Add the public App Check API files

app_check/CMakeLists.txt

@@ -17,12 +17,18 @@
 include(build_shared)
 
 # Firebase App Check Swig input files
-set(firebase_app_check_swig
+set(firebase_app_check_swig_files
   src/swig/app_check.i
 )
 
 # Firebase App Check CSharp files
 set(firebase_app_check_src
+  src/AppCheckError.cs
+  src/AppCheckToken.cs
+  src/FirebaseAppCheck.cs
+  src/IAppCheckProvider.cs
+  src/IAppCheckProviderFactory.cs
+  src/TokenChangedEventArgs.cs
 )
 
 if(NOT FIREBASE_UNI_LIBRARY AND APPLE AND NOT IOS)
@@ -40,7 +46,7 @@ firebase_swig_add_library(firebase_app_check_swig
   MODULE
     FirebaseCppAppCheck
   SOURCES
-    ${firebase_app_check_swig}
+    ${firebase_app_check_swig_files}
   DEPENDS
     firebase_app_check
   SYSTEM_DEPS

app_check/src/AppCheckError.cs

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+namespace Firebase.AppCheck {
+
+/// @brief Error codes used by App Check.
+public enum AppCheckError {
+  /// The operation was a success, no error occurred.
+  None = 0,
+  /// A network connection error.
+  ServerUnreachable = 1,
+  /// Invalid configuration error. Currently, an exception is thrown but this
+  /// error is reserved for future implementations of invalid configuration
+  /// detection.
+  InvalidConfiguration = 2,
+  /// System keychain access error. Ensure that the app has proper keychain
+  /// access.
+  SystemKeychain = 3,
+  /// Selected AppCheckProvider is not supported on the current platform
+  /// or OS version.
+  UnsupportedProvider = 4,
+  /// An unknown error occurred.
+  Unknown = 5,
+}
+
+}

app_check/src/AppCheckToken.cs

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+namespace Firebase.AppCheck {
+
+/// @brief Token used by the Firebase App Check service.
+///
+/// Struct to hold tokens emitted by the Firebase App Check service which are
+/// minted upon a successful application verification. These tokens are the
+/// federated output of a verification flow, the structure of which is
+/// independent of the mechanism by which the application was verified.
+public struct AppCheckToken {
+  /// A Firebase App Check token.
+  public string Token { get; set; }
+
+  /// The time at which the token will expire.
+  public System.DateTime ExpireTime { get; set; }
+}
+
+}

app_check/src/FirebaseAppCheck.cs

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+using System;
+using System.Collections.Generic;
+
+namespace Firebase.AppCheck {
+
+/// @brief Firebase App Check object.
+public sealed class FirebaseAppCheck {
+  // The C++ object that this wraps.
+  private AppCheckInternal appCheckInternal;
+
+  private static Dictionary<FirebaseApp, FirebaseAppCheck> appCheckMap =
+    new Dictionary<FirebaseApp, FirebaseAppCheck>();
+  // The user provided Factory.
+  private static IAppCheckProviderFactory appCheckFactory;
+  private static Dictionary<FirebaseApp, IAppCheckProvider> providerMap =
+    new Dictionary<FirebaseApp, IAppCheckProvider>();
+
+  // Make the constructor private, since users aren't meant to make it.
+  private FirebaseAppCheck(AppCheckInternal internalObject) {
+    appCheckInternal = internalObject;
+  }
+
+  private void ThrowIfNull() {
+    if (appCheckInternal == null ||
+        AppCheckInternal.getCPtr(appCheckInternal).Handle == System.IntPtr.Zero) {
+      throw new System.NullReferenceException();
+    }
+  }
+
+  /// Gets the instance of FirebaseAppCheck associated with the default
+  /// {@link FirebaseApp} instance.
+  public static FirebaseAppCheck DefaultInstance {
+    get {
+      return GetInstance(FirebaseApp.DefaultInstance);
+    }
+  }
+
+  /// Gets the instance of FirebaseAppCheck associated with the given
+  /// {@link FirebaseApp} instance.
+  public static FirebaseAppCheck GetInstance(FirebaseApp app) {
+    FirebaseAppCheck result;
+    if (!appCheckMap.TryGetValue(app, out result)) {
+      AppCheckInternal internalObject = AppCheckInternal.GetInstance(app);
+      result = new FirebaseAppCheck(internalObject);
+      appCheckMap[app] = result;
+      // TODO(amaurice): Logic to remove from map when App is destroyed?
+    }
+    return result;
+  }
+
+  /// Installs the given {@link AppCheckProviderFactory}, overwriting any that
+  /// were previously associated with this {@code FirebaseAppCheck} instance.
+  /// Any {@link AppCheckTokenListener}s attached to this
+  /// {@code FirebaseAppCheck} instance will be transferred from existing
+  /// factories to the newly installed one.
+  ///
+  /// <p>Automatic token refreshing will only occur if the global {@code
+  /// isDataCollectionDefaultEnabled} flag is set to true. To allow automatic
+  /// token refreshing for Firebase App Check without changing the {@code
+  /// isDataCollectionDefaultEnabled} flag for other Firebase SDKs, call
+  /// {@link #setTokenAutoRefreshEnabled(bool)} after installing the {@code
+  /// factory}.
+  ///
+  /// This method should be called before initializing the Firebase App.
+  public static void SetAppCheckProviderFactory(IAppCheckProviderFactory factory) {
+    appCheckFactory = factory;
+    // TODO(amaurice): Clear the provider map when the factory changes?
+  }
+
+  /// Sets the {@code isTokenAutoRefreshEnabled} flag.
+  public void SetTokenAutoRefreshEnabled(bool isTokenAutoRefreshEnabled) {
+    ThrowIfNull();
+    appCheckInternal.SetTokenAutoRefreshEnabled(isTokenAutoRefreshEnabled);
+  }
+
+  /// Requests a Firebase App Check token. This method should be used ONLY if you
+  /// need to authorize requests to a non-Firebase backend. Requests to Firebase
+  /// backends are authorized automatically if configured.
+  public System.Threading.Tasks.Task<AppCheckToken>
+      GetAppCheckTokenAsync(bool forceRefresh) {
+    ThrowIfNull();
+    throw new NotImplementedException();
+  }
+
+  /// Called on the client when an AppCheckToken is created or changed.
+  public System.EventHandler<TokenChangedEventArgs> TokenChanged;
+}
+
+}

app_check/src/IAppCheckProvider.cs

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+namespace Firebase.AppCheck {
+
+/// @brief Interface for a provider that generates {@link AppCheckToken}s.
+///
+/// This provider can be called at any time by any Firebase library that depends
+/// (optionally or  otherwise) on {@link AppCheckToken}s. This provider is
+/// responsible for determining if it can create a new token at the time of the
+/// call and returning that new token if it can.
+public interface IAppCheckProvider {
+  /// Returns an AppCheckToken or throws an exception with an error code and
+  /// error message.
+  System.Threading.Tasks.Task<AppCheckToken> GetTokenAsync();
+}
+
+}

app_check/src/IAppCheckProviderFactory.cs

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+namespace Firebase.AppCheck {
+
+/// @brief Interface for a factory that generates AppCheckProviders.
+public interface IAppCheckProviderFactory {
+  /// Gets the {@link AppCheckProvider} associated with the given
+  /// {@link FirebaseApp} instance, or creates one if none already exists.
+  IAppCheckProvider CreateProvider(FirebaseApp app);
+}
+
+}

app_check/src/TokenChangedEventArgs.cs

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+namespace Firebase.AppCheck {
+
+/// @brief Passed to the FirebaseAppCheck.TokenChanged event.
+///
+/// The AppCheck Token is passed via these arguments to the
+/// FirebaseAppCheck.TokenChanged event.
+public sealed class TokenChangedEventArgs : System.EventArgs {
+  /// A Firebase App Check token.
+  public AppCheckToken Token { get; set; }
+}
+
+}