/** * This val creates a webhook endpoint that receives text messages and sends SMS replies using the TextBelt API. * It uses blob storage to keep track of message history and conversation state. * The TextBelt API is used for sending SMS messages without requiring an API key. * The conversation history is stored as an array of message objects containing sender, content, date, and phone number. * OpenAI's GPT-4 is used to generate contextual responses based on the conversation history. */ import { blob } from "https://esm.town/v/std/blob"; import { OpenAI } from "https://esm.town/v/std/openai"; import { Buffer } from "node:buffer"; import { createHmac, timingSafeEqual } from "node:crypto"; // Change this to your own val URL const selfURL = "https://cephalization-smsjournalertextrelay.web.val.run"; // Set these up // This is the code that users must enter to register on the registration app const systemRegistrationKey = Deno.env.get("smsjournalerregistrationkey"); // This is the secret shared with the registration app in order to register users const sharedSecret = Deno.env.get("smsjournalersecret"); // This is the key for the TextBelt API const textbeltKey = Deno.env.get("textbeltkey"); // Define the structure for a message object interface Message { sender: string; content: string; date: string; phone?: string; // Optional phone number field } const makeBlobKey = (phone: string) => `conversation_${phone}`; // this is either broken or textbelt is not sending me the right stuff // this is implemented per the textbelt docs but i cant verify the sig... function validateTextbeltRequestSignature( apiKey: string, timestamp: string, requestSignature: string, requestPayload: string, ) { const mySignature = createHmac("sha256", apiKey) .update( timestamp + requestPayload, ) .digest("hex"); return timingSafeEqual( Buffer.from(requestSignature), Buffer.from(mySignature), ); } // Helper function to send SMS using TextBelt API async function sendSMS(phone: string, message: string) { const response = await fetch("https://textbelt.com/text", { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ phone, message, key: textbeltKey, // this val url replyWebhookUrl: selfURL, }), }); return response.json(); } // Helper function to get conversation history async function getConversationHistory(phone: string): Promise { const key = makeBlobKey(phone); const history = await blob.getJSON(key) as Message[] | null; return history || []; } // Helper function to update conversation history async function updateConversationHistory(phone: string, message: Message) { const key = makeBlobKey(phone); const history = await getConversationHistory(phone); history.push(message); await blob.setJSON(key, history); } // Helper function to generate AI response async function generateAIResponse(history: Message[]): Promise { const openai = new OpenAI(); const messages: { role: "user" | "assistant" | "system"; content: string }[] = history.map(msg => ({ role: msg.sender === "User" ? "user" : "assistant", content: msg.content, })); messages.unshift({ role: "system", content: "You are an AI assistant communicating via SMS. Keep your responses concise and under 160 characters. Your task is to help the user organize their daily work activities and provide brief, helpful responses.", }); const completion = await openai.chat.completions.create({ messages, model: "gpt-4-0613", max_tokens: 100, }); return completion.choices[0].message.content.trim(); } export default async function server(request: Request): Promise { const quotaResponse = await fetch( `https://textbelt.com/quota/${textbeltKey}`, ) .then(res => res.json()).then(data => data.quotaRemaining); // Add a simple HTML page to view the source const htmlResponse = ` SMS Webhook Handler

SMS Webhook Handler

Text Messages Remaining: ${quotaResponse}

This is a webhook endpoint for handling incoming SMS messages and sending AI-generated replies.

View the source code: Source

`; // Handle GET requests to display the HTML page if (request.method === "GET") { return new Response(htmlResponse, { headers: { "Content-Type": "text/html" }, }); } if (request.method !== "POST") { return new Response("This endpoint only accepts POST requests", { status: 405 }); } if (request.url.endsWith("/register")) { // validate bearer auth is the same as the shared secret const auth = request.headers.get("authorization"); if (!auth || auth !== `Bearer ${sharedSecret}`) { return new Response("Unauthorized", { status: 401 }); } // register a new phone number by sending an sms to it const { phone, registrationKey } = await request.json(); if (!registrationKey) { return new Response("Missing required field: registrationKey", { status: 400 }); } if (!phone) { return new Response("Missing required field: phone", { status: 400 }); } // validate the registration key if (registrationKey !== systemRegistrationKey) { return new Response("Invalid registration key", { status: 401 }); } // check if we have a blob already const blobKey = makeBlobKey(phone); if (await blob.getJSON(blobKey)) { return new Response("Phone number already registered", { status: 400 }); } const smsResult = await sendSMS( phone, "Thanks for registering! Let me know what you are working on day to day, and I will keep it organized for you.", ); return new Response(smsResult.success ? "SMS sent successfully" : "SMS failed to send"); } try { const rawBody = await request.text(); const signature = request.headers.get("x-textbelt-signature"); const timestamp = request.headers.get("x-textbelt-timestamp"); if (!signature || !timestamp) { return new Response("Invalid request", { status: 400 }); } const isValid = validateTextbeltRequestSignature(textbeltKey, timestamp, signature, rawBody); if (!isValid) { return new Response(rawBody + ` timestamp:${timestamp} signature:${signature}`, { status: 401 }); } const data = JSON.parse(rawBody); const { fromNumber: from, text: message } = data; if (!from || !message) { return new Response("Missing required fields: from and message", { status: 400 }); } // Create a new message object const userMessage: Message = { sender: "User", content: message, date: new Date().toISOString(), phone: from, }; // Update conversation history await updateConversationHistory(from, userMessage); // Get the entire conversation history const history = await getConversationHistory(from); // Generate AI response const aiReply = await generateAIResponse(history); // Send SMS reply const smsResult = await sendSMS(from, aiReply); if (smsResult.success) { // Create a new message object for the AI reply const aiMessage: Message = { sender: "AI", content: aiReply, date: new Date().toISOString(), phone: "system", }; // Update conversation history with the AI reply await updateConversationHistory(from, aiMessage); return new Response(JSON.stringify({ status: "success", message: "Reply sent successfully" }), { status: 200, headers: { "Content-Type": "application/json" }, }); } else { return new Response(JSON.stringify({ status: "error", message: smsResult.error }), { status: 500, headers: { "Content-Type": "application/json" }, }); } } catch (error) { return new Response(JSON.stringify({ status: "error", message: "Internal server error", error: error.message }), { status: 500, headers: { "Content-Type": "application/json" }, }); } }