/**
     * Handles an activity result that's part of the purchase flow in in-app billing. If you
     * are calling {@link #launchPurchaseFlow}, then you must call this method from your
     * Activity's {@link android.app.Activity@onActivityResult} method. This method
     * MUST be called from the UI thread of the Activity.
     *
     * @param requestCode The requestCode as you received it.
     * @param resultCode The resultCode as you received it.
     * @param data The data (Intent) as you received it.
     * @return Returns true if the result was related to a purchase flow and was handled;
     *     false if the result was not related to a purchase, in which case you should
     *     handle it normally.
     */
    public boolean handleActivityResult(int requestCode, int resultCode, Intent data) {
        IabResult result;
        if (requestCode != mRequestCode) return false;

        checkNotDisposed();
        checkSetupDone("handleActivityResult");

        // end of async purchase operation that started on launchPurchaseFlow
        flagEndAsync();

        if (data == null) {
            logError("Null data in IAB activity result.");
            result = new IabResult(IABHELPER_BAD_RESPONSE, "Null data in IAB result");
            if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, null);
            return true;
        }

        int responseCode = getResponseCodeFromIntent(data);
        String purchaseData = data.getStringExtra(RESPONSE_INAPP_PURCHASE_DATA);
        String dataSignature = data.getStringExtra(RESPONSE_INAPP_SIGNATURE);

        if (resultCode == Activity.RESULT_OK && responseCode == BILLING_RESPONSE_RESULT_OK) {
            logDebug("Successful resultcode from purchase activity.");
            logDebug("Purchase data: " + purchaseData);
            logDebug("Data signature: " + dataSignature);
            logDebug("Extras: " + data.getExtras());
            logDebug("Expected item type: " + mPurchasingItemType);

            if (purchaseData == null || dataSignature == null) {
                logError("BUG: either purchaseData or dataSignature is null.");
                logDebug("Extras: " + data.getExtras().toString());
                result = new IabResult(IABHELPER_UNKNOWN_ERROR, "IAB returned null purchaseData or dataSignature");
                if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, null);
                return true;
            }

            Purchase purchase = null;
            try {
                purchase = new Purchase(mPurchasingItemType, purchaseData, dataSignature);
                String sku = purchase.getSku();

                // Verify signature
                if (!Security.verifyPurchase(mSignatureBase64, purchaseData, dataSignature)) {
                    logError("Purchase signature verification FAILED for sku " + sku);
                    result = new IabResult(IABHELPER_VERIFICATION_FAILED, "Signature verification failed for sku " + sku);
                    if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, purchase);
                    return true;
                }
                logDebug("Purchase signature successfully verified.");
            }
            catch (JSONException e) {
                logError("Failed to parse purchase data.");
                e.printStackTrace();
                result = new IabResult(IABHELPER_BAD_RESPONSE, "Failed to parse purchase data.");
                if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, null);
                return true;
            }

            if (mPurchaseListener != null) {
                mPurchaseListener.onIabPurchaseFinished(new IabResult(BILLING_RESPONSE_RESULT_OK, "Success"), purchase);
            }
        }
        else if (resultCode == Activity.RESULT_OK) {
            // result code was OK, but in-app billing response was not OK.
            logDebug("Result code was OK but in-app billing response was not OK: " + getResponseDesc(responseCode));
            if (mPurchaseListener != null) {
                result = new IabResult(responseCode, "Problem purchashing item.");
                mPurchaseListener.onIabPurchaseFinished(result, null);
            }
        }
        else if (resultCode == Activity.RESULT_CANCELED) {
            logDebug("Purchase canceled - Response: " + getResponseDesc(responseCode));
            result = new IabResult(IABHELPER_USER_CANCELLED, "User canceled.");
            if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, null);
        }
        else {
            logError("Purchase failed. Result code: " + Integer.toString(resultCode)
                    + ". Response: " + getResponseDesc(responseCode));
            result = new IabResult(IABHELPER_UNKNOWN_PURCHASE_RESPONSE, "Unknown purchase response.");
            if (mPurchaseListener != null) mPurchaseListener.onIabPurchaseFinished(result, null);
        }
        return true;
    }