App Script Chat Bot Sample

Code.gs

// 1) Copy or Duplicate this spreadsheet (and this AppsScript project)
//
// 2) Run "setup" function once
//    - Use the menu above.
//
// 3) Create Google Cloud Service Project. And copy the Project Number.
//
// 4) This > Project Settings > Set GCM project number
//
// 5) Add the line "chat": {} to your manifest file. (IMPORTANT)
//
// 6) Setup 0Auth : https://github.com/googleworkspace/apps-script-oauth2
//
// 6) Deploy
//    - Select type "Web App" and "Add-on" (both)
//    - Set description "v1"
//    - Set "Who can access" to "Anyone"
//
// 7) Copy "Deployment Id" and "Web App URL" you will use them.
//    - Check the Web APP URL, is it working?
//    - "message" key must equals to "working"
//    - "setup" key must not equals to "null"
//
// 8) Enable Google Chat API on console.cloud.google.com
//    - Use search to find "Google Chat API" and press Enable button.
//
// 9) Go to APIs > Google Chat API > Credentials and Create a service account.
//    - Choose a account name and type a description for it. (Ex: Unity GChat )
//    - Click to "Create and Continue"
//    - Select Role : "Basic > Owner" and Click "Continue"
//    - No need to grant user access, just Click to "Done".
//
// 10) Go to APIs > Google Chat API > Configuration and fill the form.
//    - Set App Name (Ex: Unity GChat)
//    - Set Avatar URL (if you have not, use https://www.gstatic.com/images/branding/product/1x/chat_48dp.png )
//    - Set Description. (Ex: Unity GChat allows to talk with Unity)
//    - Set Functionality
//         * Receive 1:1 messages => checked
//         * Join spaces and group conversations => checked
//    - Set Connection Settings
//         * Choose "App Script Project" option
//         * Paste "Deployment Id" to textbox.
//    - Set Visibility
//         * Add your email adresses to see the bot.
//         * Add your domain if you have google workspace.
//
// 11) Create space and your providers and bot to the group..

//  ####################
//  # Setup
//  ####################
function setup(){ // please select "setup" function and run it once.
  PropertiesService.getDocumentProperties().setProperty("setup",true);
}

//  ####################
//  # API
//  ####################
// - handle GET method 
function doGet(request) {
  var output = ContentService.createTextOutput();
  output.setMimeType(ContentService.MimeType.JSON);
  output.append(JSON.stringify({
    message: "working",
    setup : PropertiesService.getDocumentProperties().getProperty("setup"),
    chat : PropertiesService.getDocumentProperties().getProperty("chat")
  }));
  return output;
}
// - handle POST method
function doPost(request){
  var json = { ok: false, request: request };
  if(!request.postData){
    json.error = "No post data";
  }else if(request.postData.type != 'application/json'){
    json.error = "Invalid json body";
  }else{
    json.input = JSON.parse(request.postData.contents);
    if(request.parameters.type){ // Ex: exec?type=create
    var type = request.parameters.type;
    if(type=="create") createThread(json);
    else if(type=="post") postToThread(json);
    else if(type=="fetch") fetchThread(json);
    else json.error ="Invalid type";

    }else{
      json.error = "Type parameter is required";
    }
  }
  return ContentService.createTextOutput(JSON.stringify(json)).setMimeType(ContentService.MimeType.JSON);
}
// - exec?type=create
function createThread(json){
  var name = "User (No Name)";
  if(json.input.name){
    name = json.input.name;
  }
  var response = postMessage({
    text: name + " created a thread."
  });
  json.responseForThread = JSON.parse(response.getContentText());
  json.thread = json.responseForThread.thread.name;
  response = postMessage({
      text: name + " : " + json.input.message,
      messageReplyOption : "REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD",
      thread : {
        name : json.thread
      }
  });
  json.responseForMessage = JSON.parse(response.getContentText());
  json.ok = true;
  json.message = "Thread created";
}
// - exec?type=post
function postToThread(json){
  var name = "User (No Name)";
  if(json.input.name){
    name = json.input.name;
  }
  if(json.input.thread){
    var response = postMessage({
        text: name + " : " + json.input.message,
        messageReplyOption : "REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD",
        thread : {
          name : json.input.thread
        }
    });
    json.responseForMessage = JSON.parse(response.getContentText());
    json.ok = true;
    json.message = "Posted to the thread";
  }else{
    json.error ="thread parameter is required";
  }
}
// - exec?type=fetch
function fetchThread(json){
  json.ok = true;
  json.message = "Thread fetched";
  if(json.input.thread){
    //var spaceId = PropertiesService.getDocumentProperties().getProperty("space");
    var service = createService();
    var url = 'https://chat.googleapis.com/v1/spaces/AAAAGZq2WUk/messages/9-lnyxdLHFU.9-lnyxdLHFU'; // test
    //url +="?filter=" + encodeURI("thread.name = " + json.input.thread);
    var response = UrlFetchApp.fetch(url, {
      method: 'get',
      headers: { 'Authorization': 'Bearer ' + service.getAccessToken() }
    });
    json.responseForMessage = JSON.parse(response.getContentText());
    json.ok = true;
    json.message = "Posted to the thread";
  }else{
    json.error ="thread parameter is required";
  }
}

//  ####################
//  # Bot
//  ####################
function onMessage(event) {
  var name = "";
  var message = "";
  if (event.space.type == "DM") {
    message = "DM is not allowed."
  } else {
    name = event.user.displayName;
    message = name + " said \"" + event.message.text + "\". Please use threads. ";
  }

  return { "text": message };
}

function onAddToSpace(event) {
  var message = "";

  if (event.space.singleUserBotDm) {
    message = "Thank you for adding me to a DM, " + event.user.displayName + "!";
  } else {
    message = "Thank you for adding me to " +
        (event.space.displayName ? event.space.displayName : "this chat");
  }

  if (event.message) {
    // Bot added through @mention.
    message = message + " and you said: \"" + event.message.text + "\"";
  }
  PropertiesService.getDocumentProperties().setProperty("space",event.space.name);
  return { "text": message };
}

var SCOPE = 'https://www.googleapis.com/auth/chat.messages';
var TOKEN_URL = 'https://accounts.google.com/o/oauth2/token';
// The values below are copied from the JSON file downloaded upon
// service account creation.
// For SERVICE_ACCOUNT_PRIVATE_KEY, remember to include the BEGIN and END lines of the private key
var SERVICE_ACCOUNT_PRIVATE_KEY = '--required--';
var SERVICE_ACCOUNT_EMAIL = '--required--';
// https://developers.google.com/chat/how-tos/apps-script#async_messages
function createService(){
  var service = OAuth2.createService('chat')
      .setTokenUrl(TOKEN_URL)
      .setPrivateKey(SERVICE_ACCOUNT_PRIVATE_KEY)
      .setClientId(SERVICE_ACCOUNT_EMAIL)
      .setPropertyStore(PropertiesService.getUserProperties())
      .setScope(SCOPE);
  if (!service.hasAccess()) {
    Logger.log('Authentication error: %s', service.getLastError());
    return null;
  }
  return service;
}

// Posts a message into the given space ID via the API, using
// service account authentication.
// https://developers.google.com/chat/api/reference/rest/v1/spaces.messages/create
function postMessage(message) {
  var spaceId = PropertiesService.getDocumentProperties().getProperty("space");
  var service = createService();
  var url = 'https://chat.googleapis.com/v1/' + spaceId + '/messages';
  if(message.messageReplyOption){
    url += '?messageReplyOption=' + message.messageReplyOption;
    delete message.messageReplyOption;
  }
  return UrlFetchApp.fetch(url, {
    method: 'post',
    headers: { 'Authorization': 'Bearer ' + service.getAccessToken() },
    contentType: 'application/json',
    payload: JSON.stringify(message),
  });
}

function testMessage(){
  postMessage({
    text: "Hello! It's a test message."
  });
}