#pragma once

#include "tl/detail/prologue.h"
#include <numeric>
#include <tl/string.h>
#include <cstdint>
#include <type_traits>

namespace tl
{

template <typename enumT>
class flag_set
{

public:

	typedef enumT							enum_type;
	typedef std::underlying_type_t<enumT>	store_type;

	store_type combine();
	store_type combine(enumT head);
	template<typename... Ts>
	store_type combine(enumT head, Ts... tail);

	template<typename ... Types>
	flag_set(Types... args);

	// Value constructor.
	//Only enabled if the storage_type and enum_type are different (i.e. one is an enum and the other is a primitive type)
	explicit flag_set(store_type value);

	template<class String>
	String get_as() const;

	flag_set& set();

	flag_set& set(enum_type flag, bool val = true);

	flag_set& reset();

	flag_set& reset(enum_type flag);

	flag_set& flip();

	flag_set& flip(enum_type flag);

	size_t count() const;

	static size_t size_in_bits();

	bool test(enum_type flag) const;

	template <typename Enum, typename...Enums>
	bool test_all(Enum first, Enums... remaining) const;

	template <typename Enum, typename...Enums>
	bool test_any(Enum first, Enums... remaining) const;

	bool any() const;

	bool none() const;

	store_type value() const;

	flag_set<enum_type>(const flag_set<enum_type>& other);
	flag_set<enum_type>& operator=(const flag_set<enum_type>& other);

	bool operator==(const flag_set<enum_type>& other) const;
	bool operator!=(const flag_set<enum_type>& other) const;

	flag_set<enum_type>& operator|=(const flag_set<enum_type>& other);
	flag_set<enum_type>& operator&=(const flag_set<enum_type>& other);
	flag_set<enum_type>& operator^=(const flag_set<enum_type>& other);
	flag_set<enum_type>& operator|=(const enum_type& other);
	flag_set<enum_type>& operator&=(const enum_type& other);
	flag_set<enum_type>& operator^=(const enum_type& other);

	flag_set<enum_type> operator~() const;

private:
	store_type flags_;
};

template<typename enumT>
flag_set<enumT> operator&(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs);

template<typename enumT>
flag_set<enumT> operator|(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs);

template<typename enumT>
flag_set<enumT> operator^(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs);

}

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

namespace tl
{

template <typename enumT>
typename flag_set<enumT>::store_type flag_set<enumT>::combine()
{
	return flag_set<enumT>::store_type(0);
}

template <typename enumT>
auto flag_set<enumT>::combine(enumT head) -> store_type
{
	return flag_set<enumT>::store_type(head);
}

template <typename enumT>
template <typename... Ts>
auto flag_set<enumT>::combine(enumT head, Ts... tail) -> store_type
{
	return static_cast<store_type>(head) | combine(std::forward<Ts>(tail)...);
}

template <typename enumT>
template <typename... Types>
flag_set<enumT>::flag_set(Types... args)
	: flags_(combine(std::forward<Types>(args)...))
{
}

template <typename enumT>
flag_set<enumT>::flag_set(store_type value)
	: flags_(value)
{
}

template <typename enumT>
template <typename String>
String flag_set<enumT>::get_as() const
{
	eastl::string str(size_in_bits(), '0');
	for (size_t x = 0; x < size_in_bits(); ++x)
		str[size_in_bits() - x - 1] = (flags_ & (1 << x) ? '1' : '0');

	return String(str);
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::set()
{
	flags_ = ~store_type(0);
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::set(enum_type flag, bool val)
{
	flags_ = (val ? (flags_ | static_cast<store_type>(flag)) : (flags_ & ~static_cast<store_type>(flag)));
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::reset()
{
	flags_ = store_type(0);
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::reset(enumT flag)
{
	flags_ &= ~static_cast<store_type>(flag);
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::flip()
{
	flags_ = ~flags_;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::flip(enum_type flag)
{
	flags_ ^= static_cast<store_type>(flag);
	return *this;
}

template <typename enumT>
size_t flag_set<enumT>::count() const
{
	// http://www-graphics.stanford.edu/~seander/bithacks.html#CountBitsSetKernighan

	store_type bits = flags_;
	size_t total = 0;
	for (; bits != 0; ++total)
	{
		bits &= bits - 1; // clear the least significant bit set
	}
	return total;
}

template <typename enumT>
size_t flag_set<enumT>::size_in_bits()
{
	return sizeof(store_type) * 8;
}

template <typename enumT>
bool flag_set<enumT>::test(enum_type flag) const
{
	return (flags_ & static_cast<store_type>(flag)) == static_cast<store_type>(flag);
}

template <typename enumT>
template <typename Enum, typename...Enums>
bool flag_set<enumT>::test_all(Enum first, Enums... remaining) const
{
	store_type expected = flag_set(first, remaining...).value();
	return (flags_ & expected) == expected;
}

template <typename enumT>
template <typename Enum, typename...Enums>
bool flag_set<enumT>::test_any(Enum first, Enums... remaining) const
{
	return (flags_ & flag_set(first, remaining...).value()) != 0;
}

template <typename enumT>
bool flag_set<enumT>::any() const
{
	return flags_ > 0;
}

template <typename enumT>
bool flag_set<enumT>::none() const
{
	return flags_ == 0;
}

template <typename enumT>
typename flag_set<enumT>::store_type flag_set<enumT>::value() const
{
	return flags_;
}

template <typename enumT>
flag_set<enumT>::flag_set(const flag_set<enumT>& other)
	: flags_(other.flags_)
{ }

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator=(const flag_set<enumT>& other)
{
	flags_ = other.flags_;
	return *this;
}

template <typename enumT>
bool flag_set<enumT>::operator==(const flag_set<enumT>& other) const
{
	return flags_ == other.flags_;
}

template <typename enumT>
bool flag_set<enumT>::operator!=(const flag_set<enumT>& other) const
{
	return !operator==(other);
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator|=(const flag_set<enumT>& other)
{
	flags_ |= other.flags_;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator&=(const flag_set<enumT>& other)
{
	flags_ &= other.flags_;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator^=(const flag_set<enumT>& other)
{
	flags_ ^= other.flags_;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator|=(const enumT& other)
{
	flags_ |= other;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator&=(const enumT& other)
{
	flags_ &= other;
	return *this;
}

template <typename enumT>
flag_set<enumT>& flag_set<enumT>::operator^=(const enumT& other)
{
	flags_ ^= other;
	return *this;
}

template <typename enumT>
flag_set<enumT> flag_set<enumT>::operator~() const
{
	flag_set<enumT> ret;
	ret.flags_ = ~flags_;
	return ret;
}

template<typename enumT>
flag_set<enumT> operator&(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs)
{
	//MBR: on VisualStudio 2015 uint8 & uint8 -> uint32, thus difering from enum store type
	return flag_set<enumT>(static_cast<typename flag_set<enumT>::store_type>(lhs.value() & rhs.value()));
}

template<typename enumT>
flag_set<enumT> operator|(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs)
{
	return flag_set<enumT>(lhs.value() | rhs.value());
}

template<typename enumT>
flag_set<enumT> operator^(const flag_set<enumT>& lhs, const flag_set<enumT>& rhs)
{
	return flag_set<enumT>(lhs.value() ^ rhs.value());
}

}