feat: redesign travel album management

suixinkan/Features/TravelAlbum/ViewModels/TravelAlbumDetailViewModel.swift

@@ -27,11 +27,21 @@ final class TravelAlbumDetailViewModel {
             case .fileNameDesc: "文件名倒序"
             }
         }
+
+        var compactTitle: String {
+            switch self {
+            case .createdAsc: "时间 ↑"
+            case .createdDesc: "时间 ↓"
+            case .fileNameAsc: "名称 ↑"
+            case .fileNameDesc: "名称 ↓"
+            }
+        }
     }
 
     private(set) var album: TravelAlbum?
     private(set) var materials: [TravelAlbumMaterial] = []
     private(set) var allPhotoCount = 0
+    private(set) var purchasedPhotoCount = 0
     private(set) var selectedTab: Tab = .all
     private(set) var sortOption: SortOption = .createdDesc
     private(set) var isLoading = true
@@ -65,6 +75,7 @@ final class TravelAlbumDetailViewModel {
         notifyStateChange()
         await loadAlbumInfo(api: api)
         await loadAllPhotoCount(api: api)
+        await loadPurchasedPhotoCount(api: api)
         await loadMaterials(reset: true, api: api)
         isRefreshing = false
         isLoading = false
@@ -102,6 +113,30 @@ final class TravelAlbumDetailViewModel {
         }
     }
 
+    /// 拉取已购照片数量；失败时保留已有数量，不影响素材列表加载。
+    func loadPurchasedPhotoCount(api: any TravelAlbumServing) async {
+        do {
+            let response = try await api.materialList(
+                userEquityTravelId: albumId,
+                page: 1,
+                pageSize: 1,
+                orderBy: sortOption.rawValue,
+                isPurchased: 1
+            )
+            purchasedPhotoCount = response.total
+            notifyStateChange()
+        } catch is CancellationError {
+            return
+        } catch {
+            return
+        }
+    }
+
+    /// 摘要卡封面地址，依次回退相册封面、首张素材封面和首张素材原图。
+    var displayCoverURL: String {
+        TravelAlbumDisplayFormatter.albumCoverURL(album: album, materials: materials)
+    }
+
     /// 切换素材 tab。
     func selectTab(_ tab: Tab, api: any TravelAlbumServing) async {
         guard selectedTab != tab else { return }
@@ -144,6 +179,8 @@ final class TravelAlbumDetailViewModel {
             canLoadMore = materials.count < response.total
             if selectedTab == .all {
                 allPhotoCount = response.total
+            } else {
+                purchasedPhotoCount = response.total
             }
             isLoadingMore = false
             notifyStateChange()