Initial commit - Route Commerce platform

src/actions/tax.ts

@@ -0,0 +1,123 @@
+"use server";
+
+import Stripe from "stripe";
+import { svcHeaders } from "@/lib/svc-headers";
+
+export type TaxCalculationResult = {
+  taxAmount: number;
+  taxRate: number;
+  taxLocation: string;
+};
+
+type BrandTaxSettings = {
+  collect_sales_tax: boolean | null;
+  nexus_states: string[] | null;
+};
+
+export async function calculateOrderTax(params: {
+  brandId: string;
+  subtotal: number;
+  items: Array<{ id: string; quantity: number; price: number; name?: string; is_taxable?: boolean }>;
+  fulfillment: "pickup" | "ship";
+  shippingAddress?: { state: string; postal_code: string; city?: string };
+}): Promise<TaxCalculationResult> {
+  // 1. If not collecting tax, return zero
+  const taxSettings = await getBrandTaxSettings(params.brandId);
+  if (!taxSettings?.collect_sales_tax) {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+
+  // 2. Pickup orders are not taxable in most states
+  if (params.fulfillment === "pickup") {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+
+  // 3. Must have a shipping address in nexus states
+  if (!params.shippingAddress?.state) {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+
+  const nexus = taxSettings.nexus_states ?? [];
+  const shipState = params.shippingAddress.state.toUpperCase();
+
+  if (!nexus.map((s) => s.toUpperCase()).includes(shipState)) {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+
+  // 4. Stripe Tax calculation
+  const stripeKey = process.env.STRIPE_SECRET_KEY;
+  if (!stripeKey) {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+
+  try {
+    const stripe = new Stripe(stripeKey);
+
+    // Build Stripe line items for tax calculation — only taxable items
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const lineItems: any[] = params.items
+      .filter((item) => item.is_taxable !== false)
+      .map((item) => ({
+        amount: Math.round(item.price * item.quantity * 100), // cents
+        reference: item.id,
+        tax_behavior: "exclusive",
+      }));
+
+    // If no taxable items, return zero tax
+    if (lineItems.length === 0) {
+      return { taxAmount: 0, taxRate: 0, taxLocation: `STATE:${shipState}` };
+    }
+
+    const calculation = await stripe.tax.calculations.create({
+      currency: "usd",
+      line_items: lineItems,
+      customer_details: {
+        address: {
+          state: shipState,
+          postal_code: params.shippingAddress.postal_code,
+          city: params.shippingAddress.city,
+          country: "US",
+        },
+        address_source: "shipping",
+      },
+    });
+
+    if (!calculation.tax_amount_exclusive) {
+      return { taxAmount: 0, taxRate: 0, taxLocation: `STATE:${shipState}` };
+    }
+
+    const taxAmount = calculation.tax_amount_exclusive / 100;
+
+    // Derive effective rate from subtotal
+    const taxRate = params.subtotal > 0 ? taxAmount / params.subtotal : 0;
+
+    return {
+      taxAmount: Math.round(taxAmount * 100) / 100,
+      taxRate: Math.round(taxRate * 10000) / 10000,
+      taxLocation: `STATE:${shipState}`,
+    };
+  } catch (err) {
+    return { taxAmount: 0, taxRate: 0, taxLocation: "" };
+  }
+}
+
+async function getBrandTaxSettings(brandId: string): Promise<BrandTaxSettings | null> {
+  const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL!;
+  const supabaseKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!;
+
+  const response = await fetch(
+    `${supabaseUrl}/rest/v1/rpc/get_brand_settings`,
+    {
+      method: "POST",
+      headers: { ...svcHeaders(supabaseKey), "Content-Type": "application/json" },
+      body: JSON.stringify({ p_brand_id: brandId }),
+    }
+  );
+
+  if (!response.ok) return null;
+  const data = await response.json();
+  return {
+    collect_sales_tax: data?.collect_sales_tax ?? null,
+    nexus_states: data?.nexus_states ?? null,
+  };
+}