unionflow-mobile-apps/lib/shared/design_system/components/union_line_chart.dart

import 'dart:math';
import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';
import '../tokens/unionflow_colors.dart';

/// Graphique en ligne UnionFlow - Pour afficher l'évolution temporelle
class UnionLineChart extends StatelessWidget {
  final List<FlSpot> spots;
  final String title;
  final String? subtitle;
  final Color? lineColor;
  final Color? gradientStartColor;
  final Color? gradientEndColor;

  const UnionLineChart({
    super.key,
    required this.spots,
    required this.title,
    this.subtitle,
    this.lineColor,
    this.gradientStartColor,
    this.gradientEndColor,
  });

  /// Calcule maxY de manière sécurisée pour éviter NaN, Infinity ou 0
  double _calculateSafeMaxY() {
    if (spots.isEmpty) return 100.0;

    final maxValue = spots.map((e) => e.y).reduce((a, b) => a > b ? a : b);

    // Si maxValue est invalide (NaN, Infinity) ou trop petit
    if (maxValue.isNaN || maxValue.isInfinite || maxValue <= 0) {
      return 100.0;
    }

    return maxValue * 1.2;
  }

  /// Calcule maxX de manière sécurisée
  double _calculateSafeMaxX() {
    if (spots.isEmpty) return 11.0; // 12 mois - 1
    return spots.length.toDouble() - 1;
  }

  /// Calcule l'intervalle de grille approprié basé sur maxY
  double _calculateGridInterval() {
    final maxY = _calculateSafeMaxY();

    // Calculer un intervalle qui donne environ 4-6 lignes de grille
    final baseInterval = maxY / 5;

    if (baseInterval == 0) return 20.0; // Fallback si maxY est trop petit

    // Arrondir à un nombre "propre" (puissance de 10)
    final magnitude = pow(10.0, (log(baseInterval) / log(10.0)).floor()).toDouble();
    final normalized = baseInterval / magnitude;

    // Arrondir vers le haut au multiple de 1, 2 ou 5 le plus proche
    double roundedInterval;
    if (normalized <= 1) {
      roundedInterval = 1;
    } else if (normalized <= 2) {
      roundedInterval = 2;
    } else if (normalized <= 5) {
      roundedInterval = 5;
    } else {
      roundedInterval = 10;
    }

    return roundedInterval * magnitude;
  }

  @override
  Widget build(BuildContext context) {
    final effectiveLineColor = lineColor ?? UnionFlowColors.unionGreen;
    final effectiveGradientStart = gradientStartColor ?? UnionFlowColors.unionGreen.withOpacity(0.3);
    final effectiveGradientEnd = gradientEndColor ?? UnionFlowColors.unionGreen.withOpacity(0.0);

    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: UnionFlowColors.surface,
        borderRadius: BorderRadius.circular(16),
        boxShadow: UnionFlowColors.softShadow,
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          // Header
          Text(
            title,
            style: const TextStyle(
              fontSize: 14,
              fontWeight: FontWeight.w600,
              color: UnionFlowColors.textPrimary,
            ),
          ),
          if (subtitle != null) ...[
            const SizedBox(height: 4),
            Text(
              subtitle!,
              style: const TextStyle(
                fontSize: 11,
                color: UnionFlowColors.textSecondary,
              ),
            ),
          ],
          const SizedBox(height: 20),

          // Chart
          SizedBox(
            height: 180,
            child: LineChart(
              LineChartData(
                gridData: FlGridData(
                  show: true,
                  drawVerticalLine: false,
                  horizontalInterval: _calculateGridInterval(),
                  getDrawingHorizontalLine: (value) {
                    return FlLine(
                      color: UnionFlowColors.border.withOpacity(0.2),
                      strokeWidth: 1,
                    );
                  },
                ),
                titlesData: FlTitlesData(
                  show: true,
                  rightTitles: const AxisTitles(
                    sideTitles: SideTitles(showTitles: false),
                  ),
                  topTitles: const AxisTitles(
                    sideTitles: SideTitles(showTitles: false),
                  ),
                  bottomTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      reservedSize: 30,
                      interval: 1,
                      getTitlesWidget: (value, meta) {
                        const months = ['Jan', 'Fév', 'Mar', 'Avr', 'Mai', 'Jun', 'Jul', 'Aoû', 'Sep', 'Oct', 'Nov', 'Déc'];
                        if (value.toInt() >= 0 && value.toInt() < months.length) {
                          return Padding(
                            padding: const EdgeInsets.only(top: 8.0),
                            child: Text(
                              months[value.toInt()],
                              style: const TextStyle(
                                fontSize: 10,
                                color: UnionFlowColors.textTertiary,
                              ),
                            ),
                          );
                        }
                        return const Text('');
                      },
                    ),
                  ),
                  leftTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      reservedSize: 40,
                      getTitlesWidget: (value, meta) {
                        return Text(
                          '${(value / 1000).toStringAsFixed(0)}K',
                          style: const TextStyle(
                            fontSize: 10,
                            color: UnionFlowColors.textTertiary,
                          ),
                        );
                      },
                    ),
                  ),
                ),
                borderData: FlBorderData(show: false),
                minX: 0,
                maxX: _calculateSafeMaxX(),
                minY: 0,
                maxY: _calculateSafeMaxY(),
                lineBarsData: [
                  LineChartBarData(
                    spots: spots,
                    isCurved: true,
                    color: effectiveLineColor,
                    barWidth: 3,
                    isStrokeCapRound: true,
                    dotData: FlDotData(
                      show: true,
                      getDotPainter: (spot, percent, barData, index) {
                        return FlDotCirclePainter(
                          radius: 4,
                          color: UnionFlowColors.surface,
                          strokeWidth: 2,
                          strokeColor: effectiveLineColor,
                        );
                      },
                    ),
                    belowBarData: BarAreaData(
                      show: true,
                      gradient: LinearGradient(
                        begin: Alignment.topCenter,
                        end: Alignment.bottomCenter,
                        colors: [
                          effectiveGradientStart,
                          effectiveGradientEnd,
                        ],
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}