From 587fd75190871c2d19e32ecd9fe132a635d90954 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Fri, 13 Sep 2019 13:55:53 +0200
Subject: [PATCH] - extended lump injection to allow injecting data into a
 PWAD's directory, not just the IWAD.

---
 src/gamedata/resourcefiles/resourcefile.h |  4 ++-
 src/gamedata/w_wad.cpp                    | 42 ++++++++++++-----------
 src/gamedata/w_wad.h                      |  3 +-
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/src/gamedata/resourcefiles/resourcefile.h b/src/gamedata/resourcefiles/resourcefile.h
index 65e0ef3f1f..a07029e842 100644
--- a/src/gamedata/resourcefiles/resourcefile.h
+++ b/src/gamedata/resourcefiles/resourcefile.h
@@ -74,7 +74,7 @@ struct FResourceLump
 	int ReleaseCache();
 
 protected:
-	virtual int FillCache() = 0;
+	virtual int FillCache() {}
 
 };
 
@@ -114,6 +114,8 @@ public:
 	uint32_t LumpCount() const { return NumLumps; }
 	uint32_t GetFirstLump() const { return FirstLump; }
 	void SetFirstLump(uint32_t f) { FirstLump = f; }
+	const FString &GetHash() const { return Hash; }
+
 
 	virtual void FindStrifeTeaserVoices ();
 	virtual bool Open(bool quiet) = 0;
diff --git a/src/gamedata/w_wad.cpp b/src/gamedata/w_wad.cpp
index 16deadc900..d7d9911d86 100644
--- a/src/gamedata/w_wad.cpp
+++ b/src/gamedata/w_wad.cpp
@@ -146,9 +146,12 @@ void FWadCollection::InitMultipleFiles (TArray<FString> &filenames, const TArray
 	{
 		int baselump = NumLumps;
 		AddFile (filenames[i]);
+		
+		if (i == (unsigned)MaxIwadIndex) MoveLumpsInFolder("after_iwad/");
+		FStringf path("filter/%s", Files.Last()->GetHash().GetChars());
+		MoveLumpsInFolder(path);
 	}
-	MoveIWadModifiers();
-
+	
 	NumLumps = LumpInfo.Size();
 	if (NumLumps == 0)
 	{
@@ -1056,39 +1059,38 @@ void FWadCollection::FixMacHexen()
 
 //==========================================================================
 //
-// MoveIWadModifiers
+// MoveLumpsInFolder
 //
-// Moves all content from the after_iwad subfolder of the internal
-// resources to the first positions in the lump directory after the IWAD.
+// Moves all content from the given subfolder of the internal
+// resources to the current end of the directory.
 // Used to allow modifying content in the base files, this is needed
 // so that Hacx and Harmony can override some content that clashes
-// with localization.
+// with localization, and to inject modifying data into mods, in case
+// this is needed for some compatibility requirement.
 //
 //==========================================================================
 
-void FWadCollection::MoveIWadModifiers()
-{
-	TArray<LumpRecord> lumpsToMove;
+static FResourceLump placeholderLump;
 
+void FWadCollection::MoveLumpsInFolder(const char *path)
+{
+	auto len = strlen(path);
+	auto wadnum = LumpInfo.Last().wadnum;
+	
 	unsigned i;
 	for (i = 0; i < LumpInfo.Size(); i++)
 	{
 		auto& li = LumpInfo[i];
 		if (li.wadnum >= GetIwadNum()) break;
-		if (li.lump->FullName.Left(11).CompareNoCase("after_iwad/") == 0)
+		if (li.lump->FullName.Left(len).CompareNoCase(path) == 0)
 		{
-			lumpsToMove.Push(li);
-			LumpInfo.Delete(i--);
+			LumpInfo.Push(li);
+			li.lump = &placeholderLump;			// Make the old entry point to something empty. We cannot delete the lump record here because it'd require adjustment of all indices in the list.
+			auto &ln = LumpInfo.Last();
+			ln.wadnum = wadnum;					// pretend this is from the WAD this is injected into.
+			ln.lump->LumpNameSetup(ln.lump->FullName.Mid(len));
 		}
 	}
-	if (lumpsToMove.Size() == 0) return;
-	for (; i < LumpInfo.Size() && LumpInfo[i].wadnum <= Wads.GetMaxIwadNum(); i++);
-	for (auto& li : lumpsToMove)
-	{
-		li.lump->LumpNameSetup(li.lump->FullName.Mid(11));
-		li.wadnum = Wads.GetMaxIwadNum();	// pretend this comes from the IWAD itself.
-		LumpInfo.Insert(i++, li);
-	}
 }
 
 //==========================================================================
diff --git a/src/gamedata/w_wad.h b/src/gamedata/w_wad.h
index be45a8f1d7..610e67e9a5 100644
--- a/src/gamedata/w_wad.h
+++ b/src/gamedata/w_wad.h
@@ -222,7 +222,8 @@ private:
 	void RenameNerve();
 	void FixMacHexen();
 	void DeleteAll();
-	void MoveIWadModifiers();
+	void MoveLumpsInFolder(const char *);
+
 	FileReader * GetFileReader(int wadnum);	// Gets a FileReader object to the entire WAD
 };