add reducer in cart context

src/store/CartProvider.js

@@ -1,12 +1,38 @@
+import { useReducer } from "react";
 import CartContext from "./cart-context";
 
-const CartProvider = (props) => {
-  const addItemToCartHandler = (item) => {};
-  const removeItemFromCartHandler = (id) => {};
-
-  const cartContext = {
+const defaultCartState = {
   items: [],
   totalAmount: 0,
+};
+
+const cartReducer = (state, action) => {
+  if (action.type === "ADD_ITEM") {
+    const updatedItems = state.items.concat(action.item);
+    const updatedTotalAmount =
+      state.totalAmount + action.item.price * action.item.amount;
+    return { items: updatedItems, totalAmount: updatedTotalAmount };
+  } else if (action.type === "REMOVE_ITEM") {
+  }
+  return defaultCartState;
+};
+
+const CartProvider = (props) => {
+  const [cartState, dispatchCartAction] = useReducer(
+    cartReducer,
+    defaultCartState
+  );
+
+  const addItemToCartHandler = (item) => {
+    dispatchCartAction({ type: "ADD_ITEM", item: item });
+  };
+  const removeItemFromCartHandler = (id) => {
+    dispatchCartAction({ type: "REMOVE_ITEM", id: id });
+  };
+
+  const cartContext = {
+    items: cartState.items,
+    totalAmount: cartState.totalAmount,
     addItem: addItemToCartHandler,
     removeItem: removeItemFromCartHandler,
   };