import 'dart:async';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

import 'package:dart_git/dart_git.dart';
import 'package:path/path.dart' as p;
import 'package:shared_preferences/shared_preferences.dart';
import 'package:synchronized/synchronized.dart';

import 'package:gitjournal/analytics.dart';
import 'package:gitjournal/core/git_repo.dart';
import 'package:gitjournal/core/note.dart';
import 'package:gitjournal/core/notes_cache.dart';
import 'package:gitjournal/core/notes_folder.dart';
import 'package:gitjournal/core/notes_folder_fs.dart';
import 'package:gitjournal/error_reporting.dart';
import 'package:gitjournal/features.dart';
import 'package:gitjournal/settings.dart';
import 'package:gitjournal/settings_migrations.dart';
import 'package:gitjournal/utils/logger.dart';

enum SyncStatus {
  Unknown,
  Done,
  Pulling,
  Pushing,
  Error,
}

class Repository with ChangeNotifier {
  final Settings settings;

  final _opLock = Lock();
  final _loadLock = Lock();

  final String gitBaseDirectory;
  final String cacheDir;
  final String id;

  GitNoteRepository _gitRepo;
  NotesCache _notesCache;

  String repoPath;

  SyncStatus syncStatus = SyncStatus.Unknown;
  String syncStatusError = "";
  int numChanges = 0;

  bool get hasJournalEntries {
    return notesFolder.hasNotes;
  }

  NotesFolderFS notesFolder;

  bool remoteGitRepoConfigured = false;

  static Future<Repository> load({
    @required String gitBaseDir,
    @required String cacheDir,
    @required SharedPreferences pref,
    @required String id,
  }) async {
    await migrateSettings(pref, gitBaseDir);

    var settings = Settings(id);
    settings.load(pref);

    logEvent(Event.Settings, parameters: settings.toLoggableMap());

    Log.i("Setting ${settings.toLoggableMap()}");

    var repoPath = settings.buildRepoPath(gitBaseDir);

    var repoDirStat = File(repoPath).statSync();
    /*
    if (Platform.isIOS &&
        repoDirStat.type == FileSystemEntityType.notFound &&
        gitRepoDir.contains("iCloud~io~gitjournal~gitjournal")) {
      Log.e("Cannot access iCloud Dir any more");
      Log.e("Reverting back to internal dir");
      settings.storeInternally = true;
      settings.save();
      gitRepoDir = settings.buildRepoPath(appState.gitBaseDirectory);
      repoDirStat = File(gitRepoDir).statSync();
    }*/

    var remoteConfigured = false;

    if (repoDirStat.type != FileSystemEntityType.directory) {
      Log.i("Calling GitInit for ${settings.folderName} at: $repoPath");
      await GitRepository.init(repoPath);

      settings.save();
    } else {
      var gitRepo = await GitRepository.load(repoPath);
      var remotes = gitRepo.config.remotes;
      remoteConfigured = remotes.isNotEmpty;
    }

    return Repository._internal(
      repoPath: repoPath,
      gitBaseDirectory: gitBaseDir,
      cacheDir: cacheDir,
      remoteGitRepoConfigured: remoteConfigured,
      settings: settings,
      id: id,
    );
  }

  Repository._internal({
    @required this.id,
    @required this.repoPath,
    @required this.gitBaseDirectory,
    @required this.cacheDir,
    @required this.settings,
    @required this.remoteGitRepoConfigured,
  }) {
    _gitRepo = GitNoteRepository(gitDirPath: repoPath, settings: settings);
    notesFolder = NotesFolderFS(null, _gitRepo.gitDirPath, settings);

    // Makes it easier to filter the analytics
    getAnalytics().firebase.setUserProperty(
          name: 'onboarded',
          value: remoteGitRepoConfigured.toString(),
        );

    var cachePath = p.join(cacheDir, "cache.json");
    _notesCache = NotesCache(
      filePath: cachePath,
      notesBasePath: _gitRepo.gitDirPath,
      settings: settings,
    );

    _loadFromCache();
    _syncNotes();
  }

  void _loadFromCache() async {
    await _notesCache.load(notesFolder);
    Log.i("Finished loading the notes cache");

    await _loadNotes();
    Log.i("Finished loading all the notes");
  }

  Future<void> _loadNotes() async {
    // FIXME: We should report the notes that failed to load
    return _loadLock.synchronized(() async {
      await notesFolder.loadRecursively();
      await _notesCache.buildCache(notesFolder);

      numChanges = await _gitRepo.numChanges();
      notifyListeners();
    });
  }

  Future<void> syncNotes({bool doNotThrow = false}) async {
    if (!remoteGitRepoConfigured) {
      Log.d("Not syncing because RemoteRepo not configured");
      return true;
    }

    logEvent(Event.RepoSynced);
    syncStatus = SyncStatus.Pulling;
    notifyListeners();

    Future noteLoadingFuture;
    try {
      await _gitRepo.fetch();
      await _gitRepo.merge();

      syncStatus = SyncStatus.Pushing;
      notifyListeners();

      noteLoadingFuture = _loadNotes();

      await _gitRepo.push();

      Log.d("Synced!");
      syncStatus = SyncStatus.Done;
      numChanges = 0;
      notifyListeners();
    } catch (e, stacktrace) {
      Log.e("Failed to Sync", ex: e, stacktrace: stacktrace);
      syncStatus = SyncStatus.Error;
      syncStatusError = e.toString();
      notifyListeners();
      if (shouldLogGitException(e)) {
        await logException(e, stacktrace);
      }
      if (!doNotThrow) rethrow;
    }

    await noteLoadingFuture;
  }

  Future<void> _syncNotes() async {
    var freq = settings.remoteSyncFrequency;
    if (freq != RemoteSyncFrequency.Automatic) {
      return;
    }
    return syncNotes(doNotThrow: true);
  }

  void createFolder(NotesFolderFS parent, String folderName) async {
    logEvent(Event.FolderAdded);

    return _opLock.synchronized(() async {
      Log.d("Got createFolder lock");
      var newFolderPath = p.join(parent.folderPath, folderName);
      var newFolder = NotesFolderFS(parent, newFolderPath, settings);
      newFolder.create();

      Log.d("Created New Folder: " + newFolderPath);
      parent.addFolder(newFolder);

      _gitRepo.addFolder(newFolder).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void removeFolder(NotesFolderFS folder) async {
    logEvent(Event.FolderDeleted);

    return _opLock.synchronized(() async {
      Log.d("Got removeFolder lock");
      Log.d("Removing Folder: " + folder.folderPath);

      folder.parentFS.removeFolder(folder);
      _gitRepo.removeFolder(folder).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void renameFolder(NotesFolderFS folder, String newFolderName) async {
    logEvent(Event.FolderRenamed);

    return _opLock.synchronized(() async {
      Log.d("Got renameFolder lock");

      var oldFolderPath = folder.folderPath;
      Log.d("Renaming Folder from $oldFolderPath -> $newFolderName");
      folder.rename(newFolderName);

      _gitRepo
          .renameFolder(oldFolderPath, folder.folderPath)
          .then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void renameNote(Note note, String newFileName) async {
    logEvent(Event.NoteRenamed);

    var oldNotePath = note.filePath;
    note.rename(newFileName);

    return _opLock.synchronized(() async {
      Log.d("Got renameNote lock");

      _gitRepo.renameNote(oldNotePath, note.filePath).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void renameFile(String oldPath, String newFileName) async {
    logEvent(Event.NoteRenamed);

    return _opLock.synchronized(() async {
      Log.d("Got renameNote lock");

      var newPath = p.join(p.dirname(oldPath), newFileName);
      await File(oldPath).rename(newPath);
      notifyListeners();

      _gitRepo.renameFile(oldPath, newPath).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void moveNote(Note note, NotesFolderFS destFolder) async {
    if (destFolder.folderPath == note.parent.folderPath) {
      return;
    }

    logEvent(Event.NoteMoved);
    return _opLock.synchronized(() async {
      Log.d("Got moveNote lock");

      var oldNotePath = note.filePath;
      note.move(destFolder);

      _gitRepo.moveNote(oldNotePath, note.filePath).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  Future<void> addNote(Note note) async {
    logEvent(Event.NoteAdded);

    note.updateModified();
    await note.save();

    note.parent.add(note);

    return _opLock.synchronized(() async {
      Log.d("Got addNote lock");

      _gitRepo.addNote(note).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void removeNote(Note note) async {
    logEvent(Event.NoteDeleted);

    return _opLock.synchronized(() async {
      Log.d("Got removeNote lock");

      // FIXME: What if the Note hasn't yet been saved?
      note.parent.remove(note);
      _gitRepo.removeNote(note).then((NoteRepoResult _) async {
        numChanges += 1;
        notifyListeners();
        // FIXME: Is there a way of figuring this amount dynamically?
        // The '4 seconds' is taken from snack_bar.dart -> _kSnackBarDisplayDuration
        // We wait an aritfical amount of time, so that the user has a change to undo
        // their delete operation, and that commit is not synced with the server, till then.
        await Future.delayed(const Duration(seconds: 4));
        _syncNotes();
      });
    });
  }

  void undoRemoveNote(Note note) async {
    logEvent(Event.NoteUndoDeleted);

    return _opLock.synchronized(() async {
      Log.d("Got undoRemoveNote lock");

      note.parent.add(note);
      _gitRepo.resetLastCommit().then((NoteRepoResult _) {
        _syncNotes();
        numChanges -= 1;
        notifyListeners();
      });
    });
  }

  Future<void> updateNote(Note note) async {
    logEvent(Event.NoteUpdated);

    note.updateModified();
    await note.save();

    return _opLock.synchronized(() async {
      Log.d("Got updateNote lock");

      _gitRepo.updateNote(note).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void saveFolderConfig(NotesFolderConfig config) async {
    if (!Features.perFolderConfig) {
      return;
    }
    logEvent(Event.FolderConfigUpdated);

    return _opLock.synchronized(() async {
      Log.d("Got saveFolderConfig lock");

      await config.saveToFS();
      _gitRepo.addFolderConfig(config).then((NoteRepoResult _) {
        _syncNotes();
        numChanges += 1;
        notifyListeners();
      });
    });
  }

  void completeGitHostSetup(String repoFolderName, String remoteName) {
    () async {
      var repoPath = p.join(gitBaseDirectory, repoFolderName);
      Log.i("completeGitHostSetup repoPath: $repoPath");

      _gitRepo = GitNoteRepository(gitDirPath: repoPath, settings: settings);

      var repo = await GitRepository.load(repoPath);
      var remote = repo.config.remote(remoteName);
      var remoteBranch = await repo.guessRemoteHead(remoteName);
      var remoteBranchName =
          remoteBranch != null ? remoteBranch.name.branchName() : "master";

      var branches = await repo.branches();
      if (branches.isEmpty) {
        Log.i("Completing - no local branch");
        if (remoteBranch != null) {
          await repo.checkoutBranch(remoteBranchName, remoteBranch.hash);
        }
        await repo.setUpstreamTo(remote, remoteBranchName);
      } else {
        var branch = branches[0];

        if (branch == remoteBranchName) {
          Log.i("Completing - localBranch: $branch");

          await repo.setUpstreamTo(remote, remoteBranchName);
          await _gitRepo.merge();
        } else {
          Log.i(
              "Completing - localBranch diff remote: $branch $remoteBranchName");

          var headRef = await repo.resolveReference(await repo.head());
          await repo.checkoutBranch(remoteBranchName, headRef.hash);
          await repo.deleteBranch(branch);
          await repo.setUpstreamTo(remote, remoteBranchName);
          await _gitRepo.merge();
        }

        // if more than one branch
        // TODO: Check if one of the branches matches the remote branch name
        //       and use that
        //       if not, then just create a new branch with the remoteBranchName
        //       and merge ..

      }

      this.repoPath = repoPath;
      _notesCache.clear();
      remoteGitRepoConfigured = true;
      notesFolder.reset(repoPath);

      settings.folderName = repoFolderName;
      settings.save();

      await _persistConfig();
      _loadNotes();
      _syncNotes();

      notifyListeners();
    }();
  }

  Future _persistConfig() async {
    await settings.save();
  }

  Future<void> moveRepoToPath() async {
    var newRepoPath = settings.buildRepoPath(gitBaseDirectory);

    if (newRepoPath != repoPath) {
      Log.i("Old Path: $repoPath");
      Log.i("New Path: $newRepoPath");

      await Directory(newRepoPath).create(recursive: true);
      await _copyDirectory(repoPath, newRepoPath);
      await Directory(repoPath).delete(recursive: true);

      repoPath = newRepoPath;
      _gitRepo = GitNoteRepository(gitDirPath: repoPath, settings: settings);

      _notesCache.clear();
      notesFolder.reset(repoPath);
      notifyListeners();

      _loadNotes();
    }
  }

  Future<void> discardChanges(Note note) async {
    var repo = await GitRepository.load(repoPath);
    await repo.checkout(note.filePath);
    return note.load();
  }
}

Future<void> _copyDirectory(String source, String destination) async {
  await for (var entity in Directory(source).list(recursive: false)) {
    if (entity is Directory) {
      var newDirectory = Directory(p.join(
          Directory(destination).absolute.path, p.basename(entity.path)));
      await newDirectory.create();
      await _copyDirectory(entity.absolute.path, newDirectory.path);
    } else if (entity is File) {
      await entity.copy(p.join(destination, p.basename(entity.path)));
    }
  }
}