<?php
/**
 * Error Protection API: WP_Recovery_Mode_Email_Link class
 *
 * @package WordPress
 * @since   5.2.0
 */

/**
 * Core class used to send an email with a link to begin Recovery Mode.
 *
 * @since 5.2.0
 */
final class WP_Recovery_Mode_Email_Service {

	const RATE_LIMIT_OPTION = 'recovery_mode_email_last_sent';

	/**
	 * Service to generate recovery mode URLs.
	 *
	 * @since 5.2.0
	 * @var WP_Recovery_Mode_Link_Service
	 */
	private $link_service;

	/**
	 * WP_Recovery_Mode_Email_Service constructor.
	 *
	 * @since 5.2.0
	 *
	 * @param WP_Recovery_Mode_Link_Service $link_service
	 */
	public function __construct( WP_Recovery_Mode_Link_Service $link_service ) {
		$this->link_service = $link_service;
	}

	/**
	 * Sends the recovery mode email if the rate limit has not been sent.
	 *
	 * @since 5.2.0
	 *
	 * @param int   $rate_limit Number of seconds before another email can be sent.
	 * @param array $error      Error details from {@see error_get_last()}
	 * @param array $extension  The extension that caused the error. {
	 *      @type string $slug The extension slug. The plugin or theme's directory.
	 *      @type string $type The extension type. Either 'plugin' or 'theme'.
	 * }
	 * @return true|WP_Error True if email sent, WP_Error otherwise.
	 */
	public function maybe_send_recovery_mode_email( $rate_limit, $error, $extension ) {

		$last_sent = get_option( self::RATE_LIMIT_OPTION );

		if ( ! $last_sent || time() > $last_sent + $rate_limit ) {
			if ( ! update_option( self::RATE_LIMIT_OPTION, time() ) ) {
				return new WP_Error( 'storage_error', __( 'Could not update the email last sent time.' ) );
			}

			$sent = $this->send_recovery_mode_email( $rate_limit, $error, $extension );

			if ( $sent ) {
				return true;
			}

			return new WP_Error( 'email_failed', __( 'The email could not be sent. Possible reason: your host may have disabled the mail() function.' ) );
		}

		$err_message = sprintf(
			/* translators: 1. Last sent as a human time diff 2. Wait time as a human time diff. */
			__( 'A recovery link was already sent %1$s ago. Please wait another %2$s before requesting a new email.' ),
			human_time_diff( $last_sent ),
			human_time_diff( $last_sent + $rate_limit )
		);

		return new WP_Error( 'email_sent_already', $err_message );
	}

	/**
	 * Clears the rate limit, allowing a new recovery mode email to be sent immediately.
	 *
	 * @since 5.2.0
	 *
	 * @return bool True on success, false on failure.
	 */
	public function clear_rate_limit() {
		return delete_option( self::RATE_LIMIT_OPTION );
	}

	/**
	 * Sends the Recovery Mode email to the site admin email address.
	 *
	 * @since 5.2.0
	 *
	 * @param int   $rate_limit Number of seconds before another email can be sent.
	 * @param array $error      Error details from {@see error_get_last()}
	 * @param array $extension  Extension that caused the error.
	 *
	 * @return bool Whether the email was sent successfully.
	 */
	private function send_recovery_mode_email( $rate_limit, $error, $extension ) {

		$url      = $this->link_service->generate_url();
		$blogname = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );

		$switched_locale = false;

		// The switch_to_locale() function is loaded before it can actually be used.
		if ( function_exists( 'switch_to_locale' ) && isset( $GLOBALS['wp_locale_switcher'] ) ) {
			$switched_locale = switch_to_locale( get_locale() );
		}

		if ( $extension ) {
			$cause   = $this->get_cause( $extension );
			$details = wp_strip_all_tags( wp_get_extension_error_description( $error ) );

			if ( $details ) {
				$header  = __( 'Error Details' );
				$details = "\n\n" . $header . "\n" . str_pad( '', strlen( $header ), '=' ) . "\n" . $details;
			}
		} else {
			$cause   = '';
			$details = '';
		}

		$message = __(
			'Howdy,

Your site recently crashed on ###LOCATION### and may not be working as expected.
###CAUSE###
Click the link below to initiate recovery mode and fix the problem.

This link expires in ###EXPIRES###.

###LINK### ###DETAILS###
'
		);
		$message = str_replace(
			array(
				'###LINK###',
				'###LOCATION###',
				'###EXPIRES###',
				'###CAUSE###',
				'###DETAILS###',
			),
			array(
				$url,
				'TBD',
				human_time_diff( time() + $rate_limit ),
				$cause ? "\n{$cause}\n" : "\n",
				$details,
			),
			$message
		);

		$email = array(
			'to'      => $this->get_recovery_mode_email_address(),
			/* translators: %s: site name */
			'subject' => __( '[%s] Your Site is Experiencing a Technical Issue' ),
			'message' => $message,
			'headers' => '',
		);

		/**
		 * Filter the contents of the Recovery Mode email.
		 *
		 * @since 5.2.0
		 *
		 * @param array  $email Used to build wp_mail().
		 * @param string $url   URL to enter recovery mode.
		 */
		$email = apply_filters( 'recovery_mode_email', $email, $url );

		$sent = wp_mail(
			$email['to'],
			wp_specialchars_decode( sprintf( $email['subject'], $blogname ) ),
			$email['message'],
			$email['headers']
		);

		if ( $switched_locale ) {
			restore_previous_locale();
		}

		return $sent;
	}

	/**
	 * Gets the email address to send the recovery mode link to.
	 *
	 * @since 5.2.0
	 *
	 * @return string Email address to send recovery mode link to.
	 */
	private function get_recovery_mode_email_address() {
		if ( defined( 'RECOVERY_MODE_EMAIL' ) && is_email( RECOVERY_MODE_EMAIL ) ) {
			return RECOVERY_MODE_EMAIL;
		}

		return get_option( 'admin_email' );
	}

	/**
	 * Gets the description indicating the possible cause for the error.
	 *
	 * @since 5.2.0
	 *
	 * @param array $extension The extension that caused the error.
	 * @return string Message about which extension caused the error.
	 */
	private function get_cause( $extension ) {

		if ( 'plugin' === $extension['type'] ) {
			if ( ! function_exists( 'get_plugins' ) ) {
				require_once ABSPATH . 'wp-admin/includes/plugin.php';
			}

			$plugins = get_plugins();

			$name = '';

			// Assume plugin main file name first since it is a common convention.
			if ( isset( $plugins[ "{$extension['slug']}/{$extension['slug']}.php" ] ) ) {
				$name = $plugins[ "{$extension['slug']}/{$extension['slug']}.php" ]['Name'];
			} else {
				foreach ( $plugins as $file => $plugin_data ) {
					if ( 0 === strpos( $file, "{$extension['slug']}/" ) ) {
						$name = $plugin_data['Name'];
						break;
					}
				}
			}

			if ( empty( $name ) ) {
				$name = $extension['slug'];
			}

			/* translators: %s: plugin name */
			$cause = sprintf( __( 'This was be caused by the %s plugin.' ), $name );
		} else {
			$theme = wp_get_theme( $extension['slug'] );
			$name  = $theme->exists() ? $theme->display( 'Name' ) : $extension['slug'];

			/* translators: %s: theme name */
			$cause = sprintf( __( 'This was be caused by the %s theme.' ), $name );
		}

		return $cause;
	}
}
