Implement EQ Preset MHOD (type 7)

src/Clickwheel/DataTypes/EQPreset.cs

@@ -0,0 +1,69 @@
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using Clickwheel.Exceptions;
+using Clickwheel.Parsers;
+
+namespace Clickwheel.DataTypes
+{
+    public sealed record EQPreset 
+    {
+        private static readonly Dictionary<int, EQPreset> Presets = new();
+
+        public static readonly EQPreset Acoustic = new(100);
+        public static readonly EQPreset BassBooster = new(101);
+        public static readonly EQPreset BassReducer = new(102);
+        public static readonly EQPreset Classical = new(103);
+        public static readonly EQPreset Dance = new(104);
+        public static readonly EQPreset Deep = new(105);
+        public static readonly EQPreset Electronic = new(106);
+        public static readonly EQPreset Flat = new(107);
+        public static readonly EQPreset HipHop = new(108);
+        public static readonly EQPreset Jazz = new(109);
+        public static readonly EQPreset Latin = new(110);
+        public static readonly EQPreset Loudness = new(111);
+        public static readonly EQPreset Lounge = new(112);
+        public static readonly EQPreset Piano = new(113);
+        public static readonly EQPreset Pop = new(114);
+        public static readonly EQPreset RhythmAndBlues = new(115);
+        public static readonly EQPreset Rock = new(116);
+        public static readonly EQPreset SmallSpeakers = new(117);
+        public static readonly EQPreset SpokenWord = new(118);
+        public static readonly EQPreset TrebleBooster = new(119);
+        public static readonly EQPreset TrebleReducer = new(120);
+        public static readonly EQPreset VocalBooster = new(121);
+
+        public string Name { get; init; }
+        public int ID { get; init; }
+
+        private EQPreset(int id, [CallerMemberName] string name = "") : this(name, id) {}
+        private EQPreset(string name, int id)
+        {
+            Name = name;
+            ID = id;
+            Presets.Add(id, this);
+        }
+
+        private const string _magicString = "#!#";
+
+        public static string EncodeAsString(EQPreset preset)
+        {
+            if (preset == null)
+                return "";
+
+            return $"{_magicString}{preset.ID}{_magicString}";
+        }
+
+        public static EQPreset DecodeFromString(string input)
+        {
+            if (input == "") return null;
+
+            if (   input.Length != 9 // three digit code, plus prefix and suffix
+                || !input.StartsWith(_magicString)
+                || !input.EndsWith(_magicString)
+                || !int.TryParse(input.Substring(3, 3), out var id)
+            ) throw new ParseException($"\"{input}\" is not a valid EQ Preset ID.", null);
+
+            return Presets.GetValueOrDefault(id) ?? new EQPreset("Unknown EQ Preset", id);
+        }
+    }
+}

src/Clickwheel/NewTrack.cs

@@ -1,3 +1,5 @@
+using Clickwheel.DataTypes;
+
 namespace Clickwheel
 {
     /// <summary>
@@ -11,6 +13,7 @@ public class NewTrack
         public string Title;
         public string Artist;
         public string Album;
+        public EQPreset EQPreset;
         public string Comments;
 
         /// <summary>

src/Clickwheel/Parsers/iTunesDB/MHOD/BaseMHODElement.cs

@@ -12,6 +12,7 @@ internal static class MHODElementType
         public const int Artist = 4;
         public const int Genre = 5;
         public const int FileType = 6;
+        public const int EQPreset = 7;
         public const int Comment = 8;
         public const int Composer = 12;
         public const int DescriptionText = 14;

src/Clickwheel/Parsers/iTunesDB/MHOD/MHODFactory.cs

@@ -25,6 +25,7 @@ public static BaseMHODElement ReadMHOD(IPod iPod, BinaryReader reader)
                 case MHODElementType.Artist:
                 case MHODElementType.Genre:
                 case MHODElementType.FileType:
+                case MHODElementType.EQPreset:
                 case MHODElementType.Comment:
                 case MHODElementType.Composer:
                 case MHODElementType.AlbumArtist:

src/Clickwheel/Parsers/iTunesDB/Track.cs

@@ -366,6 +366,11 @@ public string Album
                 }
             }
         }
+
+        public EQPreset EQPreset {
+            get => EQPreset.DecodeFromString(GetDataElement(MHODElementType.EQPreset));
+            set => SetDataElement(MHODElementType.EQPreset, EQPreset.EncodeAsString(value));
+        }
 
         public string Comment
         {
@@ -766,6 +771,7 @@ private void SetDataElement(int type, string data)
                 if (string.IsNullOrEmpty(data))
                 {
                     _childSections.Remove(mhod);
+                    _isDirty = true;
                     return;
                 }
                 mhod.Data = data;
@@ -817,6 +823,10 @@ internal void Create(IPod iPod, NewTrack newTrack)
                 this.Artist = newTrack.Artist;
             }
 
+            if (newTrack.EQPreset != null) {
+                this.EQPreset = newTrack.EQPreset;
+            }
+
             if (!string.IsNullOrEmpty(newTrack.Comments))
             {
                 this.Comment = newTrack.Comments;