centralize email parsing logic

shared/utils/email.test.ts

@@ -0,0 +1,24 @@
+import { parseEmail } from "./email";
+
+describe("parseEmail", () => {
+  it("should correctly parse email", () => {
+    expect(parseEmail("tom@example.com")).toEqual({
+      local: "tom",
+      domain: "example.com",
+    });
+    expect(parseEmail("tom.m@example.com")).toEqual({
+      local: "tom.m",
+      domain: "example.com",
+    });
+    expect(parseEmail("tom@subdomain.domain.com")).toEqual({
+      local: "tom",
+      domain: "subdomain.domain.com",
+    });
+  });
+
+  it("should throw error for invalid email", () => {
+    expect(() => parseEmail("")).toThrow();
+    expect(() => parseEmail("invalid")).toThrow();
+    expect(() => parseEmail("invalid@")).toThrow();
+  });
+});

shared/utils/email.ts

@@ -0,0 +1,15 @@
+/**
+ * Parse an email address into its local and domain parts.
+ *
+ * @param email The email address to parse
+ * @returns The local and domain parts of the email address, in lowercase
+ */
+export function parseEmail(email: string): { local: string; domain: string } {
+  const [local, domain] = email.toLowerCase().split("@");
+
+  if (!domain) {
+    throw new Error("Invalid email address");
+  }
+
+  return { local, domain };
+}