// Direct External Dependencies
// none

// UCI dependencies

// UCI communication transport communication modules
// TODO change to dynamic import so loads only if that socket type is requestd
import Socket from '@uci/socket' // tcp or named pipe
import MQTT from '@uci/mqtt' // requires broker
import WebSocket from '@uci/websocket' // server only - client is for web browser only
// UCI helpers
import { bindFuncs } from '@uci-utils/bind-funcs'
// UCI logger
import logger from '@uci-utils/logger'
let log = {} // declare module wide log to be set during construction

// Community dependencies
import to from 'await-to-js'
import EventEmitter from 'events'
// import pSettle from 'p-settle'
// import pReflect from 'p-reflect'

// Internal dependencies
import { processor, defaultCmds, namespaces } from './processing'

// Useful Constants
const SOCKET_INFO_KEYS = ['name', 'type', 'transport']
const TRANSLATE = {
  n: 'Named Pipe',
  t: 'TCP',
  s: 'Socket',
  c: 'Consumer',
  m: 'MQTT',
  w: 'Web Socket'
}

/**
 * @class Base
 * @description
 *  An inter-process inter-machine multi socket communication class. </br>
 *  It is extended to derive many other UCI classes thus the name "Base" </br>
 *  The class itself is extended from the {@link https://nodejs.org/api/events.html#events_class_eventemitter nodejs EventEmitter } to support in process communication as well
 *
 * @extends EventEmitter
 * @param {Object} opts hash of options
 * @param {String} [opts.id='ucit-base'+timestamp]  and id for this process/instance used for logging, default: uci-base + timestamp
 * @param {String} [opts.desc] additional description for humans, can be logged.
 * @param {String | Boolean} [opts.path=either full path to where socket should be created or 'true' (which uses default path]
 * @param {string} [opts.sockets] comma delimited strong of sockets to be created each socket of the form [name]#[c or s]>[n,t,m or w]
 * @param {Boolean} [opts.useRootNS=false] include the "root" of the created base instance as part of the namespace for which packet cmd's try to call corresponding function
 * @param {Object} [opts.(name of socket)] options for a particular socket created by opts.socket. see UCI guide {@link ?content=guide#sockets|creating sockets}
 * @property {array} socket collection of all sockets created and used by base instance as per opts.sockets or addSocket method
 *
 *  @example
 *  import Base from '@uci/base'
 * // options object example, credated is a socket of each transport using their defaults
 * // and a tcp consumer socket that connects to a tcp socket on another host 'somehost' at port 8888
 *  const opts =  id:mybase, sockets:'us#s>n,tc#c>t,ts#s>t,mqtts#s>m,webs#s>w', tc:{host:'somehost', port:8888}}
 *  let mybaseprocess = new Base(opts)
 */
class Base extends EventEmitter {
  constructor(opts = {}) {
    super()
    this.id = opts.id || opts.name || 'uci-base:' + new Date().getTime()
    log = logger({ name: 'base', id: this.id })
    this.desc = opts.desc // additional details for humans
    this._socket = {} // holds all the various communication sockets
    this._started = false // flag to know when instance has been initialized
    this._processors = { _default: processor }
    // _c and _s are the default namespaces
    this._namespaces = namespaces
    this._c = defaultCmds.c
    this._s = defaultCmds.s
    if (opts.useRootNS) {
      // add root of instance to checking for command functions - not recommended!
      this._namespaces.s.splice(-1, 0, null)
      this._namespaces.c.splice(-1, 0, null)
    }
    // method that will bind a whole object tree of functions
    this.bindFuncs = bindFuncs
    // predefined sockets:
    // comma delimited list of this form  '<name>#<c/p/s>><n=np/t=tcp/m=mqtt/w=web>'
    this._socket = {}
    if (opts.sockets) {
      opts.sockets.split(/[,|\s]+/).forEach(socketStr => {
        let socket = {}
        socketStr.split(/[>#]+/).map(function(prop, index) {
          socket[SOCKET_INFO_KEYS[index]] = prop
        })
        this.addSocket(
          socket.name,
          socket.type,
          socket.transport,
          opts[socket.name]
        )
      })
    }
  } // end constructor

  /*
  * --------------------------------
  * CLASS METHODS
  * --------------------------------
  */

  // PUBLIC METHODS

  /**
   * initialize the instance with the set options.  This must be called to initialize all sockets and connections
   * @async
   * @public
   * @required
   */

  async init() {

    let results = {}
    let errors = {}

    const pReflect = async socket => {
      try {
        const value = await socket.init()
        results[socket.name] = value
      } catch (error) {
        this.emit('error',{msg:'socket init error',error:error})// emit an error here, remove socket
        let res = await this.removeSocket(socket.name)
        errors[socket.name]={error:error, remove:res}
      }
    }

    let sockets = []
    for (let name of Object.keys(this._socket)) {
      sockets.push(this._initSocket(name))
    }
    await Promise.all(sockets.map(pReflect))

    if(Object.keys(errors).length===0) errors=false
    this._started = true
    return {results:results, errors:errors}
  }

  /**
   * addSocket - Add a socket at runtime as opposed to via the sockets option at creation
   *
   * @param {type}   name          Name of socket (usually something short but unique)
   * @param {string} [type=c]      consumer/client 'c' or socket/server 's'
   * @param {string} [transport=n] transport: (n) named pipe/ unix socket,  (t) tcp socket,  (m) mqtt subscribe, (w) websocket
   * @param {object} [options={}]  options for that particular type/transport of socket (i.e. path, host, port, etc)
   *
   * @returns {string} Description
   */
  async addSocket(name, type = 'c', transport = 'n', options = {}) {
    log.debug({ socketName: name, type: type, tranport: transport, options: options, method:'addSocket', line:147, msg:`adding socket ${name}`})
    options.id = this.id + ':' + name
    switch (transport) {
    case 'n':
      options.path = options.path || true
      // falls through
    case 't':
      this._socket[name] = new Socket[TRANSLATE[type]](options)
      break
    case 'm':
      if (type === 'p') type = 'c'
      options.connect = options.connect || {}
      if (options.host) options.connect.host = options.host
      if (options.port) options.connect.port = options.port
      options.connect.connectTimeout = options.connect.connectTimeout || 5000
      this._socket[name] = new MQTT(options)
      break
    case 'w':
      if (type === 's') this._socket[name] = new WebSocket(options)
      else
        log.warn({ name: name, type: type, transport: transport, method:'addSocket', line:167, msg:'Web socket not created Consumer/Client Web Socket not supported'})
    }
    this._socket[name].name = name
    this._socket[name].type = type
    this._socket[name].transport = transport
    this._socket[name]._packetProcess = this._packetProcess.bind(this, name)

    if (type==='c') { // bubble up events from client sockets
      this._socket[name].on('status', ev => {
        ev.socketName=name
        this.emit('status', ev)
      })
      this._socket[name].on('pushed', packet => {
        packet._header.socketName=name
        this.emit('pushed', packet)
      })
    }

    // do this as .then promise then addSocket doesn't need to be async before init
    if (this._started) return await this._initSocket(name)
    else return `socket ${name} added`
  }

  /**
   * removeSocket - TODO not available
   *
   * @param {string} name name of socket as created
   * @returns {String | Object } success string or error object
   */
  async removeSocket(name) {
    // NOTE: uci consumers have .end renamed as .close to match socket method for convenience
    let closeError
    let [err] = await to(this._socket[name].close())
    if (err.code !== 'ERR_SERVER_NOT_RUNNING') {
      closeError = {socket:this._socket[name].name, error:err, msg:'socket/consumer closed with errors, but removed'}
    }
    this.emit('warn', {msg:`socket ${name} has been removed`, socket:this._socket[name].opts})
    delete this._socket[name]
    return closeError ? closeError : 'success'
  }

  getSocket(name) {
    if (name) return this._socket[name]
    else return this._socket
  }

  /**
   * send - Description
   *
   * @param {String} name   name of socket for send (must be a consumer otherwise use push for server)
   * @param {Object} packet
   *
   * @returns {type} Description
   */
  async send(name, packet) {
    if (typeof name !== 'string') {
      packet = name
      let sends = []
      for (let name of Object.keys(this._socket)) {
        if (this._socket[name].type === 'c') {
          let hookedPacket = {}
          hookedPacket = this._socket[name].beforeSend ?  await this._socket[name].beforeSend.call(this,Object.assign({},packet)) : packet
          log.debug({msg:'after hook, sending packet', name:name, packet:hookedPacket, method:'send', line:235})
          sends.push(this._socket[name].send.bind(this._socket[name],hookedPacket))
        }
      }
      if (sends.length === 1) return await sends[0]()
      return Promise.all(
        sends.map(send => {
          return send()
        })
      )
    } else {
      if (this._socket[name]) {
        if (this._socket[name].beforeSend) packet = await this._socket[name].beforeSend.call(this,packet)
        log.debug({msg:'single socket hooked packet to send', name:name, packet:packet, method:'send', line:230})
        return await this._socket[name].send(packet)
      }
      else return { error: `no consumer socket of name ${name}` }
    }
  }

  async push(packet) {
    // TODO set like send to accept a name
    let broadcast = []
    for (let name of Object.keys(this._socket)) {
      if (this._socket[name].type === 's') {
        let hookedPacket = {}
        hookedPacket = this._socket[name].beforeSend ?  await this._socket[name].beforeSend.call(this,Object.assign({},packet),true) : packet
        log.debug({msg:'hooked packet to push', name:name, packet:hookedPacket, method:'push', line:243})
        broadcast.push(this._socket[name].push.bind(this._socket[name],hookedPacket))
      }
    }
    return Promise.all(
      broadcast.map(push => {
        return push()
      })
    )
  }

  // TODO make push version of all this sends

  // TODO accept alt transport string i.e. t or TCP
  async sendTransport(packet, transport) {
    let sends = []
    for (let name of Object.keys(this._socket)) {
      if (this._socket[name].type === 'c') {
        if (this._socket[name].transport === transport) {
          sends.push(this._socket[name].send.bind(this._socket[name]))
        }
      }
    }
    if (sends.length === 1) return sends[0](packet)
    return Promise.all(
      sends.map(send => {
        return send(packet)
      })
    )
  }

  // async sendMQTT(topic, packet) {return this._socket.mqtt.send(topic, packet)}
  async sendTCP(packet) {
    return this.sendTransport(packet, 't')
  }

  // TODO change this to PIPE
  async sendIPC(packet) {
    return this.sendTransport(packet, 'n')
  }

  // TODO add sendMQTT, sendWS


  socketsListen(event,fn) {
    this._eventListen('s',event,fn)
  }
  consumersListen(event,fn) {
    this._eventListen('c',event,fn)
  }


  getPacketByName(name, packets) {
    if (!packets.length) packets = [packets]
    let found = {}
    packets.some((packet, index, packets) => {
      if (packet._header.sender.name === name) {
        found = packets[index]
        return true
      }
    })
    return found
  }

  // add set of functions to class prop/space and then register with this
  addNamespace(space, type, trans) {
    if (type !=='c' || type !=='s')  {
      trans = type
      type = 's' }
    trans = this._validateTransport(trans)
    if (trans) return this._namespaces[type + trans].unshift(space)
    else return this._namespaces[type].unshift(space)
  }

  // TODO confirm Object.assign will be ok as it is not a deep copy
  // allow a single or arrary of single functions
  amendCommands(funcs, trans, type) {
    if (!trans && !type) type = 's'
    if (trans ==='c' || trans ==='s') {
      type = trans
      trans = ''
    }
    trans = this._validateTransport(trans)
    if (!this['_'+type+trans]) this['_'+type+trans] = {}
    Object.assign(this['_'+type+trans], funcs)  // trans is type here
    log.debug({msg:'amended namespace', default_key:'_'+type+trans, functions:this['_'+type+trans]})
  }

  amendConsumerCommands(funcs, trans) {
    this.amendCommands(funcs,trans,'c')
  }

  amendSocketCommands(funcs, trans) {
    this.amendCommands(funcs,trans)
  }

  // func should take and return a packet.  if type
  beforeSendHook(func,opts) {
    this._packetHook('beforeSend', func,opts)
  }

  beforeProcessHook(func,opts) {
    this._packetHook('beforeProcess', func,opts)
  }

  afterProcessHook(func,opts) {
    this._packetHook('afterProcess', func,opts)
  }

  // A Big Hammer - use only if necessary - default with hooks should suffice
  // these three will pre-empt default processor to be called in ._packetProcess

  // add and override default processor for ALL consumers, i.e. packets returning form a send or arrived from a push
  consumersProcessor(func) {
    for (let name of Object.keys(this._socket)) {
      if (this._socket[name].type === 'c') {
        this.altProcessor(func, name)
      }
    }
  }

  // add and override default processor for ALL sockets, i.e. packets coming in from consumer send
  socketsProcessor(func) {
    for (let name of Object.keys(this._socket)) {
      if (this._socket[name].type === 's') {
        this.altProcessor(func, name)
      }
    }
  }
  // add and override a processor for a particular socket/consumer to list of processors
  // if no socket name given it will replace the default processor in _processors from processing.js
  altProcessor(func, socket_name) {
    socket_name = socket_name || '_default'
    this._processors[socket_name] = func
  }

  //======================================================

  /*
  *
  * Private Methods
  *
  */

  _packetHook(hook,func,opts) {
    log.debug({msg:'hooking a socket(s)', method:'_packetHook', line:334, hook:hook, function:func, options:opts})
    let {name,type,trans,all} = opts
    if (name) this._socket[name][hook] = func
    else {
      log.debug({msg:'sockets available to hook', method:'_packetHook', line:338, sockets: Object.keys(this._socket)})
      for (let name of Object.keys(this._socket)) {
        if (this._socket[name].type === type) this._socket[name][hook] = func
        if (this._socket[name].transport === trans) this._socket[name][hook] = func
        if (all) this._socket[name][hook] = func
        if (this._socket[name][hook]) log.debug({msg:'hooked socket', method:'_packetHook', line:343, name:name, type:this._socket[name].type, trans:this._socket[name].transport})
      }
    }
  }


  /*
  **********default packet processor for all sockets
  * this can be hooked or replaced all together
  */

  async _packetProcess(socket_name, packet) {
    log.debug({ socket:socket_name, packet:packet, method:'_packetProcess', line:393, msg:'processing incoming packet'})
    let header = packet._header ? packet._header : {}  // retain header
    let err, res
    if (this._socket[socket_name].beforeProcess) {
      [err,res] = await to(this._socket[socket_name].beforeProcess.call(this,packet))
      if (err) {  // hook has forced an abort to processing
        console.log('before error', packet)
        packet.error = err
        return packet
      }
      packet = res
    }
    // if (this._socket[socket_name].beforeProcess) packet = await this._socket[socket_name].beforeProcess.call(this,packet)
    // the processor can be set via the incoming packet
    // otherwise if one is set on the socket or the default found in processing.js
    // TODO Try each "available" packet processor in some order if fails try next one before trying the default
    let processor =  packet._processor || this._processors[socket_name] ? socket_name : '_default'
    res = (await this._processors[processor].call(this,packet,socket_name))|| packet  // processor didn't return a packet then return the packet sent
    log.debug({ socket:socket_name, response:res, msg:'processed packet ready for hook'})
    if (this._socket[socket_name].afterProcess) res = await this._socket[socket_name].afterProcess.call(this,res)
    log.debug({ socket:socket_name, response:res, msg:'packet after hook complete  ready for return'})
    res._header = Object.assign(header,res._header)  // re-apply header in case hooks or processor mangled or removed it
    return res
  }

  _initSocket(name) {
    let socket = this._socket[name]
    let init = {}
    if (this._socket[name].type === 's' && this._socket[name].transport !== 'm') {
      init = socket.create
    } else {
      init = socket.connect
    }
    log.info({msg:`initializing socket ${name}, ${socket.type}, ${socket.transport}`})

    if (this._started) {
      return init().then(function(res) {
        return  `socket ${name} added and initialzed, ${res}`
      })
        .catch(function(err) {
          this.emit('error', {msg:'failed initialization', error:err, socket:socket, code:'SOCKET_INIT'})
          return {msg:`socket ${name} failed initialization`, error:err}
        }.bind(this)
        )
    }
    else return {name:name, init:init}
  }

  // all sockets are emitters.  Adds a listener to all sockets of a type with given event.
  // now sockets can emit locally processed events
  _eventListen(type,event,fn) {
    for (let name of Object.keys(this._socket)) {
      if (this._socket[name].type === type) {
        if (fn==='stop')   this._socket[name].removeAllListeners(event)
        else {
          log.debug({socket:name, type:type, event:event, msg:'adding listener to socket'})
          this._socket[name].on(event, fn)
        }
      }
    }
  }

  _validateTransport(trans, type='s') {
    const valids = {
      w:'w',
      web:'w',
      n:'n',
      named:'n',
      unix:'n',
      pipe:'n',
      t:'t',
      tcp:'t',
      net:'t',
      network:'t',
      m:'m',
      mqtt:'m',
    }
    trans = valids[trans] || ''
    if (type !== 'c' && trans ==='w') trans = ''
    return trans
  }


  _transport(name) {
    return this._socket[name].transport
  } //getter for socket transport
  _type(name) {
    return this._socket[name].type
  } //getter for socket type

  _getTransportNamespaces(socket) {
    return this._namespace[this._type(socket) + this._transport(socket)]
  }

  _getCmdFuncNamespace(cmd, namespaces) {
    let cmd_func = null
    namespaces.some(namespace => {
      namespace = namespace ? namespace + '.' + cmd : cmd
      cmd_func = this._getCmdFunc(namespace)
      if (cmd_func) return true
    })
    return cmd_func
  }

  // takes command and returns corresponding function in a hash, recurisve walk
  _getCmdFunc(cmd, obj) {
    if (typeof cmd === 'string') {
      if (!obj) obj = this
      cmd = cmd.split(/[.:/]+/)
    }
    var prop = cmd.shift()
    if (cmd.length === 0) return obj[prop]
    if (!obj[prop]) return null
    log.debug({length:cmd.length,cmd:cmd, prop:prop, objprop:obj[prop], method:'_getCmdFunc', msg:'command to corresponding function in a hash'})
    return this._getCmdFunc(cmd, obj[prop])
  }

  // primary function to find a function to call based on packet cmd
  async _callCmdFunc(packet, socket) {
    let cmd_func = this._getCmdFuncNamespace(
      packet.cmd,
      this._namespaces[this._type(socket) + this._transport(socket)]
    )
    if (cmd_func) return await cmd_func.bind(this)(packet)  // todo try .call
    cmd_func = this._getCmdFuncNamespace(
      packet.cmd,
      this._namespaces[this._type(socket)]
    )
    if (cmd_func) return await cmd_func.bind(this)(packet)
    return 'failed'
  }

} // end Base Class

export default Base