B2B-88: add starter kit structure and elements

packages/billing/lemon-squeezy/src/schema/lemon-squeezy-server-env.schema.ts

@@ -0,0 +1,32 @@
+import { z } from 'zod';
+
+/**
+ * @name getLemonSqueezyEnv
+ * @description Get the Lemon Squeezy environment variables.
+ * It will throw an error if any of the required variables are missing.
+ */
+export const getLemonSqueezyEnv = () =>
+  z
+    .object({
+      secretKey: z
+        .string({
+          description: `The secret key you created for your store. Please use the variable LEMON_SQUEEZY_SECRET_KEY to set it.`,
+        })
+        .min(1),
+      webhooksSecret: z
+        .string({
+          description: `The shared secret you created for your webhook. Please use the variable LEMON_SQUEEZY_SIGNING_SECRET to set it.`,
+        })
+        .min(1)
+        .max(40),
+      storeId: z
+        .string({
+          description: `The ID of your store. Please use the variable LEMON_SQUEEZY_STORE_ID to set it.`,
+        })
+        .min(1),
+    })
+    .parse({
+      secretKey: process.env.LEMON_SQUEEZY_SECRET_KEY,
+      webhooksSecret: process.env.LEMON_SQUEEZY_SIGNING_SECRET,
+      storeId: process.env.LEMON_SQUEEZY_STORE_ID,
+    });