#include "sgu_stdafx.h"
#include "sgu_mode_make_diff.h"
#include "sgu_utils.h"

#include "bzlib.h"

extern "C"
{
#include "bsdiff.h"
}

static int diffFileWriter(struct bsdiff_stream* stream, const void* buffer, int size)
{
	FILE* fp = (FILE*)stream->opaque;
	if (size != fwrite(buffer, 1, size, fp))
	{
		return -1;
	}
	return 0;
}

static int bzPatchFileWriter(struct bsdiff_stream* stream, const void* buffer, int size)
{
	BZFILE* bz2 = (BZFILE*)stream->opaque;

	int bz2err;
	BZ2_bzWrite(&bz2err, bz2, (void*)buffer, size);

	if (bz2err != BZ_STREAM_END && bz2err != BZ_OK)
		return -1;

	return 0;
}

bool createDiff(const char* inputFilename1, const char* inputFilename2, const char* outputFilename)
{
	if (!inputFilename1 || inputFilename1[0] == 0 || !inputFilename2 || inputFilename2[0] == 0)
	{
		printf("Error: Input filename is not specified.\n");
		return false;
	}
	if (!outputFilename || outputFilename[0] == 0)
	{
		printf("Error: Output filename is not specified.\n");
		return false;
	}

	bool result = false;
	uint8_t* pBuffer1 = nullptr;
	uint8_t* pBuffer2 = nullptr;
	FILE* fpOutput = nullptr;
	do {
		int64_t fileSize1;
		pBuffer1 = readFileToBuffer(inputFilename1, fileSize1);
		if (pBuffer1 == nullptr)
		{
			printf("Error: Failed to read input file 1: %s\n", inputFilename1);
			break;
		}

		int64_t fileSize2;
		pBuffer2 = readFileToBuffer(inputFilename2, fileSize2);
		if (pBuffer2 == nullptr)
		{
			printf("Error: Failed to read input file 2: %s\n", inputFilename2);
			break;
		}

		// Open the output file
		fopen_s(&fpOutput, outputFilename, "wb");
		if (fpOutput == nullptr)
		{
			printf("Error: Failed to open output file: %s\n", outputFilename);
			break;
		}

		// Write the header
		if (fwrite("ENDSLEY/BSDIFF43", 16, 1, fpOutput) != 1 ||
			fwrite(&fileSize2, sizeof(fileSize2), 1, fpOutput) != 1)
		{
			printf("Failed to write header\n");
			break;
		}

		int bz2err;
		BZFILE* bzHandle = BZ2_bzWriteOpen(&bz2err, fpOutput, 9, 0, 0);
		if (bzHandle == nullptr || bz2err != BZ_OK)
		{
			printf("BZ2_bzWriteOpen failed, bz2err=%d\n", bz2err);
			break;
		}

		//generate diff
		struct bsdiff_stream stream;
		stream.malloc = malloc;
		stream.free = free;
		stream.write = bzPatchFileWriter;
		stream.opaque = bzHandle;
		if (bsdiff(pBuffer1, fileSize1, pBuffer2, fileSize2, &stream))
		{
			printf("bsdiff error!\n");
			break;
		}

		BZ2_bzWriteClose(&bz2err, bzHandle, 0, NULL, NULL);
		if (bz2err != BZ_OK)
		{
			printf("BZ2_bzWriteClose failed, bz2err=%d", bz2err);
			break;
		}

		result = true;
		printf("Diff file created successfully: %s\n", outputFilename);
	} while (false);

	if (fpOutput != nullptr)
	{
		fclose(fpOutput);
		fpOutput = nullptr;
	}
	freeFileBuffer(pBuffer1);
	pBuffer1 = nullptr;

	freeFileBuffer(pBuffer2);
	pBuffer2 = nullptr;

	return result;
}