convert entity classes to Kotlin data classes (#526)

* convert entity classes to Kotlin data classes

* more data classes, code style

app/src/main/java/com/keylesspalace/tusky/entity/Attachment.kt

@@ -0,0 +1,57 @@
+/* Copyright 2017 Andrew Dawson
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+
+package com.keylesspalace.tusky.entity
+
+import com.google.gson.JsonDeserializationContext
+import com.google.gson.JsonDeserializer
+import com.google.gson.JsonElement
+import com.google.gson.JsonParseException
+import com.google.gson.annotations.JsonAdapter
+import com.google.gson.annotations.SerializedName
+
+data class Attachment(
+        var id: String,
+        var url: String,
+        @SerializedName("preview_url") val previewUrl: String,
+        @SerializedName("text_url") val textUrl: String?,
+        var type: Type,
+        var description: String?
+) {
+
+    @JsonAdapter(MediaTypeDeserializer::class)
+    enum class Type {
+        @SerializedName("image")
+        IMAGE,
+        @SerializedName("gifv")
+        GIFV,
+        @SerializedName("video")
+        VIDEO,
+        @SerializedName("unknown")
+        UNKNOWN
+    }
+
+    class MediaTypeDeserializer : JsonDeserializer<Type> {
+        @Throws(JsonParseException::class)
+        override fun deserialize(json: JsonElement, classOfT: java.lang.reflect.Type, context: JsonDeserializationContext): Type {
+            return when (json.toString()) {
+                "\"image\"" -> Type.IMAGE
+                "\"gifv\"" -> Type.GIFV
+                "\"video\"" -> Type.VIDEO
+                else -> Type.UNKNOWN
+            }
+        }
+    }
+}