Change chart's colour depending on release stream; Show whether it's populated

Fix chart requests

osu.Game/Online/API/Requests/GetChangelogChartRequest.cs

@@ -0,0 +1,21 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Game.Online.API.Requests.Responses;
+using System.Collections.Generic;
+
+namespace osu.Game.Online.API.Requests
+{
+    public class GetChangelogChartRequest : APIRequest<APIChangelogChart>
+    {
+        private readonly string updateStream;
+
+        public GetChangelogChartRequest() => updateStream = null;
+
+        public GetChangelogChartRequest(string updateStreamName) => updateStream = updateStreamName;
+
+        protected override string Target => $@"changelog/{(!string.IsNullOrEmpty(updateStream) ?
+            updateStream + "/" : "")}chart-config";
+        protected override string Uri => $@"https://houtarouoreki.github.io/fake-api/{Target}"; // for testing
+    }
+}

osu.Game/Online/API/Requests/Responses/APIChangelogChart.cs

@@ -0,0 +1,34 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using Newtonsoft.Json;
+using osu.Framework.Lists;
+using System;
+using System.Collections.Generic;
+
+namespace osu.Game.Online.API.Requests.Responses
+{
+    public class APIChangelogChart
+    {
+        [JsonProperty("build_history")]
+        public List<BuildHistory> BuildHistory { get; set; }
+
+        [JsonProperty("order")]
+        public List<string> Order { get; set; }
+
+        [JsonProperty("stream_name")]
+        public string StreamName { get; set; }
+    }
+
+    public class BuildHistory
+    {
+        [JsonProperty("created_at")]
+        public DateTimeOffset CreatedAt { get; set; }
+
+        [JsonProperty("user_count")]
+        public long UserCount { get; set; }
+
+        [JsonProperty("label")]
+        public string Label { get; set; }
+    }
+}

osu.Game/Overlays/Changelog/ChangelogChart.cs

@@ -1,11 +1,15 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using OpenTK.Graphics;
+using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Graphics.Sprites;
 using osu.Game.Graphics;
+using osu.Game.Online.API;
+using osu.Game.Online.API.Requests;
 using osu.Game.Online.API.Requests.Responses;
 
 namespace osu.Game.Overlays.Changelog
@@ -15,6 +19,8 @@ namespace osu.Game.Overlays.Changelog
     public class ChangelogChart : BufferedContainer
     {
         private Box background;
+        private SpriteText text;
+        private APIAccess api;
 
         public ChangelogChart()
         {
@@ -27,7 +33,7 @@ namespace osu.Game.Overlays.Changelog
                     Colour = StreamColour.STABLE,
                     RelativeSizeAxes = Axes.Both,
                 },
-                new SpriteText
+                text = new SpriteText
                 {
                     Text = "Graph Placeholder",
                     TextSize = 28,
@@ -37,9 +43,41 @@ namespace osu.Game.Overlays.Changelog
             };
         }
 
-        public void ShowChart(APIChangelog releaseStream)
+        public void ShowChart(APIChangelog releaseStream) => fetchAndShowChangelogChart(releaseStream);
+
+        private bool isEmpty(APIChangelogChart changelogChart)
         {
-            background.Colour = StreamColour.FromStreamName(releaseStream.UpdateStream.Name);
+            if (changelogChart != null)
+                foreach (BuildHistory buildHistory in changelogChart.BuildHistory)
+                    if (buildHistory.UserCount > 0) return false;
+            return true;
+        }
+
+        private void showChart(APIChangelogChart chartInfo, string updateStreamName)
+        {
+            if (!isEmpty(chartInfo))
+            {
+                background.Colour = StreamColour.FromStreamName(updateStreamName);
+                text.Text = "Graph placeholder\n(chart is not empty)";
+            }
+            else
+            {
+                background.Colour = Color4.Black;
+                text.Text = "Graph placeholder\n(chart is empty)";
+            }
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(APIAccess api)
+        {
+            this.api = api;
+        }
+
+        private void fetchAndShowChangelogChart(APIChangelog build)
+        {
+            var req = new GetChangelogChartRequest(build.UpdateStream.Name);
+            req.Success += res => showChart(res, build.UpdateStream.Name);
+            api.Queue(req);
         }
     }
 }