import 'package:flutter/material.dart';

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

class HomePage extends StatelessWidget {
  const HomePage({
    super.key,
    required this.state,
    required this.onStartPrimaryTask,
    required this.onOpenDialogue,
    required this.onResumeLessonDialogue,
    required this.onStartReinforcement,
    required this.onOpenAssessment,
  });

  final AppState state;
  final VoidCallback onStartPrimaryTask;
  final VoidCallback onOpenDialogue;
  final VoidCallback onResumeLessonDialogue;
  final VoidCallback onStartReinforcement;
  final ValueChanged<String> onOpenAssessment;

  @override
  Widget build(BuildContext context) {
    final isReview = state.reviewIsPrimary;
    final count = state.dueReviewCount;
    final activeLesson = lessonById(state.activeLessonId);
    final activeSegment = state.activeSegmentIndexFor(activeLesson.id) + 1;
    final resumeDialogue = state.hasResumableLessonDialogue;
    final stageStep = !resumeDialogue && !isReview && state.allLessonsComplete
        ? _stageStep()
        : null;
    final primaryTitle = resumeDialogue
        ? '继续第 ${activeLesson.number} 课的课程对话'
        : isReview
        ? '先复习 $count 项'
        : stageStep?.title ??
              '第 ${activeLesson.number} 课 · ${activeLesson.title}${activeLesson.segments.length > 1 ? ' · 第 $activeSegment/${activeLesson.segments.length} 段' : ''}';
    final primaryNote = resumeDialogue
        ? '已保留你的对话进度和提示状态。'
        : isReview
        ? (state.reviewBacklog ? '有积压项目；先花几分钟清掉到期复习。' : '昨天练过的关键句，今天换个情境再用一次。')
        : stageStep?.note ?? '预热词汇 → 听说读写 → 对话 → 独立尝试';
    final scene = state.recommendedScene;

    return AppPage(
      child: SpacedColumn(
        spacing: 16,
        children: [
          const Eyebrow('今天的学习'),
          Text(
            '今天，说几句能用的英语。',
            style: Theme.of(context).textTheme.headlineMedium,
          ),
          Text(
            isReview ? '到期复习优先；完成后再进入新内容。' : '没有到期复习，继续完成一个小任务。',
            style: Theme.of(context).textTheme.bodyMedium,
          ),
          SectionCard(
            child: Row(
              children: [
                Icon(Icons.psychology_outlined, color: AppColors.green),
                const SizedBox(width: 10),
                Expanded(
                  child: Text(
                    '已接触 ${state.knownItemCount} 项 · 可独立使用 ${state.usableMasteryCount} 项',
                  ),
                ),
              ],
            ),
          ),
          SectionCard(
            tint: AppColors.softGreen,
            child: SpacedColumn(
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Expanded(
                      child: Text(
                        primaryTitle,
                        style: const TextStyle(
                          fontSize: 16,
                          fontWeight: FontWeight.w600,
                        ),
                      ),
                    ),
                    Text(
                      isReview
                          ? '${(count * 2).clamp(2, 10)} 分钟'
                          : stageStep?.minutes ?? '12 分钟',
                      style: TextStyle(color: AppColors.green),
                    ),
                  ],
                ),
                Text(
                  primaryNote,
                  style: Theme.of(context).textTheme.bodyMedium,
                ),
                PrimaryButton(
                  label: resumeDialogue
                      ? '继续对话'
                      : isReview
                      ? '开始复习'
                      : stageStep?.action ?? '开始今天的学习',
                  onPressed: resumeDialogue
                      ? onResumeLessonDialogue
                      : stageStep?.onPressed ?? onStartPrimaryTask,
                ),
              ],
            ),
          ),
          SectionCard(
            child: SpacedColumn(
              children: [
                const Text(
                  'AI 情境对话',
                  style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
                ),
                Text(
                  '${scene.title} · ${scene.script.prompts.length} 个任务 · 文字或语音输入',
                  style: Theme.of(context).textTheme.bodyMedium,
                ),
                SecondaryButton(label: '开始情境对话', onPressed: onOpenDialogue),
              ],
            ),
          ),
          const _FrameworkNote(),
        ],
      ),
    );
  }

  /// What comes after the last A0 lesson: consolidation until the core items
  /// are ready, then the stage assessment, then waiting for A1 content.
  _StageStep _stageStep() {
    final usable =
        '可使用 ${state.coreUsableCount}/48 · 已掌握 ${state.coreMasteredCount}/30';
    if (state.a0Passed) {
      return _StageStep(
        title: 'A0 已通过',
        note: 'A1 课程准备中。先用巩固练习和情境对话保持手感。',
        action: '安排一题巩固练习',
        minutes: '3 分钟',
        onPressed: onStartReinforcement,
      );
    }
    final packId = state.nextAssessmentPackId;
    if (state.a0AssessmentReady && packId != null) {
      return _StageStep(
        title: 'A0 阶段评估 · $packId',
        note: '$usable。可以开始阶段评估，两套评估间隔至少 24 小时。',
        action: '开始阶段评估',
        minutes: '15 分钟',
        onPressed: () => onOpenAssessment(packId),
      );
    }
    return _StageStep(
      title: state.a0AssessmentReady ? '第二套评估 24 小时后开放' : 'A0 课程已学完',
      note: state.a0AssessmentReady
          ? '第一套评估已通过。等待期间继续巩固。'
          : '$usable。继续按时复习、做情境对话，达到要求后开放阶段评估。',
      action: '安排一题巩固练习',
      minutes: '3 分钟',
      onPressed: onStartReinforcement,
    );
  }
}

class _StageStep {
  const _StageStep({
    required this.title,
    required this.note,
    required this.action,
    required this.minutes,
    required this.onPressed,
  });
  final String title;
  final String note;
  final String action;
  final String minutes;
  final VoidCallback onPressed;
}

class _FrameworkNote extends StatelessWidget {
  const _FrameworkNote();

  @override
  Widget build(BuildContext context) => Container(
    padding: const EdgeInsets.all(12),
    decoration: BoxDecoration(
      color: AppColors.warm,
      borderRadius: BorderRadius.circular(14),
    ),
    child: Row(
      children: [
        Icon(Icons.info_outline, color: AppColors.warmInk),
        SizedBox(width: 8),
        Expanded(
          child: Text(
            '文字回答可用于理解与写作练习；口语掌握须以录音或语音识别结果为准。可在“我的”配置 AI 服务。',
            style: TextStyle(
              color: AppColors.warmInk,
              fontSize: 13,
              height: 1.45,
            ),
          ),
        ),
      ],
    ),
  );
}