feat: parse sign in URI

packages/connect/src/messages/build.ts

@@ -1,6 +1,7 @@
 import { SiweMessage } from "siwe";
 import { ConnectResult } from "../errors";
 import { validate } from "./validate";
+import { parseSignInURI } from "./parseSignInURI";
 import { STATEMENT, CHAIN_ID } from "./constants";
 
 export type FarcasterResourceParams = {
@@ -17,6 +18,10 @@ export const build = (params: SignInMessageParams): ConnectResult<SiweMessage> =
   return validate(siweParams);
 };
 
+export const buildFromSignInURI = (signInUri: string, fid: number): ConnectResult<SiweMessage> => {
+  return parseSignInURI(signInUri).andThen(({ params }) => build({ ...params, fid }));
+};
+
 const buildFidResource = (fid: number): string => {
   return `farcaster://fid/${fid}`;
 };

packages/connect/src/messages/parseSignInURI.test.ts

@@ -0,0 +1,17 @@
+import { parseSignInURI } from "./parseSignInURI";
+
+describe("parseSignInUri", () => {
+  test("parses protocol handler URI into message params", () => {
+    const signInUri =
+      "farcaster://connect?channelToken=76be6229-bdf7-4ad2-930a-540fb2de1e08&nonce=ESsxs6MaFio7OvqWb&siweUri=https%3A%2F%2Fexample.com%2Flogin&domain=example.com";
+    const result = parseSignInURI(signInUri);
+    expect(result._unsafeUnwrap()).toStrictEqual({
+      channelToken: "76be6229-bdf7-4ad2-930a-540fb2de1e08",
+      params: {
+        domain: "example.com",
+        siweUri: "https://example.com/login",
+        nonce: "ESsxs6MaFio7OvqWb",
+      },
+    });
+  });
+});

packages/connect/src/messages/parseSignInURI.ts

@@ -0,0 +1,31 @@
+import { err, ok } from "neverthrow";
+import { ConnectError, ConnectResult } from "../errors";
+import { SignInMessageParams } from "./build";
+
+export interface ParsedSignInURI {
+  channelToken: string;
+  params: Partial<SignInMessageParams>;
+}
+
+export const parseSignInURI = (signInUri: string): ConnectResult<ParsedSignInURI> => {
+  const url = new URL(signInUri);
+  const searchParams = Object.fromEntries(url.searchParams.entries());
+  const { channelToken, ...params } = searchParams;
+  if (!channelToken) {
+    return err(validationFail("No channel token provided"));
+  }
+  if (!params["nonce"]) {
+    return err(validationFail("No nonce provided"));
+  }
+  if (!params["siweUri"]) {
+    return err(validationFail("No SIWE URI provided"));
+  }
+  if (!params["domain"]) {
+    return err(validationFail("No domain provided"));
+  }
+  return ok({ channelToken, params });
+};
+
+const validationFail = (message: string): ConnectError => {
+  return new ConnectError("bad_request.validation_failure", message);
+};