/*
 * Copyright 2015-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

//
// Instantiate the AWS SDK and configuration objects.  The AWS SDK for 
// JavaScript (aws-sdk) is used for Cognito Identity/Authentication, and 
// the AWS IoT SDK for JavaScript (aws-iot-device-sdk) is used for the
// WebSocket connection to AWS IoT and device shadow APIs.
// 
var AWS = require('aws-sdk');
var AWSIoTData = require('aws-iot-device-sdk');
var AWSConfiguration = require('./aws-configuration.js');

console.log('Loaded AWS SDK for JavaScript and AWS IoT SDK for Node.js');

//
// Remember our current subscription topic here.
//
var currentlySubscribedTopic = 'subscribe-topic';

//
// Remember our message history here.
//
var messageHistory = '';

//
// Create a client id to use when connecting to AWS IoT.
//
var clientId = 'mqtt-explorer-' + (Math.floor((Math.random() * 100000) + 1));

//
// Initialize our configuration.
//
AWS.config.region = AWSConfiguration.region;

AWS.config.credentials = new AWS.CognitoIdentityCredentials({
   IdentityPoolId: AWSConfiguration.poolId
});

//
// Create the AWS IoT device object.  Note that the credentials must be 
// initialized with empty strings; when we successfully authenticate to
// the Cognito Identity Pool, the credentials will be dynamically updated.
//
const mqttClient = AWSIoTData.device({
   //
   // Set the AWS region we will operate in.
   //
   region: AWS.config.region,
   //
   // Use the clientId created earlier.
   //
   clientId: clientId,
   //
   // Connect via secure WebSocket
   //
   protocol: 'wss',
   //
   // Set the maximum reconnect time to 8 seconds; this is a browser application
   // so we don't want to leave the user waiting too long for reconnection after
   // re-connecting to the network/re-opening their laptop/etc...
   //
   maximumReconnectTimeMs: 8000,
   //
   // Enable console debugging information (optional)
   //
   debug: true,
   //
   // IMPORTANT: the AWS access key ID, secret key, and sesion token must be 
   // initialized with empty strings.
   //
   accessKeyId: '',
   secretKey: '',
   sessionToken: ''
});

//
// Attempt to authenticate to the Cognito Identity Pool.  Note that this
// example only supports use of a pool which allows unauthenticated 
// identities.
//
var cognitoIdentity = new AWS.CognitoIdentity();
AWS.config.credentials.get(function(err, data) {
   if (!err) {
      console.log('retrieved identity: ' + AWS.config.credentials.identityId);
      var params = {
         IdentityId: AWS.config.credentials.identityId
      };
      cognitoIdentity.getCredentialsForIdentity(params, function(err, data) {
         if (!err) {
            //
            // Update our latest AWS credentials; the MQTT client will use these
            // during its next reconnect attempt.
            //
            mqttClient.updateWebSocketCredentials(data.Credentials.AccessKeyId,
               data.Credentials.SecretKey,
               data.Credentials.SessionToken);
         } else {
            console.log('error retrieving credentials: ' + err);
            alert('error retrieving credentials: ' + err);
         }
      });
   } else {
      console.log('error retrieving identity:' + err);
      alert('error retrieving identity: ' + err);
   }
});

//
// Connect handler; update div visibility and fetch latest shadow documents.
// Subscribe to lifecycle events on the first connect event.
//
window.mqttClientConnectHandler = function() {
   console.log('connect');
   document.getElementById("connecting-div").style.visibility = 'hidden';
   document.getElementById("explorer-div").style.visibility = 'visible';
   document.getElementById('subscribe-div').innerHTML = '<p><br></p>';
   messageHistory = '';

   //
   // Subscribe to our current topic.
   //
   mqttClient.subscribe(currentlySubscribedTopic);
};

//
// Reconnect handler; update div visibility.
//
window.mqttClientReconnectHandler = function() {
   console.log('reconnect');
   document.getElementById("connecting-div").style.visibility = 'visible';
   document.getElementById("explorer-div").style.visibility = 'hidden';
};

//
// Utility function to determine if a value has been defined.
//
window.isUndefined = function( value ) {
   return typeof value === 'undefined' || typeof value === null;
};

//
// Message handler for lifecycle events; create/destroy divs as clients
// connect/disconnect.
//
window.mqttClientMessageHandler = function( topic, payload ) {
   console.log('message: '+topic+':'+payload.toString());
   messageHistory = messageHistory + topic + ':' + payload.toString() + '</br>';
   document.getElementById('subscribe-div').innerHTML = '<p>'+messageHistory+'</p>';
};

//
// Handle the UI for the current topic subscription
//
window.updateSubscriptionTopic = function() {
   var subscribeTopic = document.getElementById('subscribe-topic').value;
   document.getElementById('subscribe-div').innerHTML = '';
   mqttClient.unsubscribe(currentlySubscribedTopic);
   currentlySubscribedTopic = subscribeTopic;
   mqttClient.subscribe(currentlySubscribedTopic);
};

//
// Handle the UI to clear the history window
//
window.clearHistory= function() {
   if (confirm('Delete message history?') === true) {
      document.getElementById('subscribe-div').innerHTML = '<p><br></p>';
      messageHistory = '';
   }
};

//
// Handle the UI to update the topic we're publishing on
//
window.updatePublishTopic= function() {
};

//
// Handle the UI to update the data we're publishing
//
window.updatePublishData= function() {
   var publishText  = document.getElementById('publish-data').value;
   var publishTopic = document.getElementById('publish-topic').value;

   mqttClient.publish( publishTopic, publishText );
   document.getElementById('publish-data').value = '';
};

//
// Install connect/reconnect event handlers.
//
mqttClient.on('connect', window.mqttClientConnectHandler);
mqttClient.on('reconnect', window.mqttClientReconnectHandler);
mqttClient.on('message', window.mqttClientMessageHandler);

//
// Initialize divs.
//
document.getElementById('connecting-div').style.visibility = 'visible';
document.getElementById('explorer-div').style.visibility = 'hidden';
document.getElementById('connecting-div').innerHTML = '<p>attempting to connect to aws iot...</p>';