Initial setup

lib/cart.ts

@@ -0,0 +1,105 @@
+import { useState, useCallback } from 'react';
+import useSWR, { mutate } from 'swr';
+
+async function getText(res) {
+  try {
+    return (await res.text()) || res.statusText;
+  } catch (error) {
+    return res.statusText;
+  }
+}
+
+async function getError(res) {
+  if (res.headers.get('Content-Type')?.includes('application/json')) {
+    const data = await res.json();
+    return data.errors[0];
+  }
+  return { message: await getText(res) };
+}
+
+async function fetcher(url) {
+  const res = await fetch(url);
+
+  if (res.status === 200) {
+    return res.json();
+  }
+  throw await getError(res);
+}
+
+export function useCart() {
+  return useSWR('/api/cart', fetcher);
+}
+
+export function useAddToCart() {
+  const [{ addingToCart, error }, setStatus] = useState({
+    addingToCart: false,
+  });
+  const addToCart = useCallback(async ({ product }) => {
+    setStatus({ addingToCart: true });
+
+    const res = await fetch('/api/cart', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({ product }),
+    });
+
+    // Product added as expected
+    if (res.status === 200) {
+      setStatus({ addingToCart: false });
+      return mutate('/api/cart');
+    }
+
+    const error = await getError(res);
+
+    console.error('Adding product to cart failed with:', res.status, error);
+    setStatus({ addingToCart: false, error });
+  }, []);
+
+  return { addToCart, addingToCart, error };
+}
+
+export function useUpdateCart() {
+  const [{ updatingCart, error }, setStatus] = useState({
+    updatingCart: false,
+  });
+  const updateCart = useCallback(async ({ product, item }) => {
+    setStatus({ updatingCart: true });
+
+    const res = await fetch(
+      `/api/cart?itemId=${item.id}`,
+      product.quantity < 1
+        ? { method: 'DELETE' }
+        : {
+            method: 'PUT',
+            headers: {
+              'Content-Type': 'application/json',
+            },
+            body: JSON.stringify({ product }),
+          }
+    );
+
+    // Product updated as expected
+    if (res.status === 200) {
+      setStatus({ updatingCart: false });
+      return mutate('/api/cart');
+    }
+
+    const error = await getError(res);
+
+    console.error('Update to cart failed with:', res.status, error);
+    setStatus({ updatingCart: false, error });
+  }, []);
+
+  return { updateCart, updatingCart, error };
+}
+
+export function useRemoveFromCart() {
+  const { updateCart, updatingCart, error } = useUpdateCart();
+  const removeFromCart = async ({ item }) => {
+    updateCart({ item, product: { quantity: 0 } });
+  };
+
+  return { removeFromCart, removingFromCart: updatingCart, error };
+}