// lib/screens/savings_simulator_screen.dart

import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:provider/provider.dart';
import 'package:fl_chart/fl_chart.dart';
import 'package:google_fonts/google_fonts.dart';

import 'package:kzeduca_app/services/i18n_service.dart';
import 'package:kzeduca_app/services/firebase_service.dart';
import 'package:kzeduca_app/models/app_models.dart';

// KzEduca Palette
const _kGradientStart = Color(0xFF512DA8); // Roxo vibrante
const _kGradientEnd   = Color(0xFF000000); // Preto profundo
const _kAccent        = Color(0xFF00BFA5); // Verde água
const _kAction        = Color(0xFFFFD600); // Amarelo/dourado
const _kCardColor     = Color(0x33FFFFFF); // Vidro fosco (opacidade de 20%)

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

  @override
  State<SavingsSimulatorScreen> createState() => _SavingsSimulatorScreenState();
}

class _SavingsSimulatorScreenState extends State<SavingsSimulatorScreen> {
  final TextEditingController _initialValueController = TextEditingController();
  final TextEditingController _monthlyDepositController = TextEditingController();
  final TextEditingController _interestRateController = TextEditingController();
  final TextEditingController _periodMonthsController = TextEditingController();

  double? _result;
  bool _isLoading = false;
  String _error = '';
  List<FlSpot> _chartData = [];
  List<SavingsSimulation> _savedSimulations = [];

  @override
  void initState() {
    super.initState();
    _loadSavedSimulations();
  }

  @override
  void dispose() {
    _initialValueController.dispose();
    _monthlyDepositController.dispose();
    _interestRateController.dispose();
    _periodMonthsController.dispose();
    super.dispose();
  }

  void _showAlertDialog(String message, {bool isError = false}) {
    final i18n = Provider.of<I18nService>(context, listen: false);
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        backgroundColor: Colors.grey[900],
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
        title: Text(
          isError ? i18n.t('error_prefix') : 'Info',
          style: GoogleFonts.montserrat(color: Colors.white, fontWeight: FontWeight.bold),
        ),
        content: Text(
          message,
          style: GoogleFonts.montserrat(color: Colors.white70),
        ),
        actions: <Widget>[
          TextButton(
            child: Text('Ok', style: GoogleFonts.montserrat(color: _kAccent)),
            onPressed: () {
              Navigator.of(ctx).pop();
            },
          )
        ],
      ),
    );
  }

  Future<void> _loadSavedSimulations() async {
    final firebaseService = Provider.of<FirebaseService>(context, listen: false);
    final userId = FirebaseAuth.instance.currentUser?.uid;
    if (userId == null) return;

    firebaseService.streamSavedSimulations(userId).listen((snapshot) {
      if (mounted) {
        setState(() {
          _savedSimulations = snapshot.docs
              .map((doc) => SavingsSimulation.fromFirestore(doc))
              .toList();
        });
      }
    }, onError: (error) {
      if (mounted) {
        _showAlertDialog("Erro ao carregar simulações salvas.", isError: true);
      }
    });
  }

  void _simulateSavings() {
    final i18n = Provider.of<I18nService>(context, listen: false);
    setState(() {
      _error = '';
      _isLoading = true;
      _result = null;
      _chartData = [];
    });

    final initialValue = double.tryParse(_initialValueController.text);
    final monthlyDeposit = double.tryParse(_monthlyDepositController.text);
    final interestRate = double.tryParse(_interestRateController.text);
    final periodMonths = int.tryParse(_periodMonthsController.text);

    if (initialValue == null || monthlyDeposit == null || interestRate == null || periodMonths == null) {
      _showAlertDialog(i18n.t('fill_all_fields'), isError: true);
      setState(() { _isLoading = false; });
      return;
    }
    if (initialValue < 0 || monthlyDeposit < 0 || interestRate < 0 || periodMonths <= 0) {
      _showAlertDialog(i18n.t('invalid_numeric_input'), isError: true);
      setState(() { _isLoading = false; });
      return;
    }

    final monthlyInterestRate = interestRate / 100 / 12;
    double currentAmount = initialValue;
    List<FlSpot> spots = [FlSpot(0, initialValue)];

    for (int i = 0; i < periodMonths; i++) {
      currentAmount = (currentAmount + monthlyDeposit) * (1 + monthlyInterestRate);
      spots.add(FlSpot(i + 1.0, double.parse(currentAmount.toStringAsFixed(2))));
    }

    setState(() {
      _result = double.parse(currentAmount.toStringAsFixed(2));
      _chartData = spots;
      _isLoading = false;
    });
  }

  Future<void> _saveSimulation() async {
    final i18n = Provider.of<I18nService>(context, listen: false);
    final firebaseService = Provider.of<FirebaseService>(context, listen: false);
    final userId = FirebaseAuth.instance.currentUser?.uid;

    if (_result == null || userId == null) {
      _showAlertDialog(i18n.t('simulation_error'), isError: true);
      return;
    }

    setState(() { _isLoading = true; });
    try {
      await firebaseService.saveSimulation(userId, {
        'valorInicial': double.tryParse(_initialValueController.text) ?? 0.0,
        'depositoMensal': double.tryParse(_monthlyDepositController.text) ?? 0.0,
        'taxaJuros': double.tryParse(_interestRateController.text) ?? 0.0,
        'periodoMeses': int.tryParse(_periodMonthsController.text) ?? 0,
        'resultadoFinal': _result,
        'simulationData': _chartData.map((spot) => {'x': spot.x.toInt(), 'y': spot.y}).toList(),
        'timestamp': DateTime.now().toIso8601String(),
      });
      _showAlertDialog(i18n.t('simulation_saved'));
    } catch (e) {
      _showAlertDialog(i18n.t('save_simulation_error'), isError: true);
    } finally {
      setState(() { _isLoading = false; });
    }
  }

  @override
  Widget build(BuildContext context) {
    final i18n = Provider.of<I18nService>(context);

    return Scaffold(
      backgroundColor: Colors.black,
      body: Container(
        decoration: const BoxDecoration(
          gradient: LinearGradient(
            colors: [_kGradientStart, _kGradientEnd],
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
          ),
        ),
        child: SafeArea(
          child: SingleChildScrollView(
            padding: const EdgeInsets.symmetric(horizontal: 24.0, vertical: 16.0),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                // Header
                Row(
                  children: [
                    IconButton(
                      icon: const Icon(Icons.arrow_back_rounded, color: Colors.white),
                      onPressed: () => Navigator.pop(context),
                    ),
                    const SizedBox(width: 8),
                    Flexible(
                      child: Text(
                        i18n.t('savings_simulator'),
                        style: GoogleFonts.montserrat(
                          color: const Color.fromARGB(255, 185, 185, 185),
                          fontSize: 28,
                          fontWeight: FontWeight.w700,
                        ),
                        overflow: TextOverflow.ellipsis,
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: 24),

                // Cartão Principal de Simulação
                _GlassCard(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.stretch,
                    children: [
                      Text(
                        i18n.t('calculate_growth'),
                        style: GoogleFonts.montserrat(
                          fontSize: 18,
                          color: Colors.white,
                          fontWeight: FontWeight.w600,
                        ),
                        textAlign: TextAlign.center,
                      ),
                      const SizedBox(height: 24),
                      _buildInputField(i18n.t('initial_value'), _initialValueController, i18n: i18n),
                      _buildInputField(i18n.t('monthly_deposit'), _monthlyDepositController, i18n: i18n),
                      _buildInputField(i18n.t('annual_interest_rate'), _interestRateController, i18n: i18n),
                      _buildInputField(i18n.t('period_months'), _periodMonthsController, i18n: i18n),
                      const SizedBox(height: 24),
                      ElevatedButton(
                        onPressed: _isLoading ? null : _simulateSavings,
                        style: ElevatedButton.styleFrom(
                          backgroundColor: _kAccent,
                          foregroundColor: Colors.black87,
                          padding: const EdgeInsets.symmetric(vertical: 16),
                          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
                          elevation: 8,
                          shadowColor: _kAccent.withOpacity(0.5),
                        ),
                        child: _isLoading
                            ? const SizedBox(height: 24, width: 24, child: CircularProgressIndicator(color: Colors.white, strokeWidth: 2))
                            : Text(
                                i18n.t('simulate_savings'),
                                style: GoogleFonts.montserrat(fontSize: 18, fontWeight: FontWeight.w600),
                              ),
                      ),
                    ],
                  ),
                ),
                
                if (_result != null) ...[
                  const SizedBox(height: 24),
                  // Cartão de Resultado e Gráfico
                  _GlassCard(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.stretch,
                      children: [
                        Text(
                          i18n.t('estimated_final_value'),
                          style: GoogleFonts.montserrat(
                            fontSize: 18,
                            color: Colors.white70,
                            fontWeight: FontWeight.w500,
                          ),
                          textAlign: TextAlign.center,
                        ),
                        const SizedBox(height: 8),
                        Text(
                          '${_result!.toStringAsFixed(2)} ${i18n.t('kwanza_symbol')}',
                          style: GoogleFonts.montserrat(
                            fontSize: 32,
                            color: _kAction,
                            fontWeight: FontWeight.bold,
                          ),
                          textAlign: TextAlign.center,
                        ),
                        const SizedBox(height: 24),
                        AspectRatio(
                          aspectRatio: 1.5, // Define uma proporção fixa, que é mais responsiva que uma altura fixa
                          child: LineChart(
                            _buildLineChartData(_chartData, i18n),
                          ),
                        ),
                        const SizedBox(height: 24),
                        ElevatedButton.icon(
                          onPressed: _isLoading ? null : _saveSimulation,
                          icon: _isLoading ? const SizedBox.shrink() : const Icon(Icons.save_rounded, size: 20),
                          label: _isLoading
                              ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(color: Colors.white, strokeWidth: 2))
                              : Text(i18n.t('save_simulation'), style: GoogleFonts.montserrat(fontSize: 16, fontWeight: FontWeight.w600)),
                          style: ElevatedButton.styleFrom(
                            backgroundColor: _kAction,
                            foregroundColor: Colors.black87,
                            padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
                            shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
                            elevation: 4,
                          ),
                        ),
                      ],
                    ),
                  ),
                ],

                const SizedBox(height: 32),
                _buildSectionHeader(i18n.t('saved_simulations')),
                const SizedBox(height: 16),
                
                // Lista de Simulações Salvas
                _savedSimulations.isEmpty
                    ? Text(
                        i18n.t('no_simulations'),
                        style: GoogleFonts.montserrat(color: Colors.white54, fontStyle: FontStyle.italic),
                        textAlign: TextAlign.center,
                      )
                    : ListView.builder(
                        shrinkWrap: true,
                        physics: const NeverScrollableScrollPhysics(),
                        itemCount: _savedSimulations.length,
                        itemBuilder: (context, index) {
                          final sim = _savedSimulations[index];
                          return _SimulationResultCard(
                            sim: sim,
                            i18n: i18n,
                          );
                        },
                      ),
                const SizedBox(height: 40),
              ],
            ),
          ),
        ),
      ),
    );
  }

  LineChartData _buildLineChartData(List<FlSpot> spots, I18nService i18n) {
    return LineChartData(
      gridData: FlGridData(
        show: true,
        drawVerticalLine: true,
        getDrawingHorizontalLine: (value) => FlLine(color: Colors.white12, strokeWidth: 1),
        getDrawingVerticalLine: (value) => FlLine(color: Colors.white12, strokeWidth: 1),
      ),
      titlesData: FlTitlesData(
        show: true,
        // CORREÇÃO: Usando a nova estrutura de `getTitlesWidget` (sem SideTitleWidget)
        bottomTitles: AxisTitles(
          sideTitles: SideTitles(
            showTitles: true,
            reservedSize: 30,
            getTitlesWidget: (value, meta) {
              // Retorna o Widget Text diretamente com um Padding
              return Padding(
                padding: const EdgeInsets.only(top: 8.0),
                child: Text(
                  'Mês ${value.toInt()}',
                  style: GoogleFonts.montserrat(fontSize: 10, color: Colors.white70),
                ),
              );
            },
          ),
        ),
        leftTitles: AxisTitles(
          sideTitles: SideTitles(
            showTitles: true,
            reservedSize: 40,
            getTitlesWidget: (value, meta) {
              // Retorna o Widget Text diretamente
              return Text(
                '${value.toInt()}',
                style: GoogleFonts.montserrat(fontSize: 10, color: Colors.white70),
                textAlign: TextAlign.right,
              );
            },
          ),
        ),
        topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
        rightTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
      ),
      borderData: FlBorderData(
        show: true,
        border: Border.all(color: Colors.white24, width: 1),
      ),
      lineBarsData: [
        LineChartBarData(
          spots: spots,
          isCurved: true,
          color: _kAccent,
          barWidth: 4,
          isStrokeCapRound: true,
          dotData: FlDotData(show: true, getDotPainter: (spot, percent, barData, index) => FlDotCirclePainter(radius: 4, color: _kAccent, strokeWidth: 2, strokeColor: Colors.black)),
          belowBarData: BarAreaData(
            show: true,
            gradient: LinearGradient(
              colors: [_kAccent.withOpacity(0.5), _kAccent.withOpacity(0)],
              begin: Alignment.bottomCenter,
              end: Alignment.topCenter,
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildInputField(String label, TextEditingController controller, {required I18nService i18n}) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 8.0),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            label,
            style: GoogleFonts.montserrat(
              fontSize: 16,
              fontWeight: FontWeight.w600,
              color: Colors.white70,
            ),
          ),
          const SizedBox(height: 8),
          Container(
            decoration: BoxDecoration(
              color: _kCardColor, // Fundo transparente
              borderRadius: BorderRadius.circular(12),
              border: Border.all(color: Colors.white24),
              boxShadow: [
                BoxShadow(
                  color: Colors.black.withOpacity(0.2),
                  blurRadius: 10,
                  offset: const Offset(0, 4),
                ),
              ],
            ),
            child: TextFormField(
              controller: controller,
              keyboardType: TextInputType.number,
              style: GoogleFonts.montserrat(color: const Color.fromARGB(255, 0, 0, 0)),
              decoration: InputDecoration(
                hintText: 'Ex: 100',
                hintStyle: GoogleFonts.montserrat(color: const Color.fromARGB(137, 26, 25, 25)),
                border: InputBorder.none, // Remove a borda padrão
                contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildSectionHeader(String title) {
    return Column(
      children: [
        const Divider(height: 20, thickness: 1.5, color: Colors.white12),
        const SizedBox(height: 16),
        Text(
          title,
          style: GoogleFonts.montserrat(fontSize: 22, fontWeight: FontWeight.bold, color: const Color.fromARGB(255, 255, 255, 255)),
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 8),
      ],
    );
  }
}

class _GlassCard extends StatelessWidget {
  final Widget child;
  const _GlassCard({required this.child});

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.all(24.0),
      decoration: BoxDecoration(
        color: _kCardColor,
        borderRadius: BorderRadius.circular(24.0),
        border: Border.all(color: const Color.fromARGB(255, 255, 255, 255).withOpacity(0.2)),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.4),
            blurRadius: 20,
            offset: const Offset(0, 10),
          ),
        ],
      ),
      child: child,
    );
  }
}

class _SimulationResultCard extends StatelessWidget {
  final SavingsSimulation sim;
  final I18nService i18n;

  const _SimulationResultCard({
    required this.sim,
    required this.i18n,
  });

  @override
  Widget build(BuildContext context) {
    return _GlassCard(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            '${i18n.t('estimated_final_value')}: ${sim.resultadoFinal.toStringAsFixed(2)} ${i18n.t('kwanza_symbol')}',
            style: GoogleFonts.montserrat(fontSize: 18, fontWeight: FontWeight.w600, color: _kAccent),
          ),
          const SizedBox(height: 12),
          Text(
            '${i18n.t('initial_value')}: ${sim.valorInicial.toStringAsFixed(2)} ${i18n.t('kwanza_symbol')}',
            style: GoogleFonts.montserrat(fontSize: 14, color: const Color.fromARGB(205, 255, 255, 255)),
          ),
          Text(
            '${i18n.t('monthly_deposit')}: ${sim.depositoMensal.toStringAsFixed(2)} ${i18n.t('kwanza_symbol')}',
            style: GoogleFonts.montserrat(fontSize: 14, color: Colors.white70),
          ),
          Text(
            '${i18n.t('annual_interest_rate')}: ${sim.taxaJuros.toStringAsFixed(1)}%',
            style: GoogleFonts.montserrat(fontSize: 14, color: Colors.white70),
          ),
          Text(
            '${i18n.t('period_months')}: ${sim.periodoMeses}',
            style: GoogleFonts.montserrat(fontSize: 14, color: Colors.white70),
          ),
          Text(
            'Salvo em: ${DateTime.parse(sim.timestamp).toLocal().toString().split(' ')[0]}',
            style: GoogleFonts.montserrat(fontSize: 12, color: Colors.white54),
          ),
        ],
      ),
    );
  }
}