var ssdp = require('node-upnp-ssdp');
var UPnPDeviceClient = require('upnp-device-client');
var mqtt    = require('mqtt');

var clientId = 'kenta-upnp-gateway';

var mqttOptions = { clientId: clientId };
var mqttEndpoint = 'mqtt://beam.soracom.io';
var mqttClient = mqtt.connect(mqttEndpoint, mqttOptions);

var topicUpdateAccepted = '$aws/things/' + clientId + '/shadow/update/accepted';
var topicUpdateDelta = '$aws/things/' + clientId + '/shadow/update/delta';
var topicDevicesRoot = '$aws/things/' + clientId + '/devices';

var devices = {};

var addOrUpdateDevice = function(info){
  var udn = info.usn.split('::')[0];
  if (!devices[udn]){
    var client = new UPnPDeviceClient(info.location);
    client.getDeviceDescription(function(err, device){
      if (!err){
        console.log('UPnP: Device ' + device.friendlyName + ' found');
        device.client = client;
        device.online = true;
        publish(createDevicePresense(udn, device));
        devices[udn] = device;
      } else {
        console.error('UPnP: ' + err);
      }
    });
  } else {
    publish(createDevicePresense(udn, {online: true}));
  }
};

var createDevicePresense = function(udn, device){
  var presense = {
    devices: {}
  };
  presense.devices[udn] = {};
  for (var key in device){
    if (key !== 'client'){
      presense.devices[udn][key] = device[key];
    }
  }
  return presense;
};

var removeDevice = function(info){
  var udn = info.usn.split('::')[0];
  var device = devices[udn];
  if (device){
    console.log('UPnP: Device ' + device.friendlyName + ' gets offline');
    delete devices[udn];
    publish(createDevicePresense(udn, {online: false}));
  }
};

var publish = function(state){
  var event = {
    state: {
      reported: state
    }
  };
  mqttClient.publish('$aws/things/kenta-upnp-gateway/shadow/update', JSON.stringify(event));
};

var getContextFromTopic = function(topic){
  var path = topic.substring(topicDevicesRoot.length + 1);
  var elems = path.split('/');
  var context = {
    udn: elems[0],
    service: elems[1],
    action: elems[2]
  };
  console.log(context);
  return context;
};

var executeAction = function(context, args){
  if (devices[context.udn]){
    var client = devices[context.udn].client;
    client.callAction(context.service, context.action, args, function(err, result) {
      if (!err){
        console.log(result);
      } else {
        console.error(err);
      }
    });
  } else {
    console.error("No such device found");
  }
};


ssdp.on('DeviceFound', addOrUpdateDevice);
ssdp.on('DeviceAvailable:upnp:rootdevice', addOrUpdateDevice);
ssdp.on('DeviceUnavailable:upnp:rootdevice', removeDevice);
ssdp.on('DeviceError', console.error);

ssdp.mSearch('upnp:rootdevice');

mqttClient.on('connect', function () {

  mqttClient.subscribe([topicUpdateDelta, topicUpdateAccepted, topicDevicesRoot + '/#']);
});

mqttClient.on('message', function (topic, buffer) {
  if (topic === topicUpdateAccepted){
    console.log('MQTT: Device shadow update accepted by AWS IoT');
  } else if (topic === topicUpdateDelta){
    console.log('MQTT: Delta is received from AWS IoT');
    var delta = JSON.parse(buffer.toString());
    console.log(delta);
  } else if (topic.indexOf(topicDevicesRoot) === 0){
    console.log('MQTT: Message to a device received');
    executeAction(getContextFromTopic(topic), JSON.parse(buffer.toString()));
  } else {
    console.error('MQTT: Unknown message received on topic ' + topic);
    console.error(buffer.toString());
  }
});

mqttClient.on('error', console.error);