/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include "Host/SystemInfo.hpp"
#include "Base/Logger.hpp"
#include "Base/Utils.hpp"
#include "Math/ByteSize.hpp"
#include <fstream>
#include <iostream>
#include <string>
#include <sys/resource.h>

namespace openVulkanoCpp
{
	namespace
	{
		size_t ReadMemInfo(std::string_view value)
		{
			std::ifstream meminfoFile("/proc/meminfo");
			if (!meminfoFile)
			{
				Logger::PERF->error("Failed to open /proc/meminfo");
				return 0;
			}
			std::string line;
			while (std::getline(meminfoFile, line))
			{
				if (Utils::StartsWith(line, value))
				{
					std::string n, t;
					size_t v;
					std::istringstream ss(line);
					ss >> n >> v >> t;
					return ByteSize(v, ByteSizeUnit::FromName(t));
				}
			}
			meminfoFile.close();
			return 0;
		}

		size_t ReadProcStatus(std::string_view value)
		{
			std::ifstream statusFile("/proc/self/status");
			if (statusFile)
			{
				size_t mem = 0;
				std::string line;
				while (std::getline(statusFile, line))
				{
					if (Utils::StartsWith(line, value))
					{
						std::string n, t;
						size_t v;
						std::istringstream ss(line);
						ss >> n >> v >> t;
						return ByteSize(v, ByteSizeUnit::FromName(t));
					}
				}
				statusFile.close();
				return mem;
			}
			Logger::PERF->error("Failed to open /proc/self/status");
			return 0;
		}
	}

	size_t SystemInfo::GetSystemRam()
	{
		return ReadMemInfo("MemTotal");
	}

	size_t SystemInfo::GetSystemRamAvailable()
	{
		return ReadMemInfo("MemAvailable");
	}

	size_t SystemInfo::GetAppRamUsed()
	{
		return ReadProcStatus("VmSize");
	}

	size_t SystemInfo::GetAppRamAvailable()
	{
		return std::min(GetSystemRamAvailable(), GetAppVirtualMemoryMax() - GetAppRamUsed());
	}

	size_t SystemInfo::GetAppRamMax()
	{
		return std::min(GetSystemRam(), GetAppVirtualMemoryMax());
	}

	size_t SystemInfo::GetAppVirtualMemoryMax()
	{
		rlimit limit;
		if (getrlimit(RLIMIT_AS, &limit) == 0)
		{
			std::cout << "Maximum memory usage: " << limit.rlim_cur << " bytes" << std::endl;
			return limit.rlim_cur;
		}
		Logger::PERF->error("Failed to query max application memory");
		return 0;
	}
}