feat(ynab): add you need a budget app integration

packages/backend/src/apps/you-need-a-budget/auth/verify-credentials.js

@@ -0,0 +1,33 @@
+const verifyCredentials = async ($) => {
+  if ($.auth.data.originalState !== $.auth.data.state) {
+    throw new Error(`The 'state' parameter does not match.`);
+  }
+  const oauthRedirectUrlField = $.app.auth.fields.find(
+    (field) => field.key == 'oAuthRedirectUrl'
+  );
+  const redirectUri = oauthRedirectUrlField.value;
+  const { data } = await $.http.post('https://app.ynab.com/oauth/token', {
+    client_id: $.auth.data.clientId,
+    client_secret: $.auth.data.clientSecret,
+    redirect_uri: redirectUri,
+    grant_type: 'authorization_code',
+    code: $.auth.data.code,
+  });
+
+  await $.auth.set({
+    accessToken: data.access_token,
+    tokenType: data.token_type,
+  });
+
+  await $.auth.set({
+    clientId: $.auth.data.clientId,
+    clientSecret: $.auth.data.clientSecret,
+    scope: data.scope,
+    createdAt: data.created_at,
+    expiresIn: data.expires_in,
+    refreshToken: data.refresh_token,
+    screenName: $.auth.data.screenName,
+  });
+};
+
+export default verifyCredentials;