import 'dart:math' as math;

import 'package:easy_localization/easy_localization.dart';
import 'package:flutter/material.dart';
import 'package:gap/gap.dart';
import 'package:go_router/go_router.dart';
import 'package:material_symbols_icons/symbols.dart';
import 'package:provider/provider.dart';
import 'package:responsive_framework/responsive_framework.dart';
import 'package:styled_widget/styled_widget.dart';
import 'package:surface/providers/post.dart';
import 'package:surface/providers/userinfo.dart';
import 'package:surface/types/post.dart';
import 'package:surface/widgets/dialog.dart';
import 'package:surface/widgets/loading_indicator.dart';
import 'package:surface/widgets/post/post_comment_list.dart';
import 'package:surface/widgets/post/post_item.dart';
import 'package:surface/widgets/post/post_mini_editor.dart';

class PostDetailScreen extends StatefulWidget {
  final String slug;
  final SnPost? preload;

  const PostDetailScreen({
    super.key,
    required this.slug,
    this.preload,
  });

  @override
  State<PostDetailScreen> createState() => _PostDetailScreenState();
}

class _PostDetailScreenState extends State<PostDetailScreen> {
  bool _isBusy = false;

  SnPost? _data;

  void _fetchPost() async {
    setState(() => _isBusy = true);

    try {
      final pt = context.read<SnPostContentProvider>();
      final post = await pt.getPost(widget.slug);
      if (!mounted) return;
      _data = post;
    } catch (err) {
      context.showErrorDialog(err);
    } finally {
      setState(() => _isBusy = false);
    }
  }

  @override
  void initState() {
    super.initState();
    if (widget.preload != null) {
      _data = widget.preload;
    }
    _fetchPost();
  }

  final GlobalKey<PostCommentSliverListState> _childListKey = GlobalKey();

  @override
  Widget build(BuildContext context) {
    final ua = context.watch<UserProvider>();
    final devicePixelRatio = MediaQuery.of(context).devicePixelRatio;

    return Scaffold(
      appBar: AppBar(
        leading: BackButton(
          onPressed: () {
            if (GoRouter.of(context).canPop()) {
              GoRouter.of(context).pop(context);
              return;
            }
            GoRouter.of(context).replaceNamed('explore');
          },
        ),
        title: _data?.body['title'] != null
            ? RichText(
                textAlign: TextAlign.center,
                text: TextSpan(children: [
                  TextSpan(
                    text: _data?.body['title'] ?? 'postNoun'.tr(),
                    style: Theme.of(context).textTheme.titleLarge!.copyWith(
                          color: Theme.of(context).appBarTheme.foregroundColor!,
                        ),
                  ),
                  const TextSpan(text: '\n'),
                  TextSpan(
                    text: 'postDetail'.tr(),
                    style: Theme.of(context).textTheme.bodySmall!.copyWith(
                          color: Theme.of(context).appBarTheme.foregroundColor!,
                        ),
                  ),
                ]),
              )
            : Text('postDetail').tr(),
      ),
      body: CustomScrollView(
        slivers: [
          SliverToBoxAdapter(
            child: LoadingIndicator(isActive: _isBusy),
          ),
          if (_data != null)
            SliverToBoxAdapter(
              child: PostItem(
                data: _data!,
                maxWidth: 640,
                showComments: false,
                showFullPost: true,
                onChanged: (data) {
                  setState(() => _data = data);
                },
                onDeleted: () {
                  Navigator.pop(context);
                },
              ),
            ),
          const SliverToBoxAdapter(child: Divider(height: 1)),
          if (_data != null)
            SliverToBoxAdapter(
              child: Container(
                constraints: const BoxConstraints(maxWidth: 640),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    const Icon(Symbols.comment, size: 24),
                    const Gap(16),
                    Text('postCommentsDetailed')
                        .plural(_data!.metric.replyCount)
                        .textStyle(Theme.of(context).textTheme.titleLarge!),
                  ],
                ).padding(horizontal: 20, vertical: 12).center(),
              ),
            ),
          if (_data != null && ua.isAuthorized)
            SliverToBoxAdapter(
              child: Container(
                height: 240,
                constraints: const BoxConstraints(maxWidth: 640),
                margin:
                    ResponsiveBreakpoints.of(context).largerThan(MOBILE) ? const EdgeInsets.all(8) : EdgeInsets.zero,
                decoration: BoxDecoration(
                  borderRadius: ResponsiveBreakpoints.of(context).largerThan(MOBILE)
                      ? const BorderRadius.all(Radius.circular(8))
                      : BorderRadius.zero,
                  border: ResponsiveBreakpoints.of(context).largerThan(MOBILE)
                      ? Border.all(
                          color: Theme.of(context).dividerColor,
                          width: 1 / devicePixelRatio,
                        )
                      : Border.symmetric(
                          horizontal: BorderSide(
                            color: Theme.of(context).dividerColor,
                            width: 1 / devicePixelRatio,
                          ),
                        ),
                ),
                child: PostMiniEditor(
                  postReplyId: _data!.id,
                  onPost: () {
                    setState(() {
                      _data = _data!.copyWith(
                        metric: _data!.metric.copyWith(
                          replyCount: _data!.metric.replyCount + 1,
                        ),
                      );
                    });
                    _childListKey.currentState!.refresh();
                  },
                ),
              ).center(),
            ),
          if (_data != null)
            PostCommentSliverList(
              key: _childListKey,
              parentPostId: _data!.id,
              maxWidth: 640,
            ),
          SliverGap(math.max(MediaQuery.of(context).padding.bottom, 16)),
        ],
      ),
    );
  }
}