/*
 * 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.IO;
using System.Linq;
using UnityEngine;
using UnityEditor;
using UnityEditor.Build;
using UnityEditor.Build.Reporting;

namespace Firebase.Messaging.Editor {

// Handles the generation of the MessagingUnityPlayerActivity java file.
// Note this regenerates the file every time an Android build occurs,
// but local changes can be preserved by using the PreserveTag below.
// This is needed because the source code needs to be present to work across
// different Unity versions, due to changes in mUnityPlayer.
// It also adjusts the base class of the file based on if GameActivity is being
// used (a new feature in Unity 2023).
public class FirebaseMessagingActivityGenerator : IPreprocessBuildWithReport {
  // TODO: Ideally this should use a template file, the tricky part is locating
  // the template file when it is either in the Assets path, or the Packages path.
  // There are some similar cases in EDM4U, so a solution might be to use that.
  private readonly string[] ActivityClassContents = new string[]{
"/*",
" * This file is generated by the FirebaseMessagingActivityGenerator script.",
" * Refer to that script for more information.",
" */",
"",
"package com.google.firebase;",
"",
"import android.content.Intent;",
"import android.os.Bundle;",
"import com.google.firebase.messaging.MessageForwardingService;",
"import com.unity3d.player.{0};",
"",
"/**",
" * MessagingUnityPlayerActivity is a {0} that updates its intent when new intents",
" * are sent to it.",
" *",
" * This is a workaround for a known issue that prevents Firebase Cloud Messaging from responding to",
" * data payloads when both a data and notification payload are sent to the app while it is in the",
" * background.",
" */",
"public class MessagingUnityPlayerActivity extends {0} {{",
"  // The key in the intent's extras that maps to the incoming message's message ID. Only sent by",
"  // the server, GmsCore sends EXTRA_MESSAGE_ID_KEY below. Server can't send that as it would get",
"  // stripped by the client.",
"  private static final String EXTRA_MESSAGE_ID_KEY_SERVER = \"message_id\";",
"",
"  // An alternate key value in the intent's extras that also maps to the incoming message's message",
"  // ID. Used by upstream, and set by GmsCore.",
"  private static final String EXTRA_MESSAGE_ID_KEY = \"google.message_id\";",
"",
"  // The key in the intent's extras that maps to the incoming message's sender value.",
"  private static final String EXTRA_FROM = \"google.message_id\";",
"",
"  /**",
"   * Workaround for when a message is sent containing both a Data and Notification payload.",
"   *",
"   * <p>When the app is in the background, if a message with both a data and notification payload is",
"   * received the data payload is stored on the Intent passed to onNewIntent. By default, that",
"   * intent does not get set as the Intent that started the app, so when the app comes back online",
"   * it doesn't see a new FCM message to respond to. As a workaround, we override onNewIntent so",
"   * that it sends the intent to the MessageForwardingService which forwards the message to the",
"   * FirebaseMessagingService which in turn sends the message to the application.",
"   */",
"  @Override",
"  protected void onNewIntent(Intent intent) {{",
"    super.onNewIntent(intent);",
"",
"    // If we do not have a 'from' field this intent was not a message and should not be handled. It",
"    // probably means this intent was fired by tapping on the app icon.",
"    Bundle extras = intent.getExtras();",
"    if (extras == null) {{",
"      return;",
"    }}",
"    String from = extras.getString(EXTRA_FROM);",
"    String messageId = extras.getString(EXTRA_MESSAGE_ID_KEY);",
"    if (messageId == null) {{",
"      messageId = extras.getString(EXTRA_MESSAGE_ID_KEY_SERVER);",
"    }}",
"    if (from != null && messageId != null) {{",
"      Intent message = new Intent(this, MessageForwardingService.class);",
"      message.setAction(MessageForwardingService.ACTION_REMOTE_INTENT);",
"      message.putExtras(intent);",
"      message.setData(intent.getData());",
"      MessageForwardingService.enqueueWork(this, message);",
"    }}",
"    setIntent(intent);",
"  }}",
"",
"  /**",
"   * Dispose of the mUnityPlayer when restarting the app.",
"   *",
"   * <p>This ensures that when the app starts up again it does not start with stale data.",
"   */",
"  @Override",
"  protected void onCreate(Bundle savedInstanceState) {{",
"    if (mUnityPlayer != null) {{",
"      mUnityPlayer.{1}();",
"      mUnityPlayer = null;",
"    }}",
"    super.onCreate(savedInstanceState);",
"  }}",
"}}"
  };
  private readonly string BaseActivityClass = "UnityPlayerActivity";
#if UNITY_2023_1_OR_NEWER
  private readonly string BaseGameActivityClass = "UnityPlayerGameActivity";
#endif

#if UNITY_2023_1_OR_NEWER
  private readonly string UnityPlayerQuitFunction = "destroy";
#else
  private readonly string UnityPlayerQuitFunction = "quit";
#endif

  private readonly string GeneratedFileTag = "FirebaseMessagingActivityGenerated";
  // If this tag is present on the generated file, it will not be replaced.
  private readonly string PreserveTag = "FirebasePreserve";

  private readonly string OutputPath = Path.Combine("Plugins", "Android");
  private readonly string OutputFilename = "MessagingUnityPlayerActivity.java";

  public int callbackOrder { get { return 0; } }
  public void OnPreprocessBuild(BuildReport report) {
    // Only run this logic when building for Android.
    if (EditorUserBuildSettings.activeBuildTarget != BuildTarget.Android) {
      return;
    }

    // Determine what the contents of the generated file should be.
    string baseClass = BaseActivityClass;
#if UNITY_2023_1_OR_NEWER
    // If using the new GameActivity logic, we want to generate with that base class.
    if (PlayerSettings.Android.applicationEntry.HasFlag(AndroidApplicationEntry.GameActivity)) {
      baseClass = BaseGameActivityClass;
    }
#endif
    string fileContents = System.String.Format(System.String.Join("\n", ActivityClassContents),
                                               baseClass, UnityPlayerQuitFunction);

    // Check if the file has already been generated.
    string[] oldAssetGuids = AssetDatabase.FindAssets("l:" + GeneratedFileTag);
    if (oldAssetGuids != null && oldAssetGuids.Length > 0) {
      if (oldAssetGuids.Length != 1) {
        Debug.LogWarning("FirebaseMessagingActivityEditor found multiple generated files with the label: " +
                         GeneratedFileTag + " \n" +
                         "No changes will be made, but this can potentially cause problems on Android with duplicate classes.\n" +
                         "Please check for duplicate classes, and remove any unnecessary uses of the label.");
        return;
      }
      string oldAssetPath = AssetDatabase.GUIDToAssetPath(oldAssetGuids[0]);
      Object oldAsset = AssetDatabase.LoadMainAssetAtPath(oldAssetPath);
      if (oldAsset != null) {
        string oldAssetFullPath = Path.Combine(Application.dataPath, "..", oldAssetPath);
        string oldFileContents = System.IO.File.ReadAllText(oldAssetFullPath);
        // If the old file matches what we would generate, exit early.
        if (oldFileContents == fileContents) {
            return;
        }
        // If the generated file has been tagged to be preserved, don't change it.
        string[] labelList = AssetDatabase.GetLabels(oldAsset);
        if (labelList.Contains(PreserveTag)) {
            return;
        }
        // Delete the old asset.
        Debug.Log("Changes detected, regenerating " + oldAssetPath + "\n" +
                  "To preserve local changes to that file, add the label: " + PreserveTag);
        AssetDatabase.DeleteAsset(oldAssetPath);
      }
    }

    // Generate the new file.
    string newAssetFullDirectory = Path.Combine(Application.dataPath, OutputPath);
    System.IO.Directory.CreateDirectory(newAssetFullDirectory);
    System.IO.File.WriteAllText(Path.Combine(newAssetFullDirectory, OutputFilename), fileContents);
    string newAssetLocalPath = Path.Combine("Assets", OutputPath, OutputFilename);
    AssetDatabase.ImportAsset(newAssetLocalPath);
    Object newAsset = AssetDatabase.LoadMainAssetAtPath(newAssetLocalPath);
    AssetDatabase.SetLabels(newAsset, new[]{GeneratedFileTag});
  }
}

}  // namespace Firebase.Messaging.Editor