feat: 添加云盘与消息中心功能

suixinkan/Features/MessageCenter/ViewModels/MessageCenterViewModels.swift

@@ -0,0 +1,158 @@
+//
+//  MessageCenterViewModels.swift
+//  suixinkan
+//
+
+import Foundation
+
+/// 消息中心列表页 ViewModel，负责分页、刷新和未读点击处理。
+final class MessageCenterViewModel {
+    private(set) var items: [MessageItem] = []
+    private(set) var isLoading = false
+    private(set) var isRefreshing = false
+    private(set) var isLoadingMore = false
+    private(set) var canLoadMore = false
+
+    var onStateChange: (() -> Void)?
+    var onShowMessage: ((String) -> Void)?
+    var onOpenDetail: ((MessageItem) -> Void)?
+
+    private let pageSize = 20
+    private var lastId = 0
+
+    /// 首次加载消息列表。
+    func loadInitial(api: any MessageCenterServing) async {
+        await load(reset: true, showLoading: true, api: api)
+    }
+
+    /// 下拉刷新消息列表。
+    func refresh(api: any MessageCenterServing) async {
+        guard !isLoading else { return }
+        isRefreshing = true
+        notifyStateChange()
+        await load(reset: true, showLoading: false, api: api)
+    }
+
+    /// 滚动到底部附近时加载更多。
+    func loadMoreIfNeeded(lastVisibleIndex: Int, api: any MessageCenterServing) async {
+        guard lastVisibleIndex >= items.count - 4 else { return }
+        await load(reset: false, showLoading: false, api: api)
+    }
+
+    /// 点击消息：未读先标记已读，成功后进入详情；已读直接进入详情。
+    func selectMessage(id: Int, api: any MessageCenterServing) async {
+        guard let item = items.first(where: { $0.id == id }) else { return }
+        if item.isRead {
+            onOpenDetail?(item)
+            return
+        }
+
+        isLoading = true
+        notifyStateChange()
+        defer {
+            isLoading = false
+            notifyStateChange()
+        }
+
+        do {
+            try await api.markAsRead(messageId: id)
+            let readItem = item.markedRead()
+            items = items.map { $0.id == id ? readItem : $0 }
+            onOpenDetail?(readItem)
+        } catch is CancellationError {
+            return
+        } catch {
+            onShowMessage?("标记已读失败")
+        }
+    }
+
+    /// 删除后从本地列表移除消息。
+    func removeMessage(id: Int) {
+        items.removeAll { $0.id == id }
+        notifyStateChange()
+    }
+
+    private func load(reset: Bool, showLoading: Bool, api: any MessageCenterServing) async {
+        if reset {
+            lastId = 0
+            canLoadMore = false
+        } else {
+            guard canLoadMore, !isLoading, !isLoadingMore else { return }
+            isLoadingMore = true
+        }
+
+        isLoading = showLoading
+        notifyStateChange()
+        defer {
+            isLoading = false
+            isRefreshing = false
+            isLoadingMore = false
+            notifyStateChange()
+        }
+
+        do {
+            let response = try await api.list(lastId: reset ? 0 : lastId, limit: pageSize, unread: 0)
+            lastId = response.lastId
+            items = reset ? response.items : items + response.items
+            canLoadMore = response.hasMore && response.lastId > 0
+        } catch is CancellationError {
+            return
+        } catch {
+            if reset {
+                items = []
+                lastId = 0
+                canLoadMore = false
+            }
+            onShowMessage?(error.localizedDescription)
+        }
+    }
+
+    private func notifyStateChange() {
+        onStateChange?()
+    }
+}
+
+/// 消息详情页 ViewModel，负责删除当前消息。
+final class MessageDetailViewModel {
+    private(set) var message: MessageItem
+    private(set) var isDeleting = false
+
+    var onStateChange: (() -> Void)?
+    var onShowMessage: ((String) -> Void)?
+    var onDeleted: ((Int) -> Void)?
+
+    /// 初始化消息详情 ViewModel。
+    init(message: MessageItem) {
+        self.message = message
+    }
+
+    /// 删除当前消息。
+    func delete(api: any MessageCenterServing) async {
+        guard message.id > 0 else {
+            onShowMessage?("消息ID无效")
+            return
+        }
+
+        isDeleting = true
+        notifyStateChange()
+        defer {
+            isDeleting = false
+            notifyStateChange()
+        }
+
+        do {
+            try await api.delete(messageId: message.id)
+            onShowMessage?("删除成功")
+            onDeleted?(message.id)
+        } catch is CancellationError {
+            return
+        } catch {
+            let detail = error.localizedDescription.trimmingCharacters(in: .whitespacesAndNewlines)
+            onShowMessage?("删除失败: \(detail.isEmpty ? "请稍后重试" : detail)")
+        }
+    }
+
+    private func notifyStateChange() {
+        onStateChange?()
+    }
+}