// =====================================================================================================================
//  open-cpp-utils, an open-source cpp library with data structures that extend the STL.
//  Copyright (C) 2024  Medusa Slockbower
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================

#ifndef OPEN_CPP_UTILS_ALLOCATION_H
#define OPEN_CPP_UTILS_ALLOCATION_H

#include <cassert>
#include <memory>

namespace open_cpp_utils
{

template<typename T, class Alloc = std::allocator<T>>
class allocation
{
public:
	using data_type       = T;
	using reference       = data_type&;
	using const_reference = const data_type&;
	using pointer         = data_type*;
	using const_pointer   = const data_type*;
	
	
	allocation();
	allocation(size_t size);
	allocation(allocation&& alloc) noexcept;
	allocation(const allocation& alloc);
	~allocation();

	size_t size() const { return Size_; }
	bool operator()() const { return Buffer_ != nullptr; }

	void allocate(size_t size);
	void reallocate(size_t size);
	void free();

	void clear(size_t offset, size_t size, const T& value);
	void copy(const allocation& other, size_t offset, size_t o_offset, size_t size);

	reference       operator[](int i)       { assert(i >= 0 && i < Size_); return Buffer_[i]; }
	const_reference operator[](int i) const { assert(i >= 0 && i < Size_); return Buffer_[i]; }

	operator pointer() { return Buffer_; }
	operator const_pointer() const { return Buffer_; }

	allocation& operator=(const allocation& other);
	allocation& operator=(allocation&& other) noexcept;

	pointer       data()       { return Buffer_; }
	const_pointer data() const { return Buffer_; }

	pointer begin() { return Buffer_; }
	pointer end() { return Buffer_ + Size_; }

	const_pointer begin() const { return Buffer_; }
	const_pointer end()   const { return Buffer_ + Size_; }

private:
	Alloc  Alloc_;
	size_t Size_;
	T*     Buffer_;
};

template<typename T, class Alloc>
allocation<T, Alloc>::allocation()
: Alloc_(), Size_(0), Buffer_(nullptr) { }

template<typename T, class Alloc>
allocation<T, Alloc>::allocation(size_t size)
: Alloc_(), Size_(size), Buffer_(Alloc_.allocate(Size_)) { }

template<typename T, class Alloc>
allocation<T, Alloc>::allocation(allocation &&alloc) noexcept
: Alloc_(), Size_(alloc.Size_), Buffer_(alloc.Buffer_) { }

template<typename T, class Alloc>
allocation<T, Alloc>::allocation(const allocation &alloc)
	: Alloc_(), Size_(alloc.Size_), Buffer_(Alloc_.allocate(Size_))
{
	copy(alloc, 0, 0, Size_);
}

template<typename T, class Alloc>
allocation<T, Alloc>::~allocation()
{
	Alloc_.deallocate(Buffer_, Size_);
	Buffer_ = nullptr; Size_ = 0;
}

template<typename T, class Alloc>
void allocation<T, Alloc>::allocate(size_t size)
{
	assert(Buffer_ != nullptr);
	if(Buffer_ == nullptr) return;

	Buffer_ = Alloc_.allocate(size);
}

template<typename T, class Alloc>
void allocation<T, Alloc>::reallocate(size_t size)
{
	// Assertions for debug mode
	assert(Buffer_ != nullptr);
	
	// Safety checks
	if(Buffer_ == nullptr) return;
	
	const allocation old_ = std::move(*this);
	std::construct_at(this, size);
	std::memcpy(Buffer_, old_.Buffer_, old_.Size_);
}

template<typename T, class Alloc>
void allocation<T, Alloc>::free()
{
	Alloc_.deallocate(Buffer_, Size_);
	Buffer_ = nullptr; Size_ = 0;
}

template<typename T, class Alloc>
void allocation<T, Alloc>::clear(size_t offset, size_t size, const T &value)
{
	// Safety checks
	if(Buffer_ == nullptr) return;
	size = std::min(size, Size_ - offset);
	
	for(pointer it = Buffer_ + offset; it != Buffer_ + size; ++it)
	{
		std::destroy_at(it);
		std::construct_at(it, value);
	}
}

template<typename T, class Alloc>
void allocation<T, Alloc>::copy(const allocation &other, size_t offset, size_t o_offset, size_t size)
{
	// Assertions for debug mode
	assert(size <= Size_ - offset && size <= other.Size_ - o_offset);

	// Safety checks
	if(Buffer_ == nullptr || other.Buffer_ == nullptr) return;
	if(offset >= Size_ || o_offset >= other.Size_) return;
	size = std::min(size, Size_ - offset);
	size = std::min(size, other.Size_ - o_offset);

	std::memcpy(Buffer_ + offset, other.Buffer_ + o_offset, size * sizeof(data_type));
}

template<typename T, class Alloc>
allocation<T, Alloc> & allocation<T, Alloc>::operator=(const allocation &other)
{
	if(&other == this) return *this;
	
	Size_ = other.Size_;
	Buffer_ = Alloc_.allocate(Size_);
	copy(other, 0, 0, Size_);
	return *this;
}

template<typename T, class Alloc>
allocation<T, Alloc> & allocation<T, Alloc>::operator=(allocation &&other) noexcept
{
	if(&other == this) return *this;

	Size_ = other.Size_;
	Buffer_ = other.Buffer_;
	return *this;
}
	
}

#endif //ALLOCATION_H