feat: add AI retouch before-after comparison

suixinkan/Features/TravelAlbum/Models/TravelAlbumModels.swift

@@ -403,23 +403,45 @@ enum TravelAlbumAIRetouchWorkflow: Sendable, Equatable {
     }
 }
 
-/// AI 修图模板，包含业务 ID、展示名称和预览图地址。
+/// AI 修图模板，包含业务 ID、展示名称、卡片预览图及前后对比图片地址。
 struct TravelAlbumAIRetouchTemplate: Decodable, Sendable, Equatable, Hashable, Identifiable {
     let id: Int
     let name: String
     let previewURL: String
+    let beforeURL: String
+    let afterURL: String
 
     enum CodingKeys: String, CodingKey {
         case id
         case name
         case previewURL = "preview_url"
+        case beforeURL = "before_url"
+        case afterURL = "after_url"
     }
 
     /// 创建 AI 修图模板。
-    init(id: Int, name: String, previewURL: String) {
+    init(
+        id: Int,
+        name: String,
+        previewURL: String,
+        beforeURL: String = "",
+        afterURL: String = ""
+    ) {
         self.id = id
         self.name = name
         self.previewURL = previewURL
+        self.beforeURL = beforeURL
+        self.afterURL = afterURL
+    }
+
+    /// 解码模板；前后对比字段缺失或为 null 时按空字符串兼容旧接口响应。
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(Int.self, forKey: .id)
+        name = try container.decode(String.self, forKey: .name)
+        previewURL = try container.decode(String.self, forKey: .previewURL)
+        beforeURL = (try? container.decodeIfPresent(String.self, forKey: .beforeURL)) ?? ""
+        afterURL = (try? container.decodeIfPresent(String.self, forKey: .afterURL)) ?? ""
     }
 }
 

suixinkan/Features/TravelAlbum/Models/TravelAlbumPreviewModels.swift

@@ -5,6 +5,32 @@
 
 import Foundation
 
+/// 前后图片对比页所需的通用内容，与具体入口和 UI 框架解耦。
+struct BeforeAfterComparisonContent: Sendable, Equatable {
+    let beforeURL: String
+    let afterURL: String
+    let beforeLabel: String
+    let afterLabel: String
+
+    /// 创建前后对比内容，默认使用 AI 修图模块的中文角标。
+    init(
+        beforeURL: String,
+        afterURL: String,
+        beforeLabel: String = "原图",
+        afterLabel: String = "效果图"
+    ) {
+        self.beforeURL = beforeURL.trimmingCharacters(in: .whitespacesAndNewlines)
+        self.afterURL = afterURL.trimmingCharacters(in: .whitespacesAndNewlines)
+        self.beforeLabel = beforeLabel
+        self.afterLabel = afterLabel
+    }
+
+    /// 两张图片地址均存在时才允许进入对比页。
+    var isValid: Bool {
+        !beforeURL.isEmpty && !afterURL.isEmpty
+    }
+}
+
 /// 相册预览页横向滑动策略，由调用方通过配置注入。
 enum TravelAlbumPreviewSwipeMode: Sendable, Equatable {
     /// 横滑只切换原图项目，关联图通过 Tab 切换。
@@ -85,6 +111,19 @@ struct TravelAlbumPreviewProject: Identifiable, Sendable, Hashable {
         assets.first { $0.kind == kind }
     }
 
+    /// 为精修或氛围感结果构建与原图的对比内容；其他类型或无效地址返回 nil。
+    func comparisonContent(for kind: TravelAlbumPreviewAssetKind) -> BeforeAfterComparisonContent? {
+        guard kind == .retouched || kind == .atmosphere,
+              let original = asset(for: .original),
+              let result = asset(for: kind)
+        else { return nil }
+        let content = BeforeAfterComparisonContent(
+            beforeURL: original.displayURL,
+            afterURL: result.displayURL
+        )
+        return content.isValid ? content : nil
+    }
+
     /// 将素材映射为原图及实际存在的 AI 精修、氛围感结果图。
     init(material: TravelAlbumMaterial) {
         originalMaterialId = material.id
@@ -157,6 +196,14 @@ struct TravelAlbumPreviewProject: Identifiable, Sendable, Hashable {
     }
 }
 
+extension TravelAlbumAIRetouchTemplate {
+    /// 使用接口返回的模板示例前后图构建对比页内容。
+    var comparisonContent: BeforeAfterComparisonContent? {
+        let content = BeforeAfterComparisonContent(beforeURL: beforeURL, afterURL: afterURL)
+        return content.isValid ? content : nil
+    }
+}
+
 /// 预览分页节点，记录当前图片所属项目及类型。
 struct TravelAlbumPreviewNode: Sendable, Hashable {
     let projectIndex: Int