import 'package:fake_async/fake_async.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:patbond_flutter/features/community/feed_exposure.dart';

void main() {
  test('曝光判定：≥50% 驻留满 500ms 记一次，段内按帖去重', () {
    fakeAsync((async) {
      final segment = FeedViewSegment(now: async.getClock(DateTime(2026)).now);
      segment.updateVisibility('p-1', 0.8);
      async.elapse(const Duration(milliseconds: 600));
      expect(segment.impressionCount, 1);

      // 再次可见不重复计。
      segment.updateVisibility('p-1', 0.9);
      async.elapse(const Duration(milliseconds: 600));
      expect(segment.impressionCount, 1);
    });
  });

  test('快速滑过（<500ms 跌破阈值）不计曝光', () {
    fakeAsync((async) {
      final segment = FeedViewSegment(now: async.getClock(DateTime(2026)).now);
      segment.updateVisibility('p-1', 0.8);
      async.elapse(const Duration(milliseconds: 300));
      segment.updateVisibility('p-1', 0.2); // 滚出视口
      async.elapse(const Duration(seconds: 1));
      expect(segment.impressionCount, 0);
    });
  });

  test('可见面积不足 50% 不起计时', () {
    fakeAsync((async) {
      final segment = FeedViewSegment(now: async.getClock(DateTime(2026)).now);
      segment.updateVisibility('p-1', 0.49);
      async.elapse(const Duration(seconds: 1));
      expect(segment.impressionCount, 0);
    });
  });

  test('结算：冻结计数、取消在途驻留、幂等只出一份', () {
    fakeAsync((async) {
      final clock = async.getClock(DateTime(2026));
      final segment = FeedViewSegment(now: clock.now);
      segment.updateVisibility('p-1', 1);
      async.elapse(const Duration(milliseconds: 600));
      segment.updateVisibility('p-2', 1); // 在途驻留，结算时未满 500ms
      async.elapse(const Duration(milliseconds: 100));
      segment.recordRefresh();
      segment.recordLoadMore();
      segment.recordLoadMore();

      final summary = segment.settle();
      expect(summary, isNotNull);
      expect(summary!.impressionCount, 1);
      expect(summary.refreshCount, 1);
      expect(summary.loadMoreCount, 2);
      expect(summary.durationMs, 700);

      // 幂等：二次结算无第二条；结算后计数与曝光全部作废。
      expect(segment.settle(), isNull);
      segment.updateVisibility('p-3', 1);
      async.elapse(const Duration(seconds: 1));
      expect(segment.impressionCount, 1);
    });
  });

  test('durationMs 上限截断 30 分钟（防挂机污染 H8）', () {
    fakeAsync((async) {
      final segment = FeedViewSegment(now: async.getClock(DateTime(2026)).now);
      async.elapse(const Duration(minutes: 45));
      expect(
        segment.settle()!.durationMs,
        const Duration(minutes: 30).inMilliseconds,
      );
    });
  });
}