#include "sgu_stdafx.h"
#include "sgu_mode_rand_modify.h"
#include "sgu_utils.h"


bool randomModifyFile(const char* inputFileName, const char* outputFileName, int64_t minSize, int64_t maxSize, int32_t counts)
{
	if (!inputFileName || inputFileName[0] == 0 || !outputFileName || outputFileName[0] == 0)
	{
		printf("Invalid input or output file name.\n");
		return false;
	}

	if (minSize == 0 || maxSize == 0 || minSize > maxSize)
	{
		printf("Invalid size parameters.\n");
		return false;
	}

	// Check if input and output file names are the same
	if (compareTwoFileName(inputFileName, outputFileName) == 0)
	{
		printf("Input and output file names cannot be the same.\n");
		return false;
	}

	FILE* inputFile = nullptr;
	FILE* outputFile = nullptr;

	// Open the input file in binary mode
	fopen_s(&inputFile, inputFileName, "rb");
	if (!inputFile) 
	{
		printf("Error opening input file:%s\n", inputFileName);
		return false;
	}

	// Open the output file in binary mode
	fopen_s(&outputFile, outputFileName, "wb");
	if (!outputFile) 
	{
		printf("Error opening output file:%s", outputFileName);
		fclose(inputFile);
		return false;
	}

	// Get the size of the input file
	fseek(inputFile, 0, SEEK_END);
	int64_t inputFileSize = (int64_t)ftell(inputFile);
	fseek(inputFile, 0, SEEK_SET);

	if(maxSize*counts>inputFileSize) 
	{
		printf("Error: The specified size range(%d*%lld) and count exceed the input file size[%lld].\n", 
			counts, maxSize, inputFileSize);
		fclose(inputFile);
		fclose(outputFile);
		return false;
	}

	std::vector<std::pair< int64_t, int64_t>> segmentArray;
	generateRandomSegment(inputFileSize, minSize, maxSize, counts, segmentArray);

	printf("Input file size: %lld bytes\n", inputFileSize);
	printf("Modify %d segments, size range: %lld ~ %lld bytes\n", counts, minSize, maxSize);
	int64_t totalSize = 0;
	for (auto& p : segmentArray)
	{
		totalSize += p.second;
		printf("Modify segment: offset=%lld~%lld, size=%lld\n", p.first, p.first+p.second, p.second);
	}
	printf("Total modified size: %lld bytes\n", totalSize);

	//Temp memory
	std::vector<uint8_t> buffer;

	int64_t offset = 0;

	//read and modify each segment
	for(const auto& segment : segmentArray)
	{
		int64_t segmentOffset = segment.first;
		int64_t segmentSize = segment.second;
		int64_t dataSize = segmentOffset - offset;
		// Read file content before segment
		buffer.resize(dataSize);
		fseek(inputFile, (long)offset, SEEK_SET);
		int64_t bytesRead = fread(buffer.data(), 1, dataSize, inputFile);
		if (bytesRead != dataSize)
		{
			printf("Error reading segment before offset %lld, expected %lld bytes, got %lld bytes.\n", 
				offset, dataSize, bytesRead);
			fclose(inputFile);
			fclose(outputFile);
			return false;
		}

		//write to output file
		int64_t bytesWrite = fwrite(buffer.data(), 1, dataSize, outputFile);
		if (bytesWrite != dataSize)
		{
			printf("Error writing segment before offset %lld, expected %lld bytes, wrote %lld bytes.\n",
				offset, dataSize, bytesWrite);
			fclose(inputFile);
			fclose(outputFile);
			return false;
		}

		// create random segment (fill with random data)
		buffer.resize(segmentSize);
		fillRandomData(buffer.data(), segmentSize);

		// Write the modified segment to the output file
		if (segmentSize != fwrite(buffer.data(), 1, segmentSize, outputFile))
		{
			printf("Error writing modified segment at offset %lld, size %lld bytes.\n",
				segmentOffset, segmentSize);
			fclose(inputFile);
			fclose(outputFile);
			return false;
		}

		offset = segmentOffset + segmentSize;
	}

	//read and write the remaining part of the file
	buffer.resize(inputFileSize - offset);
	fseek(inputFile, (long)offset, SEEK_SET);
	size_t bytesRead = fread(buffer.data(), 1, inputFileSize - offset, inputFile);
	if (bytesRead != inputFileSize - offset)
	{
		printf("Error reading segment before offset %zu, expected %zu bytes, got %zu bytes.\n",
			offset, inputFileSize - offset, bytesRead);
		fclose(inputFile);
		fclose(outputFile);
		return false;
	}

	//write to output file
	fwrite(buffer.data(), 1, inputFileSize - offset, outputFile);

	// Close both files
	fclose(inputFile);
	fclose(outputFile);
	return true;
}