#include "PCH.h"
#include "Util.h"
#include "SObject.h"

#include <random>
#include <limits>
#include <sstream>
#include <iomanip>

#ifdef max
#undef max
#endif

namespace sh::core {
	auto Util::U8StringToWstring(const std::string& u8str) -> std::wstring
	{
		std::wstring result;
		for (int i = 0; i < u8str.size();)
		{
			unsigned char c0 = u8str[i];
			if (c0 >> 3 == 0b11110) //4byte utf
			{
				c0 = (c0 & 0b00000111);
				char c1 = (u8str[i + 1] & 0b00111111);
				char c2 = (u8str[i + 2] & 0b00111111);
				char c3 = (u8str[i + 3] & 0b00111111);
				int unicode = (c3 | c2 << 6) | ((c2 >> 2 | c1 << 4) << 8) | ((c1 >> 4 | c0 << 2) << 16);
				//UTF-16 incoding
				wchar_t high = 0xD800 + ((unicode - 0x10000) / 0x400);
				wchar_t low = 0xDC00 + ((unicode - 0x10000) % 0x400);
				result += high;
				result += low;
				i += 4;
			}
			else if (c0 >> 4 == 0b1110) //3byte utf
			{
				c0 = (c0 & 0b00001111);
				char c1 = (u8str[i + 1] & 0b00111111);
				char c2 = (u8str[i + 2] & 0b00111111);
				result += (c2 | c1 << 6) | ((c1 >> 2 | c0 << 4) << 8);
				i += 3;
			}
			else if (c0 >> 5 == 0b110) //2byte utf
			{
				c0 = (c0 & 0b00011111);
				char c1 = (u8str[i + 1] & 0b00111111);
				result += (c1 | c0 << 6) | (c0 >> 2 << 8);
				i += 2;
			}
			else if (c0 >> 7 == 0b0) //1byte utf
			{
				result += c0;
				++i;
			}
		}
		return result;
	}

	bool IsValid(const SObject* obj)
	{
		if (obj == nullptr)
			return false;
		return !obj->IsPendingKill();
	}

	auto Util::GetElapsedTime(const std::function<void()>& func) -> std::chrono::milliseconds
	{
		auto start = std::chrono::high_resolution_clock::now();
		func();
		auto end = std::chrono::high_resolution_clock::now();
		return std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
	}

	auto Util::AlignTo(uint32_t value, uint32_t alignment) -> uint32_t
	{
		// ex) value = 20, alignment = 16
		// value = 0001'0100
		// alignment = 0001'0000
		// alignment - 1 = 0000'1111
		// ~(alignment - 1) = 1111'0000 - 끝 4비트가 0이면 16의 배수라는 뜻.
		// 35 = 0010'0011
		// 0010'0011 & 1111'0000 = 0010'0000 = 32 
		return (value + alignment - 1) & ~(alignment - 1);
	}

	SH_CORE_API auto Util::RandomRange(uint32_t min, uint32_t max) -> uint32_t
	{
		std::uniform_int_distribution<uint32_t> rnd{ min, max };
		return rnd(gen);
	}
	SH_CORE_API auto Util::RandomRange(int min, int max) -> int
	{
		std::uniform_int_distribution<int> rnd{ min, max };
		return rnd(gen);
	}
	SH_CORE_API auto Util::RandomRange(float min, float max) -> float
	{
		std::uniform_real_distribution<float> rnd{ min, max };
		return rnd(gen);
	}
	SH_CORE_API auto Util::RandomRange(double min, double max) -> double
	{
		std::uniform_real_distribution<double> rnd{ min, max };
		return rnd(gen);
	}
}