feat: coloration des nœuds par balance nette (orange émetteur / vert récepteur)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/FlowMap.tsx

@@ -1,5 +1,25 @@
 import { useEffect, useRef, useState, useMemo } from 'react';
 import L from 'leaflet';
+
+/** Interpolation RGB linéaire entre deux couleurs hex, t ∈ [0, 1]. */
+function lerpColor(hex1: string, hex2: string, t: number): string {
+  const parse = (h: string) => [
+    parseInt(h.slice(1, 3), 16),
+    parseInt(h.slice(3, 5), 16),
+    parseInt(h.slice(5, 7), 16),
+  ];
+  const [r1, g1, b1] = parse(hex1);
+  const [r2, g2, b2] = parse(hex2);
+  const r = Math.round(r1 + (r2 - r1) * t);
+  const g = Math.round(g1 + (g2 - g1) * t);
+  const b = Math.round(b1 + (b2 - b1) * t);
+  return `#${r.toString(16).padStart(2, '0')}${g.toString(16).padStart(2, '0')}${b.toString(16).padStart(2, '0')}`;
+}
+
+const COLOR_NEUTRAL = '#d4a843'; // or Ğ1
+const COLOR_NEG     = '#ff6d00'; // orange vif
+const COLOR_POS     = '#00c853'; // vert vif
+const NEUTRAL_THRESHOLD = 0.05; // ±5 % → couleur neutre
 import type { TransactionArc } from '../data/arcData';
 import { buildCorridors } from '../data/arcData';
 
@@ -83,6 +103,7 @@ export function FlowMap({ arcs, focusCity, onCityClick }: FlowMapProps) {
 
     const maxVol     = Math.max(...corridors.map(c => c.totalVolume), 1);
     const maxNodeVol = Math.max(...[...cityNodes.values()].map(c => c.emitted + c.received), 1);
+    const maxAbsNet  = Math.max(...[...cityNodes.values()].map(d => Math.abs(d.received - d.emitted)), 1);
 
     // ---- Arcs ----
     const arcElems = corridors.map((c, idx) => {
@@ -139,7 +160,17 @@ export function FlowMap({ arcs, focusCity, onCityClick }: FlowMapProps) {
       const p   = proj(data.lat, data.lng);
       const vol = data.emitted + data.received;
       const r   = Math.max(3, Math.min(14, 3 + 9 * (vol / maxNodeVol)));
-      return { name, p, r, isSelected: focusCity === name };
+
+      // Couleur selon balance nette normalisée
+      const net = data.received - data.emitted;
+      const t   = net / maxAbsNet; // ∈ [-1, 1]
+      const fillColor = Math.abs(t) < NEUTRAL_THRESHOLD
+        ? COLOR_NEUTRAL
+        : t < 0
+          ? lerpColor(COLOR_NEUTRAL, COLOR_NEG, -t)
+          : lerpColor(COLOR_NEUTRAL, COLOR_POS,  t);
+
+      return { name, p, r, fillColor, isSelected: focusCity === name };
     });
 
     return { arcElems, nodeElems };
@@ -194,8 +225,8 @@ export function FlowMap({ arcs, focusCity, onCityClick }: FlowMapProps) {
                 cx={node.p.x}
                 cy={node.p.y}
                 r={node.r}
-                fill={node.isSelected ? '#ffffff' : '#d4a843'}
-                stroke={node.isSelected ? '#d4a843' : '#0a0b0f'}
+                fill={node.isSelected ? '#ffffff' : node.fillColor}
+                stroke={node.isSelected ? node.fillColor : '#0a0b0f'}
                 strokeWidth={1.5}
                 style={{ cursor: 'pointer' }}
                 onClick={() => onCityClick(focusCity === node.name ? null : node.name)}

src/components/StatsPanel.tsx

@@ -247,7 +247,13 @@ export function StatsPanel({ stats, loading, periodDays, source, currentUD, anim
               {/* Balance nette */}
               {flowStats.netBalance.length > 0 && (
                 <div className="bg-[#0f1016] border border-[#2e2f3a] rounded-xl p-3 space-y-1.5">
+                  <div className="flex items-center justify-between">
                     <p className="text-[#4b5563] text-xs uppercase tracking-widest">Balance nette</p>
+                    <p className="text-[10px] text-[#4b5563] flex items-center gap-1.5">
+                      <span style={{ color: '#ff6d00' }}>●</span>émetteur
+                      <span style={{ color: '#00c853' }}>●</span>récepteur
+                    </p>
+                  </div>
                   {flowStats.netBalance.map((c) => (
                     <div key={c.city} className="flex items-center justify-between">
                       <span className="text-white text-xs truncate">{c.city}</span>