var each = require('./utils').each

var event = {

  _eventData: null,

  on: function (name, func) {
    if (!this._eventData) this._eventData = {}
    if (!this._eventData[name]) this._eventData[name] = []
    var listened = false
    each(this._eventData[name], function (fuc) {
      if (fuc === func) {
        listened = true
        return false
      }
    })
    if (!listened) {
      this._eventData[name].push(func)
    }
  },

  off: function (name, func) {
    if (!this._eventData) this._eventData = {}
    if (!this._eventData[name] || !this._eventData[name].length) return
    if (func) {
      each(this._eventData[name], function (fuc, i) {
        if (fuc === func) {
          this._eventData[name].splice(i, 1)
          return false
        }
      }, this)
    } else {
      this._eventData[name] = []
    }
  },

  trigger: function (name) {
    if (!this._eventData) this._eventData = {}
    if (!this._eventData[name]) return true
    var args = this._eventData[name].slice.call(arguments, 1)
    var preventDefault = false
    each(this._eventData[name], function (fuc) {
      preventDefault = fuc.apply(this, args) === false || preventDefault
    }, this)
    return !preventDefault
  }
}

module.exports = event