// Copyright (C) 2003 Dolphin Project.

// This program 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, version 2.0 or later versions.

// This program 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 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

#include <cstdlib>
#include <cstring>
#include <snappy-c.h>

#include "ChunkFile.h"
#include "StringUtils.h"

PointerWrapSection PointerWrap::Section(const char *title, int ver) {
	return Section(title, ver, ver);
}

PointerWrapSection PointerWrap::Section(const char *title, int minVer, int ver) {
	char marker[16] = {0};
	int foundVersion = ver;

	// This is strncpy because we rely on its weird non-null-terminating truncation behaviour.
	// Can't replace it with the more sensible truncate_cpy because that would break savestates.
	strncpy(marker, title, sizeof(marker));
	if (!ExpectVoid(marker, sizeof(marker)))
	{
		// Might be before we added name markers for safety.
		if (foundVersion == 1 && ExpectVoid(&foundVersion, sizeof(foundVersion)))
			DoMarker(title);
		// Wasn't found, but maybe we can still load the state.
		else
			foundVersion = 0;
	}
	else
		Do(foundVersion);

	if (error == ERROR_FAILURE || foundVersion < minVer || foundVersion > ver) {
		WARN_LOG(SAVESTATE, "Savestate failure: wrong version %d found for %s", foundVersion, title);
		SetError(ERROR_FAILURE);
		return PointerWrapSection(*this, -1, title);
	}
	return PointerWrapSection(*this, foundVersion, title);
}

void PointerWrap::SetError(Error error_) {
	if (error < error_) {
		error = error_;
	}
	if (error > ERROR_WARNING) {
		mode = PointerWrap::MODE_MEASURE;
	}
}

bool PointerWrap::ExpectVoid(void *data, int size) {
	switch (mode) {
	case MODE_READ:	if (memcmp(data, *ptr, size) != 0) return false; break;
	case MODE_WRITE: memcpy(*ptr, data, size); break;
	case MODE_MEASURE: break;  // MODE_MEASURE - don't need to do anything
	case MODE_VERIFY:
		for (int i = 0; i < size; i++)
			_dbg_assert_msg_(COMMON, ((u8*)data)[i] == (*ptr)[i], "Savestate verification failure: %d (0x%X) (at %p) != %d (0x%X) (at %p).\n", ((u8*)data)[i], ((u8*)data)[i], &((u8*)data)[i], (*ptr)[i], (*ptr)[i], &(*ptr)[i]);
		break;
	default: break;  // throw an error?
	}
	(*ptr) += size;
	return true;
}

void PointerWrap::DoVoid(void *data, int size) {
	switch (mode) {
	case MODE_READ:	memcpy(data, *ptr, size); break;
	case MODE_WRITE: memcpy(*ptr, data, size); break;
	case MODE_MEASURE: break;  // MODE_MEASURE - don't need to do anything
	case MODE_VERIFY:
		for (int i = 0; i < size; i++)
			_dbg_assert_msg_(COMMON, ((u8*)data)[i] == (*ptr)[i], "Savestate verification failure: %d (0x%X) (at %p) != %d (0x%X) (at %p).\n", ((u8*)data)[i], ((u8*)data)[i], &((u8*)data)[i], (*ptr)[i], (*ptr)[i], &(*ptr)[i]);
		break;
	default: break;  // throw an error?
	}
	(*ptr) += size;
}

void PointerWrap::Do(std::string &x) {
	int stringLen = (int)x.length() + 1;
	Do(stringLen);

	switch (mode) {
	case MODE_READ:		x = (char*)*ptr; break;
	case MODE_WRITE:	memcpy(*ptr, x.c_str(), stringLen); break;
	case MODE_MEASURE: break;
	case MODE_VERIFY: _dbg_assert_msg_(COMMON, !strcmp(x.c_str(), (char*)*ptr), "Savestate verification failure: \"%s\" != \"%s\" (at %p).\n", x.c_str(), (char*)*ptr, ptr); break;
	}
	(*ptr) += stringLen;
}

void PointerWrap::Do(std::wstring &x) {
	int stringLen = sizeof(wchar_t)*((int)x.length() + 1);
	Do(stringLen);

	switch (mode) {
	case MODE_READ:		x = (wchar_t*)*ptr; break;
	case MODE_WRITE:	memcpy(*ptr, x.c_str(), stringLen); break;
	case MODE_MEASURE: break;
	case MODE_VERIFY: _dbg_assert_msg_(COMMON, x == (wchar_t*)*ptr, "Savestate verification failure: \"%ls\" != \"%ls\" (at %p).\n", x.c_str(), (wchar_t*)*ptr, ptr); break;
	}
	(*ptr) += stringLen;
}

struct standard_tm {
	int tm_sec;
	int tm_min;
	int tm_hour;
	int tm_mday;
	int tm_mon;
	int tm_year;
	int tm_wday;
	int tm_yday;
	int tm_isdst;
};

void PointerWrap::Do(tm &t) {
	// We savestate this separately because some platforms use extra data at the end.
	// However, old files may have the native tm in them.
	// Since the first value in the struct is 0-59, we save a funny value and check for it.
	// If our funny value ('tm' 0x1337) exists, it's a new version savestate.
	int funnyValue = 0x13376D74;
	if (ExpectVoid(&funnyValue, sizeof(funnyValue))) {
		standard_tm stm;
		if (mode == MODE_READ) {
			// Null out the extra members, e.g. tm_gmtoff or tm_zone.
			memset(&t, 0, sizeof(t));
		} else {
			memcpy(&stm, &t, sizeof(stm));
		}

		DoVoid((void *)&stm, sizeof(stm));
		memcpy(&t, &stm, sizeof(stm));
	} else {
		DoVoid((void *)&t, sizeof(t));
	}
}

void PointerWrap::DoMarker(const char *prevName, u32 arbitraryNumber) {
	u32 cookie = arbitraryNumber;
	Do(cookie);
	if (mode == PointerWrap::MODE_READ && cookie != arbitraryNumber) {
		PanicAlert("Error: After \"%s\", found %d (0x%X) instead of save marker %d (0x%X). Aborting savestate load...", prevName, cookie, cookie, arbitraryNumber, arbitraryNumber);
		SetError(ERROR_FAILURE);
	}
}

PointerWrapSection::~PointerWrapSection() {
	if (ver_ > 0) {
		p_.DoMarker(title_);
	}
}

CChunkFileReader::Error CChunkFileReader::LoadFileHeader(File::IOFile &pFile, SChunkHeader &header, std::string *title) {
	if (!pFile) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Can't open file for reading");
		return ERROR_BAD_FILE;
	}

	const u64 fileSize = pFile.GetSize();
	u64 headerSize = sizeof(SChunkHeader);
	if (fileSize < headerSize) {
		ERROR_LOG(SAVESTATE, "ChunkReader: File too small");
		return ERROR_BAD_FILE;
	}

	if (!pFile.ReadArray(&header, 1)) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Bad header size");
		return ERROR_BAD_FILE;
	}

	if (header.Revision < REVISION_MIN) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Wrong file revision, got %d expected >= %d", header.Revision, REVISION_MIN);
		return ERROR_BAD_FILE;
	}

	if (header.Revision >= REVISION_TITLE) {
		char titleFixed[128];
		if (!pFile.ReadArray(titleFixed, sizeof(titleFixed))) {
			ERROR_LOG(SAVESTATE, "ChunkReader: Unable to read title");
			return ERROR_BAD_FILE;
		}

		if (title) {
			*title = titleFixed;
		}

		headerSize += 128;
	} else if (title) {
		title->clear();
	}

	u32 sz = (u32)(fileSize - headerSize);
	if (header.ExpectedSize != sz) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Bad file size, got %u expected %u", sz, header.ExpectedSize);
		return ERROR_BAD_FILE;
	}

	return ERROR_NONE;
}

CChunkFileReader::Error CChunkFileReader::GetFileTitle(const std::string &filename, std::string *title) {
	if (!File::Exists(filename)) {
		ERROR_LOG(SAVESTATE, "ChunkReader: File doesn't exist");
		return ERROR_BAD_FILE;
	}

	File::IOFile pFile(filename, "rb");
	SChunkHeader header;
	return LoadFileHeader(pFile, header, title);
}

CChunkFileReader::Error CChunkFileReader::LoadFile(const std::string &filename, std::string *gitVersion, u8 *&_buffer, size_t &sz, std::string *failureReason) {
	if (!File::Exists(filename)) {
		*failureReason = "LoadStateDoesntExist";
		ERROR_LOG(SAVESTATE, "ChunkReader: File doesn't exist");
		return ERROR_BAD_FILE;
	}

	File::IOFile pFile(filename, "rb");
	SChunkHeader header;
	Error err = LoadFileHeader(pFile, header, nullptr);
	if (err != ERROR_NONE) {
		return err;
	}

	// read the state
	sz = header.ExpectedSize;
	u8 *buffer = new u8[sz];
	if (!pFile.ReadBytes(buffer, sz))
	{
		ERROR_LOG(SAVESTATE, "ChunkReader: Error reading file");
		delete [] buffer;
		return ERROR_BAD_FILE;
	}

	if (header.Compress) {
		u8 *uncomp_buffer = new u8[header.UncompressedSize];
		size_t uncomp_size = header.UncompressedSize;
		auto status = snappy_uncompress((const char *)buffer, sz, (char *)uncomp_buffer, &uncomp_size);
		if (status != SNAPPY_OK) {
			ERROR_LOG(SAVESTATE, "ChunkReader: Failed to decompress file");
			delete [] uncomp_buffer;
			delete [] buffer;
			return ERROR_BAD_FILE;
		}
		if ((u32)uncomp_size != header.UncompressedSize) {
			ERROR_LOG(SAVESTATE, "Size mismatch: file: %u  calc: %u", header.UncompressedSize, (u32)uncomp_size);
			delete [] uncomp_buffer;
			delete [] buffer;
			return ERROR_BAD_FILE;
		}
		_buffer = uncomp_buffer;
		sz = uncomp_size;
		delete [] buffer;
	} else {
		_buffer = buffer;
	}

	if (header.GitVersion[31]) {
		*gitVersion = std::string(header.GitVersion, 32);
	} else {
		*gitVersion = header.GitVersion;
	}

	return ERROR_NONE;
}

// Takes ownership of buffer.
CChunkFileReader::Error CChunkFileReader::SaveFile(const std::string &filename, const std::string &title, const char *gitVersion, u8 *buffer, size_t sz) {
	INFO_LOG(SAVESTATE, "ChunkReader: Writing %s", filename.c_str());

	File::IOFile pFile(filename, "wb");
	if (!pFile) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Error opening file for write");
		free(buffer);
		return ERROR_BAD_FILE;
	}

	// Make sure we can allocate a buffer to compress before compressing.
	size_t write_len = snappy_max_compressed_length(sz);
	u8 *compressed_buffer = (u8 *)malloc(write_len);
	u8 *write_buffer = buffer;
	if (!compressed_buffer) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Unable to allocate compressed buffer");
		// We'll save uncompressed.  Better than not saving...
		write_len = sz;
	} else {
		snappy_compress((const char *)buffer, sz, (char *)compressed_buffer, &write_len);
		free(buffer);

		write_buffer = compressed_buffer;
	}

	// Create header
	SChunkHeader header{};
	header.Compress = compressed_buffer ? 1 : 0;
	header.Revision = REVISION_CURRENT;
	header.ExpectedSize = (u32)write_len;
	header.UncompressedSize = (u32)sz;
	truncate_cpy(header.GitVersion, gitVersion);

	// Setup the fixed-length title.
	char titleFixed[128]{};
	truncate_cpy(titleFixed, title.c_str());

	// Now let's start writing out the file...
	if (!pFile.WriteArray(&header, 1)) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Failed writing header");
		free(write_buffer);
		return ERROR_BAD_FILE;
	}
	if (!pFile.WriteArray(titleFixed, sizeof(titleFixed))) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Failed writing title");
		free(write_buffer);
		return ERROR_BAD_FILE;
	}

	if (!pFile.WriteBytes(write_buffer, write_len)) {
		ERROR_LOG(SAVESTATE, "ChunkReader: Failed writing compressed data");
		free(write_buffer);
		return ERROR_BAD_FILE;
	} else if (sz != write_len) {
		INFO_LOG(SAVESTATE, "Savestate: Compressed %i bytes into %i", (int)sz, (int)write_len);
	}
	free(write_buffer);

	INFO_LOG(SAVESTATE, "ChunkReader: Done writing %s", filename.c_str());
	return ERROR_NONE;
}