taler-ios

commit 29db29f2ec249ff94bc8286006b0c22b12b6705a
parent d16a62de5809a46688b8ffc8671cf5d7ecc95e87
Author: Marc Stibane <marc@taler.net>
Date:   Fri, 14 Aug 2026 20:22:42 +0200

AI: PreparedTemplate to avoid instantiiating twice

Diffstat:
M
TalerWallet1/Views/Sheets/Payment/PayTemplateScan.swift
 | 
12
+++++++++---
M
TalerWallet1/Views/Sheets/Payment/PaymentScan.swift
 | 
23
+++++++++++++++++++++++

2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/TalerWallet1/Views/Sheets/Payment/PayTemplateScan.swift b/TalerWallet1/Views/Sheets/Payment/PayTemplateScan.swift
@@ -41,6 +41,9 @@ struct PayTemplateScan: View {
     @State private var isPaivana = false
     @State private var summary: String = EMPTYSTRING       // templateParam
     @State private var scope: ScopeInfo? = nil
+    /// survives PaymentScan being popped and pushed again, so that we don't
+    ///  instantiate the template (= create another order) a second time
+    @State private var prepared: PreparedTemplate? = nil
 
 //    @State private var feeAmount: Amount? = nil
 //    @State private var feeStr: String = EMPTYSTRING
@@ -122,7 +125,8 @@ struct PayTemplateScan: View {
                                      amountToTransfer: $amountToTransfer,
                                               summary: $summary,
                                      amountIsEditable: amountIsEditable,
-                                    summaryIsEditable: summaryIsEditable)
+                                    summaryIsEditable: summaryIsEditable,
+                                             prepared: $prepared)
 
             // final destination with amountShortcut, when user tapped a shortcut
             let finalDestinationS = PaymentScan(stack: stack.push(),
@@ -131,7 +135,8 @@ struct PayTemplateScan: View {
                                      amountToTransfer: $amountShortcut,
                                               summary: $summary,
                                      amountIsEditable: amountIsEditable,
-                                    summaryIsEditable: summaryIsEditable)
+                                    summaryIsEditable: summaryIsEditable,
+                                             prepared: $prepared)
 
             // destination to subject input
             let inputDestination = SubjectInputV(stack: stack.push(),
@@ -196,7 +201,8 @@ struct PayTemplateScan: View {
                  amountToTransfer: $amountToTransfer,
                           summary: $summary,
                  amountIsEditable: amountIsEditable,
-                summaryIsEditable: summaryIsEditable)
+                summaryIsEditable: summaryIsEditable,
+                         prepared: $prepared)
             }
           } .navigationTitle(navTitle)
 //            .ignoresSafeArea(.keyboard, edges: .bottom)
diff --git a/TalerWallet1/Views/Sheets/Payment/PaymentScan.swift b/TalerWallet1/Views/Sheets/Payment/PaymentScan.swift
@@ -15,6 +15,12 @@ fileprivate func feeLabel(_ feeString: String) -> String {
     feeString.isEmpty ? EMPTYSTRING : String(localized: "+ \(feeString) fee")
 }
 
+/// The pay-template instantiation which already created an order at the merchant
+struct PreparedTemplate: Equatable {
+    let key: String                 // the parameters that order was created for
+    let transactionId: String
+}
+
 // MARK: -
 // Will be called either by the user scanning a <pay> QR code or tapping the provided link,
 // both from the shop's website - or even from a printed QR code.
@@ -31,6 +37,7 @@ struct PaymentScan: View, Sendable {
     @Binding var summary: String
     let amountIsEditable: Bool                      //
     let summaryIsEditable: Bool                      //
+    var prepared: Binding<PreparedTemplate?>? = nil // template only, lives in PayTemplateScan
 
     @EnvironmentObject private var model: WalletModel
     @EnvironmentObject private var controller: Controller
@@ -42,14 +49,30 @@ struct PaymentScan: View, Sendable {
     @State private var elapsed: Int = 0
     @State private var talerTX = TalerTransaction(dummyCurrency: DEMOCURRENCY)
 
+    /// the parameters an already instantiated template order belongs to
+    private var templateKey: String {
+        url.trimmedString + "\n"
+          + (amountIsEditable ? amountToTransfer.description : EMPTYSTRING) + "\n"
+          + (summaryIsEditable ? summary : EMPTYSTRING)
+    }
+
     @MainActor
     private func viewDidLoad() async {
 //        symLog.log(".task")
         if template {
+            /// Instantiating a template creates a fresh order at the merchant, and this view is
+            ///  pushed anew (with new @State) whenever the user navigates back and forward again
+            ///  - so only instantiate once per amount/subject the user entered.
+            let key = templateKey
+            if let already = prepared?.wrappedValue, already.key == key {
+                txId = already.transactionId
+                return
+            }
             if let templateResponse = try? await model.preparePayForTemplate(url.trimmedString,
                                                    amount: amountIsEditable ? amountToTransfer : nil,
                                                  summary: summaryIsEditable ? summary : nil) {
                 txId = templateResponse.transactionId
+                prepared?.wrappedValue = PreparedTemplate(key: key, transactionId: templateResponse.transactionId)
 //                preparePayResult = templateResponse
 //                let raw = templateResponse.amountRaw
 //                controller.updateAmount(raw, forSaved: url)