feat: add Instance entity

MastodonSDK/Sources/MastodonSDK/Entity/Mastodon+Entity+Instance.swift

@@ -0,0 +1,71 @@
+//
+//  Mastodon+Entity+Instance.swift
+//  
+//
+//  Created by MainasuK Cirno on 2021/1/27.
+//
+
+import Foundation
+
+extension Mastodon.Entity {
+    public struct Instance: Codable {
+        
+        public let uri: String?
+        public let title: String?
+        public let description: String?
+        public let shortDescription: String?
+        public let email: String?
+        public let version: String?
+        public let languages: [String]?     // (ISO 639 Part 1-5 language codes)
+        public let registrations: Bool?
+        public let approvalRequired: Bool?
+        public let invitesEnabled: Bool?
+        public let urls: [InstanceURL]?
+        public let statistics: Statistics?
+        
+        public let thumbnail: String?
+        public let contactAccount: User?
+
+        enum CodingKeys: String, CodingKey {
+            case uri
+            case title
+            case description
+            case shortDescription = "short_description"
+            case email
+            case version
+            case languages
+            case registrations
+            case approvalRequired = "approval_required"
+            case invitesEnabled
+            case urls
+            case statistics
+            
+            case thumbnail = "thumbnail"
+            case contactAccount = "contact_account"
+        }
+    }
+}
+
+extension Mastodon.Entity.Instance {
+    public struct InstanceURL: Codable {
+        public let streamingAPI: String
+
+        enum CodingKeys: String, CodingKey {
+            case streamingAPI = "streaming_api"
+        }
+    }
+}
+
+extension Mastodon.Entity.Instance {
+    public struct Statistics: Codable {
+        public let userCount: Int
+        public let statusCount: Int
+        public let domainCount: Int
+        
+        enum CodingKeys: String, CodingKey {
+            case userCount = "user_count"
+            case statusCount = "status_count"
+            case domainCount = "domain_count"
+        }
+    }
+}