" />',
				esc_attr( $existing['hookname'] )
			);
			$other_fields .= sprintf( '<input name="original_sig" type="hidden" value="%s" />',
				esc_attr( $existing['sig'] )
			);
			$other_fields .= sprintf( '<input name="original_next_run" type="hidden" value="%s" />',
				esc_attr( $existing['next_run'] )
			);
			$existing['args'] = $is_php ? $existing['args']['code'] : wp_json_encode( $existing['args'] );
			$existing['next_run'] = date( 'Y-m-d H:i:s', $existing['next_run'] );
			$action = $is_php ? 'edit_php_cron' : 'edit_cron';
			$button = $is_php ? $modify_tabs['php-cron'] : $modify_tabs['cron'];
			$show_edit_tab = true;
		} else {
			$other_fields = wp_nonce_field( 'new-cron', '_wpnonce', true, false );
			$existing = array( 'hookname' => '', 'hookcode' => '', 'args' => '', 'next_run' => 'now', 'schedule' => false );
			$action = $is_php ? 'new_php_cron' : 'new_cron';
			$button = $is_php ? $new_tabs['php-cron'] : $new_tabs['cron'];
			$show_edit_tab = false;
		}
		?>
		<div id="crontrol_form" class="wrap narrow">
			<h2 class="nav-tab-wrapper">
				<a href="<?php echo esc_url( $new_links['cron'] ); ?>" class="nav-tab<?php if ( ! $show_edit_tab && ! $is_php ) { echo ' nav-tab-active'; } ?>"><?php echo esc_html( $new_tabs['cron'] ); ?></a>
				<?php if ( current_user_can( 'edit_files' ) ) { ?>
					<a href="<?php echo esc_url( $new_links['php-cron'] ); ?>" class="nav-tab<?php if ( ! $show_edit_tab && $is_php ) { echo ' nav-tab-active'; } ?>"><?php echo esc_html( $new_tabs['php-cron'] ); ?></a>
				<?php } ?>
				<?php if ( $show_edit_tab ) { ?>
					<span class="nav-tab nav-tab-active"><?php echo esc_html( $button ); ?></span>
				<?php } ?>
			</h2>
			<p><?php echo $helper_text; // WPCS:: XSS ok. ?></p>
			<form method="post" action="<?php echo esc_url( admin_url( 'tools.php?page=crontrol_admin_manage_page' ) ); ?>">
				<?php echo $other_fields; // WPCS:: XSS ok. ?>
				<table class="form-table"><tbody>
					<?php if ( $is_php ) : ?>
						<tr>
							<th valign="top" scope="row"><label for="hookcode"><?php esc_html_e( 'Hook code:', 'wp-crontrol' ); ?></label></th>
							<td><textarea class="large-text code" rows="10" cols="50" id="hookcode" name="hookcode"><?php echo esc_textarea( $existing['args'] ); ?></textarea></td>
						</tr>
					<?php else : ?>
						<tr>
							<th valign="top" scope="row"><label for="hookname"><?php esc_html_e( 'Hook name:', 'wp-crontrol' ); ?></label></th>
							<td><input type="text" class="regular-text" id="hookname" name="hookname" value="<?php echo esc_attr( $existing['hookname'] ); ?>"/></td>
						</tr>
						<tr>
							<th valign="top" scope="row"><label for="args"><?php esc_html_e( 'Arguments:', 'wp-crontrol' ); ?></label></th>
							<td>
								<input type="text" class="regular-text" id="args" name="args" value="<?php echo esc_attr( $existing['args'] ); ?>"/>
								<p class="description"><?php esc_html_e( 'e.g. [25], ["asdf"], or ["i","want",25,"cakes"]', 'wp-crontrol' ); ?></p>
							</td>
						</tr>
					<?php endif; ?>
					<tr>
						<th valign="top" scope="row"><label for="next_run"><?php esc_html_e( 'Next run (UTC):', 'wp-crontrol' ); ?></label></th>
						<td>
							<input type="text" class="regular-text" id="next_run" name="next_run" value="<?php echo esc_attr( $existing['next_run'] ); ?>"/>
							<p class="description"><?php esc_html_e( "e.g. 'now', 'tomorrow', '+2 days', or '25-02-2020 12:34:00'", 'wp-crontrol' ); ?></p>
						</td>
					</tr><tr>
						<th valign="top" scope="row"><label for="schedule"><?php esc_html_e( 'Event schedule:', 'wp-crontrol' ); ?></label></th>
						<td>
							<?php $this->schedules_dropdown( $existing['schedule'] ); ?>
						</td>
					</tr>
				</tbody></table>
				<p class="submit"><input type="submit" class="button-primary" value="<?php echo esc_attr( $button ); ?>" name="<?php echo esc_attr( $action ); ?>"/></p>
			</form>
		</div>
		<?php
	}

	public function get_cron_events() {

		$crons  = _get_cron_array();
		$events = array();

		if ( empty( $crons ) ) {
			return new WP_Error(
				'no_events',
				__( 'You currently have no scheduled cron events.', 'wp-crontrol' )
			);
		}

		foreach ( $crons as $time => $cron ) {
			foreach ( $cron as $hook => $dings ) {
				foreach ( $dings as $sig => $data ) {

					# This is a prime candidate for a Crontrol_Event class but I'm not bothering currently.
					$events[ "$hook-$sig-$time" ] = (object) array(
						'hook'     => $hook,
						'time'     => $time,
						'sig'      => $sig,
						'args'     => $data['args'],
						'schedule' => $data['schedule'],
						'interval' => isset( $data['interval'] ) ? $data['interval'] : null,
					);

				}
			}
		}

		return $events;

	}

	/**
	 * Displays the manage page for the plugin.
	 */
	public function admin_manage_page() {
		$messages = array(
			'1' => __( 'Successfully executed the cron event %s', 'wp-crontrol' ),
			'4' => __( 'Successfully edited the cron event %s', 'wp-crontrol' ),
			'5' => __( 'Successfully created the cron event %s', 'wp-crontrol' ),
			'6' => __( 'Successfully deleted the cron event %s', 'wp-crontrol' ),
			'7' => __( 'Failed to the delete the cron event %s', 'wp-crontrol' ),
			'8' => __( 'Failed to the execute the cron event %s', 'wp-crontrol' ),
		);
		if ( isset( $_GET['crontrol_name'] ) && isset( $_GET['crontrol_message'] ) && isset( $messages[ $_GET['crontrol_message'] ] ) ) {
			$hook = wp_unslash( $_GET['crontrol_name'] );
			$msg = sprintf( esc_html( $messages[ $_GET['crontrol_message'] ] ), '<strong>' . esc_html( $hook ) . '</strong>' );

			printf( '<div id="message" class="updated notice is-dismissible"><p>%s</p></div>', $msg ); // WPCS:: XSS ok.
		}
		$events = $this->get_cron_events();
		$doing_edit = ( isset( $_GET['action'] ) && 'edit-cron' == $_GET['action'] ) ? wp_unslash( $_GET['id'] ) : false ;
		$time_format = 'Y-m-d H:i:s';

		$tzstring = get_option( 'timezone_string' );
		$current_offset = get_option( 'gmt_offset' );

		if ( $current_offset >= 0 ) {
			$current_offset = '+' . $current_offset;
		}

		if ( '' === $tzstring ) {
			$tz = sprintf( 'UTC%s', $current_offset );
		} else {
			$tz = sprintf( '%s (UTC%s)', str_replace( '_', ' ', $tzstring ), $current_offset );
		}

		$this->show_cron_status();

		?>
		<div class="wrap">
		<h1><?php esc_html_e( 'WP-Cron Events', 'wp-crontrol' ); ?></h1>
		<table class="widefat striped">
		<thead>
			<tr>
				<th><?php esc_html_e( 'Hook Name', 'wp-crontrol' ); ?></th>
				<th><?php esc_html_e( 'Arguments', 'wp-crontrol' ); ?></th>
				<th><?php esc_html_e( 'Next Run', 'wp-crontrol' ); ?></th>
				<th><?php esc_html_e( 'Recurrence', 'wp-crontrol' ); ?></th>
				<th colspan="3">&nbsp;</th>
			</tr>
		</thead>
		<tbody>
		<?php
		if ( is_wp_error( $events ) ) {
			?>
			<tr><td colspan="7"><?php echo esc_html( $events->get_error_message() ); ?></td></tr>
			<?php
		} else {
			foreach ( $events as $id => $event ) {

				if ( $doing_edit && $doing_edit == $event->hook && $event->time == $_GET['next_run'] && $event->sig == $_GET['sig'] ) {
					$doing_edit = array(
						'hookname' => $event->hook,
						'next_run' => $event->time,
						'schedule' => ( $event->schedule ? $event->schedule : '_oneoff' ),
						'sig'      => $event->sig,
						'args'     => $event->args,
					);
				}

				if ( empty( $event->args ) ) {
					$args = __( 'None', 'wp-crontrol' );
				} else {
					if ( defined( 'JSON_UNESCAPED_SLASHES' ) ) {
						$args = wp_json_encode( $event->args, JSON_UNESCAPED_SLASHES );
					} else {
						$args = stripslashes( wp_json_encode( $event->args ) );
					}
				}

				echo '<tr id="cron-' . esc_attr( $id ) . '" class="">';

				if ( 'crontrol_cron_job' == $event->hook ) {
					echo '<td><em>' . esc_html__( 'PHP Cron', 'wp-crontrol' ) . '</em></td>';
					echo '<td><em>' . esc_html__( 'PHP Code', 'wp-crontrol' ) . '</em></td>';
				} else {
					echo '<td>' . esc_html( $event->hook ) . '</td>';
					echo '<td>' . esc_html( $args ) . '</td>';
				}

				echo '<td>';
				printf( '%s (%s)',
					esc_html( get_date_from_gmt( date( 'Y-m-d H:i:s', $event->time ), $time_format ) ),
					esc_html( $this->time_since( time(), $event->time ) )
				);
				echo '</td>';

				if ( $event->schedule ) {
					echo '<td>';
					echo esc_html( $this->interval( $event->interval ) );
					echo '</td>';
				} else {
					echo '<td>';
					esc_html_e( 'Non-repeating', 'wp-crontrol' );
					echo '</td>';
				}

				$link = array(
					'page'     => 'crontrol_admin_manage_page',
					'action'   => 'edit-cron',
					'id'       => urlencode( $event->hook ),
					'sig'      => urlencode( $event->sig ),
					'next_run' => urlencode( $event->time ),
				);
				$link = add_query_arg( $link, admin_url( 'tools.php' ) ) . '#crontrol_form';
				echo "<td><a class='view' href='" . esc_url( $link ) . "'>" . esc_html__( 'Edit', 'wp-crontrol' ) . '</a></td>';

				$link = array(
					'page'     => 'crontrol_admin_manage_page',
					'action'   => 'run-cron',
					'id'       => urlencode( $event->hook ),
					'sig'      => urlencode( $event->sig ),
					'next_run' => urlencode( $event->time ),
				);
				$link = add_query_arg( $link, admin_url( 'tools.php' ) );
				$link = wp_nonce_url( $link, "run-cron_{$event->hook}_{$event->sig}" );
				echo "<td><a class='view' href='". esc_url( $link ) ."'>" . esc_html__( 'Run Now', 'wp-crontrol' ) . '</a></td>';

				$link = array(
					'page'     => 'crontrol_admin_manage_page',
					'action'   => 'delete-cron',
					'id'       => urlencode( $event->hook ),
					'sig'      => urlencode( $event->sig ),
					'next_run' => urlencode( $event->time ),
				);
				$link = add_query_arg( $link, admin_url( 'tools.php' ) );
				$link = wp_nonce_url( $link, "delete-cron_{$event->hook}_{$event->sig}_{$event->time}" );
				echo "<td><a class='delete' href='".esc_url( $link )."'>" . esc_html__( 'Delete', 'wp-crontrol' ) . '</a></td>';

				echo '</tr>';

			}
		}
		?>
		</tbody>
		</table>

		<div class="tablenav">
			<p class="description">
				<?php printf( esc_html__( 'Local timezone is %s', 'wp-crontrol' ), '<code>' . esc_html( $tz ) . '</code>' ); ?>
				<span id="utc-time"><?php printf( esc_html__( 'UTC time is %s', 'wp-crontrol' ), '<code>' . esc_html( date_i18n( $time_format, false, true ) ) . '</code>' ); ?></span>
				<span id="local-time"><?php printf( esc_html__( 'Local time is %s', 'wp-crontrol' ), '<code>' . esc_html( date_i18n( $time_format ) ) . '</code>' ); ?></span>
			</p>
		</div>

		</div>
		<?php
		if ( is_array( $doing_edit ) ) {
			$this->show_cron_form( 'crontrol_cron_job' == $doing_edit['hookname'], $doing_edit );
		} else {
			$this->show_cron_form( ( isset( $_GET['action'] ) and 'new-php-cron' == $_GET['action'] ), false );
		}
	}

	/**
	 * Pretty-prints the difference in two times.
	 *
	 * @param time $older_date
	 * @param time $newer_date
	 * @return string The pretty time_since value
	 * @link http://binarybonsai.com/code/timesince.txt
	 */
	public function time_since( $older_date, $newer_date ) {
		return $this->interval( $newer_date - $older_date );
	}

	public function interval( $since ) {
		// array of time period chunks
		$chunks = array(
			array( 60 * 60 * 24 * 365, _n_noop( '%s year', '%s years', 'wp-crontrol' ) ),
			array( 60 * 60 * 24 * 30, _n_noop( '%s month', '%s months', 'wp-crontrol' ) ),
			array( 60 * 60 * 24 * 7, _n_noop( '%s week', '%s weeks', 'wp-crontrol' ) ),
			array( 60 * 60 * 24, _n_noop( '%s day', '%s days', 'wp-crontrol' ) ),
			array( 60 * 60, _n_noop( '%s hour', '%s hours', 'wp-crontrol' ) ),
			array( 60, _n_noop( '%s minute', '%s minutes', 'wp-crontrol' ) ),
			array( 1, _n_noop( '%s second', '%s seconds', 'wp-crontrol' ) ),
		);

		if ( $since <= 0 ) {
			return __( 'now', 'wp-crontrol' );
		}

		// we only want to output two chunks of time here, eg:
		// x years, xx months
		// x days, xx hours
		// so there's only two bits of calculation below:

		// step one: the first chunk
		for ( $i = 0, $j = count( $chunks ); $i < $j; $i++ ) {
			$seconds = $chunks[ $i ][0];
			$name = $chunks[ $i ][1];

			// finding the biggest chunk (if the chunk fits, break)
			if ( ( $count = floor( $since / $seconds ) ) != 0 ) {
				break;
			}
		}

		// set output var
		$output = sprintf( translate_nooped_plural( $name, $count, 'wp-crontrol' ), $count );

		// step two: the second chunk
		if ( $i + 1 < $j ) {
			$seconds2 = $chunks[ $i + 1 ][0];
			$name2 = $chunks[ $i + 1 ][1];

			if ( ( $count2 = floor( ( $since - ( $seconds * $count ) ) / $seconds2 ) ) != 0 ) {
				// add to output var
				$output .= ' ' . sprintf( translate_nooped_plural( $name2, $count2, 'wp-crontrol' ), $count2 );
			}
		}

		return $output;
	}

	public static function init() {

		static $instance = null;

		if ( ! $instance ) {
			$instance = new Crontrol;
		}

		return $instance;

	}
}

// Get this show on the road
Crontrol::init();