Feat: Implement whatsapp with vonage dart

dart/whatsapp_with_vonage/.gitignore

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+# See https://www.dartlang.org/guides/libraries/private-files
+
+# Files and directories created by pub
+.dart_tool/
+.packages
+build/
+# If you're building an application, you may want to check-in your pubspec.lock
+pubspec.lock
+
+# Directory created by dartdoc
+# If you don't generate documentation locally you can remove this line.
+doc/api/
+
+# dotenv environment variables file
+.env*
+
+# Avoid committing generated Javascript files:
+*.dart.js
+*.info.json      # Produced by the --dump-info flag.
+*.js             # When generated by dart2js. Don't specify *.js if your
+                 # project includes source files written in JavaScript.
+*.js_
+*.js.deps
+*.js.map
+
+.flutter-plugins
+.flutter-plugins-dependencies

dart/whatsapp_with_vonage/README.md

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+# 💬 Dart WhatsApp Bot with Vonage Function
+
+Simple bot to answer WhatsApp messages.
+
+## 🧰 Usage
+
+### GET /
+
+HTML form for interacting with the function.
+
+### POST /
+
+Receives a message, validates its signature, and sends a response back to the sender.
+
+**Parameters**
+
+| Name          | Description                        | Location | Type                | Sample Value         |
+| ------------- | ---------------------------------- | -------- | ------------------- | -------------------- |
+| Content-Type  | Content type of the request        | Header   | `application/json ` | N/A                  |
+| Authorization | Webhook signature for verification | Header   | String              | `Bearer <signature>` |
+| from          | Sender's identifier.               | Body     | String              | `12345`              |
+| text          | Text content of the message.       | Body     | String              | `Hello!`             |
+
+> All parameters are coming from Vonage webhook. Exact documentation can be found in [Vonage API Docs](https://developer.vonage.com/en/api/messages-olympus#inbound-message).
+
+**Response**
+
+Sample `200` Response:
+
+```json
+{
+  "ok": true
+}
+```
+
+Sample `400` Response:
+
+```json
+{
+  "ok": false,
+  "error": "Missing required parameter: from"
+}
+```
+
+Sample `401` Response:
+
+```json
+{
+  "ok": false,
+  "error": "Payload hash mismatch."
+}
+```
+
+## ⚙️ Configuration
+
+| Setting           | Value           |
+| ----------------- | -------------   |
+| Runtime           | Dart (3.1)      |
+| Entrypoint        | `lib/main.dart` |
+| Build Commands    | `pub get`       |
+| Permissions       | `any`           |
+| Timeout (Seconds) | 15              |
+
+## 🔒 Environment Variables
+
+### VONAGE_API_KEY
+
+API Key to use the Vonage API.
+
+| Question      | Answer                                                                                                                   |
+| ------------- | ------------------------------------------------------------------------------------------------------------------------ |
+| Required      | Yes                                                                                                                      |
+| Sample Value  | `62...97`                                                                                                                |
+| Documentation | [Vonage: Q&A](https://api.support.vonage.com/hc/en-us/articles/204014493-How-do-I-find-my-Voice-API-key-and-API-secret-) |
+
+### VONAGE_API_SECRET
+
+Secret to use the Vonage API.
+
+| Question      | Answer                                                                                                                   |
+| ------------- | ------------------------------------------------------------------------------------------------------------------------ |
+| Required      | Yes                                                                                                                      |
+| Sample Value  | `Zjc...5PH`                                                                                                              |
+| Documentation | [Vonage: Q&A](https://api.support.vonage.com/hc/en-us/articles/204014493-How-do-I-find-my-Voice-API-key-and-API-secret-) |
+
+### VONAGE_API_SIGNATURE_SECRET
+
+Secret to verify the webhooks sent by Vonage.
+
+| Question      | Answer                                                                                                         |
+| ------------- | -------------------------------------------------------------------------------------------------------------- |
+| Required      | Yes                                                                                                            |
+| Sample Value  | `NXOi3...IBHDa`                                                                                                |
+| Documentation | [Vonage: Webhooks](https://developer.vonage.com/en/getting-started/concepts/webhooks#decoding-signed-webhooks) |
+
+### VONAGE_WHATSAPP_NUMBER
+
+Vonage WhatsApp number to send messages from.
+
+| Question      | Answer                                                                                                                        |
+| ------------- | ----------------------------------------------------------------------------------------------------------------------------- |
+| Required      | Yes                                                                                                                           |
+| Sample Value  | `+14000000102`                                                                                                                |
+| Documentation | [Vonage: Q&A](https://api.support.vonage.com/hc/en-us/articles/4431993282580-Where-do-I-find-my-WhatsApp-Number-Certificate-) |

dart/whatsapp_with_vonage/analysis_options.yaml

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+include: package:lints/recommended.yaml

dart/whatsapp_with_vonage/lib/main.dart

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+import 'dart:convert';
+import 'dart:io';
+import 'package:crypto/crypto.dart';
+import 'package:dart_jsonwebtoken/dart_jsonwebtoken.dart';
+import 'package:whatsapp_with_vonage/utils.dart';
+import 'package:http/http.dart' as http;
+
+Future<dynamic> main(final context) async {
+  throwIfMissing(Platform.environment, [
+    'VONAGE_API_KEY',
+    'VONAGE_API_SECRET',
+    'VONAGE_API_SIGNATURE_SECRET',
+    'VONAGE_WHATSAPP_NUMBER'
+  ]);
+
+  if (context.req.method == 'GET') {
+    return context.res.send(getStaticFile('index.html'), 200,
+        {'Content-Type': 'text/html; charset=utf-8'});
+  }
+
+  final token = context.req.headers['authorization'].split(' ')[1];
+
+  if (token == null) {
+    return context.res.json({'ok': false, 'error': 'Unauthorized'}, 401);
+  }
+
+  if (context.req.body['from'] == null || context.req.body['text'] == null) {
+    return context.res.json({'ok': false, 'error': 'Missing required fields.'}, 400);
+  }
+
+  final jwt = JWT.verify(token, SecretKey(Platform.environment['VONAGE_API_SIGNATURE_SECRET']!));
+
+  if (jwt.payload['payload_hash'] == null) {
+    return context.res.json({'ok': false, 'error': 'Missing payload hash.'}, 400);
+  }
+
+  final payloadHash = sha256.convert(utf8.encode(context.req.bodyRaw)).toString();
+
+  if (jwt.payload['payload_hash'] != payloadHash) {
+    return context.res.json({'ok': false, 'error': 'Payload hash mismatch.'}, 401);
+  }
+
+  final basicAuthToken = base64Encode(utf8.encode('${Platform.environment['VONAGE_API_KEY']}:${Platform.environment['VONAGE_API_SECRET']}'));
+
+  await http.post(
+    Uri.parse('https://messages-sandbox.nexmo.com/v1/messages'),
+    headers: {
+      'Content-Type': 'application/json',
+      'Authorization': 'Basic $basicAuthToken',
+    },
+    body: jsonEncode({
+      'from': Platform.environment['VONAGE_WHATSAPP_NUMBER'],
+      'to': context.req.body['from'],
+      'message_type': 'text',
+      'text': 'Hi there! You sent me: ${context.req.body['text']}',
+      'channel': 'whatsapp',
+    }),
+  );
+
+  return context.res.json({'ok': true});
+}

dart/whatsapp_with_vonage/lib/utils.dart

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+import 'dart:io';
+import 'package:path/path.dart' as p;
+
+final staticFolder = p.join(p.dirname(Platform.script.toFilePath()), '../static');
+
+/// Throws an error if any of the keys are missing from the object
+/// Parameters:
+///   obj - The object to check
+///   keys - The list of keys to check for
+/// throws Exception
+void throwIfMissing(Map<String, String> obj, List<String> keys) {
+  final missing = <String>[];
+  for (final key in keys) {
+    if (!obj.containsKey(key) || obj[key] == null) {
+      missing.add(key); 
+    }
+  }
+
+  if (missing.isNotEmpty) {
+    throw StateError('Missing environment variables: ${missing.join(', ')}');
+  }
+}
+
+/// Returns the contents of a file in the static folder
+/// Parameters:
+///    fileName - The name of the file to read
+/// returns Contents of static/{fileName}
+String getStaticFile(String fileName) {
+  final file = File(p.join(staticFolder, fileName));
+  return file.readAsStringSync();
+}

dart/whatsapp_with_vonage/pubspec.yaml

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+name: whatsapp_with_vonage
+version: 1.0.0
+
+environment:
+  sdk: ^2.17.0
+
+dependencies:
+  crypto: ^3.0.2
+  http: ^0.13.5
+  path: ^1.8.3
+  convert: ^3.1.0
+  dart_jsonwebtoken: ^2.12.0
+
+
+dev_dependencies:
+  lints: ^2.0.0

dart/whatsapp_with_vonage/static/index.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>WhatsApp Bot with Vonage</title>
+
+    <link rel="stylesheet" href="https://unpkg.com/@appwrite.io/pink" />
+    <link rel="stylesheet" href="https://unpkg.com/@appwrite.io/pink-icons" />
+  </head>
+  <body>
+    <main class="main-content">
+      <div class="top-cover u-padding-block-end-56">
+        <div class="container">
+          <div
+            class="u-flex u-gap-16 u-flex-justify-center u-margin-block-start-16"
+          >
+            <h1 class="heading-level-1">WhatsApp Bot with Vonage</h1>
+            <code class="u-un-break-text"></code>
+          </div>
+          <p
+            class="body-text-1 u-normal u-margin-block-start-8"
+            style="max-width: 50rem"
+          >
+            This function listens to incoming webhooks from Vonage regarding
+            WhatsApp messages, and responds to them. To use the function, send
+            message to the WhatsApp user provided by Vonage.
+          </p>
+        </div>
+      </div>
+    </main>
+  </body>
+</html>