#pragma once

namespace pfc {
	void byteswap_raw(void * p_buffer,t_size p_bytes);

	template<typename T> T byteswap_t(T p_source);

	template<> inline char byteswap_t<char>(char p_source) {return p_source;}
	template<> inline unsigned char byteswap_t<unsigned char>(unsigned char p_source) {return p_source;}
	template<> inline signed char byteswap_t<signed char>(signed char p_source) {return p_source;}

	template<typename T> T byteswap_int_t(T p_source) {
		enum { width = sizeof(T) };
		typedef typename sized_int_t<width>::t_unsigned tU;
		tU in = p_source, out = 0;
		for(unsigned walk = 0; walk < width; ++walk) {
			out |= ((in >> (walk * 8)) & 0xFF) << ((width - 1 - walk) * 8);
		}
		return out;
	}

#ifdef _MSC_VER//does this even help with performance/size?
	template<> inline wchar_t byteswap_t<wchar_t>(wchar_t p_source) {return _byteswap_ushort(p_source);}

	template<> inline short byteswap_t<short>(short p_source) {return _byteswap_ushort(p_source);}
	template<> inline unsigned short byteswap_t<unsigned short>(unsigned short p_source) {return _byteswap_ushort(p_source);}

	template<> inline int byteswap_t<int>(int p_source) {return _byteswap_ulong(p_source);}
	template<> inline unsigned int byteswap_t<unsigned int>(unsigned int p_source) {return _byteswap_ulong(p_source);}

	template<> inline long byteswap_t<long>(long p_source) {return _byteswap_ulong(p_source);}
	template<> inline unsigned long byteswap_t<unsigned long>(unsigned long p_source) {return _byteswap_ulong(p_source);}

	template<> inline long long byteswap_t<long long>(long long p_source) {return _byteswap_uint64(p_source);}
	template<> inline unsigned long long byteswap_t<unsigned long long>(unsigned long long p_source) {return _byteswap_uint64(p_source);}
#else
	template<> inline wchar_t byteswap_t<wchar_t>(wchar_t p_source) {return byteswap_int_t(p_source);}

	template<> inline short byteswap_t<short>(short p_source) {return byteswap_int_t(p_source);}
	template<> inline unsigned short byteswap_t<unsigned short>(unsigned short p_source) {return byteswap_int_t(p_source);}

	template<> inline int byteswap_t<int>(int p_source) {return byteswap_int_t(p_source);}
	template<> inline unsigned int byteswap_t<unsigned int>(unsigned int p_source) {return byteswap_int_t(p_source);}

	template<> inline long byteswap_t<long>(long p_source) {return byteswap_int_t(p_source);}
	template<> inline unsigned long byteswap_t<unsigned long>(unsigned long p_source) {return byteswap_int_t(p_source);}

	template<> inline long long byteswap_t<long long>(long long p_source) {return byteswap_int_t(p_source);}
	template<> inline unsigned long long byteswap_t<unsigned long long>(unsigned long long p_source) {return byteswap_int_t(p_source);}
#endif

	template<> inline float byteswap_t<float>(float p_source) {
		float ret;
		*(t_uint32*) &ret = byteswap_t(*(const t_uint32*)&p_source );
		return ret;
	}

	template<> inline double byteswap_t<double>(double p_source) {
		double ret;
		*(t_uint64*) &ret = byteswap_t(*(const t_uint64*)&p_source );
		return ret;
	}

	//blargh at GUID byteswap issue
	template<> inline GUID byteswap_t<GUID>(GUID p_guid) {
		GUID ret;
		ret.Data1 = pfc::byteswap_t(p_guid.Data1);
		ret.Data2 = pfc::byteswap_t(p_guid.Data2);
		ret.Data3 = pfc::byteswap_t(p_guid.Data3);
		ret.Data4[0] = p_guid.Data4[0];
		ret.Data4[1] = p_guid.Data4[1];
		ret.Data4[2] = p_guid.Data4[2];
		ret.Data4[3] = p_guid.Data4[3];
		ret.Data4[4] = p_guid.Data4[4];
		ret.Data4[5] = p_guid.Data4[5];
		ret.Data4[6] = p_guid.Data4[6];
		ret.Data4[7] = p_guid.Data4[7];
		return ret;
	}

#if ! defined(_MSC_VER) || _MSC_VER >= 1900
	template<> inline char16_t byteswap_t<char16_t>(char16_t v) { return (char16_t)byteswap_t((uint16_t)v); }
	template<> inline char32_t byteswap_t<char32_t>(char32_t v) { return (char32_t)byteswap_t((uint32_t)v); }
#endif
};

#ifdef _MSC_VER

// No MSVC platform is ever big endian
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 0

#else//_MSC_VER

#if defined(__APPLE__)
#include <architecture/byte_order.h>
#else
#include <endian.h>
#endif

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 0
#else
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 1
#endif

#endif//_MSC_VER

#ifdef PFC_BYTE_ORDER_IS_BIG_ENDIAN
#define PFC_BYTE_ORDER_IS_LITTLE_ENDIAN (!(PFC_BYTE_ORDER_IS_BIG_ENDIAN))
#else
#error please update byte order #defines
#endif


namespace pfc {
	static constexpr bool byte_order_is_big_endian = !!PFC_BYTE_ORDER_IS_BIG_ENDIAN;
	static constexpr bool byte_order_is_little_endian = !!PFC_BYTE_ORDER_IS_LITTLE_ENDIAN;

	template<typename T> T byteswap_if_be_t(T p_param) {return byte_order_is_big_endian ? byteswap_t(p_param) : p_param;}
	template<typename T> T byteswap_if_le_t(T p_param) {return byte_order_is_little_endian ? byteswap_t(p_param) : p_param;}
}

namespace byte_order {

#if PFC_BYTE_ORDER_IS_BIG_ENDIAN//big endian
	template<typename T> inline void order_native_to_le_t(T& param) {param = pfc::byteswap_t(param);}
	template<typename T> inline void order_native_to_be_t(T& param) { (void)param; }
	template<typename T> inline void order_le_to_native_t(T& param) {param = pfc::byteswap_t(param);}
	template<typename T> inline void order_be_to_native_t(T& param) { (void)param; }
#else//little endian
	template<typename T> inline void order_native_to_le_t(T& param) { (void)param; }
	template<typename T> inline void order_native_to_be_t(T& param) {param = pfc::byteswap_t(param);}
	template<typename T> inline void order_le_to_native_t(T& param) { (void)param; }
	template<typename T> inline void order_be_to_native_t(T& param) {param = pfc::byteswap_t(param);}
#endif
};



namespace pfc {
	template<typename TInt,unsigned width,bool IsBigEndian>
	class __EncodeIntHelper {
	public:
		inline static void Run(TInt p_value,t_uint8 * p_out) {
			*p_out = (t_uint8)(p_value);
			__EncodeIntHelper<TInt,width-1,IsBigEndian>::Run(p_value >> 8,p_out + (IsBigEndian ? -1 : 1));
		}
	};

	template<typename TInt,bool IsBigEndian>
	class __EncodeIntHelper<TInt,1,IsBigEndian> {
	public:
		inline static void Run(TInt p_value,t_uint8* p_out) {
			*p_out = (t_uint8)(p_value);
		}
	};
	template<typename TInt,bool IsBigEndian>
	class __EncodeIntHelper<TInt,0,IsBigEndian> {
	public:
		inline static void Run(TInt,t_uint8*) {}
	};

	template<typename TInt>
	inline void encode_little_endian(t_uint8 * p_buffer,TInt p_value) {
		__EncodeIntHelper<TInt,sizeof(TInt),false>::Run(p_value,p_buffer);
	}
	template<typename TInt>
	inline void encode_big_endian(t_uint8 * p_buffer,TInt p_value) {
		__EncodeIntHelper<TInt,sizeof(TInt),true>::Run(p_value,p_buffer + (sizeof(TInt) - 1));
	}


	template<typename TInt,unsigned width,bool IsBigEndian>
	class __DecodeIntHelper {
	public:
		inline static TInt Run(const t_uint8 * p_in) {
			return (__DecodeIntHelper<TInt,width-1,IsBigEndian>::Run(p_in + (IsBigEndian ? -1 : 1)) << 8) + *p_in;
		}
	};
	
	template<typename TInt,bool IsBigEndian>
	class __DecodeIntHelper<TInt,1,IsBigEndian> {
	public:
		inline static TInt Run(const t_uint8* p_in) {return *p_in;}
	};

	template<typename TInt,bool IsBigEndian>
	class __DecodeIntHelper<TInt,0,IsBigEndian> {
	public:
		inline static TInt Run(const t_uint8*) {return 0;}
	};

	template<typename TInt>
	inline void decode_little_endian(TInt & p_out,const t_uint8 * p_buffer) {
		p_out = __DecodeIntHelper<TInt,sizeof(TInt),false>::Run(p_buffer);
	}

	template<typename TInt>
	inline void decode_big_endian(TInt & p_out,const t_uint8 * p_buffer) {
		p_out = __DecodeIntHelper<TInt,sizeof(TInt),true>::Run(p_buffer + (sizeof(TInt) - 1));
	}

	template<typename TInt>
	inline TInt decode_little_endian(const t_uint8 * p_buffer) {
		TInt temp;
		decode_little_endian(temp,p_buffer);
		return temp;
	}

	template<typename TInt>
	inline TInt decode_big_endian(const t_uint8 * p_buffer) {
		TInt temp;
		decode_big_endian(temp,p_buffer);
		return temp;
	}

	template<bool IsBigEndian,typename TInt>
	inline void decode_endian(TInt & p_out,const t_uint8 * p_buffer) {
		if (IsBigEndian) decode_big_endian(p_out,p_buffer);
		else decode_little_endian(p_out,p_buffer);
	}
	template<bool IsBigEndian,typename TInt>
	inline void encode_endian(t_uint8 * p_buffer,TInt p_in) {
		if (IsBigEndian) encode_big_endian(p_in,p_buffer);
		else encode_little_endian(p_in,p_buffer);
	}



	template<unsigned width>
	inline void reverse_bytes(t_uint8 * p_buffer) {
		pfc::swap_t(p_buffer[0],p_buffer[width-1]);
		reverse_bytes<width-2>(p_buffer+1);
	}

	template<> inline void reverse_bytes<1>(t_uint8 * ) { }
	template<> inline void reverse_bytes<0>(t_uint8 * ) { }

	inline int32_t readInt24(const void * mem) {
		const uint8_t * p = (const uint8_t*) mem;
		int32_t ret;
		if (byte_order_is_little_endian) {
			ret = p[0];
			ret |= (uint32_t)p[1] << 8;
			ret |= (int32_t)(int8_t)p[2] << 16;
			return ret;
		} else {
			ret = p[2];
			ret |= (uint32_t)p[1] << 8;
			ret |= (int32_t)(int8_t)p[0] << 16;
			return ret;
		}
	}
}