import '../../core/exceptions.dart';
import '../api/notes_api.dart';
import '../local/database.dart';
import '../models/note.dart';

/// Notes repository with read-through caching for Tier 2 offline support
/// (Phase 1+2) and offline-write queueing (Phase 3).
///
/// Reads attempt the network first; on success the response is written to
/// the local Drift cache. On `NetworkException` the read falls back to the
/// cache (rethrowing if the cache is empty so the UI can show its
/// fresh-install empty state).
///
/// Writes hit the server then sync the cache. On `NetworkException` the
/// write is queued in `pending_writes` and applied optimistically to the
/// cache (negative temp-id for creates, in-place update for edits, removal
/// for deletes). Subsequent edits to a temp-id row are coalesced into the
/// queued create — only one server call is made per offline-created row.
///
/// `AuthStatus.offline` is owned by `AuthNotifier.verify()` (a periodic
/// heartbeat). This repository deliberately does not poke that state.
class NotesRepository {
  final NotesApi _api;
  final FabledDatabase _db;

  const NotesRepository(this._api, this._db);

  Future<List<Note>> getAll() async {
    try {
      final notes = await _api.getAll();
      await _db.replaceAllNotes(notes);
      return notes;
    } on NetworkException {
      final cached = await _db.getAllNotes();
      if (cached.isEmpty) rethrow;
      return cached;
    }
  }

  Future<Note> getOne(int id) async {
    try {
      final note = await _api.getOne(id);
      await _db.upsertNote(note);
      return note;
    } on NetworkException {
      final cached = await _db.getNote(id);
      if (cached == null) rethrow;
      return cached;
    }
  }

  Future<Note> create(
    String title,
    String body, {
    List<String> tags = const [],
    int? projectId,
    String noteType = 'note',
  }) async {
    try {
      final note = await _api.create(
        title,
        body,
        tags: tags,
        projectId: projectId,
        noteType: noteType,
      );
      await _db.upsertNote(note);
      return note;
    } on NetworkException {
      final tempId = await _db.nextTempId();
      final now = DateTime.now();
      final optimistic = Note(
        id: tempId,
        title: title,
        body: body,
        tags: tags,
        noteType: noteType,
        projectId: projectId,
        createdAt: now,
        updatedAt: now,
      );
      await _db.upsertNote(optimistic);
      await _db.enqueuePending(
        domain: kSyncDomainNotes,
        verb: kWriteVerbCreate,
        tempId: tempId,
        payload: {
          'title': title,
          'body': body,
          'tags': tags,
          'project_id': projectId,
          'note_type': noteType,
        },
      );
      return optimistic;
    }
  }

  Future<Note> update(
    int id,
    String title,
    String body, {
    List<String> tags = const [],
    int? projectId,
    bool clearProject = false,
    String noteType = 'note',
  }) async {
    try {
      final updated = await _api.update(
        id,
        title,
        body,
        tags: tags,
        projectId: projectId,
        clearProject: clearProject,
        noteType: noteType,
      );
      await _db.upsertNote(updated);
      return updated;
    } on NetworkException {
      final cached = await _db.getNote(id);
      if (cached == null) rethrow;
      final payload = <String, dynamic>{
        'title': title,
        'body': body,
        'tags': tags,
        'project_id': projectId,
        'clear_project': clearProject,
        'note_type': noteType,
      };
      final optimistic = cached.copyWith(
        title: title,
        body: body,
        tags: tags,
        noteType: noteType,
        projectId: clearProject ? null : projectId,
      );
      await _db.upsertNote(optimistic);
      // Edits to an offline-created row coalesce into the queued create.
      if (id < 0) {
        final queued = await _db.findQueuedCreate(kSyncDomainNotes, id);
        if (queued != null) {
          await _db.updatePendingPayload(queued.id, payload);
          return optimistic;
        }
      }
      await _db.enqueuePending(
        domain: kSyncDomainNotes,
        verb: kWriteVerbUpdate,
        targetId: id,
        payload: payload,
        baselineUpdatedAt: cached.updatedAt,
      );
      return optimistic;
    }
  }

  Future<void> delete(int id) async {
    try {
      await _api.delete(id);
      await _db.deleteNote(id);
    } on NetworkException {
      // Deleting an offline-created row that never reached the server
      // just drops the queued create — no server call needed.
      if (id < 0) {
        final queued = await _db.findQueuedCreate(kSyncDomainNotes, id);
        if (queued != null) await _db.deletePending(queued.id);
        await _db.deleteNote(id);
        return;
      }
      await _db.deleteNote(id);
      await _db.enqueuePending(
        domain: kSyncDomainNotes,
        verb: kWriteVerbDelete,
        targetId: id,
      );
    }
  }
}