import 'package:flutter_test/flutter_test.dart';
import 'package:warp/matrix/timeline.dart';

Entry msg(String sender, DateTime time) =>
    (sender: sender, time: time, kind: EntryKind.message);
Entry notice(DateTime time) =>
    (sender: '@admin:x', time: time, kind: EntryKind.notice);
Entry hidden(DateTime time) =>
    (sender: '@a:x', time: time, kind: EntryKind.hidden);

/// Describes items compactly: `D` for a day, `m<index><first?F><last?L>`,
/// `n<index>` for a notice.
List<String> describe(List<TimelineItem> items) => [
  for (final item in items)
    switch (item) {
      DayItem() => 'D',
      EventItem(:final index, :final kind) when kind == EntryKind.notice =>
        'n$index',
      EventItem(:final index, :final firstInGroup, :final lastInGroup) =>
        'm$index${firstInGroup ? 'F' : ''}${lastInGroup ? 'L' : ''}',
    },
];

void main() {
  final t0 = DateTime(2026, 10, 18, 12);

  test('empty', () {
    expect(projectTimeline([]), isEmpty);
  });

  test('a run from one sender is one group', () {
    // Newest first, as the SDK keeps them.
    final items = projectTimeline([
      msg('@a:x', t0.add(const Duration(minutes: 2))),
      msg('@a:x', t0.add(const Duration(minutes: 1))),
      msg('@a:x', t0),
    ]);
    expect(describe(items), ['m0L', 'm1', 'm2F', 'D']);
  });

  test('a new sender starts a new group', () {
    final items = projectTimeline([
      msg('@b:x', t0.add(const Duration(minutes: 1))),
      msg('@a:x', t0),
    ]);
    expect(describe(items), ['m0FL', 'm1FL', 'D']);
  });

  test('a long pause starts a new group', () {
    final items = projectTimeline([
      msg('@a:x', t0.add(const Duration(minutes: 6))),
      msg('@a:x', t0),
    ]);
    expect(describe(items), ['m0FL', 'm1FL', 'D']);
  });

  test('hidden events are dropped and do not break a group', () {
    final items = projectTimeline([
      msg('@a:x', t0.add(const Duration(minutes: 2))),
      hidden(t0.add(const Duration(minutes: 1))),
      msg('@a:x', t0),
    ]);
    expect(describe(items), ['m0L', 'm2F', 'D']);
  });

  test('a notice breaks a group', () {
    final items = projectTimeline([
      msg('@a:x', t0.add(const Duration(minutes: 2))),
      notice(t0.add(const Duration(minutes: 1))),
      msg('@a:x', t0),
    ]);
    expect(describe(items), ['m0FL', 'n1', 'm2FL', 'D']);
  });

  test('a day separator above the first event of each day', () {
    final yesterday = t0.subtract(const Duration(days: 1));
    final items = projectTimeline([
      msg('@a:x', t0),
      msg('@a:x', yesterday.add(const Duration(minutes: 1))),
      msg('@a:x', yesterday),
    ]);
    expect(describe(items), ['m0FL', 'D', 'm1L', 'm2F', 'D']);
    expect((items[1] as DayItem).day, DateTime(2026, 10, 18));
    expect((items[4] as DayItem).day, DateTime(2026, 10, 17));
  });

  test('messages either side of midnight are separate groups', () {
    final midnight = DateTime(2026, 10, 18);
    final items = projectTimeline([
      msg('@a:x', midnight.add(const Duration(minutes: 1))),
      msg('@a:x', midnight.subtract(const Duration(minutes: 1))),
    ]);
    expect(describe(items), ['m0FL', 'D', 'm1FL', 'D']);
  });
}