Rework storage structs, link preview

CHDataManagement/Model/Post.swift

@@ -1,6 +1,8 @@
 import Foundation
 
-final class Post: Item {
+final class Post: Item, DateItem, LocalizedItem {
+
+    override var itemType: ItemType { .post }
 
     @Published
     var isDraft: Bool
@@ -142,10 +144,42 @@ final class Post: Item {
     }
 }
 
-extension Post: DateItem {
-
-}
-
-extension Post: LocalizedItem {
+extension Post {
 
+    convenience init(context: LoadingContext, id: String, data: Data) {
+        self.init(
+            content: context.content,
+            id: id,
+            isDraft: data.isDraft,
+            createdDate: data.createdDate,
+            startDate: data.startDate,
+            endDate: data.endDate,
+            tags: data.tags.compactMap(context.tag),
+            german: .init(context: context, data: data.german),
+            english: .init(context: context, data: data.english),
+            linkedPage: data.linkedPageId.map(context.page))
+    }
+
+    struct Data: Codable {
+        let isDraft: Bool
+        let createdDate: Date
+        let startDate: Date
+        let endDate: Date?
+        let tags: [String]
+        let german: LocalizedPost.Data
+        let english: LocalizedPost.Data
+        let linkedPageId: String?
+    }
+
+    var data: Data {
+        .init(
+            isDraft: isDraft,
+            createdDate: createdDate,
+            startDate: startDate,
+            endDate: hasEndDate ? endDate : nil,
+            tags: tags.map { $0.id },
+            german: german.data,
+            english: english.data,
+            linkedPageId: linkedPage?.id)
+    }
 }