From f69eb3d8a7fb2d181f44376df53ff3765d12867e Mon Sep 17 00:00:00 2001
From: Fuwn <contact@fuwn.me>
Date: Thu, 24 Jul 2025 18:10:43 +0200
Subject: feat: Development commit

---
 .../Data/PostGridViewState/PostGridViewState.swift |   1 +
 Sora/Views/Post/Grid/PostGridView.swift            | 574 +++++++++++----------
 2 files changed, 315 insertions(+), 260 deletions(-)

diff --git a/Sora/Data/PostGridViewState/PostGridViewState.swift b/Sora/Data/PostGridViewState/PostGridViewState.swift
index 266d05c..95e3396 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 scrollPostID: String?
   let createdAt = Date()
 }
diff --git a/Sora/Views/Post/Grid/PostGridView.swift b/Sora/Views/Post/Grid/PostGridView.swift
index f247370..99c7966 100644
--- a/Sora/Views/Post/Grid/PostGridView.swift
+++ b/Sora/Views/Post/Grid/PostGridView.swift
@@ -15,6 +15,8 @@ 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] = []
+  private static let topID = "PostGridScrollTop"
+  @State private var scrollID: String?
 
   @Environment(\.isSearching)
   private var isSearching
@@ -32,323 +34,366 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
       .filter { settings.displayRatings.contains($0.rating) } ?? []
   }
 
-  var body: some View {
-    ScrollViewReader { proxy in
-      ScrollView {
-        Group {
-          if let error = manager.error {
-            ContentUnavailableView(
-              "Provider Error",
-              systemImage: "exclamationmark.triangle.fill",
-              description: Text(error.localizedDescription)
-            )
-          }
+  @ViewBuilder private var gridContent: some View {
+    if let error = manager.error {
+      ContentUnavailableView(
+        "Provider Error",
+        systemImage: "exclamationmark.triangle.fill",
+        description: Text(error.localizedDescription)
+      )
+    }
 
-          if activePosts.isEmpty, manager.isLoading {
-            let gridItems = Array(
-              repeating: GridItem(.flexible()),
-              count: settings.thumbnailGridColumns
-            )
+    if activePosts.isEmpty, manager.isLoading {
+      placeholderGrid
+    } else {
+      gridView(columnCount: settings.thumbnailGridColumns)
+    }
+  }
 
-            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
+  @ViewBuilder private var placeholderGrid: some View {
+    let gridItems = Array(
+      repeating: GridItem(.flexible()),
+      count: settings.thumbnailGridColumns
+    )
 
-            if settings.alternativeThumbnailGrid {
-              let columnsData = (0..<columnCount).map { columnIndex in
-                activePosts.enumerated().compactMap { index, post in
-                  index % columnCount == columnIndex ? post : nil
-                }
-              }
+    LazyVGrid(columns: gridItems) {
+      ForEach(0..<(50 / settings.thumbnailGridColumns), id: \.self) { _ in
+        PostGridThumbnailPlaceholderView()
+      }
+    }
+    #if os(macOS)
+      .padding(8)
+    #else
+      .padding(.horizontal)
+    #endif
+    .transition(.opacity)
+  }
 
-              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 }
-                  .scrollTargetLayout()
-                }
-              }
-              #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 }
-              .scrollTargetLayout()
-              #if os(macOS)
-                .padding(8)
-              #else
-                .padding(.horizontal)
-              #endif
-              .transition(.opacity)
+  @ViewBuilder
+  private func gridView(columnCount: Int) -> some View {
+    if settings.alternativeThumbnailGrid {
+      let columnsData = computeColumnsData(columnCount: columnCount)
+
+      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 }
+          .scrollTargetLayout()
         }
-        .id(queryID)
-        .transition(.opacity)
       }
-      #if os(iOS)
-        .searchable(
-          text: $manager.searchText,
-          isPresented: $isSearchablePresented,
-          placement: .navigationBarDrawer(displayMode: .automatic),
-          prompt: "Tags"
-        )
+      #if os(macOS)
+        .padding(8)
       #else
-        .searchable(
-          text: $manager.searchText,
-          isPresented: $isSearchablePresented,
-          prompt: "Tags"
-        )
+        .padding(.horizontal)
       #endif
-      .searchSuggestions {
-        if settings.searchSuggestionsMode != .disabled && isSearchablePresented {
-          SearchSuggestionsView(
-            items: searchSuggestionsItems(),
-            searchText: $manager.searchText,
-            suppressNextSearchSubmit: $suppressNextSearchSubmit
-          )
-        }
+      .transition(.opacity)
+    } else {
+      WaterfallGrid(activePosts, id: \.id) { post in
+        waterfallGridContent(post: post)
+          .id(post.id)
+      }
+      .gridStyle(columns: columnCount)
+      .transaction { $0.animation = nil }
+      .scrollTargetLayout()
+      #if os(macOS)
+        .padding(8)
+      #else
+        .padding(.horizontal)
+      #endif
+      .transition(.opacity)
+    }
+  }
+
+  private func computeColumnsData(columnCount: Int) -> [[BooruPost]] {
+    (0..<columnCount).map { columnIndex in
+      activePosts.enumerated().compactMap { index, post in
+        index % columnCount == columnIndex ? post : nil
+      }
+    }
+  }
+
+  var body: some View {
+    ScrollView {
+      Color.clear
+        .frame(height: 0)
+        .id(Self.topID)
+        .scrollTargetLayout()
+
+      gridContent
+        .id(queryID)
+        .transition(.opacity)
+    }
+    .scrollPosition(id: $scrollID, anchor: .top)
+    .scrollTargetBehavior(.viewAligned)
+    #if os(iOS)
+      .searchable(
+        text: $manager.searchText,
+        isPresented: $isSearchablePresented,
+        placement: .navigationBarDrawer(displayMode: .automatic),
+        prompt: "Tags"
+      )
+    #else
+      .searchable(
+        text: $manager.searchText,
+        isPresented: $isSearchablePresented,
+        prompt: "Tags"
+      )
+    #endif
+    .searchSuggestions {
+      if settings.searchSuggestionsMode != .disabled && isSearchablePresented {
+        SearchSuggestionsView(
+          items: searchSuggestionsItems(),
+          searchText: $manager.searchText,
+          suppressNextSearchSubmit: $suppressNextSearchSubmit
+        )
       }
-      .onChange(of: manager.searchText) { _, newValue in
-        if settings.searchSuggestionsMode == .tags {
-          searchTask?.cancel()
+    }
+    .onChange(of: manager.searchText) { _, newValue in
+      if settings.searchSuggestionsMode == .tags {
+        searchTask?.cancel()
 
-          searchTask = Task {
-            try? await Task.sleep(nanoseconds: 300_000_000)
+        searchTask = Task {
+          try? await Task.sleep(nanoseconds: 300_000_000)
 
-            guard !Task.isCancelled else { return }
+          guard !Task.isCancelled else { return }
 
-            let searchTag = newValue.split(separator: " ").last.map(String.init) ?? ""
+          let searchTag = newValue.split(separator: " ").last.map(String.init) ?? ""
 
-            if !searchTag.isEmpty {
-              suggestions = await manager.searchTags(name: searchTag)
-            } else {
-              suggestions = []
-            }
+          if !searchTag.isEmpty {
+            suggestions = await manager.searchTags(name: searchTag)
+          } else {
+            suggestions = []
           }
         }
       }
-      .onSubmit(of: .search) {
-        if suppressNextSearchSubmit {
-          suppressNextSearchSubmit = false
-
-          return
-        }
+    }
+    .onSubmit(of: .search) {
+      if suppressNextSearchSubmit {
+        suppressNextSearchSubmit = false
 
-        Task(priority: .userInitiated) {
-          await manager.performSearch(settings: settings)
-        }
+        return
       }
-      .navigationDestination(for: BooruPost.self) { post in
-        PostDetailsView(post: post)
+
+      Task(priority: .userInitiated) {
+        await manager.performSearch(settings: settings)
       }
-      .onChange(of: isSearchablePresented) { _, isPresented in
-        if !isPresented, manager.searchText.isEmpty, !manager.isNavigatingHistory {
-          Task(priority: .userInitiated) { await manager.performSearch() }
-        }
+    }
+    .navigationDestination(for: BooruPost.self) { post in
+      PostDetailsView(post: post)
+    }
+    .onChange(of: isSearchablePresented) { _, isPresented in
+      if !isPresented, manager.searchText.isEmpty, !manager.isNavigatingHistory {
+        Task(priority: .userInitiated) { await manager.performSearch() }
       }
-      .onChange(of: manager.posts) { _, newPosts in
-        if manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count {
-          updateViewState(for: queryID, posts: newPosts)
-        }
+    }
+    .onChange(of: manager.posts) { _, newPosts in
+      if manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count {
+        updateViewState(for: queryID, posts: newPosts)
       }
-      .onChange(of: manager.currentPage) { _, newPage in
-        if manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count {
-          let queryID = manager.searchHistory[manager.historyIndex].id
+    }
+    .onChange(of: manager.currentPage) { _, newPage in
+      if manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count {
+        let queryID = manager.searchHistory[manager.historyIndex].id
 
-          updateViewState(for: queryID, currentPage: newPage)
-        }
+        updateViewState(for: queryID, currentPage: newPage)
       }
-      .onChange(of: manager.selectedPost) { _, newPost in
-        let queryID = manager.searchHistory.last { $0.tags == manager.tags }?.id ?? UUID()
+    }
+    .onChange(of: manager.selectedPost) { _, newPost in
+      let queryID = manager.searchHistory.last { $0.tags == manager.tags }?.id ?? UUID()
 
-        updateViewState(for: queryID, selectedPost: newPost, resetSelectedPost: newPost == nil)
+      updateViewState(for: queryID, selectedPost: newPost, resetSelectedPost: newPost == nil)
+    }
+    .onChange(of: scrollID) { _, newValue in
+      guard manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count else {
+        return
       }
-      .onChange(of: manager.historyIndex) { _, newIndex in
-        guard newIndex >= 0 && newIndex < manager.searchHistory.count else { return }
-
-        let queryID = manager.searchHistory[newIndex].id
-
-        if let state = viewStates[queryID] {
-          manager.posts = state.posts
-          manager.currentPage = state.currentPage
-          manager.selectedPost = state.selectedPost
-        } else {
-          manager.posts = []
-          manager.currentPage = 1
-
-          Task(priority: .userInitiated) {
-            await manager.fetchPosts(
-              page: 1,
-              tags: manager.searchHistory[newIndex].tags,
-              replace: true
-            )
-          }
-        }
 
-        proxy.scrollTo(queryID, anchor: .top)
+      let queryID = manager.searchHistory[manager.historyIndex].id
+
+      updateViewState(for: queryID, scrollPostID: newValue)
+    }
+    .onChange(of: manager.historyIndex) { _, newIndex in
+      guard newIndex >= 0 && newIndex < manager.searchHistory.count else { return }
+
+      let queryID = manager.searchHistory[newIndex].id
+
+      if let state = viewStates[queryID] {
+        manager.posts = state.posts
+        manager.currentPage = state.currentPage
+        manager.selectedPost = state.selectedPost
+      } else {
+        manager.posts = []
+        manager.currentPage = 1
+
+        Task(priority: .userInitiated) {
+          await manager.fetchPosts(
+            page: 1,
+            tags: manager.searchHistory[newIndex].tags,
+            replace: true
+          )
+        }
       }
-      .toolbar {
-        #if os(macOS)
-          ToolbarItem {
-            Button(action: {
-              Task {
-                await manager.fetchPosts(page: 1, tags: manager.tags, replace: true)
-              }
-            }) {
-              Label("Refresh", systemImage: "arrow.clockwise")
-            }
-            .disabled(manager.isLoading)
-          }
-        #endif
 
-        #if !os(macOS)
-          PlatformSpecificToolbarItem {
-            Button(action: { Task { isSearchHistoryPresented.toggle() } }) {
-              Label("Search History", systemImage: "clock.arrow.circlepath")
+      if let savedID = viewStates[queryID]?.scrollPostID {
+        scrollID = savedID
+      } else {
+        scrollID = Self.topID
+      }
+    }
+    .toolbar {
+      #if os(macOS)
+        ToolbarItem {
+          Button(action: {
+            Task {
+              await manager.fetchPosts(page: 1, tags: manager.tags, replace: true)
             }
+          }) {
+            Label("Refresh", systemImage: "arrow.clockwise")
           }
+          .disabled(manager.isLoading)
+        }
+      #endif
 
-          if #available(iOS 26, *), manager.isLoading || manager.isNavigatingHistory {
-            ToolbarItem(placement: .status) { ProgressView() }
+      #if !os(macOS)
+        PlatformSpecificToolbarItem {
+          Button(action: { Task { isSearchHistoryPresented.toggle() } }) {
+            Label("Search History", systemImage: "clock.arrow.circlepath")
           }
-        #endif
+        }
 
-        PlatformSpecificToolbarItem {
-          PostGridBookmarkButtonView()
-            .disabled(manager.tags.isEmpty)
+        if #available(iOS 26, *), manager.isLoading || manager.isNavigatingHistory {
+          ToolbarItem(placement: .status) { ProgressView() }
         }
+      #endif
 
-        PlatformSpecificToolbarItem {
-          Button(
-            action: {
-              Task(priority: .userInitiated) {
-                await manager.loadNextPage()
-              }
+      PlatformSpecificToolbarItem {
+        PostGridBookmarkButtonView()
+          .disabled(manager.tags.isEmpty)
+      }
+
+      PlatformSpecificToolbarItem {
+        Button(
+          action: {
+            Task(priority: .userInitiated) {
+              await manager.loadNextPage()
             }
-          ) {
-            Label(
-              "Manually Load Next Page",
-              systemImage: "arrow.down.to.line"
-            )
           }
-          .disabled(manager.isLoading)
+        ) {
+          Label(
+            "Manually Load Next Page",
+            systemImage: "arrow.down.to.line"
+          )
         }
+        .disabled(manager.isLoading)
+      }
 
-        #if !os(macOS)
-          if #unavailable(iOS 26), manager.isLoading || manager.isNavigatingHistory {
-            ToolbarItem(placement: .topBarTrailing) { ProgressView() }
-          }
-        #endif
-
-        PlatformSpecificToolbarItem(placement: .navigation) {
-          Menu {
-            ForEach(
-              Array(manager.searchHistory.enumerated().filter { $0.offset < manager.historyIndex }),
-              id: \.offset
-            ) { offset, query in
-              Button(action: {
-                manager.historyIndex = offset
-              }) {
-                Text(query.tags.isEmpty ? "No Tags" : query.tags.joined(separator: " "))
-              }
-            }
-          } label: {
-            Label("Previous Search", systemImage: "chevron.left")
-          } primaryAction: {
-            withAnimation {
-              manager.goBackInHistory()
+      #if !os(macOS)
+        if #unavailable(iOS 26), manager.isLoading || manager.isNavigatingHistory {
+          ToolbarItem(placement: .topBarTrailing) { ProgressView() }
+        }
+      #endif
+
+      PlatformSpecificToolbarItem(placement: .navigation) {
+        Menu {
+          ForEach(
+            Array(manager.searchHistory.enumerated().filter { $0.offset < manager.historyIndex }),
+            id: \.offset
+          ) { offset, query in
+            Button(action: {
+              manager.historyIndex = offset
+            }) {
+              Text(query.tags.isEmpty ? "No Tags" : query.tags.joined(separator: " "))
             }
           }
-          .disabled(!manager.canGoBackInHistory)
-          .id("previousSearchMenu")
+        } label: {
+          Label("Previous Search", systemImage: "chevron.left")
+        } primaryAction: {
+          withAnimation {
+            manager.goBackInHistory()
+          }
         }
+        .disabled(!manager.canGoBackInHistory)
+        .id("previousSearchMenu")
+      }
 
-        PlatformSpecificToolbarItem(placement: .navigation) {
-          Menu {
-            ForEach(
-              Array(manager.searchHistory.enumerated().filter { $0.offset > manager.historyIndex }),
-              id: \.offset
-            ) { offset, query in
-              Button(action: {
-                manager.historyIndex = offset
-              }) {
-                Text(query.tags.isEmpty ? "No Tags" : query.tags.joined(separator: " "))
-              }
-            }
-          } label: {
-            Label("Next Search", systemImage: "chevron.right")
-          } primaryAction: {
-            withAnimation {
-              manager.goForwardInHistory()
+      PlatformSpecificToolbarItem(placement: .navigation) {
+        Menu {
+          ForEach(
+            Array(manager.searchHistory.enumerated().filter { $0.offset > manager.historyIndex }),
+            id: \.offset
+          ) { offset, query in
+            Button(action: {
+              manager.historyIndex = offset
+            }) {
+              Text(query.tags.isEmpty ? "No Tags" : query.tags.joined(separator: " "))
             }
           }
-          .disabled(!manager.canGoForwardInHistory)
-          .id("nextSearchMenu")
+        } label: {
+          Label("Next Search", systemImage: "chevron.right")
+        } primaryAction: {
+          withAnimation {
+            manager.goForwardInHistory()
+          }
         }
+        .disabled(!manager.canGoForwardInHistory)
+        .id("nextSearchMenu")
       }
-      .navigationTitle("Posts")
-      .refreshable {
-        manager.clearCachedPages()
+    }
+    .navigationTitle("Posts")
+    .refreshable {
+      manager.clearCachedPages()
 
-        Task(priority: .userInitiated) {
-          await manager.fetchPosts(page: 1, tags: manager.tags, replace: true)
-        }
+      Task(priority: .userInitiated) {
+        await manager.fetchPosts(page: 1, tags: manager.tags, replace: true)
       }
-      .sheet(isPresented: $isSearchHistoryPresented) {
-        PostGridSearchHistoryView(
-          selectedTab: $selectedTab,
-          isPresented: $isSearchHistoryPresented
-        )
+    }
+    .sheet(isPresented: $isSearchHistoryPresented) {
+      PostGridSearchHistoryView(
+        selectedTab: $selectedTab,
+        isPresented: $isSearchHistoryPresented
+      )
+    }
+    .onAppear {
+      scrollID = viewStates[queryID]?.scrollPostID ?? Self.topID
+    }
+    .onDisappear {
+      guard manager.historyIndex >= 0 && manager.historyIndex < manager.searchHistory.count else {
+        return
       }
-      #if os(iOS)
-        .gesture(
-          DragGesture()
-            .onEnded { value in
-              if value.startLocation.x < 50 && value.translation.width > 100 {
-                withAnimation {
-                  manager.goBackInHistory()
-                }
-
-                debugPrint("ContentView: Swipe left, \(manager.searchHistory)")
+
+      let queryID = manager.searchHistory[manager.historyIndex].id
+
+      updateViewState(for: queryID, scrollPostID: scrollID)
+    }
+    #if os(iOS)
+      .gesture(
+        DragGesture()
+          .onEnded { value in
+            if value.startLocation.x < 50 && value.translation.width > 100 {
+              withAnimation {
+                manager.goBackInHistory()
               }
 
-              if value.startLocation.x > (UIScreen.main.bounds.width - 50)
-                && value.translation.width < -100
-              {
-                withAnimation {
-                  manager.goForwardInHistory()
-                }
+              debugPrint("ContentView: Swipe left, \(manager.searchHistory)")
+            }
 
-                debugPrint("ContentView: Swipe right, \(manager.searchHistory)")
+            if value.startLocation.x > (UIScreen.main.bounds.width - 50)
+              && value.translation.width < -100
+            {
+              withAnimation {
+                manager.goForwardInHistory()
               }
+
+              debugPrint("ContentView: Swipe right, \(manager.searchHistory)")
             }
-        )
-      #endif
-    }
+          }
+      )
+    #endif
   }
 
   private func waterfallGridContent(post: BooruPost) -> some View {
@@ -383,6 +428,7 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
     posts: [BooruPost] = [],
     currentPage: Int? = nil,
     selectedPost: BooruPost? = nil,
+    scrollPostID: String? = nil,
     resetSelectedPost: Bool = false,
   ) {
     let wasNewlyCreated = viewStates[queryID] == nil
@@ -398,6 +444,14 @@ struct PostGridView: View {  // swiftlint:disable:this type_body_length
       state.selectedPost = nil
     }
 
+    if let scrollPostID {
+      state.scrollPostID = scrollPostID
+    }
+
+    if wasNewlyCreated && state.scrollPostID == nil {
+      state.scrollPostID = Self.topID
+    }
+
     viewStates[queryID] = state
 
     if wasNewlyCreated {
-- 
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