"use strict";

const fs = require('mz/fs'),
  EventEmitter = require('events'),
  Epoll = require('epoll').Epoll,
  pSeries = require('p-series')

const GPIO_ROOT_PATH = '/sys/class/gpio/'

class Interrupt extends EventEmitter {
  // bus is i2c-bus bus object
  constructor(pin_number, opts = {}) {
    super()
    this.num = pin_number;
    this.hook = opts.hook // will be passed back with the emit
    this.path = GPIO_ROOT_PATH + 'gpio' + this.num + '/'
    this.edge = opts.edge ? opts.edge : 'falling'
    this.debounce = opts.debounce ? opts.debounce : 200
    this.poller = new Epoll(function (err, fd, events) {
      if (err) { this.emit('error', err) }
      this.clear()
      this.emit('fired', this.hook)
    }.bind(this))
  }

  init() {

    let tasks = [
      fs.writeFile(GPIO_ROOT_PATH + 'export', this.num)
      // fs.writeFile(this.path + 'direction', 'in'),
      // fs.writeFile(this.path + 'edge', this.edge),
      // fs.open(this.path + 'value', 'r+').then(fd => { this.valuefd = fd }),
      // this.clear().then(() => { this.start() })
    ]

    return this.exit()
      .then(() => { return pSeries(tasks) })
      // .then(() => { return this.exit() })

  }

  fire(name = 'fired') {
    this.emit(name, this.hook)
  }

  clear() {
    let buffer = Buffer.from([0x00])
    return fs.read(this.valuefd, buffer, 0, 1, 0);
  }

  exit() {

    return fs.access(this.path)
      .then(() => {
        console.log('unexporting')
        return fs.writeFile(GPIO_ROOT_PATH + 'unexport', this.num)
      })
      .then(() => {
        if (this.valuefd) {
          this.stop()
          return fs.close(this.valuefd)
        }
      })
      .catch(err => { return Promise.resolve('already exited') })
  }

  start() {
    this.poller.add(this.valuefd, Epoll.EPOLLPRI);
  }

  stop() {
    this.poller.remove(this.valuefd).close();
  }

}

module.exports = {
  Interrupt
}