From 76c10b1f87e8df2a7b1d13d51419cca250f59dcb Mon Sep 17 00:00:00 2001
From: eapuzzo <44156733+eapuzzo@users.noreply.github.com>
Date: Fri, 25 Mar 2022 10:43:35 +0100
Subject: [PATCH] fix: auto scroll small devices

Co-authored-by: Johnny Bueti <29045904+Fehniix@users.noreply.github.com>
---
 .../CustomPicker/CustomPickerController.swift | 31 ++++++++++++++++---
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/DGCAVerifier/UIComponents/CustomControllers/CustomPicker/CustomPickerController.swift b/DGCAVerifier/UIComponents/CustomControllers/CustomPicker/CustomPickerController.swift
index 0fc80f3..ae8e9f3 100644
--- a/DGCAVerifier/UIComponents/CustomControllers/CustomPicker/CustomPickerController.swift
+++ b/DGCAVerifier/UIComponents/CustomControllers/CustomPicker/CustomPickerController.swift
@@ -63,11 +63,10 @@ class CustomPickerController: UIViewController {
     
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-        
-        guard let scanMode = ScanMode.fetchFromLocalSettings() else { return }
-        if (scanMode == .school) {
-            let yOffset = self.scrollView.contentLayoutGuide.layoutFrame.height - self.scrollView.frameLayoutGuide.layoutFrame.size.height
-            self.scrollView.setContentOffset(CGPoint(x: 0, y: yOffset), animated: true)
+                        
+        let scrollOffset: Double = self.notVisibleOptionScrollOffset()
+        if (scrollOffset > 0) {
+            self.scrollView.setContentOffset(CGPoint(x: 0, y: scrollOffset), animated: true)
         }
     }
 
@@ -111,6 +110,28 @@ class CustomPickerController: UIViewController {
         self.optionViews.filter{ $0.scanMode == scanMode }.first?.didSelect()
     }
     
+    private func notVisibleOptionScrollOffset() -> Double {
+        guard let scanMode: ScanMode = ScanMode.fetchFromLocalSettings() else { return 0.0 }
+        guard let selectedOptionIndex: Int = self.optionViews.enumerated().compactMap({ index, optionView in
+            optionView.scanMode == scanMode ? index : nil
+        }).first else { return 0.0 }
+        
+        // Select first non-selected option to determine the height of a non-selected option.
+        // A selected option spans an additional view containing the scan mode description.
+        var baseNotSelectedOptionHeight: Double = 0.0
+        for index in 0..<self.optionsStackView.arrangedSubviews.count {
+            if index != selectedOptionIndex {
+                baseNotSelectedOptionHeight = self.optionsStackView.arrangedSubviews[index].frame.height
+                break
+            }
+        }
+
+        let unselectedOptionsHeight: Double = Double(selectedOptionIndex) * baseNotSelectedOptionHeight
+        let selectedOptionHeight: Double = self.optionsStackView.arrangedSubviews[selectedOptionIndex].frame.height
+        
+        return unselectedOptionsHeight + selectedOptionHeight - self.scrollView.frameLayoutGuide.layoutFrame.size.height
+    }
+    
     private func setupConfirmButtonInitialState() -> Void {
         Store.get(key: .scanMode) == nil ? disableConfirmButton() : enableConfirmButton()
     }