'use strict';

//This file contains the ES6 extensions to the core Promises/A+ API

var Promise = require('./core.js')
var asap = require('asap')

module.exports = Promise

/* Static Functions */

function ValuePromise(value) {
  this.then = function (onFulfilled) {
    if (typeof onFulfilled !== 'function') return this
    return new Promise(function (resolve, reject) {
      asap(function () {
        try {
          resolve(onFulfilled(value))
        } catch (ex) {
          reject(ex);
        }
      })
    })
  }
}
ValuePromise.prototype = Promise.prototype

var TRUE = new ValuePromise(true)
var FALSE = new ValuePromise(false)
var NULL = new ValuePromise(null)
var UNDEFINED = new ValuePromise(undefined)
var ZERO = new ValuePromise(0)
var EMPTYSTRING = new ValuePromise('')

Promise.resolve = function (value) {
  if (value instanceof Promise) return value

  if (value === null) return NULL
  if (value === undefined) return UNDEFINED
  if (value === true) return TRUE
  if (value === false) return FALSE
  if (value === 0) return ZERO
  if (value === '') return EMPTYSTRING

  if (typeof value === 'object' || typeof value === 'function') {
    try {
      var then = value.then
      if (typeof then === 'function') {
        return new Promise(then.bind(value))
      }
    } catch (ex) {
      return new Promise(function (resolve, reject) {
        reject(ex)
      })
    }
  }

  return new ValuePromise(value)
}

Promise.all = function (arr) {
  var args = Array.prototype.slice.call(arr)

  return new Promise(function (resolve, reject) {
    if (args.length === 0) return resolve([])
    var remaining = args.length
    function res(i, val) {
      try {
        if (val && (typeof val === 'object' || typeof val === 'function')) {
          var then = val.then
          if (typeof then === 'function') {
            then.call(val, function (val) { res(i, val) }, reject)
            return
          }
        }
        args[i] = val
        if (--remaining === 0) {
          resolve(args);
        }
      } catch (ex) {
        reject(ex)
      }
    }
    for (var i = 0; i < args.length; i++) {
      res(i, args[i])
    }
  })
}

Promise.reject = function (value) {
  return new Promise(function (resolve, reject) { 
    reject(value);
  });
}

Promise.race = function (values) {
  return new Promise(function (resolve, reject) { 
    values.forEach(function(value){
      Promise.resolve(value).then(resolve, reject);
    })
  });
}

/* Prototype Methods */

Promise.prototype['catch'] = function (onRejected) {
  return this.then(null, onRejected);
}