Handle multiple visits to Paypal approval return URI

ts/services/donations.preload.ts

@@ -262,12 +262,34 @@ export async function approvePaypalPayment({
 
   try {
     const existing = _getWorkflowFromRedux();
+    const lastReturnToken = _getLastReturnTokenFromRedux();
+
     if (!existing) {
+      // This can happen if after you finished a Paypal donation, but you go back to
+      // the Paypal website and click Return to Signal again.
+      if (returnToken === lastReturnToken) {
+        if (!isDonationPageVisible()) {
+          redirectToPage(SettingsPage.Donations);
+        }
+        return;
+      }
+
       throw new Error(
         'approvePaypalPayment: Cannot finish nonexistent workflow!'
       );
     }
 
+    // If you visit the approval link twice in succession, this can happen
+    if (isPaypalAlreadyApproved(existing)) {
+      log.warn(
+        'approvePaypalPayment: Existing workflow already approved, not trying to approve again'
+      );
+      if (!isDonationPageVisible()) {
+        redirectToPage(SettingsPage.Donations);
+      }
+      return;
+    }
+
     if (payerId == null || paymentToken == null) {
       throw new Error(
         'approvePaypalPayment: payerId or paymentToken are missing'
@@ -296,15 +318,20 @@ export async function cancelPaypalPayment(_returnToken: string): Promise<void> {
   log.info(`${logId}: User visited PayPal cancel URI, showing donate flow`);
 
   if (!isDonationPageVisible()) {
-    window.reduxActions.nav.changeLocation({
-      tab: NavTab.Settings,
-      details: {
-        page: SettingsPage.DonationsDonateFlow,
-      },
-    });
+    redirectToPage(SettingsPage.DonationsDonateFlow);
   }
 }
 
+function isPaypalAlreadyApproved(workflow: DonationWorkflow): boolean {
+  const { type } = workflow;
+  return (
+    type === donationStateSchema.Enum.PAYPAL_APPROVED ||
+    type === donationStateSchema.Enum.PAYMENT_CONFIRMED ||
+    type === donationStateSchema.Enum.RECEIPT ||
+    type === donationStateSchema.Enum.DONE
+  );
+}
+
 export async function clearDonation(): Promise<void> {
   runDonationAbortController?.abort();
   await _saveWorkflow(undefined);
@@ -531,12 +558,7 @@ export async function _runDonationWorkflow(): Promise<void> {
         } else if (type === donationStateSchema.Enum.DONE) {
           if (isDonationPageVisible()) {
             if (isDonationsDonateFlowVisible()) {
-              window.reduxActions.nav.changeLocation({
-                tab: NavTab.Settings,
-                details: {
-                  page: SettingsPage.Donations,
-                },
-              });
+              redirectToPage(SettingsPage.Donations);
             }
           } else {
             log.info(
@@ -1178,6 +1200,9 @@ async function _saveWorkflow(
   await _saveWorkflowToStorage(workflow);
   _saveWorkflowToRedux(workflow);
 }
+export function _getLastReturnTokenFromRedux(): string | undefined {
+  return window.reduxStore.getState().donations.lastReturnToken;
+}
 export function _getWorkflowFromRedux(): DonationWorkflow | undefined {
   return window.reduxStore.getState().donations.currentWorkflow;
 }
@@ -1283,6 +1308,20 @@ function isDonationsDonateFlowVisible() {
   );
 }
 
+function redirectToPage(
+  page:
+    | SettingsPage.Donations
+    | SettingsPage.DonationsDonateFlow
+    | SettingsPage.DonationsReceiptList
+) {
+  window.reduxActions.nav.changeLocation({
+    tab: NavTab.Settings,
+    details: {
+      page,
+    },
+  });
+}
+
 // Working with zkgroup receipts
 
 function getServerPublicParams(): ServerPublicParams {

ts/services/donationsLoader.preload.ts

@@ -26,6 +26,7 @@ export function getDonationsForRedux(): DonationsStateType {
     currentWorkflow,
     didResumeWorkflowAtStartup: Boolean(currentWorkflow),
     lastError: undefined,
+    lastReturnToken: undefined,
     receipts: donationReceipts,
     configCache: undefined,
   };

ts/state/ducks/donations.preload.ts

@@ -45,6 +45,7 @@ export type DonationsStateType = ReadonlyDeep<{
   currentWorkflow: DonationWorkflow | undefined;
   didResumeWorkflowAtStartup: boolean;
   lastError: DonationErrorType | undefined;
+  lastReturnToken: string | undefined;
   receipts: Array<DonationReceipt>;
   configCache: OneTimeDonationHumanAmounts | undefined;
 }>;
@@ -435,6 +436,7 @@ export function getEmptyState(): DonationsStateType {
     currentWorkflow: undefined,
     didResumeWorkflowAtStartup: false,
     lastError: undefined,
+    lastReturnToken: undefined,
     receipts: [],
     configCache: undefined,
   };
@@ -475,6 +477,14 @@ export function reducer(
   if (action.type === UPDATE_WORKFLOW) {
     const { nextWorkflow } = action.payload;
 
+    let lastReturnToken: string | undefined;
+    const { currentWorkflow } = state;
+    if (currentWorkflow && 'returnToken' in currentWorkflow) {
+      lastReturnToken = currentWorkflow.returnToken;
+    } else {
+      lastReturnToken = state.lastReturnToken;
+    }
+
     // If we've cleared the workflow or are starting afresh, we clear the startup flag
     const didResumeWorkflowAtStartup =
       !nextWorkflow || nextWorkflow.type === donationStateSchema.Enum.INTENT
@@ -485,6 +495,7 @@ export function reducer(
       ...state,
       didResumeWorkflowAtStartup,
       currentWorkflow: nextWorkflow,
+      lastReturnToken,
     };
   }
 

ts/windows/main/preload_test.preload.ts

@@ -137,6 +137,7 @@ window.testUtilities = {
         currentWorkflow: undefined,
         didResumeWorkflowAtStartup: false,
         lastError: undefined,
+        lastReturnToken: undefined,
         receipts: [],
         configCache: undefined,
       },