import 'dart:ui';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'dart:async';
import 'package:flutter_markdown/flutter_markdown.dart';
import 'database_helper.dart';

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

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

class _ChatScreenState extends State<ChatScreen> with TickerProviderStateMixin {
  final List<ChatMessage> _messages = [];
  final List<ChatSession> _sessions = [];
  ChatSession? _currentSession;
  
  final TextEditingController _textController = TextEditingController();
  final ScrollController _scrollController = ScrollController();
  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
  
  bool _isTyping = false;
  late AnimationController _typingController;

  @override
  void initState() {
    super.initState();
    _typingController = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 1200),
    )..repeat();

    _loadInitialData();
  }

  Future<void> _loadInitialData() async {
    await _loadSessions();
    if (_sessions.isNotEmpty) {
      await _selectSession(_sessions.first);
    } else {
      await _createNewSession();
    }
  }

  Future<void> _loadSessions() async {
    final sessions = await DatabaseHelper.instance.getSessions();
    if (mounted) {
      setState(() {
        _sessions.clear();
        _sessions.addAll(sessions);
      });
    }
  }

  Future<void> _selectSession(ChatSession session) async {
    final messages = await DatabaseHelper.instance.getMessages(session.id!);
    if (mounted) {
      setState(() {
        _currentSession = session;
        _messages.clear();
        _messages.addAll(messages.reversed);
        _isTyping = false;
      });
    }
    if (_scaffoldKey.currentState?.isDrawerOpen ?? false) {
      Navigator.pop(context);
    }
  }

  Future<void> _createNewSession() async {
    final title = "Chat ${DateTime.now().hour}:${DateTime.now().minute}";
    final id = await DatabaseHelper.instance.createSession(title);
    await _loadSessions();
    final newSession = _sessions.firstWhere((s) => s.id == id);
    await _selectSession(newSession);
  }

  Future<void> _deleteSession(int id) async {
    await DatabaseHelper.instance.deleteSession(id);
    await _loadSessions();
    if (_currentSession?.id == id) {
      if (_sessions.isNotEmpty) {
        await _selectSession(_sessions.first);
      } else {
        await _createNewSession();
      }
    } else {
      setState(() {});
    }
  }

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

  Future<void> _handleSubmitted(String text) async {
    if (text.trim().isEmpty || _isTyping) return;

    // Se por algum motivo não houver sessão, cria uma antes de enviar
    if (_currentSession == null) {
      await _createNewSession();
    }

    final userMsgText = text.trim();
    _textController.clear();

    final userMsg = ChatMessage(
      sessionId: _currentSession!.id!,
      text: userMsgText,
      isAssistant: false,
      timestamp: DateTime.now().toIso8601String(),
    );

    await DatabaseHelper.instance.insertMessage(userMsg);

    setState(() {
      _messages.insert(0, userMsg);
      _isTyping = true;
    });

    try {
      final url = Uri.parse('http://89.114.196.110:11434/api/chat');

      final response = await http.post(
        url,
        headers: {'Content-Type': 'application/json'},
        body: jsonEncode({
          'model': 'qwen3-coder:30b',
          'messages': [{'role': 'user', 'content': userMsgText}],
          'stream': false,
        }),
      ).timeout(const Duration(seconds: 60));

      if (response.statusCode == 200) {
        final data = jsonDecode(response.body);
        final replyText = data['message']?['content'] ?? 'Sem resposta.';

        final assistantMsg = ChatMessage(
          sessionId: _currentSession!.id!,
          text: replyText,
          isAssistant: true,
          timestamp: DateTime.now().toIso8601String(),
        );

        await DatabaseHelper.instance.insertMessage(assistantMsg);

        if (mounted) {
          setState(() {
            _isTyping = false;
            _messages.insert(0, assistantMsg);
          });
        }
      } else {
        throw Exception('Erro HTTP ${response.statusCode}');
      }
    } catch (e) {
      if (mounted) {
        setState(() {
          _isTyping = false;
          _messages.insert(0, ChatMessage(
            sessionId: _currentSession!.id!,
            text: "Erro de ligação. Verifique se o servidor está online.",
            isAssistant: true,
            timestamp: DateTime.now().toIso8601String(),
          ));
        });
      }
    }
  }

  Widget _buildMessage(ChatMessage message) {
    bool isAssistant = message.isAssistant;
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 12.0, horizontal: 16.0),
      child: Row(
        mainAxisAlignment: isAssistant ? MainAxisAlignment.start : MainAxisAlignment.end,
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          if (isAssistant) _buildAvatar(Icons.auto_awesome),
          Flexible(
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 10.0),
              decoration: BoxDecoration(
                gradient: isAssistant
                    ? const LinearGradient(colors: [Color(0xFFF1F5F9), Color(0xFFE2E8F0)])
                    : const LinearGradient(colors: [Color(0xFF8ad5c9), Color(0xFF57a7ed)]),
                borderRadius: BorderRadius.only(
                  topLeft: const Radius.circular(20),
                  topRight: const Radius.circular(20),
                  bottomLeft: Radius.circular(isAssistant ? 4 : 20),
                  bottomRight: Radius.circular(isAssistant ? 20 : 4),
                ),
                boxShadow: [
                  BoxShadow(color: Colors.black.withOpacity(0.05), blurRadius: 5, offset: const Offset(0, 2)),
                ],
              ),
              child: isAssistant
                ? MarkdownBody(
                    data: message.text,
                    styleSheet: MarkdownStyleSheet(
                      p: const TextStyle(color: Colors.black87, fontSize: 15, height: 1.4),
                      strong: const TextStyle(color: Colors.black, fontWeight: FontWeight.bold),
                    ),
                  )
                : Text(message.text, style: const TextStyle(color: Colors.white, fontSize: 15)),
            ),
          ),
          if (!isAssistant) _buildAvatar(Icons.person),
        ],
      ),
    );
  }

  Widget _buildAvatar(IconData icon) {
    return Container(
      margin: EdgeInsets.only(left: icon == Icons.person ? 12 : 0, right: icon == Icons.auto_awesome ? 12 : 0),
      decoration: const BoxDecoration(
        shape: BoxShape.circle,
        gradient: LinearGradient(colors: [Color(0xFF8ad5c9), Color(0xFF57a7ed)]),
      ),
      child: CircleAvatar(backgroundColor: Colors.transparent, radius: 16, child: Icon(icon, color: Colors.white, size: 18)),
    );
  }

  Widget _buildTypingIndicator() {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 12.0, horizontal: 16.0),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
          _buildAvatar(Icons.auto_awesome),
          Container(
            padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 12.0),
            decoration: BoxDecoration(
              color: const Color(0xFFF1F5F9),
              borderRadius: const BorderRadius.only(topLeft: Radius.circular(20), topRight: Radius.circular(20), bottomLeft: Radius.circular(4), bottomRight: Radius.circular(20)),
            ),
            child: Row(
              mainAxisSize: MainAxisSize.min,
              children: [_buildAnimatedDot(0), const SizedBox(width: 4), _buildAnimatedDot(1), const SizedBox(width: 4), _buildAnimatedDot(2)],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildAnimatedDot(int index) {
    return AnimatedBuilder(
      animation: _typingController,
      builder: (context, child) {
        double value = (_typingController.value + (index * 0.15)) % 1.0;
        double intensity = 1.0 - (value - 0.5).abs() * 2;
        return Opacity(
          opacity: 0.3 + (0.7 * intensity),
          child: Transform.translate(offset: Offset(0, -3 * intensity), child: Container(width: 6, height: 6, decoration: const BoxDecoration(color: Colors.black54, shape: BoxShape.circle))),
        );
      },
    );
  }

  Widget _buildTextComposer() {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 12.0),
      decoration: BoxDecoration(
        color: Colors.white,
        border: Border(top: BorderSide(color: Colors.black.withOpacity(0.05))),
      ),
      child: SafeArea(
        child: Row(
          children: [
            Expanded(
              child: Container(
                decoration: BoxDecoration(
                  color: const Color(0xFFF1F5F9),
                  borderRadius: BorderRadius.circular(30.0),
                ),
                child: TextField(
                  controller: _textController,
                  enabled: !_isTyping,
                  onSubmitted: _handleSubmitted,
                  decoration: const InputDecoration(
                    hintText: "Mensagem EPVChat...",
                    border: InputBorder.none,
                    contentPadding: EdgeInsets.symmetric(horizontal: 24.0, vertical: 14.0),
                  ),
                ),
              ),
            ),
            const SizedBox(width: 12),
            Container(
              decoration: BoxDecoration(
                gradient: LinearGradient(
                  colors: _isTyping ? [Colors.grey, Colors.grey] : [const Color(0xFF8ad5c9), const Color(0xFF57a7ed)],
                ),
                shape: BoxShape.circle,
              ),
              child: IconButton(
                icon: const Icon(Icons.send_rounded, color: Colors.white),
                onPressed: _isTyping ? null : () => _handleSubmitted(_textController.text),
              ),
            ),
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final screenWidth = MediaQuery.of(context).size.width;

    return Scaffold(
      key: _scaffoldKey,
      drawer: _buildSidebar(),
      backgroundColor: Colors.white,
      body: Stack(
        children: [
          // Sombreado Mint
          Positioned(
            top: -screenWidth * 0.45,
            left: -screenWidth * 0.2,
            right: -screenWidth * 0.2,
            child: Container(
              height: screenWidth * 1.1,
              decoration: BoxDecoration(
                shape: BoxShape.circle,
                gradient: RadialGradient(
                  center: Alignment.center,
                  radius: 0.5,
                  colors: [const Color(0xFF8ad5c9).withOpacity(0.6), const Color(0xFF8ad5c9).withOpacity(0.0)],
                  stops: const [0.2, 1.0],
                ),
              ),
            ),
          ),

          Column(
            children: [
              // Área do Topo (Menu e Logo)
              SafeArea(
                child: Container(
                  height: 100,
                  padding: const EdgeInsets.symmetric(horizontal: 16),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      IconButton(
                        icon: const Icon(Icons.menu_rounded, color: Color(0xFF57a7ed), size: 32),
                        onPressed: () => _scaffoldKey.currentState?.openDrawer(),
                      ),
                      Image.asset('assets/logo.png', height: 100, errorBuilder: (c,e,s) => const SizedBox(width: 100)),
                      const SizedBox(width: 48), // Equilíbrio para o ícone do menu
                    ],
                  ),
                ),
              ),

              Expanded(
                child: ListView.builder(
                  controller: _scrollController,
                  padding: const EdgeInsets.symmetric(vertical: 20),
                  reverse: true,
                  itemCount: _messages.length + (_isTyping ? 1 : 0),
                  itemBuilder: (context, index) {
                    if (_isTyping && index == 0) return _buildTypingIndicator();
                    int msgIndex = _isTyping ? index - 1 : index;
                    return _buildMessage(_messages[msgIndex]);
                  },
                ),
              ),
              _buildTextComposer(),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildSidebar() {
    return Drawer(
      width: MediaQuery.of(context).size.width * 0.75,
      child: Column(
        children: [
          DrawerHeader(
            decoration: const BoxDecoration(
              gradient: LinearGradient(colors: [Color(0xFF8ad5c9), Color(0xFF57a7ed)]),
            ),
            child: Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  const Icon(Icons.auto_awesome, color: Colors.white, size: 40),
                  const SizedBox(height: 10),
                  const Text('Histórico de Chats', style: TextStyle(color: Colors.white, fontSize: 18, fontWeight: FontWeight.bold)),
                ],
              ),
            ),
          ),
          ListTile(
            leading: const Icon(Icons.add_comment_rounded, color: Color(0xFF57a7ed)),
            title: const Text('Nova Conversa', style: TextStyle(fontWeight: FontWeight.bold)),
            onTap: _createNewSession,
          ),
          const Divider(),
          Expanded(
            child: ListView.builder(
              padding: EdgeInsets.zero,
              itemCount: _sessions.length,
              itemBuilder: (context, index) {
                final session = _sessions[index];
                final isSelected = _currentSession?.id == session.id;
                return Container(
                  margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
                  decoration: BoxDecoration(
                    color: isSelected ? const Color(0xFF8ad5c9).withOpacity(0.1) : Colors.transparent,
                    borderRadius: BorderRadius.circular(12),
                  ),
                  child: ListTile(
                    title: Text(session.title, maxLines: 1, overflow: TextOverflow.ellipsis),
                    trailing: IconButton(
                      icon: const Icon(Icons.delete_outline_rounded, color: Colors.redAccent),
                      onPressed: () => _deleteSession(session.id!),
                    ),
                    onTap: () => _selectSession(session),
                  ),
                );
              },
            ),
          ),
        ],
      ),
    );
  }
}