// native imports
import { promisify } from 'util'
import readline from 'readline'
import { dirname } from 'path'
import { readFile } from 'fs'
const read = promisify(readFile)
// third party imports
import to from 'await-to-js'
import { readFile as readConfig } from 'fs-read-data'
import { Client } from 'ssh2'
import logger from '@uci-utils/logger'
import Conf from 'conf'
let log = {} // declare module wide log to be set during construction

// ssh client is already an event emitter
class Ssh extends Client {
  constructor(opts={}) {
    super()
    this.opts = opts
    log = logger({id: opts.id })
    this.ready = false
    this.config = new Conf({projectName:'ssh-uci'})
    this.configsDir = process.env.SSH_CONFIG_DIR || this.config.get('configsDir') || dirname(this.config.path)
    log.debug({configsDir:this.configsDir, msg:'configuration files directory'})
    this.rpath = opts.rpath || '/opt'  // can be used to make all commands run in a particular remote path
  }

  async configure(opts,overwrite) {
    let configPath
    if (typeof opts ==='boolean' || !opts ) {
      if (typeof opts ==='boolean') overwrite = opts
      configPath =  this.configsDir+'/'+this.config.get('defaultConfig')
      opts = await readConfig(configPath)
    }
    if (typeof opts === 'string') {
      configPath = (opts.indexOf('/') === -1)? this.configsDir+'/'+opts : opts
      opts = await readConfig(configPath)
    }

    log.debug({configPath:this.configPath, msg:'path to actual configuration file used'})
    log.debug({opts:opts, msg:'connection options as read in from file'})
    this.opts = overwrite ? Object.assign(this.opts,opts) : Object.assign(opts, this.opts)
    log.debug({opts:opts, msg:'connection options as ammended from configure() argument'})
  }

  async connect(copts = {}) {
    const opts = Object.assign({},this.opts,copts) // merge any changes pasted via connect
    log.debug({opts:opts, msg:'final connection options as ammend via connect() argument and as used'})
    if (opts.agentenv) opts.agent = process.env[opts.agentenv]
    opts.readyTimeout = opts.readyTimeout | 5000  // default was 20 seconds...too long
    opts.privateKey = opts.privateKey || opts.privateKeyPath ? await read(opts.privateKeyPath) : null
    //  log.info(opts.privateKeyPath, opts.privateKey)
    super.connect(opts)
    return new Promise( (resolve,reject) => {
      this.on('ready', async () => {
        this.ready=true
        log.info(`connected to ${this.opts.host}`)
        resolve(`connected to ${this.opts.host}`)
      })
      this.on('error', (err) => {
        log.warn({err:err, opts:this.opts, msg:'connection error'})
        reject(err)
      })
    })
  }

  close() {
    this.ready=false
    log.info('closing ssh connection')
    this.end()
  }

  async shell(command, opts={}) {
    if (Object.prototype.toString.call(command) === '[object Object]') {
      opts = command
      if (!opts.cli) {
        this.close()
        let err = new Error('no terminal interactive shell must pass a command')
        log.fatal({command:command, opts:opts, err:err, msg:'no terminal interactive shell must pass a command'})
        return err
      }
      command = []  // a place to store all terminal commands
    }
    opts.shell=true
    return this.exec(command,opts)
  }

  async exec(cmd = 'ls -la', opts={}) {
    if (!this.ready) {
      log.info('not connected, attempting connect first')
      let [err] = await to(this.connect())
      if (err) return err
    }
    const remote = this  // TODO bind this on promise instead
    const superexec = opts.shell? super.shell.bind(this) : super.exec.bind(this)
    let command = opts.shell ? opts : cmd
    // log.info(`executing command ${command} on shell? ${opts.shell}`)
    return new Promise(function(resolve, reject) {
      let reply =''
      let error = ''
      superexec(command, function(err, stream) {
        log.info({command:command, cmd:cmd, opts:opts, msg:'before ssh exec/shell'})
        const done = () => {
          if (error) remote.emit('remote:error',error)
          resolve({command:command,cmds:cmd,reply:reply,error:error})
        }
        if (err) reject(err)
        stream.once('close', () => {
          if (remote.opts.close || opts.close || opts.cli) {
            remote.on('end', done)
            remote.close()
          } else done()
        }).on('data', function(data) {
          reply += data.toString()
          if (opts.cli) process.stdout.write(data.toString())
          else log.info(`${remote.opts.host}$ ${data}`)
        }).stderr.on('data', function(data) {
          error += data.toString()
          if (opts.cli) process.stderr.write(data.toString())
          else log.info(`${remote.opts.host}:ERR $: ${data}`)
        })
        // alternate shell processing
        if (opts.shell) {
          if (opts.cli) { // terminal interactive shell sesssion
            const cli= readline.createInterface({input:process.stdin, output:process.stdout})
            cli.on('line', line => {
              cmd.push(line)
              if(line.trim() === 'exit') {
                cli.removeAllListeners()
                cli.close()
                stream.end(`${line}\n`)
              } else {
                stream.write(`${line}\n`)
              }
            }) // end terminal listener
          }
          else {
            // give a bit of time for MOTD to display so it's not part of reply
            setTimeout(() => {
              reply=''
              stream.end(`${cmd}\nexit\n`)
            }, opts.delay || 300)
          }
        } // end shell processing
      }) // end super
    }) // end Promise
  }
}

export default  Ssh