/**
 * Copyright (c) 2014 Petka Antonov
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:</p>
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 */
"use strict";
module.exports = function(
    Promise, Promise$_CreatePromiseArray,
    PromiseArray, apiRejection, INTERNAL) {

    var ASSERT = require("./assert.js");

    function Reduction(callback, index, accum, items, receiver) {
        this.promise = new Promise(INTERNAL);
        this.index = index;
        this.length = items.length;
        this.items = items;
        this.callback = callback;
        this.receiver = receiver;
        this.accum = accum;
    }

    Reduction.prototype.reject = function Reduction$reject(e) {
        this.promise._reject(e);
    };

    Reduction.prototype.fulfill = function Reduction$fulfill(value, index) {
        this.accum = value;
        this.index = index + 1;
        this.iterate();
    };

    Reduction.prototype.iterate = function Reduction$iterate() {
        var i = this.index;
        var len = this.length;
        var items = this.items;
        var result = this.accum;
        var receiver = this.receiver;
        var callback = this.callback;
        var iterate = this.iterate;

        for(; i < len; ++i) {
            result = Promise._cast(
                callback.call(
                    receiver,
                    result,
                    items[i],
                    i,
                    len
                ),
                iterate,
                void 0
            );

            if (result instanceof Promise) {
                result._then(
                    this.fulfill, this.reject, void 0, this, i, iterate);
                return;
            }
        }
        this.promise._fulfill(result);
    };

    function Promise$_reducer(fulfilleds, initialValue) {
        var fn = this;
        var receiver = void 0;
        if (typeof fn !== "function")  {
            receiver = fn.receiver;
            fn = fn.fn;
        }
        var len = fulfilleds.length;
        var accum = void 0;
        var startIndex = 0;

        if (initialValue !== void 0) {
            accum = initialValue;
            startIndex = 0;
        }
        else {
            startIndex = 1;
            if (len > 0) accum = fulfilleds[0];
        }
        var i = startIndex;

        if (i >= len) {
            return accum;
        }

        var reduction = new Reduction(fn, i, accum, fulfilleds, receiver);
        reduction.iterate();
        return reduction.promise;
    }

    function Promise$_unpackReducer(fulfilleds) {
        var fn = this.fn;
        var initialValue = this.initialValue;
        return Promise$_reducer.call(fn, fulfilleds, initialValue);
    }

    function Promise$_slowReduce(
        promises, fn, initialValue, useBound, caller) {
        return initialValue._then(function callee(initialValue) {
            return Promise$_Reduce(
                promises, fn, initialValue, useBound, callee);
        }, void 0, void 0, void 0, void 0, caller);
    }

    function Promise$_Reduce(promises, fn, initialValue, useBound, caller) {
        if (typeof fn !== "function") {
            return apiRejection("fn must be a function");
        }

        if (useBound === true && promises._isBound()) {
            fn = {
                fn: fn,
                receiver: promises._boundTo
            };
        }

        if (initialValue !== void 0) {
            if (Promise.is(initialValue)) {
                if (initialValue.isFulfilled()) {
                    initialValue = initialValue._settledValue;
                }
                else {
                    return Promise$_slowReduce(promises,
                        fn, initialValue, useBound, caller);
                }
            }

            return Promise$_CreatePromiseArray(promises, PromiseArray, caller,
                useBound === true && promises._isBound()
                    ? promises._boundTo
                    : void 0)
                .promise()
                ._then(Promise$_unpackReducer, void 0, void 0, {
                    fn: fn,
                    initialValue: initialValue
                }, void 0, Promise.reduce);
        }
        return Promise$_CreatePromiseArray(promises, PromiseArray, caller,
                useBound === true && promises._isBound()
                    ? promises._boundTo
                    : void 0).promise()
            ._then(Promise$_reducer, void 0, void 0, fn, void 0, caller);
    }


    Promise.reduce = function Promise$Reduce(promises, fn, initialValue) {
        return Promise$_Reduce(promises, fn,
            initialValue, false, Promise.reduce);
    };

    Promise.prototype.reduce = function Promise$reduce(fn, initialValue) {
        return Promise$_Reduce(this, fn, initialValue,
                                true, this.reduce);
    };
};