// Copyright 2026 Google LLC. 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.

// You may obtain a copy of the License at

//

// https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License 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.

// Service that handles Vertex AI Agent operations.

// Submits a query to the AI agent and returns the response string synchronously

function queryAgent(input) {

let systemPrompt = "SYSTEM PROMPT START Do not respond with tables but use bullet points instead." +

" Do not ask the user follow-up questions or converse with them as history is not kept in this interface." +

" SYSTEM PROMPT END\n\n";

const requestPayload = {

"class_method": "async_stream_query",

"input": {

"user_id": "vertex_ai_add_on",

"message": { "role": "user", "parts": [{ "text": systemPrompt + input.text }] },

"state_delta": {

"enterprise-ai_999": `${ScriptApp.getOAuthToken()}`

}

}

};

const responseContentText = UrlFetchApp.fetch(

`https://${getLocation()}-aiplatform.googleapis.com/v1/${getReasoningEngine()}:streamQuery?alt=sse`,

{

method: 'post',

headers: { 'Authorization': `Bearer ${ScriptApp.getOAuthToken()}` },

contentType: 'application/json',

payload: JSON.stringify(requestPayload),

muteHttpExceptions: true

}

).getContentText();

if (isInDebugMode()) {

console.log(`Response: ${responseContentText}`);

}

const events = responseContentText.split('\n').map(s => s.replace(/^data:\s*/, '')).filter(s => s.trim().length > 0);

console.log(`Received ${events.length} agent events.`);

let author = "default";

let answerText = "";

for (const eventJson of events) {

if (isInDebugMode()) {

console.log("Event: " + eventJson);

}

const event = JSON.parse(eventJson);

// Retrieve the agent responsible for generating the content

author = event.author;

// Ignore events that are not useful for the end-user

if (!event.content) {

console.log(`${author}: internal event`);

continue;

}

// Handle text answers

const parts = event.content.parts || [];

const textPart = parts.find(p => p.text);

if (textPart) {

answerText += textPart.text;

}

}

return { author: author, text: answerText };

}

// --- UI Management ---

// Sends an answer as a Chat message.

function answer(author, text, success) {

const widgets = createMarkdownWidgets(text);

createMessage(buildMessage(author, [wrapWidgetsInCardsV2(widgets)], success));

}

// Sends a request to the AI agent and processes the response for Chat UI

function requestAgent(input) {

try {

const response = queryAgent(input);

if (response.text) {

answer(response.author, response.text, true);

}

} catch (err) {

answer(response.author, err.message, false);

}

}

// Builds a Chat message for the given author, state, and cards_v2.

function buildMessage(author, cardsV2, success = true) {

const messageBuilder = CardService.newChatResponseBuilder();

messageBuilder.setText(`${getAuthorEmoji(author)} *${snakeToUserReadable(author)}* ${success ? '✅' : '❌'}`);

cardsV2.forEach(cardV2 => { messageBuilder.addCardsV2(cardV2) });

let message = JSON.parse(messageBuilder.build().printJson());

if (isInDebugMode()) {

console.log(`Built message: ${JSON.stringify(message)}`);

}

return message;

}

// Converts a snake_case_string to a user-readable Title Case string.

function snakeToUserReadable(snakeCaseString = "") {

return snakeCaseString.replace(/_/g, ' ').split(' ').map(word => {

if (!word) return '';

return word.charAt(0).toUpperCase() + word.slice(1).toLowerCase();

}).join(' ');

}

// Wraps the given widgets in Chat cards_v2 structure.

function wrapWidgetsInCardsV2(widgets = []) {

const section = CardService.newCardSection();

widgets.forEach(widget => { section.addWidget(widget) });

return CardService.newCardWithId().setCard(CardService.newCardBuilder().addSection(section).build());

}

// Returns an emoji representing the author.

function getAuthorEmoji(author) {

switch (author) {

case "enterprise_ai": return "ℹ️";

default: return "🤖";

}

}

// Creates widgets for markdown text response.

function createMarkdownWidgets(markdown) {

if (!markdown) return [];

const textParagraph = CardService.newTextParagraph();

textParagraph.setText(new showdown.Converter().makeHtml(markdown));

return [textParagraph];

}