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.Stream();
  this._keepAlive = config.keepAlive;
  this.lastBuffer = false;
  this.lastOffset = 0;
  this.buffer = null;
  this.offset = null;
  this.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');
  });

  this.stream.on('error', 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('close', function() {
    // NOTE: node-0.10 emits both 'end' and 'close'
    //       for streams closed by the peer, while
    //       node-0.8 only emits 'close'
    self.emit('end');
  });

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

  this.stream.once('data', function(buffer) {
    var responseCode = buffer.toString('utf8');
    if(responseCode != 'S') {
      return self.emit('error', new Error('The server does not support SSL connections'));
    }
    var tls = require('tls');
    self.stream = tls.connect({
      socket: self.stream,
      servername: host,
      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.emit('sslconnect');

    self.stream.on('error', function(error){
      self.emit('error', error);
    });
  });
};

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();
    }
  });
};

Connection.prototype.requestSsl = function() {
  this.checkSslResponse = true;

  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(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);
};

Connection.prototype.end = function() {
  //0x58 = 'X'
  this.writer.add(emptyBuffer);
  this._ending = true;
  this._send(0x58);
};

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 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 = new Buffer(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, true);
  this.offset += 4;
  return value;
};

Connection.prototype.parseInt16 = function(buffer) {
  var value = buffer.readInt16BE(this.offset, true);
  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;
  while(buffer[this.offset++] !== 0) { }
  return buffer.toString(this.encoding, start, this.offset - 1);
};
//end parsing methods
module.exports = Connection;
