feat: Development commit

4 files changed, 145 insertions, 78 deletions

diff --git a/Sora/Data/PostGridViewState/PostGridViewState.swift b/Sora/Data/PostGridViewState/PostGridViewState.swift
index 266d05c..ff7a32a 100644
--- a/Sora/Data/PostGridViewState/PostGridViewState.swift
+++ b/Sora/Data/PostGridViewState/PostGridViewState.swift
@@ -4,5 +4,6 @@ struct PostGridViewState: Equatable {
   var posts: [BooruPost] = []
   var currentPage: Int = 1
   var selectedPost: BooruPost?
+  var scrollPosition: BooruPost.ID?
   let createdAt = Date()
 }
diff --git a/Sora/Data/Scroll/ScrollPositionPreference.swift b/Sora/Data/Scroll/ScrollPositionPreference.swift
new file mode 100644
index 0000000..fb36bb1
--- /dev/null
+++ b/Sora/Data/Scroll/ScrollPositionPreference.swift
@@ -0,0 +1,6 @@
+import SwiftUI
+
+struct ScrollPositionPreference: Equatable {
+  let id: BooruPost.ID
+  let yPosition: CGFloat
+}
diff --git a/Sora/Data/Scroll/ScrollPositionPreferenceKey.swift b/Sora/Data/Scroll/ScrollPositionPreferenceKey.swift
new file mode 100644
index 0000000..6b78bdc
--- /dev/null
+++ b/Sora/Data/Scroll/ScrollPositionPreferenceKey.swift
@@ -0,0 +1,19 @@
+import SwiftUI
+
+struct ScrollPositionPreferenceKey: PreferenceKey {
+  typealias Value = ScrollPositionPreference?
+
+  static var defaultValue: Value = nil
+
+  static func reduce(value: inout Value, nextValue: () -> Value) {
+    guard let next = nextValue() else { return }
+
+    if let current = value {
+      if abs(next.yPosition) < abs(current.yPosition) {
+        value = next
+      }
+    } else {
+      value = next
+    }
+  }
+}
diff --git a/Sora/Views/Post/Grid/PostGridView.swift b/Sora/Views/Post/Grid/PostGridView.swift
index 97604e5..5b48e1e 100644
--- a/Sora/Views/Post/Grid/PostGridView.swift
+++ b/Sora/Views/Post/Grid/PostGridView.swift
@@ -1,3 +1,5 @@
+// swiftlint:disable file_length
+
 import SwiftUI
 import WaterfallGrid
 
@@ -13,100 +15,120 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
   @State private var suppressNextSearchSubmit = false
   @State private var searchTask: Task<Void, Never>?
   @State private var suggestions: [BooruTag] = []
+  @State private var topItemID: BooruPost.ID?
+  @State private var debounceTask: Task<Void, Never>?
 
   @Environment(\.isSearching)
   private var isSearching
 
-  var filteredPosts: [BooruPost] {
-    manager.posts
-      .filter { settings.displayRatings.contains($0.rating) }
+  private var activePosts: [BooruPost] {
+    guard manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count else {
+      return []
+    }
+
+    let queryID = manager.searchHistory[manager.historyIndex].id
+
+    return viewStates[queryID]?.posts
+      .filter { settings.displayRatings.contains($0.rating) } ?? []
   }
 
   var body: some View {
-    ScrollViewReader { _ in
-      ZStack {
-        ForEach(Array(manager.searchHistory.enumerated()), id: \.element.id) { index, query in
-          let isActive = index == manager.historyIndex
-          let filteredPosts =
-            viewStates[query.id]?.posts
-            .filter { settings.displayRatings.contains($0.rating) } ?? []
-
-          ScrollView {
-            Group {
-              if let error = manager.error {
-                ContentUnavailableView(
-                  "Provider Error",
-                  systemImage: "exclamationmark.triangle.fill",
-                  description: Text(error.localizedDescription)
-                )
-              }
+    ScrollViewReader { proxy in
+      ScrollView {
+        Group {
+          if let error = manager.error {
+            ContentUnavailableView(
+              "Provider Error",
+              systemImage: "exclamationmark.triangle.fill",
+              description: Text(error.localizedDescription)
+            )
+          }
 
-              if filteredPosts.isEmpty, isActive, manager.isLoading {
-                let gridItems = Array(
-                  repeating: GridItem(.flexible()),
-                  count: settings.thumbnailGridColumns
-                )
+          if activePosts.isEmpty, manager.isLoading {
+            let gridItems = Array(
+              repeating: GridItem(.flexible()),
+              count: settings.thumbnailGridColumns
+            )
 
-                LazyVGrid(columns: gridItems) {
-                  ForEach(0..<(50 / settings.thumbnailGridColumns), id: \.self) { _ in
-                    PostGridThumbnailPlaceholderView()
-                  }
+            LazyVGrid(columns: gridItems) {
+              ForEach(0..<(50 / settings.thumbnailGridColumns), id: \.self) { _ in
+                PostGridThumbnailPlaceholderView()
+              }
+            }
+            #if os(macOS)
+              .padding(8)
+            #else
+              .padding(.horizontal)
+            #endif
+            .transition(.opacity)
+          } else {
+            let columnCount = settings.thumbnailGridColumns
+
+            if settings.alternativeThumbnailGrid {
+              let columnsData = (0..<columnCount).map { columnIndex in
+                activePosts.enumerated().compactMap { index, post in
+                  index % columnCount == columnIndex ? post : nil
                 }
-                #if os(macOS)
-                  .padding(8)
-                #else
-                  .padding(.horizontal)
-                #endif
-                .transition(.opacity)
-              } else {
-                let columnCount = settings.thumbnailGridColumns
-
-                if settings.alternativeThumbnailGrid {
-                  let columnsData = (0..<columnCount).map { columnIndex in
-                    filteredPosts.enumerated().compactMap { index, post in
-                      index % columnCount == columnIndex ? post : nil
-                    }
-                  }
+              }
 
-                  HStack(alignment: .top) {
-                    ForEach(0..<columnCount, id: \.self) { columnIndex in
-                      LazyVStack {
-                        ForEach(columnsData[columnIndex], id: \.id) { post in
-                          waterfallGridContent(post: post)
-                            .id(post.id)
-                        }
-                      }
-                      .transaction { $0.animation = nil }
+              HStack(alignment: .top) {
+                ForEach(0..<columnCount, id: \.self) { columnIndex in
+                  LazyVStack {
+                    ForEach(columnsData[columnIndex], id: \.id) { post in
+                      waterfallGridContent(post: post)
+                        .id(post.id)
                     }
                   }
-                  #if os(macOS)
-                    .padding(8)
-                  #else
-                    .padding(.horizontal)
-                  #endif
-                  .transition(.opacity)
-                } else {
-                  WaterfallGrid(filteredPosts, id: \.id) { post in
-                    waterfallGridContent(post: post)
-                      .id(post.id)
-                  }
-                  .gridStyle(columns: columnCount)
                   .transaction { $0.animation = nil }
-                  #if os(macOS)
-                    .padding(8)
-                  #else
-                    .padding(.horizontal)
-                  #endif
-                  .transition(.opacity)
                 }
               }
+              #if os(macOS)
+                .padding(8)
+              #else
+                .padding(.horizontal)
+              #endif
+              .transition(.opacity)
+            } else {
+              WaterfallGrid(activePosts, id: \.id) { post in
+                waterfallGridContent(post: post)
+                  .id(post.id)
+              }
+              .gridStyle(columns: columnCount)
+              .transaction { $0.animation = nil }
+              #if os(macOS)
+                .padding(8)
+              #else
+                .padding(.horizontal)
+              #endif
+              .transition(.opacity)
             }
-            .animation(.easeInOut, value: manager.isLoading)
           }
-          .id(query.id)
-          .opacity(isActive ? 1 : 0)
-          .frame(height: isActive ? nil : 0)
-          .animation(.easeInOut, value: isActive)
+        }
+        .id(manager.historyIndex)
+        .animation(.easeInOut, value: manager.isLoading)
+      }
+      .coordinateSpace(name: "scrollview")
+      .onPreferenceChange(ScrollPositionPreferenceKey.self) { preference in
+        topItemID = preference?.id
+      }
+      .onChange(of: topItemID) { _, newID in
+        debounceTask?.cancel()
+
+        debounceTask = Task {
+          do {
+            try await Task.sleep(for: .seconds(0.5))
+
+            guard let newID,
+              manager.historyIndex >= 0,
+              manager.historyIndex < manager.searchHistory.count
+            else { return }
+
+            let queryID = manager.searchHistory[manager.historyIndex].id
+
+            updateViewState(for: queryID, scrollPosition: newID)
+          } catch {
+            return
+          }
         }
       }
       .animation(.easeInOut, value: manager.historyIndex)
@@ -199,6 +221,12 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
           manager.posts = state.posts
           manager.currentPage = state.currentPage
           manager.selectedPost = state.selectedPost
+
+          if let scrollPosition = state.scrollPosition {
+            DispatchQueue.main.async {
+              proxy.scrollTo(scrollPosition, anchor: .top)
+            }
+          }
         } else {
           manager.posts = []
           manager.currentPage = 1
@@ -344,7 +372,17 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
     Button {
       if !manager.isLoading { manager.selectedPost = post }
     } label: {
-      PostGridThumbnailView(post: post, posts: filteredPosts)
+      PostGridThumbnailView(post: post, posts: activePosts)
+        .background(
+          GeometryReader { geometry in
+            let frame = geometry.frame(in: .named("scrollview"))
+
+            Color.clear.preference(
+              key: ScrollPositionPreferenceKey.self,
+              value: ScrollPositionPreference(id: post.id, yPosition: frame.minY)
+            )
+          }
+        )
     }
     .buttonStyle(PlainButtonStyle())
     .contextMenu {
@@ -372,7 +410,8 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
     posts: [BooruPost] = [],
     currentPage: Int? = nil,
     selectedPost: BooruPost? = nil,
-    resetSelectedPost: Bool = false
+    resetSelectedPost: Bool = false,
+    scrollPosition: BooruPost.ID? = nil
   ) {
     let wasNewlyCreated = viewStates[queryID] == nil
     var state = viewStates[queryID] ?? PostGridViewState()
@@ -381,6 +420,8 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
 
     if let currentPage { state.currentPage = currentPage }
 
+    if let scrollPosition { state.scrollPosition = scrollPosition }
+
     if let selectedPost {
       state.selectedPost = selectedPost
     } else if resetSelectedPost {