import 'package:drift/drift.dart';
import 'package:notas/data/app_database.dart';
import 'package:notas/data/api_client.dart';
import 'package:notas/data/sync_models.dart';
import 'package:notas/models/note.dart';
import 'package:notas/models/category.dart';

import 'package:notas/data/note_encryption.dart';

class NoteRepository {
  NoteRepository({
    required AppDatabase database,
    required AuthApi authApi,
    required String masterKey,
  }) : _database = database,
       _authApi = authApi,
       _masterKey = masterKey;

  final AppDatabase _database;
  final AuthApi _authApi;
  final String _masterKey;

  Future<List<Note>> loadNotes() async {
    return _loadNotesFromDatabase();
  }

  Future<Note> createNote(Note note) async {
    final int id = await _database.insertNoteAtTop(
      NotesCompanion.insert(
        uuid: note.uuid,
        title: note.title,
        body: note.body,
        createdAt: note.createdAt,
        updatedAt: note.updatedAt,
        sortIndex: 0,
        serverVersion: const Value(0),
        isDeleted: const Value(false),
        categoryId: const Value(null),
      ),
    );

    return note.copyWith(id: id, index: 0);
  }

  Future<Note> updateNote(Note note) async {
    final int noteId =
        note.id ??
        (throw ArgumentError('Note id is required to update a note.'));

    await _database.updateNoteRow(
      DbNote(
        id: noteId,
        uuid: note.uuid,
        title: note.title,
        body: note.body,
        createdAt: note.createdAt,
        updatedAt: note.updatedAt,
        sortIndex: note.index,
        serverVersion: note.serverVersion,
        isDeleted: note.isDeleted,
        categoryId: note.categoryId,
      ),
    );

    return note;
  }

  Future<void> deleteNote(Note note) async {
    final int noteId =
        note.id ??
        (throw ArgumentError('Note id is required to delete a note.'));

    await _database.deleteNoteAndShift(id: noteId, removedIndex: note.index);
  }

  Future<void> moveNote(Note note, int newIndex) async {
    final int noteId =
        note.id ??
        (throw ArgumentError('Note id is required to reorder a note.'));

    await _database.moveNote(
      id: noteId,
      oldIndex: note.index,
      newIndex: newIndex,
    );
  }

  // ========== Sync logic ==========

  /// Sincroniza notas con el servidor.
  /// Requiere que el usuario esté autenticado (token válido).
  Future<Map<String, dynamic>> performSync({bool forceFull = false}) async {
    try {
      // Get last sync timestamp
      final DateTime? lastSync = await _authApi.getLastSyncAt();
      final DateTime? lastSyncForRequest = forceFull
          ? DateTime.utc(1970, 1, 1)
          : lastSync;

      // Collect pending local changes.
      // If we already synced at least once, use updatedAt to avoid re-sending
      // old notes that were already uploaded.
      final List<DbNote> unsyncedNotes;
      final List<DbCategory> unsyncedCategories;

      if (forceFull || lastSync == null) {
        unsyncedNotes = await _database.getUnsyncedNotes();
        unsyncedCategories = await _database.getUnsyncedCategories();
      } else {
        unsyncedNotes = await _database.getNotesChangedSince(lastSync);
        unsyncedCategories = await _database.getCategoriesChangedSince(
          lastSync,
        );
      }

      // Build sync request (note: we send encrypted data, but locally we have plaintext)
      // Encrypt all notes before sending
      final List<SyncNotePayload> encryptedNotesPayload = [];
      for (final dbNote in unsyncedNotes) {
        final note = _fromDbNote(dbNote);
        final encryptedTitle = await NoteEncryption.encryptNote(
          note.title,
          _masterKey,
        );
        final encryptedBody = await NoteEncryption.encryptNote(
          note.body,
          _masterKey,
        );
        encryptedNotesPayload.add(
          SyncNotePayload.fromNote(
            note,
            encryptedTitle: encryptedTitle,
            encryptedBody: encryptedBody,
          ),
        );
      }

      final List<SyncCategoryPayload> categoriesPayload = unsyncedCategories
          .map((cat) => SyncCategoryPayload.fromCategory(_fromDbCategory(cat)))
          .toList();

      final SyncRequest syncRequest = SyncRequest(
        lastSyncAt: lastSyncForRequest,
        changes: SyncChanges(
          categories: categoriesPayload,
          notes: encryptedNotesPayload,
        ),
      );

      // Call sync API
      final Map<String, dynamic> syncResult = await _authApi.sync(syncRequest);

      if (syncResult['error'] == true) {
        return {'error': true, 'message': syncResult['body']};
      }

      final SyncResponse response = syncResult['data'] as SyncResponse;

      // Apply server changes to local database
      await _applySyncResponse(response);

      // Update lastSyncAt
      await _authApi.setLastSyncAt(response.serverTimestamp);

      return {
        'error': false,
        'synced': response.synced,
        'notesCount': response.changes.notes.length,
        'categoriesCount': response.changes.categories.length,
      };
    } catch (e) {
      return {'error': true, 'message': e.toString()};
    }
  }

  Future<void> _applySyncResponse(SyncResponse response) async {
    // Apply categories from server
    for (final SyncCategoryResponse catResponse
        in response.changes.categories) {
      await _database.upsertCategory(
        CategoriesCompanion(
          uuid: Value(catResponse.id),
          encryptedName: Value(catResponse.encryptedName),
          serverVersion: Value(catResponse.serverVersion),
          isDeleted: Value(catResponse.isDeleted),
          updatedAt: Value(catResponse.updatedAt),
        ),
      );
    }

    // Apply notes from server
    for (final SyncNoteResponse noteResponse in response.changes.notes) {
      final existingNote = await (_database.select(
        _database.notes,
      )..where((n) => n.uuid.equals(noteResponse.id))).getSingleOrNull();

      // Decrypt note content
      String decryptedTitle = 'Encrypted';
      String decryptedBody = 'Encrypted';
      try {
        decryptedTitle = await NoteEncryption.decryptNote(
          noteResponse.encryptedTitle,
          _masterKey,
        );
        decryptedBody = await NoteEncryption.decryptNote(
          noteResponse.encryptedBody,
          _masterKey,
        );
      } catch (e) {
        // If decryption fails, keep default encrypted placeholders
        print('Failed to decrypt note ${noteResponse.id}: $e');
      }

      if (existingNote != null) {
        // Update existing note
        await _database.updateNoteRow(
          DbNote(
            id: existingNote.id,
            uuid: noteResponse.id,
            title: decryptedTitle,
            body: decryptedBody,
            createdAt: existingNote.createdAt,
            updatedAt: noteResponse.updatedAt,
            sortIndex: noteResponse.position,
            serverVersion: noteResponse.serverVersion,
            isDeleted: noteResponse.isDeleted,
            categoryId: noteResponse.categoryId,
          ),
        );
      } else {
        // Insert new note
        await _database
            .into(_database.notes)
            .insert(
              NotesCompanion(
                uuid: Value(noteResponse.id),
                title: Value(decryptedTitle),
                body: Value(decryptedBody),
                createdAt: Value(noteResponse.updatedAt),
                updatedAt: Value(noteResponse.updatedAt),
                sortIndex: Value(noteResponse.position),
                serverVersion: Value(noteResponse.serverVersion),
                isDeleted: Value(noteResponse.isDeleted),
                categoryId: Value(noteResponse.categoryId),
              ),
            );
      }
    }
  }

  Future<List<Note>> _loadNotesFromDatabase() async {
    final List<DbNote> rows = await _database.getAllNotes();
    return rows.map(_fromDbNote).toList();
  }

  Note _fromDbNote(DbNote row) {
    return Note(
      id: row.id,
      uuid: row.uuid,
      title: row.title,
      body: row.body,
      createdAt: row.createdAt,
      updatedAt: row.updatedAt,
      index: row.sortIndex,
      serverVersion: row.serverVersion,
      isDeleted: row.isDeleted,
      categoryId: row.categoryId,
    );
  }

  Category _fromDbCategory(DbCategory row) {
    return Category(
      uuid: row.uuid,
      encryptedName: row.encryptedName,
      serverVersion: row.serverVersion,
      isDeleted: row.isDeleted,
      updatedAt: row.updatedAt,
    );
  }
}