[DTINAPPXO-3265][DTINAPPXO-3391] Resume Flow fix: Extract query-style params embedded in the hash fragment

src/lib/appSwitchResume.js

@@ -16,13 +16,67 @@ export type AppSwitchResumeParams = {|
   checkoutState: "onApprove" | "onCancel" | "onError",
 |};
 
+// When the merchant's return_url contains a hash fragment (e.g. /checkout/#payment),
+// PayPal params (token, PayerID) end up inside the hash as /checkout/#payment?token=...&PayerID=...
+// This helper splits the hash into its name and query-string parts,
+// checking for ? delimiter first, then falling back to &.
+function parseHashFragment(): {| hash: string, queryString: string |} {
+  const hashString =
+    window.location.hash && String(window.location.hash).slice(1);
+  if (!hashString) {
+    return { hash: "", queryString: "" };
+  }
+
+  // Check for ? delimiter first (e.g. #payment?token=...)
+  const questionMarkIndex = hashString.indexOf("?");
+  if (questionMarkIndex !== -1) {
+    return {
+      hash: hashString.slice(0, questionMarkIndex),
+      queryString: hashString.slice(questionMarkIndex + 1),
+    };
+  }
+
+  // Fallback to & delimiter (e.g. #payment&token=...)
+  const ampersandIndex = hashString.indexOf("&");
+  if (ampersandIndex !== -1) {
+    return {
+      hash: hashString.slice(0, ampersandIndex),
+      queryString: hashString.slice(ampersandIndex + 1),
+    };
+  }
+
+  return { hash: hashString, queryString: "" };
+}
+
+function getParamsFromHashFragment(): { [string]: string } {
+  const { queryString } = parseHashFragment();
+  if (!queryString) {
+    return {};
+  }
+  // eslint-disable-next-line compat/compat
+  return Object.fromEntries(new URLSearchParams(queryString));
+}
+
 // The Web fallback flow uses different set of query params then appswitch flow.
 function getAppSwitchParamsWebFallback(): AppSwitchResumeParams | null {
   try {
-    const params = Object.fromEntries(
+    const searchParams = Object.fromEntries(
       // eslint-disable-next-line compat/compat
       new URLSearchParams(window.location.search)
     );
+
+    // If no PayPal params found in query string, check if they are embedded
+    // inside the hash fragment. This happens when the merchant's return_url
+    // contains a hash (e.g. /checkout/#payment) and PayPal params were appended
+    // after the fragment: /checkout/#payment?token=...&PayerID=...
+    const params =
+      searchParams.token ||
+      searchParams.vaultSetupToken ||
+      searchParams.approval_token_id ||
+      searchParams.approval_session_id
+        ? searchParams
+        : { ...getParamsFromHashFragment(), ...searchParams };
+
     const {
       button_session_id: buttonSessionID,
       fundingSource,
@@ -57,31 +111,11 @@ function getAppSwitchParamsWebFallback(): AppSwitchResumeParams | null {
 }
 
 export function getAppSwitchResumeParams(): AppSwitchResumeParams | null {
-  const hashString =
-    window.location.hash && String(window.location.hash).slice(1);
-  if (!hashString) {
+  const { hash, queryString } = parseHashFragment();
+  if (!hash) {
     return getAppSwitchParamsWebFallback();
   }
 
-  let hash = "";
-  let queryString = "";
-
-  // first check for ? as the hash/query separator
-  const questionMarkIndex = hashString.indexOf("?");
-
-  if (questionMarkIndex !== -1) {
-    [hash, queryString] = hashString.split("?");
-  } else {
-    const ampersandIndex = hashString.indexOf("&");
-
-    if (ampersandIndex !== -1) {
-      hash = hashString.slice(0, ampersandIndex);
-      queryString = hashString.slice(ampersandIndex + 1);
-    } else {
-      hash = hashString;
-    }
-  }
-
   const isPostApprovalAction = [
     APP_SWITCH_RETURN_HASH.ONAPPROVE,
     APP_SWITCH_RETURN_HASH.ONCANCEL,