From 53b9c27ec9653df3bbc940b2361a4aaeada194ef Mon Sep 17 00:00:00 2001
From: Kurt <kaphotics@gmail.com>
Date: Sun, 6 Oct 2024 14:50:17 -0500
Subject: [PATCH] Add Battle Test metadata properties

Set the magic, set the flags to whatever, and refresh the checksum -> NPC recognizes you have DLC battle test ready and lets you challenge it immediately when starting a conversation with him.
Of course, it crashes immediately because we don't know what the 0x000 - 0x5C1 region data should be, but hey, this is progress for unlocking unreleased content.
---
 .../Saves/Substructures/Gen5/BattleTest5.cs   | 34 +++++++++++++++++++
 .../Saves/Substructures/Gen5/MusicalShow5.cs  |  1 +
 .../Subforms/Save Editors/Gen5/SAV_DLC5.cs    | 17 ++++++++--
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/PKHeX.Core/Saves/Substructures/Gen5/BattleTest5.cs b/PKHeX.Core/Saves/Substructures/Gen5/BattleTest5.cs
index 7d346bc0b..ac99155f2 100644
--- a/PKHeX.Core/Saves/Substructures/Gen5/BattleTest5.cs
+++ b/PKHeX.Core/Saves/Substructures/Gen5/BattleTest5.cs
@@ -1,4 +1,5 @@
 using System;
+using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
 
@@ -9,4 +10,37 @@ public class BattleTest5(Memory<byte> Raw)
 
     private Span<byte> Data => Raw.Span;
     public bool IsUninitialized => !Data.ContainsAnyExcept<byte>(0xFF, 0);
+
+    public const ushort Sentinel = 0x0D68;
+
+    // Should be equal to Sentinel otherwise the data is not valid.
+    public ushort Magic { get => ReadUInt16LittleEndian(Data[0x5C2..]); set => WriteUInt16LittleEndian(Data[0x5C2..], value); }
+    public ushort Flags { get => ReadUInt16LittleEndian(Data[0x5C4..]); set => WriteUInt16LittleEndian(Data[0x5C4..], value); }
+    public ushort Checksum { get => ReadUInt16LittleEndian(Data[0x5C6..]); set => WriteUInt16LittleEndian(Data[0x5C6..], value); }
+
+    public bool IsDoubles
+    {
+        get => (Flags & 0x8000) != 0;
+        set
+        {
+            if (value)
+                Flags |= 0x8000;
+            else
+                Flags &= 0x7FFF;
+        }
+    }
+
+    public ushort CalculateChecksum() => Checksums.CRC16_CCITT(Data[..0x5C6]);
+    public void RefreshChecksums() => Checksum = CalculateChecksum();
+
+    // Script command 0x1F2 in B2/W2
+    public ushort GetScriptResultIsValid()
+    {
+        var chk = CalculateChecksum();
+        if (chk != Checksum)
+            return 0;
+        if (Magic != Sentinel)
+            return 0;
+        return IsDoubles ? (ushort)2 : (ushort)1;
+    }
 }
diff --git a/PKHeX.Core/Saves/Substructures/Gen5/MusicalShow5.cs b/PKHeX.Core/Saves/Substructures/Gen5/MusicalShow5.cs
index 1a71efe18..c90defe1e 100644
--- a/PKHeX.Core/Saves/Substructures/Gen5/MusicalShow5.cs
+++ b/PKHeX.Core/Saves/Substructures/Gen5/MusicalShow5.cs
@@ -10,6 +10,7 @@ public sealed class MusicalShow5(Memory<byte> Raw)
     public const string Extension = "pms";
 
     public Span<byte> Data => Raw.Span;
+    public bool IsUninitialized => !Data.ContainsAnyExcept<byte>(0xFF, 0);
 
     public int Length
     {
diff --git a/PKHeX.WinForms/Subforms/Save Editors/Gen5/SAV_DLC5.cs b/PKHeX.WinForms/Subforms/Save Editors/Gen5/SAV_DLC5.cs
index 46016a167..65a224ba5 100644
--- a/PKHeX.WinForms/Subforms/Save Editors/Gen5/SAV_DLC5.cs	
+++ b/PKHeX.WinForms/Subforms/Save Editors/Gen5/SAV_DLC5.cs	
@@ -141,7 +141,7 @@ private void LoadPWT(SAV5B2W2 sav)
         LB_PWT.SelectedIndex = 0;
     }
 
-    private string? LastImportedFile = null;
+    private string? LastImportedFile;
 
     private bool ImportFile(string extension, string name, int expectSize, out byte[] data, string? initialName = null, int otherSize = -1)
     {
@@ -349,9 +349,11 @@ private void B_MusicalImport_Click(object sender, EventArgs e)
         const int pporg = 0x17D78;
         if (!ImportFile(MusicalShow5.Extension, MusicalShowFileName, size, out var data, otherSize: pporg))
             return;
+
+        var musical = new MusicalShow5(data);
         SAV.SetMusical(data);
         if (LastImportedFile is { } name)
-            SAV.Musical.MusicalName = Path.GetFileNameWithoutExtension(name).Trim();
+            SAV.Musical.MusicalName = musical.IsUninitialized ? "" : Path.GetFileNameWithoutExtension(name).Trim();
     }
 
     private void B_MusicalExport_Click(object sender, EventArgs e)
@@ -367,7 +369,8 @@ private void B_BattleVideoImport_Click(object sender, EventArgs e)
         bool decrypted = BattleVideo5.GetIsDecrypted(data);
         var bvid = new BattleVideo5(data) { IsDecrypted = decrypted };
         bvid.Encrypt();
-        bvid.RefreshChecksums();
+        if (!bvid.IsUninitialized)
+            bvid.RefreshChecksums();
 
         var index = LB_BattleVideo.SelectedIndex;
         SAV.SetBattleVideo(index, data);
@@ -454,6 +457,14 @@ private void B_BattleTestImport_Click(object sender, EventArgs e)
     {
         if (!ImportFile(BattleTest5.Extension, BattleTestFileName, BattleTest5.SIZE, out var data))
             return;
+
+        // Ensure checksums are valid for user-fuzzed data.
+        var test = new BattleTest5(data);
+        if (!test.IsUninitialized)
+        {
+            test.Magic = BattleTest5.Sentinel;
+            test.RefreshChecksums();
+        }
         SAV.SetBattleTest(data);
     }
 }