retrieve_password() WordPress Function

function retrieve_password( $user_login = null ) {
	$errors    = new WP_Error();
	$user_data = false;

	// Use the passed $user_login if available, otherwise use $_POST['user_login'].
	if ( ! $user_login && ! empty( $_POST['user_login'] ) ) {
		$user_login = $_POST['user_login'];
	}

	if ( empty( $user_login ) ) {
		$errors->add( 'empty_username', __( '<strong>Error</strong>: Please enter a username or email address.' ) );
	} elseif ( strpos( $user_login, '@' ) ) {
		$user_data = get_user_by( 'email', trim( wp_unslash( $user_login ) ) );
		if ( empty( $user_data ) ) {
			$errors->add( 'invalid_email', __( '<strong>Error</strong>: There is no account with that username or email address.' ) );
		}
	} else {
		$user_data = get_user_by( 'login', trim( wp_unslash( $user_login ) ) );
	}

	/**
	 * Filters the user data during a password reset request.
	 *
	 * Allows, for example, custom validation using data other than username or email address.
	 *
	 * @since 5.7.0
	 *
	 * @param WP_User|false $user_data WP_User object if found, false if the user does not exist.
	 * @param WP_Error      $errors    A WP_Error object containing any errors generated
	 *                                 by using invalid credentials.
	 */
	$user_data = apply_filters( 'lostpassword_user_data', $user_data, $errors );

	/**
	 * Fires before errors are returned from a password reset request.
	 *
	 * @since 2.1.0
	 * @since 4.4.0 Added the `$errors` parameter.
	 * @since 5.4.0 Added the `$user_data` parameter.
	 *
	 * @param WP_Error      $errors    A WP_Error object containing any errors generated
	 *                                 by using invalid credentials.
	 * @param WP_User|false $user_data WP_User object if found, false if the user does not exist.
	 */
	do_action( 'lostpassword_post', $errors, $user_data );

	/**
	 * Filters the errors encountered on a password reset request.
	 *
	 * The filtered WP_Error object may, for example, contain errors for an invalid
	 * username or email address. A WP_Error object should always be returned,
	 * but may or may not contain errors.
	 *
	 * If any errors are present in $errors, this will abort the password reset request.
	 *
	 * @since 5.5.0
	 *
	 * @param WP_Error      $errors    A WP_Error object containing any errors generated
	 *                                 by using invalid credentials.
	 * @param WP_User|false $user_data WP_User object if found, false if the user does not exist.
	 */
	$errors = apply_filters( 'lostpassword_errors', $errors, $user_data );

	if ( $errors->has_errors() ) {
		return $errors;
	}

	if ( ! $user_data ) {
		$errors->add( 'invalidcombo', __( '<strong>Error</strong>: There is no account with that username or email address.' ) );
		return $errors;
	}

	/**
	 * Filters whether to send the retrieve password email.
	 *
	 * Return false to disable sending the email.
	 *
	 * @since 6.0.0
	 *
	 * @param bool    $send       Whether to send the email.
	 * @param string  $user_login The username for the user.
	 * @param WP_User $user_data  WP_User object.
	 */
	if ( ! apply_filters( 'send_retrieve_password_email', true, $user_login, $user_data ) ) {
		return true;
	}

	// Redefining user_login ensures we return the right case in the email.
	$user_login = $user_data->user_login;
	$user_email = $user_data->user_email;
	$key        = get_password_reset_key( $user_data );

	if ( is_wp_error( $key ) ) {
		return $key;
	}

	// Localize password reset message content for user.
	$locale = get_user_locale( $user_data );

	$switched_locale = switch_to_locale( $locale );

	if ( is_multisite() ) {
		$site_name = get_network()->site_name;
	} else {
		/*
		 * The blogname option is escaped with esc_html on the way into the database
		 * in sanitize_option. We want to reverse this for the plain text arena of emails.
		 */
		$site_name = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
	}

	$message = __( 'Someone has requested a password reset for the following account:' ) . "\r\n\r\n";
	/* translators: %s: Site name. */
	$message .= sprintf( __( 'Site Name: %s' ), $site_name ) . "\r\n\r\n";
	/* translators: %s: User login. */
	$message .= sprintf( __( 'Username: %s' ), $user_login ) . "\r\n\r\n";
	$message .= __( 'If this was a mistake, ignore this email and nothing will happen.' ) . "\r\n\r\n";
	$message .= __( 'To reset your password, visit the following address:' ) . "\r\n\r\n";
	$message .= network_site_url( "wp-login.php?action=rp&key=$key&login=" . rawurlencode( $user_login ), 'login' ) . '&wp_lang=' . $locale . "\r\n\r\n";

	if ( ! is_user_logged_in() ) {
		$requester_ip = $_SERVER['REMOTE_ADDR'];
		if ( $requester_ip ) {
			$message .= sprintf(
				/* translators: %s: IP address of password reset requester. */
				__( 'This password reset request originated from the IP address %s.' ),
				$requester_ip
			) . "\r\n";
		}
	}

	/* translators: Password reset notification email subject. %s: Site title. */
	$title = sprintf( __( '[%s] Password Reset' ), $site_name );

	/**
	 * Filters the subject of the password reset email.
	 *
	 * @since 2.8.0
	 * @since 4.4.0 Added the `$user_login` and `$user_data` parameters.
	 *
	 * @param string  $title      Email subject.
	 * @param string  $user_login The username for the user.
	 * @param WP_User $user_data  WP_User object.
	 */
	$title = apply_filters( 'retrieve_password_title', $title, $user_login, $user_data );

	/**
	 * Filters the message body of the password reset mail.
	 *
	 * If the filtered message is empty, the password reset email will not be sent.
	 *
	 * @since 2.8.0
	 * @since 4.1.0 Added `$user_login` and `$user_data` parameters.
	 *
	 * @param string  $message    Email message.
	 * @param string  $key        The activation key.
	 * @param string  $user_login The username for the user.
	 * @param WP_User $user_data  WP_User object.
	 */
	$message = apply_filters( 'retrieve_password_message', $message, $key, $user_login, $user_data );

	// Short-circuit on falsey $message value for backwards compatibility.
	if ( ! $message ) {
		return true;
	}

	/*
	 * Wrap the single notification email arguments in an array
	 * to pass them to the retrieve_password_notification_email filter.
	 */
	$defaults = array(
		'to'      => $user_email,
		'subject' => $title,
		'message' => $message,
		'headers' => '',
	);

	/**
	 * Filters the contents of the reset password notification email sent to the user.
	 *
	 * @since 6.0.0
	 *
	 * @param array $defaults {
	 *     The default notification email arguments. Used to build wp_mail().
	 *
	 *     @type string $to      The intended recipient - user email address.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The body of the email.
	 *     @type string $headers The headers of the email.
	 * }
	 * @type string  $key        The activation key.
	 * @type string  $user_login The username for the user.
	 * @type WP_User $user_data  WP_User object.
	 */
	$notification_email = apply_filters( 'retrieve_password_notification_email', $defaults, $key, $user_login, $user_data );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	if ( is_array( $notification_email ) ) {
		// Force key order and merge defaults in case any value is missing in the filtered array.
		$notification_email = array_merge( $defaults, $notification_email );
	} else {
		$notification_email = $defaults;
	}

	list( $to, $subject, $message, $headers ) = array_values( $notification_email );

	$subject = wp_specialchars_decode( $subject );

	if ( ! wp_mail( $to, $subject, $message, $headers ) ) {
		$errors->add(
			'retrieve_password_email_failure',
			sprintf(
				/* translators: %s: Documentation URL. */
				__( '<strong>Error</strong>: The email could not be sent. Your site may not be correctly configured to send emails. <a href="%s">Get support for resetting your password</a>.' ),
				esc_url( __( 'https://wordpress.org/support/article/resetting-your-password/' ) )
			)
		);
		return $errors;
	}

	return true;
}