import pify from 'pify'
import to from 'await-to-js'
import i2c from 'i2c-bus'
import PQueue from 'p-queue'
import Base from '@uci/base'

import logger from '@uci-utils/logger'
let log = {}

class I2CBus extends Base {
  constructor(opts) {
    opts.path =opts.path || 'i2c-bus' // always a pipe by default
    if (typeof opts.port === 'boolean') opts.port=1776
    opts.name = opts.name || 'i2c-bus'
    super(opts)
    log = logger({
      name: 'i2c-bus',
      id: this.id,
      file: 'src/bus.js',
      class: 'Bus'
    })
    this.busnum = opts.busnum || 1
    this.i2cbus = i2c.open(this.busnum, () => {})
    this._funcs = bus_funcs
    this.bus = {}
    this.addBusFuncs()
    this.addNamespace('bus')
    this.bus.busFuncs = async (packet) => {
      packet.functions = this.busFuncs
      packet.cmd='reply'
      return packet
    }
    this.bus.ack = async function (){
      //
      let bus = await this.bus.scan()
      if (bus.error || !bus.response.length) bus.ack =false
      else bus.ack = true
      return bus
    },
    this.ackInterval = opts.ackInterval!=null ? opts.ackInterval : 5
    this._queue = new PQueue({concurrency: opts.concurrency || 1})
    this.ready.addObserver('bus:ack')
  }  // constructor

  async init() {
    await super.init()
    let count = 0
    const ack = (await this.bus.ack.call(this)).ack
    this.emit('bus:ack',ack) // will be picked up by ready observer
    this.autoAck(this.ackInterval) // if auto on then will notice when there is issue/connection with i2cbus
    this._queue.on('active', () => {
      log.debug(`Queue: working on item #${++count}.  Size: ${this._queue.size}  Pending: ${this._queue.pending}`)
    })
  }

  get busFuncs() { return this._funcs}

  autoAck(interval) {
    if (interval>.9)  this._autoAck = setInterval(async ()=> {
      let ack = (await this.bus.ack.call(this)).ack
      this.emit('bus:ack',ack) // will be picked up by ready observer
    },interval*1000)
    else clearInterval(this._autoAck)
  }

  addBusFuncs() {
    for (let alias in this.busFuncs) {
      let func = this.busFuncs[alias]
      this.addBusFunc(alias,func.name || alias, func.args)
    }
  }

  addBusFunc(alias,name, args) {
    if (!name) name=alias
    if (Array.isArray(name)) {
      args=name
      name=alias
    }
    this.bus[alias] = busFunction.bind(this, alias, pify(this.i2cbus[name]), args ||[])
  }

} // end of Bus Packet Class

export default I2CBus

const validateArg = function (arg,value) {
  let valid = false
  switch (arg) {
  case 'address':
    valid = Number.isInteger(value) && value >=0 && value <= 119
    break
  case 'length':
  case 'cmd':
    valid = Number.isInteger(value)
    break
  case 'byte':
    valid = Number.isInteger(value) && value >= 0 && value <= 255
    break
  case 'word':
    valid = Number.isInteger(value) && value >= 0 && value <= 65535
    break
  case 'bit':
    valid = Number.isInteger(value) && (value === 0 || value === 1)
    break
  case 'buffer':
    valid = Buffer.isBuffer(value)
  }
  return valid
}

async function busFunction (name, func, args=[],packet={}) {
  let argsV = []
  args.some(arg => {
    if (packet.args) {
      let argv = packet.args[arg]
      if (argv != null) {
        if(validateArg(arg,argv)) argsV.push(argv)
        else {
          packet.error = `argument ${arg} has an invalid value ${argv} for function ${name}`
          return true
        }
      } else {
        packet.error = `missing argument, ${arg}, for function ${name}`
        return true
      }
    }
  })
  // this.emit('log', {level:'i2c', packet:packet, error:packet.error, msg:'packet going to bus'})
  if (!packet.error) {
    log.trace({msg:'adding to queue', function:name,arguments:argsV})
    let [err,res] = await to(this._queue.add(() => func.call(this.i2cbus,...argsV)))
    if (err) packet.error = `error during call to ${name} with arguments ${JSON.stringify(packet.args)}: ${err}`
    else  packet.response = res
  }
  packet.cmd = 'reply'
  return packet
}

// default function set
const bus_funcs = {
  scan:  {},
  close: {},
  methods: {name:'i2cFuncs'},
  deviceId: {args:['address']},
  readRaw: {name:'i2cRead', args:['address','length','buffer']},
  writeRaw: {name:'i2cWrite', args:['address','length','buffer']},
  read: {name:'readByte', args:['address','cmd']},
  write: {name:'writeByte', args:['address','cmd','byte']},
  read2: {name:'readWord', args:['address','cmd']},
  write2: {name:'writeWord', args:['address','cmd','word']},
  receive: {name:'receiveByte', args:['address']},
  send: {name:'sendByte', args:['address','byte']}
}