Added a sorting mechanism to emulate how windows sorts files. Refactored cache to support chapter folders as well.

API/Comparators/NumericComparer.cs

@@ -0,0 +1,17 @@
+using System.Collections;
+
+namespace API.Comparators
+{
+    public class NumericComparer : IComparer
+    {
+
+        public int Compare(object x, object y)
+        {
+            if((x is string xs) && (y is string ys))
+            {
+                return StringLogicalComparer.Compare(xs, ys);
+            }
+            return -1;
+        }
+    }
+}

API/Comparators/StringLogicalComparer.cs

@@ -0,0 +1,130 @@
+//(c) Vasian Cepa 2005
+// Version 2
+// Taken from: https://www.codeproject.com/Articles/11016/Numeric-String-Sort-in-C
+
+using System;
+
+namespace API.Comparators
+{
+    public static class StringLogicalComparer
+    {
+        public static int Compare(string s1, string s2)
+		{
+			//get rid of special cases
+			if((s1 == null) && (s2 == null)) return 0;
+			if(s1 == null) return -1;
+			if(s2 == null) return 1;
+
+			if (string.IsNullOrEmpty(s1) && string.IsNullOrEmpty(s2)) return 0;
+			if (string.IsNullOrEmpty(s1)) return -1;
+			if (string.IsNullOrEmpty(s2)) return -1;
+
+			//WE style, special case
+			bool sp1 = Char.IsLetterOrDigit(s1, 0);
+			bool sp2 = Char.IsLetterOrDigit(s2, 0);
+			if(sp1 && !sp2) return 1;
+			if(!sp1 && sp2) return -1;
+
+			int i1 = 0, i2 = 0; //current index
+			while(true)
+			{
+				bool c1 = Char.IsDigit(s1, i1);
+				bool c2 = Char.IsDigit(s2, i2);
+				var r = 0; // temp result
+				if(!c1 && !c2)
+				{
+					bool letter1 = Char.IsLetter(s1, i1);
+					bool letter2 = Char.IsLetter(s2, i2);
+					if((letter1 && letter2) || (!letter1 && !letter2))
+					{
+						if(letter1 && letter2)
+						{
+							r = Char.ToLower(s1[i1]).CompareTo(Char.ToLower(s2[i2]));
+						}
+						else
+						{
+							r = s1[i1].CompareTo(s2[i2]);
+						}
+						if(r != 0) return r;
+					}
+					else if(!letter1 && letter2) return -1;
+					else if(letter1 && !letter2) return 1;
+				}
+				else if(c1 && c2)
+				{
+					r = CompareNum(s1, ref i1, s2, ref i2);
+					if(r != 0) return r;
+				}
+				else if(c1)
+				{
+					return -1;
+				}
+				else if(c2)
+				{
+					return 1;
+				}
+				i1++;
+				i2++;
+				if((i1 >= s1.Length) && (i2 >= s2.Length))
+				{
+					return 0;
+				}
+				if(i1 >= s1.Length)
+				{
+					return -1;
+				}
+				if(i2 >= s2.Length)
+				{
+					return -1;
+				}
+			}
+		}
+
+		private static int CompareNum(string s1, ref int i1, string s2, ref int i2)
+		{
+			int nzStart1 = i1, nzStart2 = i2; // nz = non zero
+			int end1 = i1, end2 = i2;
+
+			ScanNumEnd(s1, i1, ref end1, ref nzStart1); 
+			ScanNumEnd(s2, i2, ref end2, ref nzStart2);
+			var start1 = i1; i1 = end1 - 1;
+			var start2 = i2; i2 = end2 - 1;
+
+			var nzLength1 = end1 - nzStart1;
+			var nzLength2 = end2 - nzStart2;
+
+			if(nzLength1 < nzLength2) return -1;
+			if(nzLength1 > nzLength2) return 1;
+
+			for(int j1 = nzStart1,j2 = nzStart2; j1 <= i1; j1++,j2++)
+			{
+				var r = s1[j1].CompareTo(s2[j2]);
+				if(r != 0) return r;
+			}
+			// the nz parts are equal
+			var length1 = end1 - start1;
+			var length2 = end2 - start2;
+			if(length1 == length2) return 0;
+			if(length1 > length2) return -1;
+			return 1;
+		}
+
+		//lookahead
+		private static void ScanNumEnd(string s, int start, ref int end, ref int nzStart)
+		{
+			nzStart = start;
+			end = start;
+			bool countZeros = true;
+			while(Char.IsDigit(s, end))
+			{
+				if(countZeros && s[end].Equals('0'))
+				{
+					nzStart++;
+				}
+				else countZeros = false;
+				end++;
+				if(end >= s.Length) break;
+			}
+		}
+    }
+}