import 'dart:async';
import 'dart:typed_data';

import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_gateway.dart';

/// A [StudysetGateway] in memory: ids are `studyset-1`, `studyset-2`, …, and
/// [receiveRemoteChange] and [receiveRemoteDeletion] play a sync that brought
/// changes.
class FakeStudysetGateway() implements StudysetGateway {
  final _rows = <String, StudysetRow>{};
  final _remoteChanges = StreamController<void>.broadcast();
  var _nextId = 1;

  /// Every payload written, in order, as (id, payload).
  final writes = <(String, ByteData)>[];

  /// The ids of the deleted rows, in order.
  final deleted = <String>[];

  /// Every move, in order, as (id, parent, position).
  final moves = <(String, String?, String)>[];

  /// When set, reading the studysets fails with it.
  Exception? failReads;

  /// Stores [payload] as if another device had written it and a sync had
  /// brought it here, with the other columns given.
  void receiveRemoteChange(
    String id,
    ByteData payload, {
    String? parentId,
    String position = 'a0',
    DateTime? archivedAt,
    DateTime? deletedAt,
    DateTime? starredAt,
    DateTime? updatedAt,
  }) {
    _rows[id] = (
      id: id,
      payload: payload,
      parentId: parentId,
      position: position,
      archivedAt: archivedAt,
      deletedAt: deletedAt,
      starredAt: starredAt,
      updatedAt: updatedAt,
    );
    _remoteChanges.add(null);
  }

  /// Removes the studyset [id] as if another device had deleted it and a
  /// sync had brought that here.
  void receiveRemoteDeletion(String id) {
    _rows.remove(id);
    _remoteChanges.add(null);
  }

  @override
  Future<List<StudysetRow>> all() async {
    if (failReads case final error?) {
      throw error;
    }
    return [..._rows.values];
  }

  @override
  Future<String> insert(
    ByteData payload,
    DateTime updatedAt, {
    String? parentId,
    String position = 'a0',
  }) async {
    final id = 'studyset-${_nextId++}';
    _rows[id] = (
      id: id,
      payload: payload,
      parentId: parentId,
      position: position,
      archivedAt: null,
      deletedAt: null,
      starredAt: null,
      updatedAt: updatedAt,
    );
    writes.add((id, payload));
    return id;
  }

  @override
  Future<void> updatePayload(
    String id,
    ByteData payload,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: payload,
        parentId: row.parentId,
        position: row.position,
        archivedAt: row.archivedAt,
        deletedAt: row.deletedAt,
        starredAt: row.starredAt,
        updatedAt: updatedAt,
      );
      writes.add((id, payload));
    }
  }

  @override
  Future<void> updateStarredAt(
    String id,
    DateTime? starredAt,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: row.payload,
        parentId: row.parentId,
        position: row.position,
        archivedAt: row.archivedAt,
        deletedAt: row.deletedAt,
        starredAt: starredAt,
        updatedAt: updatedAt,
      );
    }
  }

  @override
  Future<void> updateParent(
    String id,
    String? parentId,
    String position,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: row.payload,
        parentId: parentId,
        position: position,
        archivedAt: row.archivedAt,
        deletedAt: row.deletedAt,
        starredAt: row.starredAt,
        updatedAt: updatedAt,
      );
      moves.add((id, parentId, position));
    }
  }

  @override
  Future<void> updatePosition(
    String id,
    String position,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: row.payload,
        parentId: row.parentId,
        position: position,
        archivedAt: row.archivedAt,
        deletedAt: row.deletedAt,
        starredAt: row.starredAt,
        updatedAt: updatedAt,
      );
      moves.add((id, row.parentId, position));
    }
  }

  @override
  Future<void> updateArchivedAt(
    String id,
    DateTime? archivedAt,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: row.payload,
        parentId: row.parentId,
        position: row.position,
        archivedAt: archivedAt,
        deletedAt: row.deletedAt,
        starredAt: row.starredAt,
        updatedAt: updatedAt,
      );
    }
  }

  @override
  Future<void> updateDeletedAt(
    String id,
    DateTime? deletedAt,
    DateTime updatedAt,
  ) async {
    if (_rows[id] case final row?) {
      _rows[id] = (
        id: id,
        payload: row.payload,
        parentId: row.parentId,
        position: row.position,
        archivedAt: row.archivedAt,
        deletedAt: deletedAt,
        starredAt: row.starredAt,
        updatedAt: updatedAt,
      );
    }
  }

  @override
  Future<void> delete(String id) async {
    _rows.remove(id);
    deleted.add(id);
  }

  @override
  Stream<void> get remoteChanges => _remoteChanges.stream;
}