import 'package:flutter/material.dart';
import '../services/ai_recommendation_service.dart';

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

  @override
  State<AiChatScreen> createState() => _AiChatScreenState();
}

class _AiChatScreenState extends State<AiChatScreen> {
  final TextEditingController _controller = TextEditingController();
  final ScrollController _scrollController = ScrollController();
  final AiRecommendationService _service = AiRecommendationService();
  final List<_ChatMessage> _messages = [
    const _ChatMessage(
      text:
          'Olá! Diz-me uma ocasião, destino ou plano e eu recomendo o que deves levar. Ex: "uma viagem para Itália de 5 dias".',
      isUser: false,
    ),
  ];
  bool _isLoading = false;

  Future<void> _sendMessage([String? suggestion]) async {
    final text = (suggestion ?? _controller.text).trim();
    if (text.isEmpty || _isLoading) return;

    setState(() {
      _messages.add(_ChatMessage(text: text, isUser: true));
      _isLoading = true;
    });
    _controller.clear();
    _scrollToBottom();

    try {
      final response = await _service.recommendForOccasion(text);
      if (!mounted) return;
      setState(() {
        _messages.add(_ChatMessage(text: response, isUser: false));
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _messages.add(
          _ChatMessage(
            text: 'Não consegui gerar uma recomendação agora. Tenta novamente.',
            isUser: false,
          ),
        );
      });
    } finally {
      if (mounted) {
        setState(() => _isLoading = false);
        _scrollToBottom();
      }
    }
  }

  void _scrollToBottom() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!_scrollController.hasClients) return;
      _scrollController.animateTo(
        _scrollController.position.maxScrollExtent,
        duration: const Duration(milliseconds: 250),
        curve: Curves.easeOut,
      );
    });
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFFFFE5CC),
      appBar: AppBar(
        backgroundColor: const Color(0xFF0066CC),
        elevation: 0,
        title: const Text(
          'DayMaker IA',
          style: TextStyle(color: Colors.white, fontSize: 20),
        ),
        centerTitle: true,
      ),
      body: SafeArea(
        child: Column(
          children: [
            _buildSuggestions(),
            Expanded(
              child: ListView.builder(
                controller: _scrollController,
                padding: const EdgeInsets.all(16),
                itemCount: _messages.length + (_isLoading ? 1 : 0),
                itemBuilder: (context, index) {
                  if (_isLoading && index == _messages.length) {
                    return const _TypingBubble();
                  }
                  return _MessageBubble(message: _messages[index]);
                },
              ),
            ),
            _buildInput(),
          ],
        ),
      ),
    );
  }

  Widget _buildSuggestions() {
    final suggestions = [
      'Viagem para Itália',
      'Fim de semana na praia',
      'Reunião de trabalho',
    ];

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.fromLTRB(16, 12, 16, 8),
      color: const Color(0xFFFFE5CC),
      child: SingleChildScrollView(
        scrollDirection: Axis.horizontal,
        child: Row(
          children: suggestions.map((suggestion) {
            return Padding(
              padding: const EdgeInsets.only(right: 8),
              child: ActionChip(
                backgroundColor: Colors.white,
                side: const BorderSide(color: Color(0xFFE0E0E0)),
                label: Text(suggestion),
                onPressed: () => _sendMessage(suggestion),
              ),
            );
          }).toList(),
        ),
      ),
    );
  }

  Widget _buildInput() {
    return Container(
      padding: const EdgeInsets.fromLTRB(12, 8, 12, 12),
      decoration: const BoxDecoration(color: Colors.white),
      child: Row(
        children: [
          Expanded(
            child: Container(
              decoration: BoxDecoration(
                color: const Color(0xFFF5F5F5),
                borderRadius: BorderRadius.circular(24),
              ),
              child: TextField(
                controller: _controller,
                minLines: 1,
                maxLines: 4,
                textInputAction: TextInputAction.send,
                onSubmitted: (_) => _sendMessage(),
                decoration: const InputDecoration(
                  hintText: 'Ex: viagem para Itália de 5 dias...',
                  border: InputBorder.none,
                  contentPadding: EdgeInsets.symmetric(
                    horizontal: 16,
                    vertical: 12,
                  ),
                ),
              ),
            ),
          ),
          const SizedBox(width: 8),
          SizedBox(
            width: 48,
            height: 48,
            child: ElevatedButton(
              onPressed: _isLoading ? null : () => _sendMessage(),
              style: ElevatedButton.styleFrom(
                backgroundColor: const Color(0xFF0066CC),
                shape: const CircleBorder(),
                padding: EdgeInsets.zero,
              ),
              child: const Icon(Icons.send, color: Colors.white),
            ),
          ),
        ],
      ),
    );
  }
}

class _ChatMessage {
  final String text;
  final bool isUser;

  const _ChatMessage({required this.text, required this.isUser});
}

class _MessageBubble extends StatelessWidget {
  final _ChatMessage message;

  const _MessageBubble({required this.message});

  @override
  Widget build(BuildContext context) {
    final alignment = message.isUser
        ? Alignment.centerRight
        : Alignment.centerLeft;
    final backgroundColor = message.isUser
        ? const Color(0xFF0066CC)
        : Colors.white;
    final textColor = message.isUser ? Colors.white : const Color(0xFF333333);

    return Align(
      alignment: alignment,
      child: Container(
        constraints: BoxConstraints(
          maxWidth: MediaQuery.of(context).size.width * 0.78,
        ),
        margin: const EdgeInsets.only(bottom: 10),
        padding: const EdgeInsets.all(14),
        decoration: BoxDecoration(
          color: backgroundColor,
          borderRadius: BorderRadius.circular(18),
        ),
        child: Text(
          message.text,
          style: TextStyle(color: textColor, fontSize: 15, height: 1.35),
        ),
      ),
    );
  }
}

class _TypingBubble extends StatelessWidget {
  const _TypingBubble();

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.centerLeft,
      child: Container(
        margin: const EdgeInsets.only(bottom: 10),
        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
        decoration: BoxDecoration(
          color: Colors.white,
          borderRadius: BorderRadius.circular(18),
        ),
        child: const SizedBox(
          width: 18,
          height: 18,
          child: CircularProgressIndicator(strokeWidth: 2),
        ),
      ),
    );
  }
}