wikimedia/mediawiki-extensions-Translate

( function () {
    'use strict';

    /**
     * Call list of callbacks returning promises in serial order and returns a list of promises.
     *
     * @internal
     * @author Niklas Laxström
     *
     * @param {Function[]} list List of callbacks returning promises.
     * @param {number} maxRetries Maximum number of times a failed promise is retried.
     * @return {jQuery.Promise}
     */
    function ajaxDispatcher( list, maxRetries ) {
        var deferred = $.Deferred();

        maxRetries = maxRetries || 0;

        return $.when( helper( list, maxRetries ) )
            .then( function ( promises ) {
                return deferred.resolve( promises );
            } ).fail( function ( errmsg ) {
                return deferred.reject( errmsg );
            } );
    }

    function helper( list, maxRetries ) {
        var deferred = $.Deferred();

        if ( list.length === 0 ) {
            deferred.resolve( [] );
            return deferred;
        }

        var first = list.slice( 0, 1 )[ 0 ];
        var rest = list.slice( 1 );

        var retries = 0;
        var retrier = function ( result, promise ) {
            if ( !promise.state ) {
                return;
            }

            if ( promise.state() === 'rejected' ) {
                if ( retries < maxRetries ) {
                    retries += 1;
                    return first.call().always( retrier );
                }
            }

            if ( promise.state() !== 'pending' ) {
                helper( rest, maxRetries ).always( function ( promises ) {
                    deferred.resolve( [].concat( promise, promises ) );
                } );
            }
        };

        first.call().always( retrier ).catch( function ( errmsg ) {
            return deferred.reject( errmsg );
        } );

        return deferred;
    }

    $.extend( $, { ajaxDispatcher: ajaxDispatcher } );

}() );