'use strict'
/**
 * Copyright (c) 2010-2017 Brian Carlson (brian.m.carlson@gmail.com)
 * All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * README.md file in the root directory of this source tree.
 */

var net = require('net')
var EventEmitter = require('events').EventEmitter
var util = require('util')

var Writer = require('buffer-writer')
var Reader = require('packet-reader')

var TEXT_MODE = 0
var BINARY_MODE = 1
var Connection = function (config) {
  EventEmitter.call(this)
  config = config || {}
  this.stream = config.stream || new net.Socket()
  this._keepAlive = config.keepAlive
  this.lastBuffer = false
  this.lastOffset = 0
  this.buffer = null
  this.offset = null
  this.encoding = config.encoding || 'utf8'
  this.parsedStatements = {}
  this.writer = new Writer()
  this.ssl = config.ssl || false
  this._ending = false
  this._mode = TEXT_MODE
  this._emitMessage = false
  this._reader = new Reader({
    headerSize: 1,
    lengthPadding: -4
  })
  var self = this
  this.on('newListener', function (eventName) {
    if (eventName === 'message') {
      self._emitMessage = true
    }
  })
}

util.inherits(Connection, EventEmitter)

Connection.prototype.connect = function (port, host) {
  if (this.stream.readyState === 'closed') {
    this.stream.connect(port, host)
  } else if (this.stream.readyState === 'open') {
    this.emit('connect')
  }

  var self = this

  this.stream.on('connect', function () {
    if (self._keepAlive) {
      self.stream.setKeepAlive(true)
    }
    self.emit('connect')
  })

  const reportStreamError = function (error) {
    // don't raise ECONNRESET errors - they can & should be ignored
    // during disconnect
    if (self._ending && error.code === 'ECONNRESET') {
      return
    }
    self.emit('error', error)
  }
  this.stream.on('error', reportStreamError)

  this.stream.on('close', function () {
    self.emit('end')
  })

  if (!this.ssl) {
    return this.attachListeners(this.stream)
  }

  this.stream.once('data', function (buffer) {
    var responseCode = buffer.toString('utf8')
    switch (responseCode) {
      case 'N': // Server does not support SSL connections
        return self.emit('error', new Error('The server does not support SSL connections'))
      case 'S': // Server supports SSL connections, continue with a secure connection
        break
      default: // Any other response byte, including 'E' (ErrorResponse) indicating a server error
        return self.emit('error', new Error('There was an error establishing an SSL connection'))
    }
    var tls = require('tls')
    self.stream = tls.connect({
      socket: self.stream,
      servername: host,
      checkServerIdentity: self.ssl.checkServerIdentity || tls.checkServerIdentity,
      rejectUnauthorized: self.ssl.rejectUnauthorized,
      ca: self.ssl.ca,
      pfx: self.ssl.pfx,
      key: self.ssl.key,
      passphrase: self.ssl.passphrase,
      cert: self.ssl.cert,
      NPNProtocols: self.ssl.NPNProtocols
    })
    self.attachListeners(self.stream)
    self.stream.on('error', reportStreamError)

    self.emit('sslconnect')
  })
}

Connection.prototype.attachListeners = function (stream) {
  var self = this
  stream.on('data', function (buff) {
    self._reader.addChunk(buff)
    var packet = self._reader.read()
    while (packet) {
      var msg = self.parseMessage(packet)
      if (self._emitMessage) {
        self.emit('message', msg)
      }
      self.emit(msg.name, msg)
      packet = self._reader.read()
    }
  })
  stream.on('end', function () {
    self.emit('end')
  })
}

Connection.prototype.requestSsl = function () {
  var bodyBuffer = this.writer
    .addInt16(0x04D2)
    .addInt16(0x162F).flush()

  var length = bodyBuffer.length + 4

  var buffer = new Writer()
    .addInt32(length)
    .add(bodyBuffer)
    .join()
  this.stream.write(buffer)
}

Connection.prototype.startup = function (config) {
  var writer = this.writer
    .addInt16(3)
    .addInt16(0)

  Object.keys(config).forEach(function (key) {
    var val = config[key]
    writer.addCString(key).addCString(val)
  })

  writer.addCString('client_encoding').addCString("'utf-8'")

  var bodyBuffer = writer.addCString('').flush()
  // this message is sent without a code

  var length = bodyBuffer.length + 4

  var buffer = new Writer()
    .addInt32(length)
    .add(bodyBuffer)
    .join()
  this.stream.write(buffer)
}

Connection.prototype.cancel = function (processID, secretKey) {
  var bodyBuffer = this.writer
    .addInt16(1234)
    .addInt16(5678)
    .addInt32(processID)
    .addInt32(secretKey)
    .flush()

  var length = bodyBuffer.length + 4

  var buffer = new Writer()
    .addInt32(length)
    .add(bodyBuffer)
    .join()
  this.stream.write(buffer)
}

Connection.prototype.password = function (password) {
  // 0x70 = 'p'
  this._send(0x70, this.writer.addCString(password))
}

Connection.prototype._send = function (code, more) {
  if (!this.stream.writable) {
    return false
  }
  if (more === true) {
    this.writer.addHeader(code)
  } else {
    return this.stream.write(this.writer.flush(code))
  }
}

Connection.prototype.query = function (text) {
  // 0x51 = Q
  this.stream.write(this.writer.addCString(text).flush(0x51))
}

// send parse message
// "more" === true to buffer the message until flush() is called
Connection.prototype.parse = function (query, more) {
  // expect something like this:
  // { name: 'queryName',
  //   text: 'select * from blah',
  //   types: ['int8', 'bool'] }

  // normalize missing query names to allow for null
  query.name = query.name || ''
  if (query.name.length > 63) {
    console.error('Warning! Postgres only supports 63 characters for query names.')
    console.error('You supplied', query.name, '(', query.name.length, ')')
    console.error('This can cause conflicts and silent errors executing queries')
  }
  // normalize null type array
  query.types = query.types || []
  var len = query.types.length
  var buffer = this.writer
    .addCString(query.name) // name of query
    .addCString(query.text) // actual query text
    .addInt16(len)
  for (var i = 0; i < len; i++) {
    buffer.addInt32(query.types[i])
  }

  var code = 0x50
  this._send(code, more)
}

// send bind message
// "more" === true to buffer the message until flush() is called
Connection.prototype.bind = function (config, more) {
  // normalize config
  config = config || {}
  config.portal = config.portal || ''
  config.statement = config.statement || ''
  config.binary = config.binary || false
  var values = config.values || []
  var len = values.length
  var useBinary = false
  for (var j = 0; j < len; j++) { useBinary |= values[j] instanceof Buffer }
  var buffer = this.writer
    .addCString(config.portal)
    .addCString(config.statement)
  if (!useBinary) { buffer.addInt16(0) } else {
    buffer.addInt16(len)
    for (j = 0; j < len; j++) { buffer.addInt16(values[j] instanceof Buffer) }
  }
  buffer.addInt16(len)
  for (var i = 0; i < len; i++) {
    var val = values[i]
    if (val === null || typeof val === 'undefined') {
      buffer.addInt32(-1)
    } else if (val instanceof Buffer) {
      buffer.addInt32(val.length)
      buffer.add(val)
    } else {
      buffer.addInt32(Buffer.byteLength(val))
      buffer.addString(val)
    }
  }

  if (config.binary) {
    buffer.addInt16(1) // format codes to use binary
    buffer.addInt16(1)
  } else {
    buffer.addInt16(0) // format codes to use text
  }
  // 0x42 = 'B'
  this._send(0x42, more)
}

// send execute message
// "more" === true to buffer the message until flush() is called
Connection.prototype.execute = function (config, more) {
  config = config || {}
  config.portal = config.portal || ''
  config.rows = config.rows || ''
  this.writer
    .addCString(config.portal)
    .addInt32(config.rows)

  // 0x45 = 'E'
  this._send(0x45, more)
}

var emptyBuffer = Buffer.alloc(0)

Connection.prototype.flush = function () {
  // 0x48 = 'H'
  this.writer.add(emptyBuffer)
  this._send(0x48)
}

Connection.prototype.sync = function () {
  // clear out any pending data in the writer
  this.writer.flush(0)

  this.writer.add(emptyBuffer)
  this._ending = true
  this._send(0x53)
}

const END_BUFFER = Buffer.from([0x58, 0x00, 0x00, 0x00, 0x04])

Connection.prototype.end = function () {
  // 0x58 = 'X'
  this.writer.add(emptyBuffer)
  this._ending = true
  return this.stream.write(END_BUFFER, () => {
    this.stream.end()
  })
}

Connection.prototype.close = function (msg, more) {
  this.writer.addCString(msg.type + (msg.name || ''))
  this._send(0x43, more)
}

Connection.prototype.describe = function (msg, more) {
  this.writer.addCString(msg.type + (msg.name || ''))
  this._send(0x44, more)
}

Connection.prototype.sendCopyFromChunk = function (chunk) {
  this.stream.write(this.writer.add(chunk).flush(0x64))
}

Connection.prototype.endCopyFrom = function () {
  this.stream.write(this.writer.add(emptyBuffer).flush(0x63))
}

Connection.prototype.sendCopyFail = function (msg) {
  // this.stream.write(this.writer.add(emptyBuffer).flush(0x66));
  this.writer.addCString(msg)
  this._send(0x66)
}

var Message = function (name, length) {
  this.name = name
  this.length = length
}

Connection.prototype.parseMessage = function (buffer) {
  this.offset = 0
  var length = buffer.length + 4
  switch (this._reader.header) {
    case 0x52: // R
      return this.parseR(buffer, length)

    case 0x53: // S
      return this.parseS(buffer, length)

    case 0x4b: // K
      return this.parseK(buffer, length)

    case 0x43: // C
      return this.parseC(buffer, length)

    case 0x5a: // Z
      return this.parseZ(buffer, length)

    case 0x54: // T
      return this.parseT(buffer, length)

    case 0x44: // D
      return this.parseD(buffer, length)

    case 0x45: // E
      return this.parseE(buffer, length)

    case 0x4e: // N
      return this.parseN(buffer, length)

    case 0x31: // 1
      return new Message('parseComplete', length)

    case 0x32: // 2
      return new Message('bindComplete', length)

    case 0x33: // 3
      return new Message('closeComplete', length)

    case 0x41: // A
      return this.parseA(buffer, length)

    case 0x6e: // n
      return new Message('noData', length)

    case 0x49: // I
      return new Message('emptyQuery', length)

    case 0x73: // s
      return new Message('portalSuspended', length)

    case 0x47: // G
      return this.parseG(buffer, length)

    case 0x48: // H
      return this.parseH(buffer, length)

    case 0x57: // W
      return new Message('replicationStart', length)

    case 0x63: // c
      return new Message('copyDone', length)

    case 0x64: // d
      return this.parsed(buffer, length)
  }
}

Connection.prototype.parseR = function (buffer, length) {
  var code = 0
  var msg = new Message('authenticationOk', length)
  if (msg.length === 8) {
    code = this.parseInt32(buffer)
    if (code === 3) {
      msg.name = 'authenticationCleartextPassword'
    }
    return msg
  }
  if (msg.length === 12) {
    code = this.parseInt32(buffer)
    if (code === 5) { // md5 required
      msg.name = 'authenticationMD5Password'
      msg.salt = Buffer.alloc(4)
      buffer.copy(msg.salt, 0, this.offset, this.offset + 4)
      this.offset += 4
      return msg
    }
  }
  throw new Error('Unknown authenticationOk message type' + util.inspect(msg))
}

Connection.prototype.parseS = function (buffer, length) {
  var msg = new Message('parameterStatus', length)
  msg.parameterName = this.parseCString(buffer)
  msg.parameterValue = this.parseCString(buffer)
  return msg
}

Connection.prototype.parseK = function (buffer, length) {
  var msg = new Message('backendKeyData', length)
  msg.processID = this.parseInt32(buffer)
  msg.secretKey = this.parseInt32(buffer)
  return msg
}

Connection.prototype.parseC = function (buffer, length) {
  var msg = new Message('commandComplete', length)
  msg.text = this.parseCString(buffer)
  return msg
}

Connection.prototype.parseZ = function (buffer, length) {
  var msg = new Message('readyForQuery', length)
  msg.name = 'readyForQuery'
  msg.status = this.readString(buffer, 1)
  return msg
}

var ROW_DESCRIPTION = 'rowDescription'
Connection.prototype.parseT = function (buffer, length) {
  var msg = new Message(ROW_DESCRIPTION, length)
  msg.fieldCount = this.parseInt16(buffer)
  var fields = []
  for (var i = 0; i < msg.fieldCount; i++) {
    fields.push(this.parseField(buffer))
  }
  msg.fields = fields
  return msg
}

var Field = function () {
  this.name = null
  this.tableID = null
  this.columnID = null
  this.dataTypeID = null
  this.dataTypeSize = null
  this.dataTypeModifier = null
  this.format = null
}

var FORMAT_TEXT = 'text'
var FORMAT_BINARY = 'binary'
Connection.prototype.parseField = function (buffer) {
  var field = new Field()
  field.name = this.parseCString(buffer)
  field.tableID = this.parseInt32(buffer)
  field.columnID = this.parseInt16(buffer)
  field.dataTypeID = this.parseInt32(buffer)
  field.dataTypeSize = this.parseInt16(buffer)
  field.dataTypeModifier = this.parseInt32(buffer)
  if (this.parseInt16(buffer) === TEXT_MODE) {
    this._mode = TEXT_MODE
    field.format = FORMAT_TEXT
  } else {
    this._mode = BINARY_MODE
    field.format = FORMAT_BINARY
  }
  return field
}

var DATA_ROW = 'dataRow'
var DataRowMessage = function (length, fieldCount) {
  this.name = DATA_ROW
  this.length = length
  this.fieldCount = fieldCount
  this.fields = []
}

// extremely hot-path code
Connection.prototype.parseD = function (buffer, length) {
  var fieldCount = this.parseInt16(buffer)
  var msg = new DataRowMessage(length, fieldCount)
  for (var i = 0; i < fieldCount; i++) {
    msg.fields.push(this._readValue(buffer))
  }
  return msg
}

// extremely hot-path code
Connection.prototype._readValue = function (buffer) {
  var length = this.parseInt32(buffer)
  if (length === -1) return null
  if (this._mode === TEXT_MODE) {
    return this.readString(buffer, length)
  }
  return this.readBytes(buffer, length)
}

// parses error
Connection.prototype.parseE = function (buffer, length) {
  var fields = {}
  var msg, item
  var input = new Message('error', length)
  var fieldType = this.readString(buffer, 1)
  while (fieldType !== '\0') {
    fields[fieldType] = this.parseCString(buffer)
    fieldType = this.readString(buffer, 1)
  }
  if (input.name === 'error') {
    // the msg is an Error instance
    msg = new Error(fields.M)
    for (item in input) {
      // copy input properties to the error
      if (input.hasOwnProperty(item)) {
        msg[item] = input[item]
      }
    }
  } else {
    // the msg is an object literal
    msg = input
    msg.message = fields.M
  }
  msg.severity = fields.S
  msg.code = fields.C
  msg.detail = fields.D
  msg.hint = fields.H
  msg.position = fields.P
  msg.internalPosition = fields.p
  msg.internalQuery = fields.q
  msg.where = fields.W
  msg.schema = fields.s
  msg.table = fields.t
  msg.column = fields.c
  msg.dataType = fields.d
  msg.constraint = fields.n
  msg.file = fields.F
  msg.line = fields.L
  msg.routine = fields.R
  return msg
}

// same thing, different name
Connection.prototype.parseN = function (buffer, length) {
  var msg = this.parseE(buffer, length)
  msg.name = 'notice'
  return msg
}

Connection.prototype.parseA = function (buffer, length) {
  var msg = new Message('notification', length)
  msg.processId = this.parseInt32(buffer)
  msg.channel = this.parseCString(buffer)
  msg.payload = this.parseCString(buffer)
  return msg
}

Connection.prototype.parseG = function (buffer, length) {
  var msg = new Message('copyInResponse', length)
  return this.parseGH(buffer, msg)
}

Connection.prototype.parseH = function (buffer, length) {
  var msg = new Message('copyOutResponse', length)
  return this.parseGH(buffer, msg)
}

Connection.prototype.parseGH = function (buffer, msg) {
  var isBinary = buffer[this.offset] !== 0
  this.offset++
  msg.binary = isBinary
  var columnCount = this.parseInt16(buffer)
  msg.columnTypes = []
  for (var i = 0; i < columnCount; i++) {
    msg.columnTypes.push(this.parseInt16(buffer))
  }
  return msg
}

Connection.prototype.parsed = function (buffer, length) {
  var msg = new Message('copyData', length)
  msg.chunk = this.readBytes(buffer, msg.length - 4)
  return msg
}

Connection.prototype.parseInt32 = function (buffer) {
  var value = buffer.readInt32BE(this.offset)
  this.offset += 4
  return value
}

Connection.prototype.parseInt16 = function (buffer) {
  var value = buffer.readInt16BE(this.offset)
  this.offset += 2
  return value
}

Connection.prototype.readString = function (buffer, length) {
  return buffer.toString(this.encoding, this.offset, (this.offset += length))
}

Connection.prototype.readBytes = function (buffer, length) {
  return buffer.slice(this.offset, (this.offset += length))
}

Connection.prototype.parseCString = function (buffer) {
  var start = this.offset
  var end = buffer.indexOf(0, start)
  this.offset = end + 1
  return buffer.toString(this.encoding, start, end)
}
// end parsing methods
module.exports = Connection
