import 'package:flutter/material.dart';

import '../../core/app_state.dart';
import '../../core/app_theme.dart';
import '../../core/courses/courses.dart';
import '../../widgets/app_widgets.dart';

/// 课程路径：全部课程按顺序排列，显示完成、当前与锁定状态。
class LessonPath extends StatelessWidget {
  const LessonPath({
    super.key,
    required this.state,
    required this.onOpenLesson,
  });
  final AppState state;
  final ValueChanged<String> onOpenLesson;

  @override
  Widget build(BuildContext context) {
    final done = allLessons
        .where((lesson) => state.completedLessonIds.contains(lesson.id))
        .length;
    return SpacedColumn(
      spacing: 10,
      children: [
        Row(
          children: [
            Expanded(
              child: Text(
                '课程路径',
                style: Theme.of(context).textTheme.titleMedium,
              ),
            ),
            Text(
              '$done/${allLessons.length} 完成',
              style: TextStyle(fontSize: 13, color: AppColors.muted),
            ),
          ],
        ),
        if (state.reviewBacklog)
          Text(
            '复习有积压：先完成到期复习，新课暂时锁定；已学课程仍可重温。',
            style: TextStyle(fontSize: 13, color: AppColors.warmInk),
          ),
        for (final lesson in allLessons)
          _LessonTile(
            lesson: lesson,
            state: state,
            onTap: () => onOpenLesson(lesson.id),
          ),
      ],
    );
  }
}

class _LessonTile extends StatelessWidget {
  const _LessonTile({
    required this.lesson,
    required this.state,
    required this.onTap,
  });
  final SeedLesson lesson;
  final AppState state;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final completed = state.completedLessonIds.contains(lesson.id);
    final current = lesson.id == state.activeLessonId && !completed;
    final open =
        state.isLessonUnlocked(lesson.id) &&
        (!state.reviewBacklog || completed);
    final segments = lesson.segments.length;
    final segmentsDone = lesson.segments
        .where((segment) => state.isSegmentComplete(segment.id))
        .length;
    return SectionCard(
      tint: current ? AppColors.softGreen : null,
      onTap: open ? onTap : null,
      child: Row(
        children: [
          Icon(
            completed
                ? Icons.check_circle
                : open
                ? Icons.play_circle_outline
                : Icons.lock_outline,
            color: completed || current ? AppColors.green : AppColors.muted,
          ),
          const SizedBox(width: 10),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  '第 ${lesson.number} 课 · ${lesson.title}',
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
                const SizedBox(height: 3),
                Text(
                  segments > 1
                      ? '${lesson.outcome} · 小段 $segmentsDone/$segments'
                      : lesson.outcome,
                  style: Theme.of(context).textTheme.bodyMedium,
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}