// 🗣️ 커뮤니티 게시판(백판) 홈 화면 (UI 전용). 카테고리 탭 + 글 목록 + 글쓰기.
// 서버 통신/상태는 lib/function/board_list_controller.dart, board_write_controller.dart가 담당한다.
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import '../config.dart';
import '../function/board_list_controller.dart';
import '../theme/app_palette.dart';
import 'board_post_detail_screen.dart';
import 'board_report_screen.dart';
import 'board_write_screen.dart';
import 'launchpad_transition.dart';
import 'title_pill.dart';

class BoardHomeScreen extends StatefulWidget {
  final String studentId;
  final bool canModerate;

  const BoardHomeScreen({
    super.key,
    required this.studentId,
    this.canModerate = false,
  });

  @override
  State<BoardHomeScreen> createState() => _BoardHomeScreenState();
}

class _BoardHomeScreenState extends State<BoardHomeScreen>
    with SingleTickerProviderStateMixin {
  List<dynamic> _categories = [];
  bool _isLoadingCategories = true;
  TabController? _tabController;
  final Map<String, BoardListController> _controllers = {};

  @override
  void initState() {
    super.initState();
    _fetchCategories();
  }

  @override
  void dispose() {
    _tabController?.dispose();
    for (final c in _controllers.values) {
      c.dispose();
    }
    super.dispose();
  }

  Future<void> _fetchCategories() async {
    try {
      final response = await http.get(
        Uri.parse('$baseUrl/api/board/categories'),
      );
      if (response.statusCode == 200) {
        final data = jsonDecode(utf8.decode(response.bodyBytes));
        _categories = data['categories'] ?? [];
      }
    } catch (_) {
      // 조용히 무시 - 아래에서 목록이 비어있으면 에러로 처리한다.
    } finally {
      if (mounted) {
        setState(() {
          _isLoadingCategories = false;
          if (_categories.isNotEmpty) {
            _tabController = TabController(
              length: _categories.length,
              vsync: this,
            );
          }
        });
      }
    }
  }

  BoardListController _controllerFor(String category) {
    return _controllers.putIfAbsent(
      category,
      () =>
          BoardListController(category: category, studentId: widget.studentId)
            ..init(),
    );
  }

  Future<void> _openWrite() async {
    final tabController = _tabController;
    if (tabController == null) return;
    final category = _categories[tabController.index];
    final changed = await pushLaunchpad<bool>(
      context,
      (context) => BoardWriteScreen(
        studentId: widget.studentId,
        category: category['key'],
        categoryName: category['name'],
      ),
    );
    if (changed == true) {
      _controllerFor(category['key']).refresh();
    }
  }

  void _openModeration() {
    pushLaunchpad(
      context,
      (context) => BoardReportScreen(reviewerId: widget.studentId),
    );
  }

  Future<void> _openPost(int postId, String category) async {
    final changed = await pushLaunchpad<bool>(
      context,
      (context) =>
          BoardPostDetailScreen(postId: postId, studentId: widget.studentId),
    );
    if (changed == true) {
      _controllerFor(category).refresh();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppPalette.mist,
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        foregroundColor: AppPalette.ink,
        elevation: 0,
        centerTitle: true,
        title: const TitlePill('백판'),
        actions: [
          if (widget.canModerate)
            IconButton(
              icon: const Icon(Icons.shield_outlined),
              tooltip: '신고 검토',
              onPressed: _openModeration,
            ),
        ],
        bottom: _tabController == null
            ? null
            : TabBar(
                controller: _tabController,
                labelColor: AppPalette.ink,
                unselectedLabelColor: Colors.grey,
                indicatorColor: AppPalette.ink,
                tabs: [for (final c in _categories) Tab(text: c['name'])],
              ),
      ),
      floatingActionButton: _tabController == null
          ? null
          : FloatingActionButton(
              backgroundColor: AppPalette.ink,
              foregroundColor: AppPalette.paper,
              onPressed: _openWrite,
              child: const Icon(Icons.edit_rounded),
            ),
      body: _isLoadingCategories
          ? const Center(child: CircularProgressIndicator())
          : _tabController == null
          ? Center(
              child: TextButton(
                onPressed: () {
                  setState(() => _isLoadingCategories = true);
                  _fetchCategories();
                },
                child: const Text('게시판을 불러오지 못했습니다. 다시 시도'),
              ),
            )
          : TabBarView(
              controller: _tabController,
              children: [
                for (final c in _categories)
                  _CategoryBoardList(
                    controller: _controllerFor(c['key']),
                    onOpenPost: (postId) => _openPost(postId, c['key']),
                  ),
              ],
            ),
    );
  }
}

class _CategoryBoardList extends StatefulWidget {
  final BoardListController controller;
  final ValueChanged<int> onOpenPost;

  const _CategoryBoardList({
    required this.controller,
    required this.onOpenPost,
  });

  @override
  State<_CategoryBoardList> createState() => _CategoryBoardListState();
}

class _CategoryBoardListState extends State<_CategoryBoardList> {
  final _scrollController = ScrollController();

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(() {
      if (_scrollController.position.pixels >=
          _scrollController.position.maxScrollExtent - 200) {
        widget.controller.loadMore();
      }
    });
  }

  @override
  void dispose() {
    _scrollController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: widget.controller,
      builder: (context, _) {
        if (widget.controller.isLoading) {
          return const Center(child: CircularProgressIndicator());
        }
        final posts = widget.controller.posts;
        if (posts.isEmpty) {
          return Center(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                const Text(
                  '아직 글이 없어요.\n첫 글을 남겨보세요.',
                  textAlign: TextAlign.center,
                  style: TextStyle(color: Colors.grey),
                ),
                const SizedBox(height: 8),
                TextButton(
                  onPressed: widget.controller.refresh,
                  child: const Text('새로고침'),
                ),
              ],
            ),
          );
        }
        return RefreshIndicator(
          onRefresh: widget.controller.refresh,
          child: ListView.builder(
            controller: _scrollController,
            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            itemCount: posts.length + (widget.controller.hasMore ? 1 : 0),
            itemBuilder: (context, index) {
              if (index >= posts.length) {
                return const Padding(
                  padding: EdgeInsets.symmetric(vertical: 16),
                  child: Center(
                    child: SizedBox(
                      width: 20,
                      height: 20,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    ),
                  ),
                );
              }
              final post = posts[index];
              return Container(
                margin: const EdgeInsets.only(bottom: 8),
                decoration: BoxDecoration(
                  color: AppPalette.paper,
                  borderRadius: BorderRadius.circular(14),
                  border: Border.all(color: AppPalette.sage),
                ),
                child: ListTile(
                  title: Text(
                    post['title'] ?? '',
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: const TextStyle(fontWeight: FontWeight.bold),
                  ),
                  subtitle: Text(
                    '${post['createdAt'] ?? ''}',
                    style: const TextStyle(fontSize: 12),
                  ),
                  trailing: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      const Icon(
                        Icons.mode_comment_outlined,
                        size: 15,
                        color: Colors.grey,
                      ),
                      const SizedBox(width: 3),
                      Text('${post['commentCount'] ?? 0}'),
                    ],
                  ),
                  onTap: () => widget.onOpenPost(post['id'] as int),
                ),
              );
            },
          ),
        );
      },
    );
  }
}