#include "sgu_stdafx.h"
#include "sgu_mode_gen_rand_file.h"
#include "sgu_utils.h"

bool generateRandomFile(size_t minSize, size_t maxSize, const char* outputFilename)
{
	if (!outputFilename || !*outputFilename) {
		printf("Error: Output filename is not specified.\n");
		return false;
	}
	if (minSize > maxSize) {
		printf("Error: Min size cannot be greater than max size.\n");
		return false;
	}
	if (maxSize - minSize >= 2ULL * 1024ULL * 1024ULL * 1024ULL) {
		printf("Error: Size range is too large(>2GB). Please specify a smaller range.\n");
		return false;
	}

	size_t fileSize = randomInRange(minSize, maxSize);

	FILE* file = nullptr;
	fopen_s(&file, outputFilename, "wb");
	if (!file) {
		printf("Error: Cannot open output file %s for writing.\n", outputFilename);
		return false;
	}

	const size_t kMaxBufSize = 1 * 1024 * 1024; // 1 MB
	uint8_t* buffer = new uint8_t[kMaxBufSize];
	if (!buffer) {
		fclose(file);
		printf("Error: Memory allocation failed for buffer.\n");
		return false;
	}

	size_t remainSize = fileSize;

	while (remainSize > 0)
	{
		size_t chunkSize = (remainSize > kMaxBufSize) ? kMaxBufSize : remainSize;
		// Fill the buffer with random data
		fillRandomData(buffer, chunkSize);

		// Write the buffer to the file
		if (fwrite(buffer, 1, chunkSize, file) != chunkSize) 
		{
			fclose(file);
			delete[] buffer;
			printf("Error: Failed to write to output file %s.\n", outputFilename);
			return false;
		}
		remainSize -= chunkSize;
	}
	fclose(file);
	delete[] buffer;
	printf("Random file generated successfully: %s (%s)\n", outputFilename, sizeToString(fileSize).c_str());
	return true;
}