Add getSongsByGenre api call.

Signed-off-by: Yahor Berdnikau <egorr.berd@gmail.com>

subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicApiGetSongsByGenreTest.kt

@@ -0,0 +1,82 @@
+package org.moire.ultrasonic.api.subsonic
+
+import org.amshove.kluent.`should equal to`
+import org.amshove.kluent.`should equal`
+import org.junit.Test
+import org.moire.ultrasonic.api.subsonic.models.MusicDirectoryChild
+
+/**
+ * Integration test for [SubsonicAPIDefinition.getSongsByGenre] call.
+ */
+class SubsonicApiGetSongsByGenreTest : SubsonicAPIClientTest() {
+    @Test
+    fun `Should handle error response`() {
+        val response = checkErrorCallParsed(mockWebServerRule) {
+            client.api.getSongsByGenre("Metal").execute()
+        }
+
+        response.songsList `should equal` emptyList()
+    }
+
+    @Test
+    fun `Should handle ok response`() {
+        mockWebServerRule.enqueueResponse("get_songs_by_genre_ok.json")
+
+        val response = client.api.getSongsByGenre("Trance").execute()
+
+        assertResponseSuccessful(response)
+        response.body().songsList.size `should equal to` 2
+        with(response.body().songsList) {
+            this[0] `should equal` MusicDirectoryChild(id = 575, parent = 576, isDir = false,
+                    title = "Time Machine (Vadim Zhukov Remix)", album = "668",
+                    artist = "Tasadi", year = 2008, genre = "Trance", size = 22467672,
+                    contentType = "audio/mpeg", suffix = "mp3", duration = 561, bitRate = 320,
+                    path = "Tasadi/668/00 Time Machine (Vadim Zhukov Remix).mp3",
+                    isVideo = false, playCount = 0, created = parseDate("2016-10-23T21:58:29.000Z"),
+                    albumId = 0, artistId = 0, type = "music")
+            this[1] `should equal` MusicDirectoryChild(id = 621, parent = 622, isDir = false,
+                    title = "My Heart (Vadim Zhukov Remix)", album = "668",
+                    artist = "DJ Polyakov PPK Feat Kate Cameron", year = 2009, genre = "Trance",
+                    size = 26805932, contentType = "audio/mpeg", suffix = "mp3", duration = 670,
+                    bitRate = 320,
+                    path = "DJ Polyakov PPK Feat Kate Cameron/668/00 My Heart (Vadim Zhukov Remix).mp3",
+                    isVideo = false, playCount = 2, created = parseDate("2016-10-23T21:58:29.000Z"),
+                    albumId = 5, artistId = 4, type = "music")
+        }
+    }
+
+    @Test
+    fun `Should pass genre in request param`() {
+        val genre = "Rock"
+        mockWebServerRule.assertRequestParam(expectedParam = "genre=$genre") {
+            client.api.getSongsByGenre(genre = genre).execute()
+        }
+    }
+
+    @Test
+    fun `Should pass count in request param`() {
+        val count = 494
+
+        mockWebServerRule.assertRequestParam(expectedParam = "count=$count") {
+            client.api.getSongsByGenre("Trance", count = count).execute()
+        }
+    }
+
+    @Test
+    fun `Should pass offset in request param`() {
+        val offset = 31
+
+        mockWebServerRule.assertRequestParam(expectedParam = "offset=$offset") {
+            client.api.getSongsByGenre("Trance", offset = offset).execute()
+        }
+    }
+
+    @Test
+    fun `Should pass music folder id in request param`() {
+        val musicFolderId = 1010L
+
+        mockWebServerRule.assertRequestParam(expectedParam = "musicFolderId=$musicFolderId") {
+            client.api.getSongsByGenre("Trance", musicFolderId = musicFolderId).execute()
+        }
+    }
+}

subsonic-api/src/integrationTest/resources/get_songs_by_genre_ok.json

@@ -0,0 +1,51 @@
+{
+  "subsonic-response" : {
+    "status" : "ok",
+    "version" : "1.15.0",
+    "songsByGenre" : {
+      "song" : [ {
+        "id" : "575",
+        "parent" : "576",
+        "isDir" : false,
+        "title" : "Time Machine (Vadim Zhukov Remix)",
+        "album" : "668",
+        "artist" : "Tasadi",
+        "year" : 2008,
+        "genre" : "Trance",
+        "size" : 22467672,
+        "contentType" : "audio/mpeg",
+        "suffix" : "mp3",
+        "duration" : 561,
+        "bitRate" : 320,
+        "path" : "Tasadi/668/00 Time Machine (Vadim Zhukov Remix).mp3",
+        "isVideo" : false,
+        "playCount" : 0,
+        "created" : "2016-10-23T21:58:29.000Z",
+        "albumId" : "0",
+        "artistId" : "0",
+        "type" : "music"
+      }, {
+        "id" : "621",
+        "parent" : "622",
+        "isDir" : false,
+        "title" : "My Heart (Vadim Zhukov Remix)",
+        "album" : "668",
+        "artist" : "DJ Polyakov PPK Feat Kate Cameron",
+        "year" : 2009,
+        "genre" : "Trance",
+        "size" : 26805932,
+        "contentType" : "audio/mpeg",
+        "suffix" : "mp3",
+        "duration" : 670,
+        "bitRate" : 320,
+        "path" : "DJ Polyakov PPK Feat Kate Cameron/668/00 My Heart (Vadim Zhukov Remix).mp3",
+        "isVideo" : false,
+        "playCount" : 2,
+        "created" : "2016-10-23T21:58:29.000Z",
+        "albumId" : "5",
+        "artistId" : "4",
+        "type" : "music"
+      } ]
+    }
+  }
+}

subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIDefinition.kt

@@ -16,6 +16,7 @@ import org.moire.ultrasonic.api.subsonic.response.GetPlaylistResponse
 import org.moire.ultrasonic.api.subsonic.response.GetPlaylistsResponse
 import org.moire.ultrasonic.api.subsonic.response.GetPodcastsResponse
 import org.moire.ultrasonic.api.subsonic.response.GetRandomSongsResponse
+import org.moire.ultrasonic.api.subsonic.response.GetSongsByGenreResponse
 import org.moire.ultrasonic.api.subsonic.response.GetStarredResponse
 import org.moire.ultrasonic.api.subsonic.response.GetStarredTwoResponse
 import org.moire.ultrasonic.api.subsonic.response.JukeboxResponse
@@ -201,4 +202,11 @@ interface SubsonicAPIDefinition {
 
     @GET("getGenres.view")
     fun getGenres(): Call<GenresResponse>
+
+    @GET("getSongsByGenre.view")
+    fun getSongsByGenre(
+            @Query("genre") genre: String,
+            @Query("count") count: Int = 10,
+            @Query("offset") offset: Int = 0,
+            @Query("musicFolderId") musicFolderId: Long? = null): Call<GetSongsByGenreResponse>
 }

subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/GetSongsByGenreResponse.kt

@@ -0,0 +1,18 @@
+package org.moire.ultrasonic.api.subsonic.response
+
+import com.fasterxml.jackson.annotation.JsonProperty
+import org.moire.ultrasonic.api.subsonic.SubsonicAPIVersions
+import org.moire.ultrasonic.api.subsonic.SubsonicError
+import org.moire.ultrasonic.api.subsonic.models.MusicDirectoryChild
+
+class GetSongsByGenreResponse(
+        status: Status,
+        version: SubsonicAPIVersions,
+        error: SubsonicError?) : SubsonicResponse(status, version, error) {
+    @JsonProperty("songsByGenre") private val songsByGenreList = SongsByGenreWrapper()
+
+    val songsList get() = songsByGenreList.songsList
+}
+
+internal class SongsByGenreWrapper(
+        @JsonProperty("song") val songsList: List<MusicDirectoryChild> = emptyList())