import 'package:flutter/material.dart';
import '../services/ai_recommendation_service.dart';
import '../theme/app_theme.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,
    bool silent = false,
    bool hideUserMessage = false,
  }) async {
    final text = (suggestion ?? _controller.text).trim();
    if (text.isEmpty || _isLoading) return;

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

    try {
      final response = await _service.sendMessage(text, silent: silent);
      if (!mounted) return;
      setState(() {
        _messages.add(_ChatMessage(text: response, isUser: false));
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _messages.add(
          _ChatMessage(
            text: 'Nao consegui gerar uma recomendacao 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: AppColors.background,
      body: SafeArea(
        child: Column(
          children: [
            _buildHeader(),
            _buildSuggestions(),
            Expanded(
              child: ListView.builder(
                controller: _scrollController,
                padding: const EdgeInsets.fromLTRB(16, 8, 16, 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 _buildHeader() {
    return Container(
      padding: const EdgeInsets.fromLTRB(20, 16, 20, 16),
      decoration: BoxDecoration(
        gradient: AppColors.brandGradient,
        boxShadow: AppShadows.brand,
      ),
      child: Row(
        children: [
          Container(
            width: 44,
            height: 44,
            decoration: BoxDecoration(
              color: Colors.white.withValues(alpha: 0.22),
              borderRadius: BorderRadius.circular(AppRadius.md),
            ),
            child: const Icon(
              Icons.auto_awesome_rounded,
              color: Colors.white,
              size: 24,
            ),
          ),
          const SizedBox(width: 12),
          const Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'DayMaker IA',
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 18,
                    fontWeight: FontWeight.w700,
                  ),
                ),
                SizedBox(height: 2),
                Text(
                  'Pergunta-me sobre o teu dia ou viagem',
                  style: TextStyle(color: Colors.white70, fontSize: 12),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  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, 14, 16, 8),
      color: AppColors.background,
      child: SingleChildScrollView(
        scrollDirection: Axis.horizontal,
        child: Row(
          children: suggestions.map((suggestion) {
            return Padding(
              padding: const EdgeInsets.only(right: 8),
              child: AppChip(
                label: suggestion,
                icon: Icons.bolt_rounded,
                onTap: () => _sendMessage(suggestion: suggestion),
              ),
            );
          }).toList(),
        ),
      ),
    );
  }

  Widget _buildInput() {
    return Container(
      padding: const EdgeInsets.fromLTRB(12, 10, 12, 14),
      decoration: BoxDecoration(
        color: AppColors.surface,
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.04),
            blurRadius: 16,
            offset: const Offset(0, -4),
          ),
        ],
      ),
      child: Row(
        children: [
          Expanded(
            child: Container(
              decoration: BoxDecoration(
                color: AppColors.surfaceAlt,
                borderRadius: BorderRadius.circular(AppRadius.pill),
                border: Border.all(color: AppColors.border),
              ),
              child: TextField(
                controller: _controller,
                minLines: 1,
                maxLines: 4,
                textInputAction: TextInputAction.send,
                onSubmitted: (_) => _sendMessage(),
                style: AppText.body,
                decoration: const InputDecoration(
                  hintText: 'Escreve uma mensagem...',
                  hintStyle: TextStyle(color: AppColors.textTertiary),
                  border: InputBorder.none,
                  contentPadding: EdgeInsets.symmetric(
                    horizontal: 16,
                    vertical: 12,
                  ),
                ),
              ),
            ),
          ),
          const SizedBox(width: 10),
          Container(
            width: 48,
            height: 48,
            decoration: BoxDecoration(
              gradient: AppColors.brandGradient,
              shape: BoxShape.circle,
              boxShadow: AppShadows.brand,
            ),
            child: Material(
              color: Colors.transparent,
              shape: const CircleBorder(),
              child: InkWell(
                customBorder: const CircleBorder(),
                onTap: _isLoading ? null : () => _sendMessage(),
                child: const Icon(
                  Icons.send_rounded,
                  color: Colors.white,
                  size: 22,
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

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 isUser = message.isUser;
    final alignment = isUser ? Alignment.centerRight : Alignment.centerLeft;

    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.symmetric(horizontal: 16, vertical: 12),
        decoration: BoxDecoration(
          gradient: isUser ? AppColors.brandGradient : null,
          color: isUser ? null : AppColors.surface,
          borderRadius: BorderRadius.only(
            topLeft: const Radius.circular(AppRadius.lg),
            topRight: const Radius.circular(AppRadius.lg),
            bottomLeft: Radius.circular(isUser ? AppRadius.lg : 4),
            bottomRight: Radius.circular(isUser ? 4 : AppRadius.lg),
          ),
          boxShadow: isUser ? AppShadows.brand : AppShadows.soft,
        ),
        child: Text(
          message.text,
          style: TextStyle(
            color: isUser ? Colors.white : AppColors.textPrimary,
            fontSize: 15,
            height: 1.4,
          ),
        ),
      ),
    );
  }
}

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: 16, vertical: 14),
        decoration: BoxDecoration(
          color: AppColors.surface,
          borderRadius: const BorderRadius.only(
            topLeft: Radius.circular(AppRadius.lg),
            topRight: Radius.circular(AppRadius.lg),
            bottomLeft: Radius.circular(4),
            bottomRight: Radius.circular(AppRadius.lg),
          ),
          boxShadow: AppShadows.soft,
        ),
        child: const SizedBox(
          width: 20,
          height: 20,
          child: CircularProgressIndicator(
            strokeWidth: 2.2,
            valueColor: AlwaysStoppedAnimation<Color>(AppColors.primary),
          ),
        ),
      ),
    );
  }
}