Rework storage structs, link preview

CHDataManagement/Model/Item/ItemReference.swift

@@ -0,0 +1,68 @@
+
+enum ItemReference {
+
+    case general
+
+    case post(Post)
+
+    case feed
+
+    case page(Page)
+
+    case tagPage(Tag)
+
+    case tagOverview
+}
+
+extension ItemReference: Equatable {
+
+}
+
+extension ItemReference: Hashable {
+
+}
+
+extension ItemReference: Identifiable {
+
+    var id: String {
+        switch self {
+        case .general:
+            return "0-general"
+        case .feed:
+            return "1-feed"
+        case .post(let post):
+            return "2-post-\(post.id)"
+        case .page(let page):
+            return "3-page-\(page.id)"
+        case .tagPage(let tag):
+            return "5-tag-\(tag.id)"
+        case .tagOverview:
+            return "4-tag-overview"
+        }
+    }
+
+    init?(context: LoadingContext, rawValue: String) {
+        if rawValue == "0-general" {
+            self = .general
+        } else if rawValue == "1-feed" {
+            self = .feed
+        } else if rawValue == "4-tag-overview" {
+            self = .tagOverview
+        } else if let id = rawValue.removingPrefix("3-page-"), let page = context.page(id) {
+            self = .page(page)
+        } else if let id = rawValue.removingPrefix("2-post-"), let post = context.post(id) {
+            self = .post(post)
+        } else if let id = rawValue.removingPrefix("5-tag-"), let tag = context.tag(id) {
+            self = .tagPage(tag)
+        } else {
+            return nil
+        }
+    }
+}
+
+extension ItemReference: Comparable {
+
+    static func < (lhs: ItemReference, rhs: ItemReference) -> Bool {
+        lhs.id < rhs.id
+    }
+}