node_modules/pomelo/lib/connectors/common/coder.js

var Message = require('pomelo-protocol').Message;
var Constants = require('../../util/constants');
var logger = require('pomelo-logger').getLogger('pomelo', __filename);

var encode = function(reqId, route, msg) {
  if(!!reqId) {
    return composeResponse(this, reqId, route, msg);
  } else {
    return composePush(this, route, msg);
  }
};

var decode = function(msg) {
  msg = Message.decode(msg.body);
  var route = msg.route;

  // decode use dictionary
  if(!!msg.compressRoute) {
    if(!!this.connector.useDict) {
      var abbrs = this.dictionary.getAbbrs();
      if(!abbrs[route]) {
        logger.error('dictionary error! no abbrs for route : %s', route);
        return null;
      }
      route = msg.route = abbrs[route];
    } else {
      logger.error('fail to uncompress route code for msg: %j, server not enable dictionary.', msg);
      return null;
    }
  }

  // decode use protobuf
  if(!!this.protobuf && !!this.protobuf.getProtos().client[route]) {
    msg.body = this.protobuf.decode(route, msg.body);
  } else if(!!this.decodeIO_protobuf && !!this.decodeIO_protobuf.check(Constants.RESERVED.CLIENT, route)) {
    msg.body = this.decodeIO_protobuf.decode(route, msg.body);
  } else {
    msg.body = JSON.parse(msg.body.toString('utf8'));
  }

  return msg;
};

var composeResponse = function(server, msgId, route, msgBody) {
  if(!msgId || !route || !msgBody) {
    return null;
  }
  msgBody = encodeBody(server, route, msgBody);
  return Message.encode(msgId, Message.TYPE_RESPONSE, 0, null, msgBody);
};

var composePush = function(server, route, msgBody) {
  if(!route || !msgBody){
    return null;
  }
  msgBody = encodeBody(server, route, msgBody);
  // encode use dictionary
  var compressRoute = 0;
  if(!!server.dictionary) {
    var dict = server.dictionary.getDict();
    if(!!server.connector.useDict && !!dict[route]) {
      route = dict[route];
      compressRoute = 1;
    }
  }
  return Message.encode(0, Message.TYPE_PUSH, compressRoute, route, msgBody);
};

var encodeBody = function(server, route, msgBody) {
    // encode use protobuf
  if(!!server.protobuf && !!server.protobuf.getProtos().server[route]) {
    msgBody = server.protobuf.encode(route, msgBody);
  } else if(!!server.decodeIO_protobuf && !!server.decodeIO_protobuf.check(Constants.RESERVED.SERVER, route)) {
     msgBody = server.decodeIO_protobuf.encode(route, msgBody);
  } else {
    msgBody = new Buffer(JSON.stringify(msgBody), 'utf8');
  }
  return msgBody;
};

module.exports = {
  encode: encode,
  decode: decode
};