import 'dart:async';
import 'dart:convert';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../services/connection_service.dart';
import '../services/api_service.dart';
import '../services/theme_service.dart';
import '../models/message.dart';
import '../models/channel.dart';
import '../models/guild.dart';
import '../widgets/message_bubble.dart';
import '../widgets/chat_input.dart';

class ChatScreen extends StatefulWidget {
  const ChatScreen({super.key});

  @override
  State<ChatScreen> createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  final TextEditingController _messageController = TextEditingController();
  final ScrollController _scrollController = ScrollController();
  final List<Message> _messages = [];
  StreamSubscription? _sub;
  bool _loading = true;
  bool _atBottom = true;

  late Channel _channel;
  late Guild _guild;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    final args = ModalRoute.of(context)?.settings.arguments as Map?;
    if (args != null) {
      _channel = args['channel'] as Channel;
      _guild = args['guild'] as Guild;
    }
  }

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_onScroll);
    WidgetsBinding.instance.addPostFrameCallback((_) => _loadMessages());
    _sub = context.read<ConnectionService>().messageStream.listen(_onMessage);
  }

  @override
  void dispose() {
    _sub?.cancel();
    _messageController.dispose();
    _scrollController.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (_scrollController.hasClients) {
      final atBottom = _scrollController.position.pixels >=
          _scrollController.position.maxScrollExtent - 50;
      if (atBottom != _atBottom) {
        setState(() => _atBottom = atBottom);
      }
    }
  }

  Future<void> _loadMessages() async {
    try {
      final conn = context.read<ConnectionService>();
      final api = ApiService();
      api.updateFromWsUrl(conn.serverUrl);
      final messages = await api.getMessages(_channel.id);
      if (mounted) {
        setState(() {
          _messages.addAll(messages.reversed);
          _loading = false;
        });
        _scrollToBottom();
      }
    } catch (_) {
      if (mounted) setState(() => _loading = false);
    }
  }

  void _scrollToBottom() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (_scrollController.hasClients) {
        _scrollController.animateTo(
          _scrollController.position.maxScrollExtent,
          duration: const Duration(milliseconds: 200),
          curve: Curves.easeOut,
        );
      }
    });
  }

  void _onMessage(Map<String, dynamic> data) {
    final msgChannelId = data['channel_id'] as String?;
    if (msgChannelId != _channel.id) return;

    final msg = Message.fromJson(data);
    setState(() => _messages.add(msg));
    if (_atBottom) _scrollToBottom();
  }

  void _sendMessage(String text) {
    if (text.trim().isEmpty) return;
    final conn = context.read<ConnectionService>();
    final content = Uint8List.fromList(utf8.encode(text));
    conn.sendMessage(channelId: _channel.id, content: content);
    _messageController.clear();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: ThemeService.backgroundPrimary,
      body: Column(
        children: [
          _buildHeader(),
          Expanded(
            child: _loading
                ? const Center(child: CircularProgressIndicator(strokeWidth: 2))
                : _messages.isEmpty
                    ? _buildEmptyState()
                    : ListView.builder(
                        controller: _scrollController,
                        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                        itemCount: _messages.length,
                        itemBuilder: (context, index) {
                          final msg = _messages[index];
                          final showAuthor = index == 0 ||
                              _messages[index - 1].authorId != msg.authorId;
                          return MessageBubble(
                            message: msg,
                            showAuthor: showAuthor,
                            onReply: (m) => _messageController.text = '@${m.authorUsername ?? "unknown"} ',
                          );
                        },
                      ),
          ),
          ChatInput(
            controller: _messageController,
            onSendMessage: _sendMessage,
            channelId: _channel.id,
          ),
        ],
      ),
    );
  }

  Widget _buildHeader() {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
      decoration: const BoxDecoration(
        color: ThemeService.surfaceSecondary,
        border: Border(bottom: BorderSide(color: Color(0xFF3F4147))),
      ),
      child: Row(
        children: [
          Icon(
            _channel.isText ? Icons.tag : Icons.volume_up,
            size: 20,
            color: ThemeService.textMuted,
          ),
          const SizedBox(width: 8),
          Text(
            _channel.name,
            style: const TextStyle(
              color: ThemeService.textPrimary,
              fontSize: 16,
              fontWeight: FontWeight.w600,
            ),
          ),
          const Spacer(),
          if (_channel.isVoice)
            IconButton(
              icon: const Icon(Icons.call, size: 20),
              color: ThemeService.success,
              onPressed: () {},
              tooltip: 'Start call',
            ),
          IconButton(
            icon: const Icon(Icons.search, size: 20),
            color: ThemeService.textSecondary,
            onPressed: () {},
            tooltip: 'Search',
          ),
        ],
      ),
    );
  }

  Widget _buildEmptyState() {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(
            _channel.isText ? Icons.tag : Icons.volume_up,
            size: 48,
            color: ThemeService.textMuted.withValues(alpha: 0.5),
          ),
          const SizedBox(height: 12),
          Text(
            '#${_channel.name}',
            style: const TextStyle(
              color: ThemeService.textPrimary,
              fontSize: 20,
              fontWeight: FontWeight.w700,
            ),
          ),
          if (_channel.topic != null && _channel.topic!.isNotEmpty) ...[
            const SizedBox(height: 4),
            Text(
              _channel.topic!,
              style: const TextStyle(
                color: ThemeService.textSecondary,
                fontSize: 13,
              ),
            ),
          ],
          const SizedBox(height: 16),
          Text(
            'No messages yet. Start the conversation!',
            style: TextStyle(
              color: ThemeService.textMuted.withValues(alpha: 0.8),
              fontSize: 14,
            ),
          ),
        ],
      ),
    );
  }
}