import 'package:flutter/material.dart';

import '../../core/app_state.dart';
import '../../core/app_theme.dart';
import '../../core/models.dart';
import '../../core/seed_courses.dart';
import '../../core/assessment_bank.dart';
import '../../widgets/app_widgets.dart';
import '../dialogue/dialogue_flow.dart';
import '../assessment/assessment_page.dart';
import '../home/home_page.dart';
import '../lesson/lesson_flow.dart';
import '../progress/progress_pages.dart';
import '../review/review_page.dart';

class LearningShell extends StatefulWidget {
  const LearningShell({super.key, required this.state});
  final AppState state;

  @override
  State<LearningShell> createState() => _LearningShellState();
}

class _LearningShellState extends State<LearningShell> {
  AppTab tab = AppTab.home;
  var route = _ShellRoute.tab;
  bool dialogueInLesson = false;
  AssessmentPack? assessmentPack;
  DialogueSummaryData? dialogueSummary;

  void showTab(AppTab value) => setState(() {
    tab = value;
    route = _ShellRoute.tab;
  });

  void showLesson() => setState(() => route = _ShellRoute.lesson);
  void showDialogueScene() => setState(() => route = _ShellRoute.scene);
  void showDialogue({bool inLesson = false}) => setState(() {
    dialogueInLesson = inLesson;
    route = _ShellRoute.dialogue;
  });
  void showSummary(DialogueSummaryData summary) => setState(() {
    dialogueSummary = summary;
    route = _ShellRoute.summary;
  });
  void showSettings() => setState(() => route = _ShellRoute.settings);
  void showAssessment(AssessmentPack pack) => setState(() {
    assessmentPack = pack;
    route = _ShellRoute.assessmentPreparation;
  });
  void startAssessment() => setState(() => route = _ShellRoute.assessment);
  void showAdaptiveLesson() =>
      setState(() => route = _ShellRoute.adaptiveLesson);

  @override
  Widget build(BuildContext context) {
    Widget body;
    switch (route) {
      case _ShellRoute.lesson:
        body = LessonFlow(
          state: widget.state,
          onOpenDialogue: () => showDialogue(inLesson: true),
          onFinish: () => showTab(AppTab.home),
        );
      case _ShellRoute.scene:
        body = DialogueScenePage(onStart: showDialogue);
      case _ShellRoute.dialogue:
        body = DialoguePage(
          state: widget.state,
          isLessonDialogue: dialogueInLesson,
          onFinished: dialogueInLesson
              ? (_) => showLesson()
              : (summary) {
                  if (summary != null) showSummary(summary);
                },
        );
      case _ShellRoute.summary:
        body = DialogueSummaryPage(
          summary: dialogueSummary!,
          onHome: () => showTab(AppTab.home),
          onLesson: showLesson,
          onRetry: showDialogue,
        );
      case _ShellRoute.settings:
        body = SettingsPage(state: widget.state);
      case _ShellRoute.adaptiveLesson:
        body = AdaptiveLessonPage(
          state: widget.state,
          onFinished: () => showTab(AppTab.review),
        );
      case _ShellRoute.assessment:
        body = AssessmentPage(
          state: widget.state,
          pack: assessmentPack!,
          onFinished: () => showTab(AppTab.progress),
          onStartReplacement: showAssessment,
        );
      case _ShellRoute.assessmentPreparation:
        body = AssessmentPreparationPage(
          state: widget.state,
          pack: assessmentPack!,
          onStart: startAssessment,
          onBack: () => showTab(AppTab.progress),
        );
      case _ShellRoute.tab:
        body = _tabContent();
    }

    return AnimatedBuilder(
      animation: widget.state,
      builder: (context, _) => Scaffold(
        body: body,
        bottomNavigationBar: route == _ShellRoute.tab
            ? NavigationBar(
                selectedIndex: tab.index,
                height: 70,
                indicatorColor: AppColors.softGreen,
                onDestinationSelected: (index) => showTab(AppTab.values[index]),
                destinations: const [
                  NavigationDestination(
                    icon: Icon(Icons.home_outlined),
                    selectedIcon: Icon(Icons.home),
                    label: '首页',
                  ),
                  NavigationDestination(
                    icon: Icon(Icons.menu_book_outlined),
                    selectedIcon: Icon(Icons.menu_book),
                    label: '学习',
                  ),
                  NavigationDestination(
                    icon: Icon(Icons.chat_bubble_outline),
                    selectedIcon: Icon(Icons.chat_bubble),
                    label: '对话',
                  ),
                  NavigationDestination(
                    icon: Icon(Icons.refresh_outlined),
                    selectedIcon: Icon(Icons.refresh),
                    label: '复习',
                  ),
                  NavigationDestination(
                    icon: Icon(Icons.person_outline),
                    selectedIcon: Icon(Icons.person),
                    label: '我的',
                  ),
                ],
              )
            : null,
      ),
    );
  }

  Widget _tabContent() {
    switch (tab) {
      case AppTab.home:
        return HomePage(
          state: widget.state,
          onStartPrimaryTask: widget.state.reviewIsPrimary
              ? () => showTab(AppTab.review)
              : showLesson,
          onOpenDialogue: showDialogue,
          onResumeLessonDialogue: () => showDialogue(inLesson: true),
        );
      case AppTab.learn:
        return _LearningMap(
          onOpenLesson: (id) {
            widget.state.openLesson(id);
            showLesson();
          },
          onStartReinforcement: () {
            widget.state.scheduleA0Reinforcement();
            showTab(AppTab.review);
          },
          onOpenReview: () => showTab(AppTab.review),
          state: widget.state,
        );
      case AppTab.dialogue:
        return DialogueScenePage(onStart: showDialogue);
      case AppTab.review:
        return ReviewPage(
          state: widget.state,
          onFinished: () => showTab(AppTab.home),
          onOpenAdaptiveLesson: showAdaptiveLesson,
        );
      case AppTab.progress:
        return ProgressPage(
          state: widget.state,
          onSettings: showSettings,
          onOpenAssessment: showAssessment,
        );
    }
  }
}

enum _ShellRoute {
  tab,
  lesson,
  scene,
  dialogue,
  summary,
  settings,
  adaptiveLesson,
  assessmentPreparation,
  assessment,
}

class _LearningMap extends StatelessWidget {
  const _LearningMap({
    required this.onOpenLesson,
    required this.onStartReinforcement,
    required this.onOpenReview,
    required this.state,
  });
  final ValueChanged<String> onOpenLesson;
  final VoidCallback onStartReinforcement;
  final VoidCallback onOpenReview;
  final AppState state;

  @override
  Widget build(BuildContext context) {
    return AppPage(
      child: SpacedColumn(
        children: [
          const Eyebrow('学习地图 · 按掌握状态推进'),
          Text('从认识到开口', style: Theme.of(context).textTheme.headlineMedium),
          const Text('每节课都围绕一个能完成的小任务。'),
          if (state.reviewBacklog)
            SectionCard(
              tint: AppColors.warm,
              child: SpacedColumn(
                children: [
                  Text(
                    '复习已有积压，今天先完成 ${state.dueReviewCount} 项到期复习，再开启新课。',
                    style: const TextStyle(color: AppColors.warmInk),
                  ),
                  SecondaryButton(label: '先去复习', onPressed: onOpenReview),
                ],
              ),
            ),
          for (final lesson in a0SeedLessons)
            SectionCard(
              tint: lesson.id == state.activeLessonId
                  ? AppColors.softGreen
                  : null,
              onTap:
                  state.isLessonUnlocked(lesson.id) &&
                      (!state.reviewBacklog ||
                          state.completedLessonIds.contains(lesson.id))
                  ? () => onOpenLesson(lesson.id)
                  : null,
              child: Row(
                children: [
                  Icon(
                    state.completedLessonIds.contains(lesson.id)
                        ? Icons.check_circle
                        : state.reviewBacklog
                        ? Icons.lock_outline
                        : state.isLessonUnlocked(lesson.id)
                        ? Icons.play_circle_outline
                        : Icons.lock_outline,
                    color: state.completedLessonIds.contains(lesson.id)
                        ? AppColors.green
                        : AppColors.muted,
                  ),
                  const SizedBox(width: 10),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          '第 ${lesson.number} 课 · ${lesson.title}',
                          style: const TextStyle(fontWeight: FontWeight.w600),
                        ),
                        const SizedBox(height: 3),
                        Text(
                          lesson.segments.length > 1
                              ? '${lesson.outcome} · 小段 ${lesson.segments.where((segment) => state.isSegmentComplete(segment.id)).length}/${lesson.segments.length}'
                              : lesson.outcome,
                          style: Theme.of(context).textTheme.bodyMedium,
                        ),
                      ],
                    ),
                  ),
                ],
              ),
            ),
          if (state.completedLessonIds.length == a0SeedLessons.length)
            SectionCard(
              tint: AppColors.softGreen,
              child: SpacedColumn(
                children: [
                  const Text(
                    'A0 巩固变式',
                    style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
                  ),
                  const Text('换一个人物、地点或情境，继续巩固尚未稳定的核心表达。'),
                  PrimaryButton(
                    label: '安排一题巩固练习',
                    onPressed: onStartReinforcement,
                  ),
                ],
              ),
            ),
        ],
      ),
    );
  }
}