From a74139acfacd35cb199595835815f0acf3a0bf60 Mon Sep 17 00:00:00 2001
From: Qijia Liu <liumeo@pku.edu.cn>
Date: Sun, 15 Dec 2024 15:10:08 -0500
Subject: [PATCH] ListView: refactor vm; fix crash on delete; scroll on
 addition

---
 src/config/ListView.swift | 110 +++++++++++++++++++++-----------------
 1 file changed, 60 insertions(+), 50 deletions(-)

diff --git a/src/config/ListView.swift b/src/config/ListView.swift
index 79dca2c..c483930 100644
--- a/src/config/ListView.swift
+++ b/src/config/ListView.swift
@@ -1,40 +1,20 @@
 import SwiftUI
 
-private func deserialize(_ value: Any) -> [Any] {
+private struct ListItem: Identifiable {
+  let id = UUID()
+  var value: Any
+}
+
+private func deserialize(_ value: Any) -> [ListItem] {
   guard let value = value as? [String: Any] else {
     return []
   }
-  return (0..<value.count).compactMap { i in value[String(i)] }
+  return (0..<value.count).compactMap { i in ListItem(value: value[String(i)]!) }
 }
 
-private func serialize(_ value: [Any]) -> [String: Any] {
+private func serialize(_ value: [ListItem]) -> [String: Any] {
   return value.enumerated().reduce(into: [String: Any]()) { result, pair in
-    result[String(pair.offset)] = pair.element
-  }
-}
-
-private struct ListSectionHeader: View {
-  let children: Any?
-  @Binding var value: Any
-
-  var body: some View {
-    HStack {
-      Spacer()
-      Button {
-        var list = deserialize(value)
-        if let children = children as? [[String: Any]] {
-          list.append(
-            children.reduce(into: [:]) { result, child in
-              result[child["Option"] as! String] = child["DefaultValue"] ?? ""
-            } as NSDictionary)
-        } else {
-          list.append("")
-        }
-        value = serialize(list)
-      } label: {
-        Image(systemName: "plus")
-      }
-    }
+    result[String(pair.offset)] = pair.element.value
   }
 }
 
@@ -42,35 +22,65 @@ struct ListSubView: OptionViewProtocol {
   let label: String
   let data: [String: Any]
   @Binding var value: Any
+  @State private var list = [ListItem]()
 
   var body: some View {
     let type = data["Type"] as! String
     let optionViewType = toOptionViewType(["Type": String(type.suffix(type.count - "List|".count))])
-    var list = deserialize(value)
-    List {
-      Section(header: ListSectionHeader(children: data["Children"], value: $value)) {
-        ForEach(list.indices, id: \.self) { i in
-          AnyView(
-            optionViewType.init(
-              label: "", data: data,  // List|Entries need this.
-              value: Binding<Any>(
-                get: { list[i] },
-                set: {
-                  list[i] = $0
-                  value = serialize(list)
+    ScrollViewReader { proxy in
+      List {
+        Section {
+          ForEach(Array(zip(list.indices, list)), id: \.1.id) { i, item in
+            AnyView(
+              optionViewType.init(
+                label: "", data: data,  // List|Entries need this.
+                value: Binding<Any>(
+                  get: { item.value },
+                  set: {
+                    list[i] = ListItem(value: $0)
+                    value = serialize(list)
+                  }
+                ))
+            ).id(item.id)  // For scrolling.
+          }
+          .onDelete { offsets in
+            list.remove(atOffsets: offsets)
+            value = serialize(list)
+          }
+          .onMove { indices, newOffset in
+            list.move(fromOffsets: indices, toOffset: newOffset)
+            value = serialize(list)
+          }
+        } header: {
+          HStack {
+            Spacer()
+            Button {
+              if let children = data["Children"] as? [[String: Any]] {
+                list.append(
+                  ListItem(
+                    value:
+                      children.reduce(into: [:]) { result, child in
+                        result[child["Option"] as! String] = child["DefaultValue"] ?? ""
+                      }))
+              } else {
+                list.append(ListItem(value: ""))
+              }
+              value = serialize(list)
+              DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
+                withAnimation {
+                  proxy.scrollTo(list.last?.id)
                 }
-              )))
-        }
-        .onDelete { offsets in
-          list.remove(atOffsets: offsets)
-          value = serialize(list)
-        }
-        .onMove { indices, newOffset in
-          list.move(fromOffsets: indices, toOffset: newOffset)
-          value = serialize(list)
+              }
+            } label: {
+              Image(systemName: "plus")
+            }
+          }
         }
       }
     }.navigationTitle(label)
+      .onAppear {
+        list = deserialize(value)
+      }
   }
 }