/**
 Copyright (c) 2016 hustcc http://www.atool.org/
 License: MIT
 https://github.com/hustcc/onfire.js
 **/

const __onfireEvents = {}
let __cnt = 0 // event counter

const string_str = 'string'
const function_str = 'function'
const hasOwnKey = Function.call.bind(Object.hasOwnProperty)
const slice = Function.call.bind(Array.prototype.slice)

function _bind(eventName, callback, is_one, context) {
  if (typeof eventName !== string_str || typeof callback !== function_str) {
    throw new Error('args: ' + string_str + ', ' + function_str + '')
  }

  if (!hasOwnKey(__onfireEvents, eventName)) {
    __onfireEvents[eventName] = {}
  }

  __onfireEvents[eventName][++__cnt] = [callback, is_one, context]
  return [eventName, __cnt]
}

function _each(obj, callback) {
  for (const key in obj) {
    if (hasOwnKey(obj, key)) callback(key, obj[key])
  }
}

function on(eventName, callback, context) {
  return _bind(eventName, callback, 0, context)
}

function one(eventName, callback, context) {
  return _bind(eventName, callback, 1, context)
}

function _fire_func(eventName, args) {
  if (hasOwnKey(__onfireEvents, eventName)) {
    _each(__onfireEvents[eventName], (key, item) => {
      item[0].apply(item[2], args) // do the function
      if (item[1]) delete __onfireEvents[eventName][key] // when is one, delete it after trigger
    })
  }
}

function fire(eventName) {
  // fire events
  const args = slice(arguments, 1)
  setTimeout(() => {
    _fire_func(eventName, args)
  })
}

function fireSync(eventName) {
  _fire_func(eventName, slice(arguments, 1))
}

function un(event) {
  let eventName,
    key,
    r = false
  const type = typeof event

  if (type === string_str) {
    // cancel the event name if exist
    if (hasOwnKey(__onfireEvents, event)) {
      delete __onfireEvents[event]
      return true
    }
    return false
  } else if (type === 'object') {
    eventName = event[0]
    key = event[1]

    if (hasOwnKey(__onfireEvents, eventName) && hasOwnKey(__onfireEvents[eventName], key)) {
      delete __onfireEvents[eventName][key]
      return true
    }
    return false
  } else if (type === function_str) {
    _each(__onfireEvents, (key1, item1) => {
      _each(item1, (key2, item2) => {
        if (item2[0] === event) {
          delete __onfireEvents[key1][key2]
          r = true
        }
      })
    })
    return r
  }

  return true
}

function clear() {
  for (const key in __onfireEvents) {
    delete __onfireEvents[key]
  }
}

export default {
  on,
  one,
  un,
  fire,
  fireSync,
  clear,
}