"use strict";

const fs = require('mz/fs'),
  EventEmitter = require('events'),
  Epoll = require('epoll').Epoll,
  _ = require('uci-utils')

const pWaitFor = require('p-wait-for')
const pathExists = require('path-exists');
const debounce = require('debounce');

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.delay = opts.delay ? opts.delay : 50
    this.dbt = opts.debounce ? opts.debounce : 300
      // this.poller = new Epoll(
      //   debounce((err, fd, events) => {
      //     if (err) { this.emit('error', err) } else { this.clear().then(this.emit('fired', this.hook)) }
      //   }, this.dbt, true)
      // )
  }

  init() {

    let tasks = [
      fs.writeFile(GPIO_ROOT_PATH + 'export', this.num).then(() => { console.log('exported', this.num) }),
      pWaitFor(() => pathExists(this.path + 'direction')).then(_.pDelay(this.delay))
      .then(() => { return fs.writeFile(this.path + 'direction', 'in').then(() => { console.log('direction', 'in') }) }),
      fs.writeFile(this.path + 'edge', this.edge).then(() => { console.log('edge', this.edge) }),
      fs.open(this.path + 'value', 'r+').then(fd => { this.valuefd = fd }),
      this.clear().then(() => { return this.start() })
    ]

    process.on('SIGINT', () => {
      this.exit().then(() => console.log('\nunexported and closed')) // unexport on cntrl-c
    })

    return this.exit() // make sure pin is unexported
      .then((resp) => {
        console.log('ready to init', tasks)
        return _.pSeries(tasks).then(console.log('finsihed tasks'))
      })

  }

  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 pathExists(this.path)
      .then(() => {
        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 unexported') })
  }

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

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

}

module.exports = {
  Interrupt
}