HORIZON PROJECT

'use strict';

Object.defineProperty(exports, "__esModule", {

    value: true

});

exports.default = function (tasks, callback) {

    callback = (0, _once2.default)(callback || _noop2.default);

    if (!(0, _isArray2.default)(tasks)) return callback(new Error('First argument to waterfall must be an array of functions'));

    if (!tasks.length) return callback();

    var taskIndex = 0;

    function nextTask(args) {

        if (taskIndex === tasks.length) {

            return callback.apply(null, [null].concat(args));

        }

        var taskCallback = (0, _onlyOnce2.default)((0, _rest2.default)(function (err, args) {

            if (err) {

                return callback.apply(null, [err].concat(args));

            }

            nextTask(args);

        }));

        args.push(taskCallback);

        var task = tasks[taskIndex++];

        task.apply(null, args);

    }

    nextTask([]);

};

var _isArray = require('lodash/isArray');

var _isArray2 = _interopRequireDefault(_isArray);

var _noop = require('lodash/noop');

var _noop2 = _interopRequireDefault(_noop);

var _once = require('./internal/once');

var _once2 = _interopRequireDefault(_once);

var _rest = require('./internal/rest');

var _rest2 = _interopRequireDefault(_rest);

var _onlyOnce = require('./internal/onlyOnce');

var _onlyOnce2 = _interopRequireDefault(_onlyOnce);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

module.exports = exports['default'];

/**

 * Runs the `tasks` array of functions in series, each passing their results to

 * the next in the array. However, if any of the `tasks` pass an error to their

 * own callback, the next function is not executed, and the main `callback` is

 * immediately called with the error.

 *

 * @name waterfall

 * @static

 * @memberOf module:ControlFlow

 * @method

 * @category Control Flow

 * @param {Array} tasks - An array of functions to run, each function is passed

 * a `callback(err, result1, result2, ...)` it must call on completion. The

 * first argument is an error (which can be `null`) and any further arguments

 * will be passed as arguments in order to the next task.

 * @param {Function} [callback] - An optional callback to run once all the

 * functions have completed. This will be passed the results of the last task's

 * callback. Invoked with (err, [results]).

 * @returns undefined

 * @example

 *

 * async.waterfall([

 *     function(callback) {

 *         callback(null, 'one', 'two');

 *     },

 *     function(arg1, arg2, callback) {

 *         // arg1 now equals 'one' and arg2 now equals 'two'

 *         callback(null, 'three');

 *     },

 *     function(arg1, callback) {

 *         // arg1 now equals 'three'

 *         callback(null, 'done');

 *     }

 * ], function (err, result) {

 *     // result now equals 'done'

 * });

 *

 * // Or, with named functions:

 * async.waterfall([

 *     myFirstFunction,

 *     mySecondFunction,

 *     myLastFunction,

 * ], function (err, result) {

 *     // result now equals 'done'

 * });

 * function myFirstFunction(callback) {

 *     callback(null, 'one', 'two');

 * }

 * function mySecondFunction(arg1, arg2, callback) {

 *     // arg1 now equals 'one' and arg2 now equals 'two'

 *     callback(null, 'three');

 * }

 * function myLastFunction(arg1, callback) {

 *     // arg1 now equals 'three'

 *     callback(null, 'done');

 * }

 */