#pragma once
#include <algorithm>
#include <numeric>
#include <cassert>
#include <stdexcept>
namespace API
{
	template<typename T>
	class Container
	{
	public:
		using pointer = T*;
		using const_pointer = const T*;
		using iterator = T*; //aliases for generic code
		using const_iterator = const T*; 
		using value_type = T;
		using size_type = size_t;
		using reference = T&;
		using const_reference = const T&;

		friend void swap(Container& a, Container& b) noexcept;

		Container() = default;
		explicit Container(size_type count) : _data(new T[count]), _count(count), _capacity(count){
			std::fill(begin(), end(), T());
		};

		explicit Container(const Container& that) : _data(new T[that._capacity]), _count(that._count), _capacity(that._capacity)  {
			std::copy(begin(), end(), _data);
		}

		Container(Container&& that) noexcept {
			_count = that._count;
			_capacity = that._capacity;
			_data = that._data;
			that._data = nullptr;
			that._count = 0;
			that._capacity = 0;
		}

		Container& operator=(Container&& that) noexcept {
			swap(that);
			return *this;
		}
		
		void swap(Container& that) noexcept {
			using std::swap;
			swap(_data, that._data);
			swap(_count, that._count);
			swap(_capacity, that._capacity);
		}

		Container& operator=(const Container& that) { // copy assignment
			delete[] _data;
			_data = new T[that._capacity]; //overwrites an existing pointer
			_count = that._count;
			_capacity = that._capacity;
			std::copy(that.begin(), that.end(), _data);
			return *this;			
		}
		
		~Container() {
			//TODO: maybe have to call destructors or T (~T)
			delete[] _data;
		}

		void reserve(size_type newCapacity) {
			if (newCapacity <= _capacity) { return;  } //never decrease the allocation
			pointer newBuffer = new T[newCapacity];
			std::move(begin(), end(), newBuffer);
			delete[] _data; //TODO: potentially need to deconstruct objects
			_data = newBuffer;
			_capacity = newCapacity;
		}

		void push_back(const T& value) {
			if (_capacity == 0) {
				reserve(2);
			}
			else if (_count == _capacity) {
				reserve(2 * _capacity);
			}
			_data[_count] = value;
			_count++;
		}

		reference at(size_type index) {
			if (index >= size()) {
				throw std::out_of_range("Container at() index is out of range!");
			}
			return _data[index];
		}
		const_reference at(size_type index) const {
			if (index >= size()) {
				throw std::out_of_range("Container at() index is out of range!");
			}
			return _data[index];
		}

		reference operator[](size_type index) noexcept{
			assert(index < size() && "Container operator[] index is out of range!");
			return _data[index];
		}
		const_reference operator[](size_type index) const noexcept {
			assert(index < size() && "Container operator[] index is out of range!");
			return _data[index];
		}

		reference front() noexcept {
			assert(!empty() && "front() on empty container is UB");
			return _data[0];
		}
		const_reference front() const noexcept {
			assert(!empty() && "front() on empty container is UB");
			return _data[0];
		}

		const_reference back() const noexcept {
			assert(!empty() && "back() on empty container is UB");
			return _data[size() - 1];
		}
		reference back() noexcept {
			assert(!empty() && "back() on empty container is UB");
			return _data[size() - 1];
		}
		
		[[nodiscard]] constexpr bool empty() const noexcept {
			return size() == 0;
		}

		size_type size() const noexcept {
			return _count;
		}

		//TODO: make free functions of these
		const_iterator begin() const noexcept { return _data; }		
		const_iterator cbegin() const noexcept { return _data; }
		iterator begin() noexcept { return _data; }

		const_iterator end() const noexcept { return _data + _count; }
		const_iterator cend() const noexcept { return _data + _count; }		
		iterator end() noexcept { return _data + _count; }

	private:
		T* _data = nullptr;
		size_type _count = 0;
		size_type _capacity = 0;
	};

	template<typename T>
	void swap(Container<T>& a, Container<T>& b) noexcept {
		a.swap(b);
		/*std::swap(a._capacity, b._capacity);
		std::swap(a._count, b._count);
		std::swap(a._data, b._data);*/
	}

	template<typename T>
	bool operator==(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		if (std::size(lhs) != std::size(rhs)) { return false; }
		return std::equal(std::begin(lhs), std::end(lhs), std::begin(rhs));
	}
	template<typename T>
	bool operator<(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		return std::lexicographical_compare(lhs.begin(), lhs.end(),
			rhs.begin(), rhs.end());
	}

	template<typename T>
	bool operator!=(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		return not(lhs == rhs);
	}
	template<typename T>
	bool operator>(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		return rhs < lhs;
	}
	template<typename T>
	bool operator<=(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		!(lhs > rhs);
	}
	template<typename T>
	bool operator>=(const Container<T>& lhs, const Container<T>& rhs) noexcept {
		!(lhs < rhs);
	}
}