Ajout de Promotion et de Commande fonctionnel

src/context/PromotionsContext.jsx

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+import {
+  createContext,
+  useCallback,
+  useContext,
+  useEffect,
+  useMemo,
+  useState,
+} from 'react'
+
+const STORAGE_KEY = 'librairie-promotions'
+
+function loadPromotions() {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY)
+    if (raw === null) return []
+    const parsed = JSON.parse(raw)
+    return Array.isArray(parsed) ? parsed : []
+  } catch {
+    return []
+  }
+}
+
+function savePromotions(promotions) {
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(promotions))
+}
+
+function normalizeCode(code) {
+  return String(code || '')
+    .trim()
+    .toUpperCase()
+    .replace(/\s+/g, '')
+}
+
+const PromotionsContext = createContext(null)
+
+export function PromotionsProvider({ children }) {
+  const [promotions, setPromotions] = useState(loadPromotions)
+
+  useEffect(() => {
+    savePromotions(promotions)
+  }, [promotions])
+
+  const createPromotion = useCallback((promo) => {
+    const code = normalizeCode(promo.code)
+    const value = Number(promo.value)
+    if (!code) throw new Error('Code promo invalide')
+    if (!Number.isFinite(value) || value <= 0) {
+      throw new Error('Valeur de promo invalide')
+    }
+
+    setPromotions((prev) => {
+      if (prev.some((p) => p.code === code)) {
+        throw new Error('Ce code promo existe déjà')
+      }
+      return [
+        ...prev,
+        {
+          id: crypto.randomUUID(),
+          code,
+          type: 'percent',
+          value,
+          active: true,
+          createdAt: new Date().toISOString(),
+        },
+      ]
+    })
+  }, [])
+
+  const setPromotionActive = useCallback((code, active) => {
+    const normalized = normalizeCode(code)
+    setPromotions((prev) =>
+      prev.map((p) => (p.code === normalized ? { ...p, active } : p)),
+    )
+  }, [])
+
+  const removePromotion = useCallback((code) => {
+    const normalized = normalizeCode(code)
+    setPromotions((prev) => prev.filter((p) => p.code !== normalized))
+  }, [])
+
+  const getActivePromotionByCode = useCallback(
+    (code) => {
+      const normalized = normalizeCode(code)
+      return promotions.find((p) => p.code === normalized && p.active) || null
+    },
+    [promotions],
+  )
+
+  const value = useMemo(
+    () => ({
+      promotions,
+      createPromotion,
+      removePromotion,
+      setPromotionActive,
+      getActivePromotionByCode,
+      normalizeCode,
+    }),
+    [
+      promotions,
+      createPromotion,
+      removePromotion,
+      setPromotionActive,
+      getActivePromotionByCode,
+    ],
+  )
+
+  return (
+    <PromotionsContext.Provider value={value}>
+      {children}
+    </PromotionsContext.Provider>
+  )
+}
+
+// eslint-disable-next-line react-refresh/only-export-components
+export function usePromotions() {
+  const ctx = useContext(PromotionsContext)
+  if (!ctx) {
+    throw new Error('usePromotions doit être utilisé dans un PromotionsProvider')
+  }
+  return ctx
+}
+