[Identity] Live user feedback during document capture to flip ID Document over if incorrect side is detected, center ID if off center, if it is an invalid document, and show if ID is blurry

StripeIdentity/StripeIdentity/Resources/Localizations/en.lproj/Localizable.strings

@@ -64,6 +64,9 @@
 /* Instructional text for scanning back of a identity card */
 "Flip your identity card over to the other side" = "Flip your identity card over to the other side";
 
+/* Instructional text when the opposite side of the ID is shown */
+"Incorrect side detected, flip document over" = "Incorrect side detected, flip document over";
+
 /* Accessibility label when front driver's license, passport, or government issued photo id photo has successfully uploaded */
 "Front %@ photo successfully uploaded" = "Front %@ photo successfully uploaded";
 

StripeIdentity/StripeIdentity/Source/Helpers/String+Localized.swift

@@ -75,6 +75,13 @@ extension String.Localized {
         )
     }
 
+    static var incorrect_side_flip: String {
+        return STPLocalizedString(
+            "Incorrect side detected, flip document over",
+            "Instructional text when the opposite side of the ID is shown"
+        )
+    }
+
     static var position_in_center_identity_card: String {
         return STPLocalizedString(
             "Position your identity document in the center of the frame",

StripeIdentity/StripeIdentity/Source/NativeComponents/ViewControllers/DocumentCaptureViewController+Strings.swift

@@ -70,7 +70,15 @@ extension DocumentCaptureViewController {
             let zoomLevel = idDetectorOutput.computeZoomLevel()
             switch (side, matchesClassification, zoomLevel) {
             case (.front, false, _), (.back, false, _):
-                return scanningTextWithNoInput(availableIDTypes: availableIDTypes, for: side)
+                // If wrong side is shown, provide explicit flip guidance
+                switch (side, foundClassification) {
+                case (.front, .idCardBack):
+                    return String.Localized.incorrect_side_flip
+                case (.back, .idCardFront), (.back, .passport):
+                    return String.Localized.incorrect_side_flip
+                default:
+                    return scanningTextWithNoInput(availableIDTypes: availableIDTypes, for: side)
+                }
             case (_, true, .ok):
                 return String.Localized.scanning
             case (_, true, .tooClose):