Add few hitsounds check

osu.Game/Rulesets/Edit/BeatmapVerifier.cs

@@ -23,6 +23,7 @@ namespace osu.Game.Rulesets.Edit
             new CheckAudioPresence(),
             new CheckAudioQuality(),
             new CheckMutedObjects(),
+            new CheckFewHitsounds(),
 
             // Compose
             new CheckUnsnappedObjects(),

osu.Game/Rulesets/Edit/Checks/CheckFewHitsounds.cs

@@ -0,0 +1,161 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.Linq;
+using osu.Game.Audio;
+using osu.Game.Rulesets.Edit.Checks.Components;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Rulesets.Edit.Checks
+{
+    public class CheckFewHitsounds : ICheck
+    {
+        /// <summary>
+        /// 2 measures (4/4) of 120 BPM, typically makes up a few patterns in the map.
+        /// This is almost always ok, but can still be useful for the mapper to make sure hitsounding coverage is good.
+        /// </summary>
+        private const int negligible_threshold_time = 4000;
+
+        /// <summary>
+        /// 4 measures (4/4) of 120 BPM, typically makes up a large portion of a section in the song.
+        /// This is ok if the section is a quiet intro, for example.
+        /// </summary>
+        private const int warning_threshold_time = 8000;
+
+        /// <summary>
+        /// 12 measures (4/4) of 120 BPM, typically makes up multiple sections in the song.
+        /// </summary>
+        private const int problem_threshold_time = 24000;
+
+        // Should pass at least this many objects without hitsounds to be considered an issue (should work for Easy diffs too).
+        private const int warning_threshold_objects = 4;
+        private const int problem_threshold_objects = 16;
+
+        private static readonly string[] hitsound_types = { HitSampleInfo.HIT_CLAP, HitSampleInfo.HIT_WHISTLE, HitSampleInfo.HIT_FINISH };
+
+        public CheckMetadata Metadata { get; } = new CheckMetadata(CheckCategory.Audio, "Few or no hitsounds");
+
+        public IEnumerable<IssueTemplate> PossibleTemplates => new IssueTemplate[]
+        {
+            new IssueTemplateLongPeriodProblem(this),
+            new IssueTemplateLongPeriodWarning(this),
+            new IssueTemplateNoHitsounds(this)
+        };
+
+        private bool hasHitsounds;
+        private int objectsWithoutHitsounds;
+        private double lastHitsoundTime;
+
+        public IEnumerable<Issue> Run(BeatmapVerifierContext context)
+        {
+            if (!context.Beatmap.HitObjects.Any())
+                yield break;
+
+            hasHitsounds = false;
+            objectsWithoutHitsounds = 0;
+            lastHitsoundTime = context.Beatmap.HitObjects.First().StartTime;
+
+            var hitObjectCount = context.Beatmap.HitObjects.Count;
+
+            for (int i = 0; i < hitObjectCount; ++i)
+            {
+                var hitObject = context.Beatmap.HitObjects[i];
+
+                // Samples play on the end of objects. Some objects have nested objects to accomplish playing them elsewhere (e.g. slider head/repeat).
+                foreach (var nestedHitObject in hitObject.NestedHitObjects)
+                {
+                    foreach (var issue in applyHitsoundUpdate(nestedHitObject))
+                        yield return issue;
+                }
+
+                // This is used to perform an update at the end so that the period after the last hitsounded object can be an issue.
+                bool isLastObject = i == hitObjectCount - 1;
+
+                foreach (var issue in applyHitsoundUpdate(hitObject, isLastObject))
+                    yield return issue;
+            }
+
+            if (!hasHitsounds)
+                yield return new IssueTemplateNoHitsounds(this).Create();
+        }
+
+        private IEnumerable<Issue> applyHitsoundUpdate(HitObject hitObject, bool isLastObject = false)
+        {
+            var time = hitObject.GetEndTime();
+
+            // Only generating issues on hitsounded or last objects ensures we get one issue per long period.
+            // If there are no hitsounds we let the "No hitsounds" template take precedence.
+            if (hasHitsound(hitObject) || isLastObject && hasHitsounds)
+            {
+                var timeWithoutHitsounds = time - lastHitsoundTime;
+
+                if (timeWithoutHitsounds > problem_threshold_time && objectsWithoutHitsounds > problem_threshold_objects)
+                    yield return new IssueTemplateLongPeriodProblem(this).Create(lastHitsoundTime, timeWithoutHitsounds);
+                else if (timeWithoutHitsounds > warning_threshold_time && objectsWithoutHitsounds > warning_threshold_objects)
+                    yield return new IssueTemplateLongPeriodWarning(this).Create(lastHitsoundTime, timeWithoutHitsounds);
+                else if (timeWithoutHitsounds > negligible_threshold_time && objectsWithoutHitsounds > warning_threshold_objects)
+                    yield return new IssueTemplateLongPeriodNegligible(this).Create(lastHitsoundTime, timeWithoutHitsounds);
+            }
+
+            if (hasHitsound(hitObject))
+            {
+                hasHitsounds = true;
+                objectsWithoutHitsounds = 0;
+                lastHitsoundTime = time;
+            }
+            else if (couldHaveHitsound(hitObject))
+                ++objectsWithoutHitsounds;
+        }
+
+        private bool hasHitsound(HitObject hitObject) => hitObject.Samples.Any(isHitsound);
+        private bool couldHaveHitsound(HitObject hitObject) => hitObject.Samples.Any(isHitnormal);
+
+        private bool isHitsound(HitSampleInfo sample) => hitsound_types.Any(sample.Name.Contains);
+        private bool isHitnormal(HitSampleInfo sample) => sample.Name.Contains(HitSampleInfo.HIT_NORMAL);
+
+        public abstract class IssueTemplateLongPeriod : IssueTemplate
+        {
+            protected IssueTemplateLongPeriod(ICheck check, IssueType type)
+                : base(check, type, "Long period without hitsounds ({0:F1} seconds).")
+            {
+            }
+
+            public Issue Create(double time, double duration) => new Issue(this, duration / 1000f) { Time = time };
+        }
+
+        public class IssueTemplateLongPeriodProblem : IssueTemplateLongPeriod
+        {
+            public IssueTemplateLongPeriodProblem(ICheck check)
+                : base(check, IssueType.Problem)
+            {
+            }
+        }
+
+        public class IssueTemplateLongPeriodWarning : IssueTemplateLongPeriod
+        {
+            public IssueTemplateLongPeriodWarning(ICheck check)
+                : base(check, IssueType.Warning)
+            {
+            }
+        }
+
+        public class IssueTemplateLongPeriodNegligible : IssueTemplateLongPeriod
+        {
+            public IssueTemplateLongPeriodNegligible(ICheck check)
+                : base(check, IssueType.Negligible)
+            {
+            }
+        }
+
+        public class IssueTemplateNoHitsounds : IssueTemplate
+        {
+            public IssueTemplateNoHitsounds(ICheck check)
+                : base(check, IssueType.Problem, "There are no hitsounds.")
+            {
+            }
+
+            public Issue Create() => new Issue(this);
+        }
+    }
+}