filesystem_zip.h

/*
 * This file is part of EasyRPG Player.
 *
 * EasyRPG Player is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * EasyRPG Player is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with EasyRPG Player. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef EP_FILESYSTEM_ZIP_H
#define EP_FILESYSTEM_ZIP_H

#include "filesystem.h"
#include "filesystem_stream.h"
#include <fstream>
#include <memory>
#include <unordered_map>
#include <vector>

/**
 * A virtual filesystem that allows file/directory operations inside a ZIP archive.
 */
class ZipFilesystem : public Filesystem {
public:
	/**
	 * Initializes a filesystem inside the given ZIP File
	 *
	 * @param base_path Path passed to parent_fs to open the zip file
	 * @param parent_fs Filesystem used to create handles on the zip file
	 * @param encoding Encoding to use, use empty string for autodetection
	 */
	ZipFilesystem(std::string base_path, FilesystemView parent_fs, StringView encoding = "");

protected:
	/**
 	 * Implementation of abstract methods
 	 */
	/** @{ */
	bool IsFile(StringView path) const override;
	bool IsDirectory(StringView path, bool follow_symlinks) const override;
	bool Exists(StringView path) const override;
	int64_t GetFilesize(StringView path) const override;
	std::streambuf* CreateInputStreambuffer(StringView path, std::ios_base::openmode mode) const override;
	bool GetDirectoryContent(StringView path, std::vector<DirectoryTree::Entry>& entries) const override;
	std::string Describe() const override;
	/** @} */

private:
	enum class StorageMethod {Unknown, Plain, Deflate};
	struct ZipEntry {
		uint32_t compressed_size;
		uint32_t uncompressed_size;
		uint32_t fileoffset;
		bool is_directory;
	};

	bool FindCentralDirectory(std::istream& stream, uint32_t& offset, uint32_t& size, uint16_t& num_entries) const;
	bool ReadCentralDirectoryEntry(std::istream& zipfile, std::string& filepath, ZipEntry& entry, bool& is_utf8) const;
	bool ReadLocalHeader(std::istream& zipfile, StorageMethod& method, ZipEntry& entry) const;
	const ZipEntry* Find(StringView what) const;

	std::vector<std::pair<std::string, ZipEntry>> zip_entries;
	std::vector<std::pair<std::string, ZipEntry>> zip_entries_cp437;
	std::string encoding;
	mutable std::vector<char> filename_buffer;
};

#endif