Add convenience method

Author: ResurrectedTrader

src/D2SSharp.Tests/RoundTripTests.cs

@@ -151,7 +151,7 @@ public void RoundTrip_CompleteItem_Personalized()
         item.Quality = ItemQuality.Unique;
         item.Flags |= ItemFlags.Identified | ItemFlags.Personalized;
         item.PersonalizedName = "TestName";
-        item.QualityData = new SetUniqueQualityData { FileIndex = 5 };
+        item.QualityData = new SetUniqueQualityData { SetUniqueFileIndex = 5 };
         AssertItemRoundTrip(item);
     }
 
@@ -235,7 +235,7 @@ public void RoundTrip_CompleteItem_SetWithBonuses()
         var item = CreateArmorItem("cap ", defense: 30, maxDur: 40, dur: 40);
         item.Quality = ItemQuality.Set;
         item.Flags |= ItemFlags.Identified;
-        item.QualityData = new SetUniqueQualityData { FileIndex = 10 };
+        item.QualityData = new SetUniqueQualityData { SetUniqueFileIndex = 10 };
         item.SetItemMask = 0b00101; // Bits 0 and 2 set
 
         // Main stats

src/D2SSharp/Model/D2Save.cs

@@ -343,14 +343,7 @@ private void ConvertD2RTo114()
     private PreviewItem CreatePreviewItem(Item item, Composits composit, ItemFlags flags = 0)
     {
         // Extract FileIndex from quality data if available
-        ushort fileIndex = item.QualityData switch
-        {
-            SetUniqueQualityData setUnique => setUnique.FileIndex,
-            InferiorQualityData inferior => inferior.FileIndex,
-            SuperiorQualityData superior => superior.FileIndex,
-            NormalBodyPartQualityData bodyPart => bodyPart.FileIndex,
-            _ => 0
-        };
+        ushort fileIndex = item.QualityData?.FileIndex ?? 0;
 
         return new PreviewItem
         {

src/D2SSharp/Model/ItemQualityData.cs

@@ -18,6 +18,19 @@ namespace D2SSharp.Model;
 [JsonDerivedType(typeof(NormalScrollBookQualityData), "NormalScrollBook")]
 public abstract partial class ItemQualityData
 {
+    /// <summary>
+    /// Gets the file index for this quality type, if applicable.
+    /// Returns null for quality types that don't have a file index (Magic, Rare, Craft, Tempered, Charm, ScrollBook).
+    /// </summary>
+    public ushort? FileIndex => this switch
+    {
+        InferiorQualityData inferior => inferior.InferiorFileIndex,
+        SuperiorQualityData superior => superior.SuperiorFileIndex,
+        SetUniqueQualityData setUnique => setUnique.SetUniqueFileIndex,
+        NormalBodyPartQualityData bodyPart => bodyPart.BodyPartFileIndex,
+        _ => null
+    };
+
     /// <summary>Writes the quality data to a BitWriter.</summary>
     /// <param name="writer">The BitWriter to write to.</param>
     /// <param name="magicPrefixOffset">Magic prefix ID offset from external data (applied to prefixes only).</param>
@@ -30,20 +43,20 @@ public abstract partial class ItemQualityData
 public partial class InferiorQualityData : ItemQualityData
 {
     /// <summary>Low quality type file index (0-7).</summary>
-    public byte FileIndex { get; set; }
+    public byte InferiorFileIndex { get; set; }
 
     public static InferiorQualityData Read(ref BitReader reader)
     {
         return new InferiorQualityData
         {
-            FileIndex = (byte)reader.ReadBits(3)
+            InferiorFileIndex = (byte)reader.ReadBits(3)
         };
     }
 
     public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
     {
         // C++: clamps to 0-7 (3 bits)
-        writer.WriteBits(Math.Clamp(FileIndex, (byte)0, (byte)7), 3);
+        writer.WriteBits(Math.Clamp(InferiorFileIndex, (byte)0, (byte)7), 3);
     }
 }
 
@@ -53,20 +66,20 @@ public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
 public partial class SuperiorQualityData : ItemQualityData
 {
     /// <summary>Superior type file index (0-7).</summary>
-    public byte FileIndex { get; set; }
+    public byte SuperiorFileIndex { get; set; }
 
     public static SuperiorQualityData Read(ref BitReader reader)
     {
         return new SuperiorQualityData
         {
-            FileIndex = (byte)reader.ReadBits(3)
+            SuperiorFileIndex = (byte)reader.ReadBits(3)
         };
     }
 
     public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
     {
         // C++: clamps to 0-7 (3 bits)
-        writer.WriteBits(Math.Clamp(FileIndex, (byte)0, (byte)7), 3);
+        writer.WriteBits(Math.Clamp(SuperiorFileIndex, (byte)0, (byte)7), 3);
     }
 }
 
@@ -118,20 +131,20 @@ public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
 public partial class SetUniqueQualityData : ItemQualityData
 {
     /// <summary>Set or Unique item file index (0-4095).</summary>
-    public ushort FileIndex { get; set; }
+    public ushort SetUniqueFileIndex { get; set; }
 
     public static SetUniqueQualityData Read(ref BitReader reader)
     {
         return new SetUniqueQualityData
         {
-            FileIndex = (ushort)reader.ReadBits(12)
+            SetUniqueFileIndex = (ushort)reader.ReadBits(12)
         };
     }
 
     public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
     {
         // C++: clamps to 0-4095 (12 bits), also handles negative as 4095
-        writer.WriteBits(Math.Clamp(FileIndex, (ushort)0, (ushort)4095), 12);
+        writer.WriteBits(Math.Clamp(SetUniqueFileIndex, (ushort)0, (ushort)4095), 12);
     }
 }
 
@@ -311,20 +324,20 @@ public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
 public partial class NormalBodyPartQualityData : ItemQualityData
 {
     /// <summary>Monster ID file index (0-1023).</summary>
-    public ushort FileIndex { get; set; }
+    public ushort BodyPartFileIndex { get; set; }
 
     public static NormalBodyPartQualityData Read(ref BitReader reader)
     {
         return new NormalBodyPartQualityData
         {
-            FileIndex = (ushort)reader.ReadBits(10)
+            BodyPartFileIndex = (ushort)reader.ReadBits(10)
         };
     }
 
     public override void Write(ref BitWriter writer, int magicPrefixOffset = 0)
     {
         // C++: clamps to 0-1023 (10 bits)
-        writer.WriteBits(Math.Clamp(FileIndex, (ushort)0, (ushort)1023), 10);
+        writer.WriteBits(Math.Clamp(BodyPartFileIndex, (ushort)0, (ushort)1023), 10);
     }
 }