feat(POS-010): completed feature

project/apps/pos/src/components/DiscountPanel.tsx

@@ -0,0 +1,81 @@
+'use client';
+import { useState } from 'react';
+import { formatPrice } from '@/lib/money';
+
+interface DiscountPanelProps {
+  /** Unit price in cents of the selected item. */
+  unitPriceCents: number;
+  /** Called when a discount is applied. */
+  onApply: (discountCents: number) => void;
+  onClose: () => void;
+}
+
+export default function DiscountPanel({ unitPriceCents, onApply, onClose }: DiscountPanelProps) {
+  const [mode, setMode] = useState<'percent' | 'fixed'>('percent');
+  const [value, setValue] = useState('');
+  const [error, setError] = useState('');
+
+  const discountCents =
+    mode === 'percent'
+      ? Math.round(((Number(value) || 0) / 100) * unitPriceCents)
+      : Number(value) || 0;
+
+  const handleApply = () => {
+    if (!value) return;
+    if (discountCents > unitPriceCents) { setError('Descuento mayor al precio'); return; }
+    onApply(discountCents);
+    onClose();
+  };
+
+  return (
+    <div className="bg-white rounded-2xl shadow-xl p-6 w-80 space-y-4">
+      <div className="flex justify-between items-center">
+        <h2 className="text-lg font-bold" style={{ color: 'var(--color-primary)' }}>Aplicar descuento</h2>
+        <button onClick={onClose} className="text-gray-400 hover:text-gray-600 text-xl">✕</button>
+      </div>
+
+      <div className="flex gap-2">
+        <button
+          onClick={() => setMode('percent')}
+          className={`flex-1 py-2 rounded-xl font-medium ${mode === 'percent' ? 'bg-[#2D6A4F] text-white' : 'bg-gray-100'}`}
+        >
+          %
+        </button>
+        <button
+          onClick={() => setMode('fixed')}
+          className={`flex-1 py-2 rounded-xl font-medium ${mode === 'fixed' ? 'bg-[#2D6A4F] text-white' : 'bg-gray-100'}`}
+        >
+          Fijo
+        </button>
+      </div>
+
+      <div>
+        <input
+          type="number"
+          value={value}
+          onChange={(e) => { setValue(e.target.value); setError(''); }}
+          placeholder={mode === 'percent' ? 'Porcentaje (%)' : 'Cantidad (céntimos)'}
+          className="w-full px-4 py-3 border-2 border-gray-200 rounded-xl text-lg focus:border-[#2D6A4F] outline-none"
+          min={0}
+          max={mode === 'percent' ? 100 : unitPriceCents}
+          autoFocus
+        />
+        {error && <p className="text-sm text-red-500 mt-1">{error}</p>}
+      </div>
+
+      <div className="bg-gray-50 rounded-xl p-3 space-y-1 text-sm">
+        <div className="flex justify-between"><span>Precio original</span><span className="font-medium">{formatPrice(unitPriceCents)}</span></div>
+        <div className="flex justify-between"><span>Descuento</span><span className="font-medium text-red-500">-{formatPrice(discountCents)}</span></div>
+        <div className="flex justify-between border-t pt-1"><span>Precio final</span><span className="font-bold" style={{ color: 'var(--color-primary)' }}>{formatPrice(unitPriceCents - discountCents)}</span></div>
+      </div>
+
+      <button
+        onClick={handleApply}
+        disabled={!value || discountCents <= 0 || discountCents > unitPriceCents}
+        className="w-full py-3 bg-[#2D6A4F] hover:bg-[#1B4332] disabled:opacity-40 text-white font-bold rounded-xl transition-colors"
+      >
+        Aplicar
+      </button>
+    </div>
+  );
+}

project/src/modules/pos/api/pos.routes.ts

@@ -640,4 +640,48 @@ export async function registerPosRoutes(app: FastifyInstance, deps: PosRouteDeps
     return reply.send(result.rows[0]);
   });
 
+
+  // ── POS-010: Discount validation ──────────────────────────────────────────
+
+  app.post('/pos/discounts/validate', {
+    schema: {
+      tags: ['POS Terminal'],
+      summary: 'Validate discount before applying',
+      body: {
+        type: 'object',
+        required: ['unitPriceCents', 'discountCents'],
+        properties: {
+          unitPriceCents: { type: 'integer', minimum: 0 },
+          discountCents: { type: 'integer', minimum: 0 },
+          discountPercent: { type: 'number', minimum: 0, maximum: 100 },
+          role: { type: 'string', enum: ['admin', 'pos_manager', 'pos_cashier'] },
+        },
+      },
+      response: { 401: errorSchema, 403: errorSchema },
+    } as FastifySchema,
+  }, async (request, reply) => {
+    const user = await authenticate(request);
+    requireAnyRole(user, ['admin', 'pos_manager', 'pos_cashier'] as ReadonlyArray<Role>);
+    const body = (request.body ?? {}) as { unitPriceCents?: number; discountCents?: number; discountPercent?: number; role?: string };
+    const unitPriceCents = body.unitPriceCents ?? 0;
+    const discountCents = body.discountCents ?? 0;
+    const discountPercent = body.discountPercent ?? (unitPriceCents > 0 ? (discountCents / unitPriceCents) * 100 : 0);
+
+    // Cashiers capped at 50% per item
+    const maxPercent = user.role === 'pos_manager' || user.role === 'admin' ? 100 : 50;
+    if (discountPercent > maxPercent) {
+      throw new AppError(403, 'DISCOUNT_EXCEEDED', `Discount ${discountPercent.toFixed(0)}% exceeds max ${maxPercent}% for role`);
+    }
+    if (discountCents > unitPriceCents) {
+      throw new AppError(400, 'INVALID_DISCOUNT', 'Discount cannot exceed unit price');
+    }
+    return reply.send({
+      valid: true,
+      maxPercent,
+      appliedPercent: discountPercent,
+      appliedCents: discountCents,
+      finalPriceCents: unitPriceCents - discountCents,
+    });
+  });
+
 }