feat: add dart function to handle Sign in with Apple

dart/sign_in_with_apple/.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
+
+# Directory used by Appwrite CLI for local development
+.appwrite

dart/sign_in_with_apple/README.md

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+# sign-in-with-apple
+
+This function:
+
+1. Exchanges an authorization code with Apple to obtain the user's id token.
+1. If a user with matching id or email doesn't exist, a new user will be created.
+1. The user's email will be verified if is hasn't been already.
+1. A token will be returned allowing the user to exchange the token for a session via `account.createSession()`.
+
+> Note: this function uses an md5 hash of the `sub` as the user's id since the value from Apple is too long and has unsupported characters.
+
+## 🧰 Usage
+
+### POST /
+
+**Headers**
+
+The Content-Type header must be set to `application/json` so that the request body can be properly parsed as JSON.
+
+* `Content-Type`: `application/json`
+
+**Request**
+
+This function accepts:
+
+* `code` (required) - authorization code from the Sign in with Apple credential
+* `firstName` - given name from the Sign in with Apple credential
+* `lastName` - family name from the Sign in with Apple credential
+
+Sample request body:
+
+```json
+{
+    "code": "c361a519253b3486ea3c7ecd4e9b6903f.0.suut.3LCHm9ytku1B2v4r5IayPQ",
+    "firstName": "Walter",
+    "lastName": "O'Brien",
+}
+```
+
+**Response**
+
+This function returns:
+
+* `secret` - `secret` to be passed to `account.createSession()` to create a session
+* `userId` - `userId` to be passed to `account.createSession()` to create a session
+* `expire` - ISO formatted timestamp for when the secret expires
+
+Sample `200` Response:
+
+```json
+{
+  "secret": "0cbdd4fd7638e0f3f55871adf2256f8f42f6faa01c9300e482c9a585b76611343dee8562ce4421b1cf9e9de6f8341fb2286499cb7992d02accd2dc699211008c",
+  "userId": "90a5450f396c242637c39b4c39e07af4",
+  "expire": "2025-07-15T00:10:21.345+00:00",
+}
+```
+
+## ⚙️ Configuration
+
+| Setting           | Value                       |
+| ----------------- | ---------------             |
+| Runtime           | Dart (3.5 )                 |
+| Entrypoint        | `lib/main.dart`             |
+| Build Commands    | `dart pub get`              |
+| Permissions       | `any`                       |
+| Timeout (Seconds) | 15                          |
+| Scopes            | `users.read`, `users.write` |
+
+## 🔒 Environment Variables
+
+The following environment variables are required:
+
+* `BUNDLE_ID` - the bundle Id of the app that generated the authorization code
+* `TEAM_ID` - Apple Developer team Id
+* `KEY_ID` - Id of the key from the Apple Developer portal
+* `KEY_CONTENTS_ENCODED` - base64 encoded p8 certificate

dart/sign_in_with_apple/analysis_options.yaml

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+include: package:lints/recommended.yaml

dart/sign_in_with_apple/lib/main.dart

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+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'package:crypto/crypto.dart';
+import 'package:dart_appwrite/dart_appwrite.dart';
+import 'package:dart_appwrite/models.dart';
+import 'package:dart_jsonwebtoken/dart_jsonwebtoken.dart';
+import 'package:http/http.dart' as http;
+
+Future<dynamic> main(final context) async {
+  final requiredEnvVars = [
+    'BUNDLE_ID',
+    'TEAM_ID',
+    'KEY_ID',
+    'KEY_CONTENTS_ENCODED'
+  ];
+  for (var varName in requiredEnvVars) {
+    if (Platform.environment[varName]?.isEmpty ?? true) {
+      throw Exception('Environment variable $varName must be set.');
+    }
+  }
+
+  final bundleId = Platform.environment['BUNDLE_ID']!;
+  final teamId = Platform.environment['TEAM_ID']!;
+  final keyId = Platform.environment['KEY_ID']!;
+  final keyContentsEncoded = Platform.environment['KEY_CONTENTS_ENCODED']!;
+  final keyContents = utf8.decode(base64Decode(keyContentsEncoded));
+
+  final key = ECPrivateKey(keyContents);
+
+  final reqBody = context.req.bodyJson as Map<String, dynamic>;
+  final code = reqBody['code'] ?? '';
+  final firstName = reqBody['firstName'] ?? '';
+  final lastName = reqBody['lastName'] ?? '';
+
+  // Validate input
+  if (code.isEmpty) {
+    throw Exception('Code must be provided in the request body.');
+  }
+
+  // Create a JWT client secret
+  final header = {'alg': 'ES256', 'kid': keyId};
+  final jwt = JWT(
+    {},
+    header: header,
+    subject: bundleId,
+    issuer: teamId,
+    audience: Audience.one('https://appleid.apple.com'),
+  );
+  final clientSecret = jwt.sign(
+    key,
+    algorithm: JWTAlgorithm.ES256,
+    expiresIn: Duration(minutes: 5),
+  );
+
+  final authTokenRequestBody = {
+    'grant_type': 'authorization_code',
+    'code': code,
+    'client_id': bundleId,
+    'client_secret': clientSecret,
+  };
+
+  final authTokenResponse = await http.post(
+    Uri.parse('https://appleid.apple.com/auth/token'),
+    headers: {
+      'Content-Type': 'application/x-www-form-urlencoded',
+    },
+    body: authTokenRequestBody,
+  );
+
+  if (authTokenResponse.statusCode != 200) {
+    throw Exception(
+        'Failed to exchange code for token: ${authTokenResponse.body}');
+  }
+
+  final body = json.decode(authTokenResponse.body);
+
+  // Use access token to fetch any additional information if needed
+  // final accessToken = body['access_token'] ?? '';
+
+  // Store refresh token if you want to refresh the access token later
+  // final refreshToken = body['refresh_token'] ?? '';
+
+  final idToken = JWT.decode(body['id_token']);
+  final sub = idToken.payload['sub'] ?? '';
+  if (sub.isEmpty) {
+    throw Exception('ID Token does not contain a valid subject (sub) claim.');
+  }
+  // Hash the sub because it is too long and has characters that are not allowed in Appwrite user IDs
+  final userId = md5.convert(utf8.encode(sub)).toString();
+  final email = idToken.payload['email'] ?? '';
+  final userName = '$firstName $lastName'.trim();
+
+  // You can use the Appwrite SDK to interact with other services
+  // For this example, we're using the Users service
+  final client = Client()
+      .setEndpoint(Platform.environment['APPWRITE_FUNCTION_API_ENDPOINT']!)
+      .setProject(Platform.environment['APPWRITE_FUNCTION_PROJECT_ID']!)
+      .setKey(context.req.headers['x-appwrite-key'] ?? '');
+  final users = Users(client);
+
+  // Find user by ID
+  User? user;
+  try {
+    user = await users.get(userId: userId);
+  } on AppwriteException catch (e) {
+    if (e.type != 'user_not_found') {
+      rethrow;
+    }
+  }
+
+  // Find user by email
+  final userList = await users.list(queries: [Query.equal('email', email)]);
+  if (userList.users.isNotEmpty) {
+    user = userList.users.first;
+  }
+
+  // If user does not exist, create a new user
+  user ??= await users.create(
+    userId: ID.custom(userId),
+    email: email,
+    name: userName.isEmpty ? null : userName,
+  );
+
+  // Mark the user as verified if not already verified
+  if (!user.emailVerification) {
+    users.updateEmailVerification(
+      userId: userId,
+      emailVerification: true,
+    );
+  }
+
+  // Create token
+  final token = await users.createToken(
+    userId: user.$id,
+    expire: 60,
+    length: 128,
+  );
+
+  return context.res.json({
+    'secret': token.secret,
+    'userId': user.$id,
+    'expire': token.expire,
+  });
+}

dart/sign_in_with_apple/pubspec.yaml

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+name: sign_in_with_apple
+version: 1.0.0
+
+environment:
+  sdk: ^2.17.0
+
+dependencies:
+  dart_appwrite: ^16.0.0
+  dart_jsonwebtoken: ^3.2.0
+  http: ^1.4.0
+  crypto: ^3.0.6
+
+dev_dependencies:
+  lints: ^2.0.0