import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:intl/intl.dart';

import '../../../core/models/comment_model.dart';
import '../../auth/providers/auth_provider.dart';
import '../providers/comments_provider.dart';

class CommentsScreen extends ConsumerStatefulWidget {
  const CommentsScreen({
    super.key,
    required this.novelId,
    this.chapterId,
  });

  final String novelId;
  final String? chapterId;

  @override
  ConsumerState<CommentsScreen> createState() => _CommentsScreenState();
}

class _CommentsScreenState extends ConsumerState<CommentsScreen> {
  final _textCtrl = TextEditingController();
  bool _submitting = false;

  String get _key =>
      widget.chapterId != null ? '${widget.novelId}:${widget.chapterId}' : widget.novelId;

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

  Future<void> _submit() async {
    final text = _textCtrl.text.trim();
    if (text.isEmpty) return;
    setState(() => _submitting = true);
    try {
      await ref.read(commentsProvider(_key).notifier).post(text);
      _textCtrl.clear();
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context)
            .showSnackBar(SnackBar(content: Text('Lỗi: $e')));
      }
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final isAuth = ref.watch(isAuthenticatedProvider);
    final commentsAsync = ref.watch(commentsProvider(_key));

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.chapterId != null ? 'Bình luận chương' : 'Bình luận'),
      ),
      body: Column(
        children: [
          Expanded(
            child: commentsAsync.when(
              loading: () => const Center(child: CircularProgressIndicator()),
              error: (e, _) => Center(child: Text('Lỗi: $e')),
              data: (comments) {
                if (comments.isEmpty) {
                  return const Center(child: Text('Chưa có bình luận nào'));
                }
                return ListView.separated(
                  padding: const EdgeInsets.symmetric(vertical: 8),
                  itemCount: comments.length,
                  separatorBuilder: (_, separatorIndex) =>
                      const Divider(height: 1),
                  itemBuilder: (context, index) =>
                      _CommentTile(comment: comments[index]),
                );
              },
            ),
          ),
          if (isAuth)
            _CommentInput(
              controller: _textCtrl,
              submitting: _submitting,
              onSubmit: _submit,
            ),
        ],
      ),
    );
  }
}

class _CommentTile extends StatelessWidget {
  final CommentModel comment;
  const _CommentTile({required this.comment});

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              CircleAvatar(
                radius: 16,
                child: Text(
                  comment.username[0].toUpperCase(),
                ),
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      comment.username,
                      style: const TextStyle(fontWeight: FontWeight.w600),
                    ),
                    Text(
                      _formatDate(comment.createdAt),
                      style: Theme.of(context).textTheme.bodySmall,
                    ),
                  ],
                ),
              ),
            ],
          ),
          const SizedBox(height: 8),
          Text(comment.content),
        ],
      ),
    );
  }

  String _formatDate(DateTime? dt) {
    if (dt == null) return '';
    return DateFormat('dd/MM/yyyy HH:mm').format(dt.toLocal());
  }
}

class _CommentInput extends StatelessWidget {
  final TextEditingController controller;
  final bool submitting;
  final VoidCallback onSubmit;

  const _CommentInput({
    required this.controller,
    required this.submitting,
    required this.onSubmit,
  });

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.only(
        left: 12,
        right: 12,
        top: 8,
        bottom: MediaQuery.of(context).padding.bottom + 8,
      ),
      color: Theme.of(context).colorScheme.surface,
      child: Row(
        children: [
          Expanded(
            child: TextField(
              controller: controller,
              maxLines: 3,
              minLines: 1,
              decoration: InputDecoration(
                hintText: 'Viết bình luận...',
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(12),
                ),
                isDense: true,
              ),
              textInputAction: TextInputAction.newline,
            ),
          ),
          const SizedBox(width: 8),
          IconButton.filled(
            onPressed: submitting ? null : onSubmit,
            icon: submitting
                ? const SizedBox(
                    width: 18,
                    height: 18,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  )
                : const Icon(Icons.send),
          ),
        ],
      ),
    );
  }
}