Implement seasonal content framework

to ensure that New Year's songs won't play in summer.

CHANGELOG.md

@@ -7,6 +7,7 @@
 - Added a new track Paarden.
 - Added a new track DiscoKapot.
 - Added an accessibility option to reduce the intensity of overly distracting visual effects.
+- Seasonal content like New Year's songs (IkWilJe, Paarden, DiscoKapot) will only be available for selection during their respective seasons.
 
 ## MuzikaGromche 1337.9001.3 - v73 Happy New Year Edition
 

MuzikaGromche/Exporter.cs

@@ -56,6 +56,7 @@ namespace MuzikaGromche
             {
                 ["Name"] = audioTrack.Name, // may be different from selectableTrack.Name, if selectable track is a group
                 ["IsExplicit"] = selectableTrack.IsExplicit,
+                ["Season"] = selectableTrack.Season?.Name,
                 ["Language"] = selectableTrack.Language.Full,
                 ["WindUpTimer"] = audioTrack.WindUpTimer,
                 ["Bpm"] = audioTrack.Bpm,

MuzikaGromche/Plugin.cs

@@ -884,6 +884,7 @@ namespace MuzikaGromche
                 Name = "IkWilJe",
                 AudioType = AudioType.OGGVORBIS,
                 Language = Language.ENGLISH,
+                Season = Season.NewYear,
                 WindUpTimer = 43.03f,
                 Beats = 13 * 4 + 2, // = 54
                 BeatsOffset = 0f,
@@ -909,6 +910,7 @@ namespace MuzikaGromche
                 Name = "Paarden",
                 AudioType = AudioType.OGGVORBIS,
                 Language = Language.RUSSIAN,
+                Season = Season.NewYear,
                 WindUpTimer = 36.12f,
                 Bars = 8,
                 BeatsOffset = 0f,
@@ -934,6 +936,7 @@ namespace MuzikaGromche
                 Name = "DiscoKapot",
                 AudioType = AudioType.OGGVORBIS,
                 Language = Language.RUSSIAN,
+                Season = Season.NewYear,
                 WindUpTimer = 30.3f,
                 Bars = 8,
                 BeatsOffset = 0f,
@@ -970,12 +973,19 @@ namespace MuzikaGromche
         public static ISelectableTrack ChooseTrack()
         {
             var seed = GetCurrentSeed();
-            var tracks = Config.SkipExplicitTracks.Value ? [.. Tracks.Where(track => !track.IsExplicit)] : Tracks;
-            int[] weights = [.. tracks.Select(track => track.Weight.Value)];
+            var today = DateTime.Today;
+            var season = SeasonalContentManager.CurrentSeason(today);
+            var tracksEnumerable = SeasonalContentManager.Filter(Tracks, season);
+            if (Config.SkipExplicitTracks.Value)
+            {
+                tracksEnumerable = tracksEnumerable.Where(track => !track.IsExplicit);
+            }
+            var tracks = tracksEnumerable.ToArray();
+            int[] weights = tracks.Select(track => track.Weight.Value).ToArray();
             var rwi = new RandomWeightedIndex(weights);
             var trackId = rwi.GetRandomWeightedIndex(seed);
             var track = tracks[trackId];
-            Log.LogInfo($"Seed is {seed}, chosen track is \"{track.Name}\", #{trackId} of {rwi}");
+            Log.LogInfo($"Seed is {seed}, season is {season?.Name ?? "<none>"}, chosen track is \"{track.Name}\", #{trackId} of {rwi}");
             return tracks[trackId];
         }
 
@@ -1212,7 +1222,7 @@ namespace MuzikaGromche
 
     // An instance of a track which appears as a configuration entry and
     // can be selected using weighted random from a list of selectable tracks.
-    public interface ISelectableTrack
+    public interface ISelectableTrack : ISeasonalContent
     {
         // Name of the track, as shown in config entry UI; also used for default file names.
         public string Name { get; init; }
@@ -1423,6 +1433,7 @@ namespace MuzikaGromche
     {
         public /* required */ Language Language { get; init; }
         public bool IsExplicit { get; init; } = false;
+        public Season? Season { get; init; } = null;
         ConfigEntry<int> ISelectableTrack.Weight { get; set; } = null!;
 
         IAudioTrack[] ISelectableTrack.GetTracks() => [this];
@@ -1440,6 +1451,7 @@ namespace MuzikaGromche
         public /* required */ string Name { get; init; } = "";
         public /* required */ Language Language { get; init; }
         public bool IsExplicit { get; init; } = false;
+        public Season? Season { get; init; } = null;
         ConfigEntry<int> ISelectableTrack.Weight { get; set; } = null!;
 
         public /* required */ IAudioTrack[] Tracks = [];
@@ -2480,8 +2492,9 @@ namespace MuzikaGromche
                 }
 
                 // Create slider entry for track
+                var seasonal = track.Season is Season season ? $"This is seasonal content for {season.Name}.\n\n" : "";
                 string warning = track.IsExplicit ? "Explicit Content/Lyrics!\n\n" : "";
-                string description = $"Language: {language.Full}\n\n{warning}Random (relative) chance of selecting this track.\n\nSet to zero to effectively disable the track.";
+                string description = $"Language: {language.Full}\n\n{seasonal}{warning}Random (relative) chance of selecting this track.\n\nSet to zero to effectively disable the track.";
                 track.Weight = configFile.Bind(
                     new ConfigDefinition(section, track.Name),
                     50,

MuzikaGromche/SeasonalContent.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MuzikaGromche;
+
+public delegate bool SeasonalContentPredicate(DateTime dateTime);
+
+// I'm not really sure what to do with seasonal content yet.
+//
+// There could be two approaches:
+// - Force seasonal content tracks to be the only available tracks during their season.
+//   Then seasons must be short, so they don't cut off too much content for too long.
+// - Exclude seasonal content tracks from the pool when their season is not active.
+//   Considering how many tracks are there in the playlist permanently already,
+//   this might not give the seasonal content enough visibility.
+//
+// Either way, seasonal content tracks would be listed in the config UI at all times,
+// which makes it confusing if you try to select only seasonal tracks outside of their season.
+
+// Seasons may NOT overlap. There is at most ONE active season at any given date.
+public readonly record struct Season(string Name, string Description, SeasonalContentPredicate IsActive)
+{
+    public override string ToString() => Name;
+
+    public static readonly Season NewYear = new("New Year", "New Year and Christmas holiday season", dateTime =>
+    {
+        // December 10 - February 29
+        var month = dateTime.Month;
+        var day = dateTime.Day;
+        return (month == 12 && day >= 10) || (month == 1) || (month == 2 && day <= 29);
+    });
+
+    // Note: it is important that this property goes last
+    public static readonly Season[] All = [NewYear];
+}
+
+public interface ISeasonalContent
+{
+    public Season? Season { get; init; }
+}
+
+public static class SeasonalContentManager
+{
+    public static Season? CurrentSeason(DateTime dateTime)
+    {
+        foreach (var season in Season.All)
+        {
+            if (season.IsActive(dateTime))
+            {
+                return season;
+            }
+        }
+        return null;
+    }
+
+    public static Season? CurrentSeason() => CurrentSeason(DateTime.Today);
+
+    // Take second approach: filter out seasonal content that is not in the current season.
+    public static IEnumerable<T> Filter<T>(this IEnumerable<T> items, Season? season) where T : ISeasonalContent
+    {
+        return items.Where(item =>
+        {
+            if (item.Season == null)
+            {
+                return true; // always available
+            }
+            return item.Season == season;
+        });
+    }
+
+    public static IEnumerable<T> Filter<T>(this IEnumerable<T> items, DateTime dateTime) where T : ISeasonalContent
+    {
+        var season = CurrentSeason(dateTime);
+        return Filter(items, season);
+    }
+
+    public static IEnumerable<T> Filter<T>(this IEnumerable<T> items) where T : ISeasonalContent
+    {
+        return Filter(items, DateTime.Today);
+    }
+}