feat: Add remaining auth providers and secrets (#190)

- Adds support for remaining auth providers
- Adds support for secrets

packages/celest/lib/src/auth/auth_provider.dart

@@ -1,3 +1,5 @@
+import 'package:celest/src/config/env.dart';
+
 /// {@template celest.auth.auth_provider}
 /// An authentication provider which can be used to sign in to Celest.
 ///
@@ -14,6 +16,33 @@ sealed class AuthProvider {
 
   /// A provider which enables SMS sign-in with OTP codes.
   const factory AuthProvider.sms() = _SmsAuthProvider;
+
+  /// A provider which enables GitHub sign-in.
+  ///
+  /// [clientId] and [clientsecret] are required to authenticate with GitHub.
+  const factory AuthProvider.gitHub({
+    required secret clientId,
+    required secret clientsecret,
+  }) = _GitHubAuthProvider;
+
+  /// A provider which enables Google sign-in.
+  ///
+  /// [clientId] and [clientsecret] are required to authenticate with Google.
+  const factory AuthProvider.google({
+    required secret clientId,
+    required secret clientsecret,
+  }) = _GoogleAuthProvider;
+
+  /// A provider which enables Sign In with Apple.
+  ///
+  /// [clientId], [teamId], [keyId], and [key] are required to authenticate
+  /// with Apple.
+  const factory AuthProvider.apple({
+    required secret clientId,
+    required secret teamId,
+    required secret keyId,
+    required secret key,
+  }) = _AppleAuthProvider;
 }
 
 final class _EmailAuthProvider extends AuthProvider {
@@ -23,3 +52,37 @@ final class _EmailAuthProvider extends AuthProvider {
 final class _SmsAuthProvider extends AuthProvider {
   const _SmsAuthProvider();
 }
+
+final class _GitHubAuthProvider extends AuthProvider {
+  const _GitHubAuthProvider({
+    required this.clientId,
+    required this.clientsecret,
+  });
+
+  final secret clientId;
+  final secret clientsecret;
+}
+
+final class _GoogleAuthProvider extends AuthProvider {
+  const _GoogleAuthProvider({
+    required this.clientId,
+    required this.clientsecret,
+  });
+
+  final secret clientId;
+  final secret clientsecret;
+}
+
+final class _AppleAuthProvider extends AuthProvider {
+  const _AppleAuthProvider({
+    required this.clientId,
+    required this.teamId,
+    required this.keyId,
+    required this.key,
+  });
+
+  final secret clientId;
+  final secret teamId;
+  final secret keyId;
+  final secret key;
+}

packages/celest/lib/src/config/env.dart

@@ -1,4 +1,22 @@
-import 'package:celest/src/core/cloud_widget.dart';
+import 'package:celest/src/core/context.dart';
+
+/// A configuration value that can be used to configure a Celest backend.
+sealed class ConfigurationValue implements ContextKey<String> {
+  const ConfigurationValue._(this.name);
+
+  /// The name of the configuration value in the environment.
+  final String name;
+
+  @override
+  String? read(Context context) {
+    return context.platform.environment[name];
+  }
+
+  @override
+  void set(Context context, String? value) {
+    throw UnsupportedError('Cannot set a configuration value at runtime.');
+  }
+}
 
 /// {@template celest.config.environment_variable}
 /// A reference to an environment variable within a Celest backend.
@@ -8,12 +26,23 @@ import 'package:celest/src/core/cloud_widget.dart';
 /// configuration to your backend. They allow you to keep configuration values
 /// separate from your codebase, improving flexibility when running in different
 /// environments.
-final class EnvironmentVariable extends CloudWidget {
+final class env extends ConfigurationValue {
   /// {@macro celest.config.environment_variable}
-  const EnvironmentVariable({
-    required this.name,
-  });
+  const env(super.name) : super._();
 
-  /// The name of the environment variable as it appears in its environment.
-  final String name;
+  /// The active Celest environment.
+  ///
+  /// For example, `production`.
+  static const env environment = env('CELEST_ENVIRONMENT');
+}
+
+/// {@template celest.config.secret}
+/// A secret value that should be kept confidential within a Celest backend.
+///
+/// Secrets behave much like environment variables except that their values
+/// are encrypted in the transit and only exposed to the backend itself.
+/// {@endtemplate}
+final class secret extends ConfigurationValue {
+  /// {@macro celest.config.secret}
+  const secret(super.name) : super._();
 }

packages/celest/lib/src/core/context.dart

@@ -1,13 +1,14 @@
 import 'dart:async';
-import 'dart:io';
 
+import 'package:celest/src/config/env.dart';
 import 'package:celest/src/core/environment.dart';
 import 'package:celest/src/runtime/gcp/gcp.dart';
 import 'package:celest_core/_internal.dart';
 // ignore: implementation_imports
 import 'package:celest_core/src/auth/user.dart';
 import 'package:cloud_http/cloud_http.dart';
 import 'package:meta/meta.dart';
+import 'package:platform/platform.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
 /// The [Context] for the current request.
@@ -37,6 +38,9 @@ final class Context {
   /// The [Context] for the current execution scope.
   static Context get current => Context.of(Zone.current);
 
+  /// The platform of the current context.
+  final Platform platform = const LocalPlatform();
+
   /// Context-specific values.
   final Map<ContextKey<Object>, Object> _values = {};
 
@@ -80,7 +84,10 @@ final class Context {
 
   /// The Celest [Environment] of the running service.
   Environment get environment {
-    return Environment(Platform.environment['ENV']!);
+    return switch (get(env.environment)) {
+      final env? => Environment(env),
+      _ => throw StateError('No environment set in context'),
+    };
   }
 
   (Context, V)? _get<V extends Object>(ContextKey<V> key) {

packages/celest/pubspec.yaml

@@ -24,6 +24,7 @@ dependencies:
   http_sfv: ^0.1.0
   logging: ^1.2.0
   meta: ^1.11.0
+  platform: ^3.1.5
   shelf: ^1.4.1
   shelf_router: ^1.1.4
   shelf_web_socket: ^2.0.0