lightningbolt/lib/bolt/Reader.cpp

#include <base/ByteSwap.hpp>
#include <base/MmapFile.hpp>
#include <bolt/Reader.hpp>
#include <structs/BoltStructs.hpp>

namespace lightningbolt {

	fs::path MakeGamePath(BoltReader::Game game) {
		switch(game) {
			case BoltReader::Game::LooseBolt:
				return "./"; // for now
				break;

			case BoltReader::Game::SimpsonsSkateboarding: return "ASSETS.BLT"; break;
			case BoltReader::Game::NamcoMuseumGCN: return "Data0.blt"; break;
		}
	}

	struct BoltReader::Impl {
		Impl(Game game) : game(game) { std::printf("game %04x\n", game); }

		ErrorOr<void> OpenBolt(const fs::path& path) {
			// Load the BOLT file
			if(auto error = boltFile.Open(path / MakeGamePath(game)); error.HasError())
				return error;

			std::printf("mewow\n");

			lib = std::bit_cast<BoltLibraryHeader*>(boltFile.GetMapping());

			if(!lib->Validate())
				return std::make_error_code(BoltErrc::InvalidMagic);

			if(game == Game::SimpsonsSkateboarding) {
				if(auto error = elfFile.Open(path / "SLUS_201.14"); error.HasError())
					return error;

				// Load table entries.
				GetTableEntries();
			}

			std::printf("ret\n");

			return {};
		}

		const std::vector<BoltReader::File>& GetTableEntries() {
			if(game == Game::SimpsonsSkateboarding) {
				if(entryTable.empty()) {
					auto* base = elfFile.GetMapping();
					auto* table = std::bit_cast<elf::BoltTableEntry*>(base + elf::BoltTableOffsets.usTable);
					while(table->filenamePtr != 0x0) {
						auto string_offset = elf::AddressToElfFileOffset(table->filenamePtr);

						BoltReader::File te;
						te.filename = { std::bit_cast<char*>(base + string_offset) };
						te.index = table->entryId;
						te.gid = table->groupId;

						if(te.filename == "")
							break;

						entryTable.emplace_back(te);

						table++;
					}
				}
			}
			return entryTable;
		}

		template <class T>
		auto SwapIfGcn(T v) {
			return (game == Game::NamcoMuseumGCN) ? ByteSwap(v) : v;
		}

		template <class F>
		void ForEachFile(F f) {
			if(game == Game::SimpsonsSkateboarding) {
				for(auto& file : entryTable) {
					if(file.uncompressedData == nullptr) {
						auto gid = (file.gid >> 8);
						auto entries = lib->GroupDescriptors()[gid].Entries(boltFile.GetMapping());
						auto size = entries[file.index & 0x00ff].fileSize;
						auto offset = entries[file.index & 0x00ff].fileOffset;

						file.compressed = !(entries[file.index & 0x00ff].unk & 0x8);

						file.uncompressedData = std::bit_cast<u8*>(boltFile.GetMapping() + offset);
						file.uncompressedSize = size;
					}

					if(!f(file))
						break;
				}
			} else {
				// generic "We don't have a table" implementation. You don't get nice filenames like this,
				// simply because we cannot create them (.. maybe, if the unk3 is a hash, we could crack it,
				// but that would bloat extraction times to potentionally hours if not days, and also might
				// end up with wrong filenames at the end anyways due to the hash algorithm possibly being weak)
				//
				// We still end up synthesizing a File object for the user to interact with anyways.
				
				for(u32 i = 0; i < lib->groupCount; ++i) {
					auto groupDescriptor = lib->GroupDescriptors()[i];

					// We can't use the helper since it doesn't know about GCN byteswapping.
					// FIXME/TODO?
					std::span<BoltGroupEntry> groupEntries = {
						std::bit_cast<BoltGroupEntry*>(boltFile.GetMapping() + SwapIfGcn(groupDescriptor.groupOffset)), groupDescriptor.EntryCount()
					};

					for(u32 j = 0; j < groupEntries.size(); ++j) {
						auto& ent = groupEntries[j];
						auto filename = std::format("blt_{:02x}_{:02x}.bin", i, j);
						BoltReader::File file;

						file.gid = i;
						file.index = j;

						// Maybe BANG! but this is only accessed here.
						file.filename = filename;

						file.compressed = !(ent.unk & 0x8);

						file.uncompressedSize = SwapIfGcn(ent.fileSize);
						file.uncompressedData = std::bit_cast<u8*>(boltFile.GetMapping() + SwapIfGcn(ent.fileOffset));

						if(!f(file))
							return;
					}
				}
			}
		}

	   private:
		Game game;
		MmapFile boltFile;

		// Only applicable if game == Game::SimpsonsSkateboarding
		std::vector<BoltReader::File> entryTable;
		MmapFile elfFile;

		BoltLibraryHeader* lib;
	};

	BoltReader::Game BoltReader::GuessGame(const fs::path& path) {
		if(fs::exists(path / "SLUS_201.14") && fs::exists(path / "ASSETS.BLT"))
			return Game::SimpsonsSkateboarding;
		else if(fs::exists(path / "Data0.blt"))
			return Game::NamcoMuseumGCN;
		else
			return Game::LooseBolt;
	}

	BoltReader::BoltReader(Game game) : impl(std::make_unique<Impl>(game)) {
	}

	BoltReader::~BoltReader() = default;

	ErrorOr<void> BoltReader::OpenBolt(const fs::path& path) {
		return impl->OpenBolt(path);
	}

	void BoltReader::ForEachFile(std::function<bool(File&)> f) {
		impl->ForEachFile([&f](auto& file) { return f(file); });
	}

} // namespace lightningbolt