add data reading & selection table population

Data/Song/Song.cs

@@ -1,22 +1,29 @@
 using System;
 using System.Collections.Generic;
 using Avalonia.Media;
+using SaturnData.Notation.Core;
 
 namespace MercuryConverter.Data;
 
+/// <summary>
+/// Combining SaturnData's Entry & Chart.
+/// </summary>
 public class Song
 {
-    /// <summary>
-    /// Format: `Snn-nnn` where `n` is a digit.
-    /// </summary>
-    public required string Id { get; set;}
+    public required string Id { get; set; } // Snn-nnn
     public required string Name { get; set; }
     public required string Artist { get; set; }
-    public required string Source { get; set; }
-    public string rubi;
-    public string copyright;
-    public string tempo;
-    public int genreId;
-    public string jacket;
-    public Chart?[] charts = { null, null, null, null };
+    public required uint Source { get; set; }
+    public required string Rubi { get; set; }
+    public string? Copyright { get; set; } // May have never been used?
+    public required int Genre { get; set; }
+    public required string? Jacket { get; set; }
+    public required float PreviewTime { get; set; }
+    public required float PreviewLen { get; set; }
+    public string SourceName => Consts.NUM_SOURCE[Source];
+    
+
+    // TODO: For SaturnData.Entry instances, use this Guid format:
+    // MERCURY_[SONGID]_[DIFF] (each var is int)
+    public List<(Difficulty, Entry, Chart)> charts = new();
 }