NodeInfo: implement nodeinfo fetching

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

@@ -0,0 +1,63 @@
+/* Copyright 2020 Alibek Omarov
+ * 
+ * This file is a part of Husky.
+ *
+ * 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.annotations.SerializedName
+import java.util.*
+
+// .well-known/nodeinfo
+data class NodeInfoLink(
+    val href: String,
+    val rel: String
+)
+
+data class NodeInfoLinks(
+    val links: ArrayList<NodeInfoLink>
+)
+
+// we care only about supported postFormats
+// so implement only metadata fetching
+data class NodeInfo(
+    val metadata: NodeInfoMetadata? = null,
+    val software: NodeInfoSoftware
+)
+
+data class NodeInfoSoftware(
+    val name: String,
+    val version: String
+)
+
+data class NodeInfoPleromaUploadLimits(
+    val avatar: Int?,
+    val background: Int?,
+    val banner: Int?,
+    val general: Int?        
+)
+
+data class NodeInfoPixelfedUploadLimits(
+    @SerializedName("max_photo_size") val maxPhotoSize: Int?
+)
+
+data class NodeInfoPixelfedConfig(
+    val uploader: NodeInfoPixelfedUploadLimits?
+)
+
+data class NodeInfoMetadata(
+    val postFormats: ArrayList<String>?,
+    val uploadLimits: NodeInfoPleromaUploadLimits?,
+    val config: NodeInfoPixelfedConfig?
+)
+

app/src/main/java/com/keylesspalace/tusky/network/MastodonApi.kt

@@ -556,5 +556,10 @@ interface MastodonApi {
             @Query("offset") offset: Int? = null,
             @Query("following") following: Boolean? = null
     ): Single<SearchResult>
-
+    
+    @GET(".well-known/nodeinfo")
+    fun getNodeinfoLinks() : Single<NodeInfoLinks>
+    
+    @GET
+    fun getNodeinfo(@Url url: String) : Single<NodeInfo>
 }