import 'dart:async';

import 'package:commons_core/commons_core.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:tane/services/message_store.dart';
import 'package:tane/state/messages_cubit.dart';

import '../support/test_support.dart';

/// In-memory [MessageTransport]: records sends, lets a test push inbox messages.
class FakeMessageTransport implements MessageTransport {
  final List<({String to, String text})> sent = [];
  final StreamController<PrivateMessage> _inbox =
      StreamController<PrivateMessage>.broadcast();

  void receive(PrivateMessage message) => _inbox.add(message);

  @override
  Future<void> send({required String toPubkey, required String text}) async =>
      sent.add((to: toPubkey, text: text));

  @override
  Stream<PrivateMessage> inbox() => _inbox.stream;

  @override
  Future<void> close() async => _inbox.close();
}

/// A transport whose [send] always fails (e.g. no relay reachable).
class _FailingSendTransport implements MessageTransport {
  @override
  Future<void> send({required String toPubkey, required String text}) async =>
      throw StateError('no relay');

  @override
  Stream<PrivateMessage> inbox() => const Stream.empty();

  @override
  Future<void> close() async {}
}

void main() {
  const peer = 'aa';
  const me = 'bb';

  PrivateMessage msg(String from, String text) =>
      PrivateMessage(fromPubkey: from, text: text, at: DateTime(2026));

  test('receives messages from the peer only', () async {
    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me)
      ..start();

    transport.receive(msg(peer, 'hola'));
    transport.receive(msg('cc', 'not for this chat')); // other conversation
    await pumpEventQueue();

    expect(cubit.state.messages, hasLength(1));
    expect(cubit.state.messages.single.text, 'hola');
    expect(cubit.isMine(cubit.state.messages.single), isFalse);
    await cubit.close();
  });

  test('send delivers to the peer and appends our own message', () async {
    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);

    await cubit.send('  ¿cambiamos?  ');
    expect(transport.sent, [(to: peer, text: '¿cambiamos?')]);
    expect(cubit.state.messages, hasLength(1));
    expect(cubit.isMine(cubit.state.messages.single), isTrue);
    expect(cubit.state.sending, isFalse);
    await cubit.close();
  });

  test('a full exchange keeps order and sides', () async {
    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me)
      ..start();

    await cubit.send('hi');
    transport.receive(msg(peer, 'hello'));
    await pumpEventQueue();

    expect(cubit.state.messages.map((m) => m.text), ['hi', 'hello']);
    expect(cubit.state.messages.map(cubit.isMine), [true, false]);
    await cubit.close();
  });

  test(
    'a failed send surfaces an error and drops the optimistic message',
    () async {
      final transport = _FailingSendTransport();
      final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);
      await cubit.send('hi');
      expect(cubit.state.error, isNotNull);
      expect(cubit.state.sending, isFalse);
      expect(cubit.state.messages, isEmpty);
      await cubit.close();
    },
  );

  test('a message containing a link is not sent', () async {
    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);
    await cubit.send('check https://evil.example/login');
    expect(transport.sent, isEmpty);
    expect(cubit.state.messages, isEmpty);
    await cubit.close();
  });

  test('empty/whitespace text is not sent', () async {
    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);
    await cubit.send('   ');
    expect(transport.sent, isEmpty);
    expect(cubit.state.messages, isEmpty);
    await cubit.close();
  });

  test(
    'loads saved history on start and persists across a new cubit',
    () async {
      // History is ordered by each message's own timestamp, so use realistic
      // monotonic times: 'earlier' predates the sent 'hi' (stamped now() by the
      // cubit), and 'reply' comes after it.
      PrivateMessage at(String from, String text, DateTime when) =>
          PrivateMessage(fromPubkey: from, text: text, at: when);

      final store = MessageStore(newTestChatDatabase());
      await store.append(
        peer,
        at(peer, 'earlier', DateTime(2020)),
      ); // from a previous session

      final transport = FakeMessageTransport();
      final cubit = MessagesCubit(
        transport,
        peerPubkey: peer,
        selfPubkey: me,
        store: store,
      );
      await cubit.start();
      expect(cubit.state.messages.map((m) => m.text), ['earlier']);

      await cubit.send('hi'); // persisted, stamped now()
      transport.receive(at(peer, 'reply', DateTime(2100))); // persisted, later
      await pumpEventQueue();
      expect(cubit.state.messages.map((m) => m.text), [
        'earlier',
        'hi',
        'reply',
      ]);
      await cubit.close();

      // A fresh cubit (even offline) sees the saved conversation.
      final reopened = MessagesCubit(
        null,
        peerPubkey: peer,
        selfPubkey: me,
        store: store,
      );
      await reopened.start();
      expect(reopened.state.messages.map((m) => m.text), [
        'earlier',
        'hi',
        'reply',
      ]);
      await reopened.close();
    },
  );

  test(
    'a re-delivered wrap is shown once (relay resends stored events)',
    () async {
      final transport = FakeMessageTransport();
      final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me)
        ..start();

      final same = msg(peer, 'hola'); // identical sender+timestamp+text
      transport.receive(same);
      transport.receive(same); // relay re-delivery on the same subscription
      await pumpEventQueue();

      expect(cubit.state.messages, hasLength(1));
      await cubit.close();
    },
  );

  test('history already surfaced live is not shown twice', () async {
    // The stored message is ALSO handed back by the live subscription on open.
    final store = MessageStore(newTestChatDatabase());
    final m = msg(peer, 'hola');
    await store.append(peer, m);

    final transport = FakeMessageTransport();
    final cubit = MessagesCubit(
      transport,
      peerPubkey: peer,
      selfPubkey: me,
      store: store,
    );
    unawaited(cubit.start());
    transport.receive(m); // live redelivery races the history load
    await pumpEventQueue();

    expect(cubit.state.messages.map((m) => m.text), ['hola']);
    await cubit.close();
  });

  test('offline (no transport) never throws', () async {
    final cubit = MessagesCubit(null, peerPubkey: peer, selfPubkey: me)
      ..start();
    expect(cubit.isOnline, isFalse);
    await cubit.send('hi');
    expect(cubit.state.messages, isEmpty);
    await cubit.close();
  });
}