improve hierachi of classes for contents and posts

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/api/ReadPostsAPI.kt

@@ -1,17 +1,16 @@
 package com.insanusmokrassar.postssystem.core.api
 
-import com.insanusmokrassar.postssystem.core.post.Post
-import com.insanusmokrassar.postssystem.core.post.PostId
 import com.insanusmokrassar.postssystem.core.content.ContentId
+import com.insanusmokrassar.postssystem.core.post.*
 import com.insanusmokrassar.postssystem.core.utils.pagination.*
 import com.insanusmokrassar.postssystem.core.utils.pagination.Pagination
 import com.insanusmokrassar.postssystem.core.utils.pagination.PaginationResult
 import org.joda.time.DateTime
 
 interface ReadPostsAPI {
-    suspend fun getPostById(id: PostId): Post?
-    suspend fun getPostsByContent(id: ContentId): List<Post>
-    suspend fun getPostsByDates(from: DateTime? = null, to: DateTime? = null): List<Post>
+    suspend fun getPostById(id: PostId): RegisteredPost?
+    suspend fun getPostsByContent(id: ContentId): List<RegisteredPost>
+    suspend fun getPostsByDates(from: DateTime? = null, to: DateTime? = null): List<RegisteredPost>
 
-    suspend fun getPostsByPagination(pagination: Pagination): PaginationResult<out Post>
+    suspend fun getPostsByPagination(pagination: Pagination): PaginationResult<out RegisteredPost>
 }

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/api/WritePostsAPI.kt

@@ -5,12 +5,12 @@ import com.insanusmokrassar.postssystem.core.post.*
 import kotlinx.coroutines.flow.Flow
 
 interface WritePostsAPI {
-    val postCreatedFlow: Flow<Post>
-    val postDeletedFlow: Flow<Post>
-    val postUpdatedFlow: Flow<Post>
+    val postCreatedFlow: Flow<RegisteredPost>
+    val postDeletedFlow: Flow<RegisteredPost>
+    val postUpdatedFlow: Flow<RegisteredPost>
 
-    suspend fun createPost(content: PostContents): Post?
+    suspend fun createPost(post: Post): RegisteredPost?
     suspend fun deletePost(id: PostId): Boolean
 
-    suspend fun updatePostContent(postId: PostId, content: PostContents): Boolean
+    suspend fun updatePostContent(postId: PostId, post: Post): Boolean
 }

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/Content.kt

@@ -2,6 +2,8 @@ package com.insanusmokrassar.postssystem.core.content
 
 typealias ContentId = String
 
-interface Content {
+interface Content
+
+interface RegisteredContent : Content {
     val id: ContentId
 }

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/content/TextContent.kt

@@ -1,5 +1,20 @@
 package com.insanusmokrassar.postssystem.core.content
 
+import kotlinx.serialization.Serializable
+
 interface TextContent : Content {
     val text: String
-}
+}
+
+interface TextRegisteredContent : RegisteredContent, TextContent
+
+@Serializable
+data class SimpleTextContent(
+    override val text: String
+) : TextContent
+
+@Serializable
+data class SimpleTextRegisteredContent(
+    override val id: ContentId,
+    override val text: String
+) : TextRegisteredContent

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/post/Post.kt

@@ -1,21 +1,36 @@
 package com.insanusmokrassar.postssystem.core.post
 
 import com.insanusmokrassar.postssystem.core.content.Content
+import com.insanusmokrassar.postssystem.core.content.RegisteredContent
 import kotlinx.serialization.Serializable
+import org.joda.time.DateTime
 
 typealias PostId = String
 typealias PostContents = List<Content>
+typealias RegisteredPostContents = List<RegisteredContent>
 
 interface Post {
-    val id: PostId
     val content: PostContents
+}
 
-    val meta: PostMetaInfo
+interface RegisteredPost : Post {
+    val id: PostId
+
+    override val content: RegisteredPostContents
+
+    val creationDate: DateTime
+    val modificationDate: DateTime
 }
 
 @Serializable
 data class SimplePost(
-    override val id: PostId,
-    override val content: PostContents,
-    override val meta: PostMetaInfo
+    override val content: PostContents
 ) : Post
+
+@Serializable
+data class SimpleRegisteredPost(
+    override val id: PostId,
+    override val content: RegisteredPostContents,
+    override val creationDate: DateTime,
+    override val modificationDate: DateTime = creationDate
+) : RegisteredPost

Core/src/main/kotlin/com/insanusmokrassar/postssystem/core/post/PostMetaInfo.kt

@@ -1,9 +0,0 @@
-package com.insanusmokrassar.postssystem.core.post
-
-import org.joda.time.DateTime
-
-interface PostMetaInfo {
-    val postId: PostId
-    val creationDate: DateTime
-    val modificationDate: DateTime
-}