Improve supported extension openfiledialog

Existing code supported 3-x, wasn't updated for gen1/2.
Allows gens1/2 to override to their own gen format filter, and allows
gen7 to allow finding of pk1 files (not yet converted).

Noticed the backup would overwrite an existing backup; thus we only back
up if the target file exists AND the backup doesn't already exist.

PKHeX/MainWindow/Main.cs

@@ -270,14 +270,7 @@ namespace PKHeX
             string pkx = pkm.Extension;
             string ekx = 'e' + pkx.Substring(1, pkx.Length-1);
 
-            string supported = "*.pkm;";
+            string supported = string.Join(";", SAV.PKMExtensions.Select(s => "*."+s).Concat(new[] {"*.pkm"}));
-            for (int i = 3; i <= SAV.Generation; i++)
-            {
-                supported += $"*.pk{i}";
-                if (i != pkm.Format)
-                    supported += ";";
-            }
-
             OpenFileDialog ofd = new OpenFileDialog
             {
                 Filter = $"Supported Files|main;*.sav;*.bin;*.{ekx};{supported};*.bak" +
@@ -320,8 +313,12 @@ namespace PKHeX
             if (File.Exists(path))
             {
                 // File already exists, save a .bak
-                byte[] backupfile = File.ReadAllBytes(path);
+                string bakpath = path + ".bak";
-                File.WriteAllBytes(path + ".bak", backupfile);
+                if (!File.Exists(bakpath))
+                {
+                    byte[] backupfile = File.ReadAllBytes(path);
+                    File.WriteAllBytes(bakpath, backupfile);
+                }
             }
 
             if (new[] {".ekx", "."+ekx, ".bin"}.Contains(ext))

PKHeX/PKM/PKM.cs

@@ -6,6 +6,7 @@ namespace PKHeX
 {
     public abstract class PKM
     {
+        public static readonly string[] Extensions = PKX.getPKMExtensions();
         public abstract int SIZE_PARTY { get; }
         public abstract int SIZE_STORED { get; }
         public virtual string Extension => "pk" + Format;

PKHeX/PKM/PKX.cs

@@ -1385,7 +1385,7 @@ namespace PKHeX
                 default: return (PID & 0xFF) <= genderratio ? 1 : 0;
             }
         }
-#region Gen 3 Species Table
+        #region Gen 3 Species Table
         internal static int[] newindex => new[]
         {
             0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,
@@ -1429,8 +1429,8 @@ namespace PKHeX
             388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,
             409,410,411,
         };
-#endregion
+        #endregion
-#region Gen 3/4 Character Tables (Val->Unicode)
+        #region Gen 3/4 Character Tables (Val->Unicode)
 
         internal static readonly ushort[] G4Values =
         {
@@ -1821,7 +1821,7 @@ namespace PKHeX
             209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 289, // E
             452, 355, 373, 379, 387, 405, 411                                               // F
         };
-#endregion
+        #endregion
 
         public static readonly byte[][] G4TransferTrashBytes = {
             new byte[] { }, // Unused
@@ -1964,7 +1964,7 @@ namespace PKHeX
             return item == ITEM_UNK && item > 0;
         }
 
-#region Gen 1 Character Tables
+        #region Gen 1 Character Tables
         private static Dictionary<byte, string> RBY2U_U => new Dictionary<byte, string>{
             {0x50, "\0"},
             {0x5D, "[TRAINER]"},
@@ -2472,7 +2472,7 @@ namespace PKHeX
             {0xFE, "8"},
             {0xFF, "9"}
         };
-#endregion
+        #endregion
 
         public static int getG1Species(int raw_id)
         {
@@ -2523,5 +2523,15 @@ namespace PKHeX
                 .PadRight(value.Length + 1, (char)0); // Null Terminator
             return Encoding.BigEndianUnicode.GetBytes(TempNick);
         }
+
+        public static string[] getPKMExtensions()
+        {
+            const int gens = 7;
+            var result = new List<string>();
+            result.AddRange(new [] {"ck3", "xk3", "bk4"}); // Special Cases
+            for (int i = 1; i < gens; i++)
+                result.Add("pk"+i);
+            return result.ToArray();
+        }
     }
 }

PKHeX/Saves/SAV1.cs

@@ -8,6 +8,11 @@ namespace PKHeX
         public override string BAKName => $"{FileName} [{OT} ({Version}) - {PlayTimeString}].bak";
         public override string Filter => "SAV File|*.sav|All Files|*.*";
         public override string Extension => ".sav";
+        public override string[] PKMExtensions => PKM.Extensions.Where(f =>
+        {
+            int gen = f.Last() - 0x30;
+            return 1 <= gen && gen <= 2;
+        }).ToArray();
 
         public SAV1(byte[] data = null)
         {
@@ -153,10 +158,8 @@ namespace PKHeX
 
         public override int SIZE_STORED => Japanese ? PKX.SIZE_1JLIST : PKX.SIZE_1ULIST;
         public override int SIZE_PARTY => Japanese ? PKX.SIZE_1JLIST : PKX.SIZE_1ULIST;
-
+        private int SIZE_BOX => BoxSlotCount*SIZE_STORED;
-        public int SIZE_BOX => BoxSlotCount*SIZE_STORED;
+        private int SIZE_STOREDBOX => PokemonList1.GetDataLength(Japanese ? PokemonList1.CapacityType.StoredJP : PokemonList1.CapacityType.Stored, Japanese);
-
-        public int SIZE_STOREDBOX => PokemonList1.GetDataLength(Japanese ? PokemonList1.CapacityType.StoredJP : PokemonList1.CapacityType.Stored, Japanese);
 
         public override PKM BlankPKM => new PK1(null, null, Japanese);
         public override Type PKMType => typeof(PK1);

PKHeX/Saves/SAV2.cs

@@ -8,6 +8,11 @@ namespace PKHeX
         public override string BAKName => $"{FileName} [{OT} ({Version}) - {PlayTimeString}].bak";
         public override string Filter => "SAV File|*.sav|All Files|*.*";
         public override string Extension => ".sav";
+        public override string[] PKMExtensions => PKM.Extensions.Where(f => 
+        {
+            int gen = f.Last() - 0x30;
+            return 1 <= gen && gen <= 2;
+        }).ToArray();
 
         public SAV2(byte[] data = null)
         {
@@ -202,14 +207,12 @@ namespace PKHeX
 
         public override int SIZE_STORED => Japanese ? PKX.SIZE_2JLIST : PKX.SIZE_2ULIST;
         public override int SIZE_PARTY => Japanese ? PKX.SIZE_2JLIST : PKX.SIZE_2ULIST;
-
-        public int SIZE_BOX => BoxSlotCount*SIZE_STORED;
-
-        public int SIZE_STOREDBOX => PokemonList2.GetDataLength(Japanese ? PokemonList2.CapacityType.StoredJP : PokemonList2.CapacityType.Stored, Japanese);
-
         public override PKM BlankPKM => new PK2(null, null, Japanese);
         public override Type PKMType => typeof(PK2);
 
+        private int SIZE_BOX => BoxSlotCount*SIZE_STORED;
+        private int SIZE_STOREDBOX => PokemonList2.GetDataLength(Japanese ? PokemonList2.CapacityType.StoredJP : PokemonList2.CapacityType.Stored, Japanese);
+
         public override int MaxMoveID => 251;
         public override int MaxSpeciesID => Legal.MaxSpeciesID_2;
         public override int MaxAbilityID => 0;

PKHeX/Saves/SAV7.cs

@@ -10,6 +10,12 @@ namespace PKHeX
         public override string BAKName => $"{FileName} [{OT} ({Version}) - {LastSavedTime}].bak";
         public override string Filter => "Main SAV|*.*";
         public override string Extension => "";
+        public override string[] PKMExtensions => PKM.Extensions.Where(f =>
+        {
+            int gen = f.Last() - 0x30;
+            return gen == 1 || (3 <= gen && gen <= 7);
+        }).ToArray();
+
         public SAV7(byte[] data = null)
         {
             Data = data == null ? new byte[SaveUtil.SIZE_G7SM] : (byte[])data.Clone();

PKHeX/Saves/SaveFile.cs

@@ -25,6 +25,12 @@ namespace PKHeX
         public virtual bool IndeterminateGame => false;
         public virtual bool IndeterminateLanguage => false;
         public virtual bool IndeterminateSubVersion => false;
+        public abstract string Extension { get; }
+        public virtual string[] PKMExtensions => PKM.Extensions.Where(f => 
+        {
+            int gen = f.Last() - 0x30;
+            return 3 <= gen && gen <= 7;
+        }).ToArray();
 
         // General PKM Properties
         public abstract Type PKMType { get; }
@@ -322,7 +328,6 @@ namespace PKHeX
         public virtual uint Money { get; set; }
         public abstract int BoxCount { get; }
         public virtual int PartyCount { get; protected set; }
-        public abstract string Extension { get; }
 
         // Varied Methods
         protected abstract void setChecksums();