#pragma once

#include <mutex>
#include <shared_mutex>
#include "assets/data/shader_source_data.hpp"
#include "assets/data_views/shader_source_view.hpp"

namespace assets
{

class shader_source_store;

template<typename Char>
class shader_source_store_iterator
{
public:
	using size_type = std::size_t;
	using length_type = ztu::u32;
	using id_type = shader_source_id;
	using metadata_type = shader_source_data::metadata;
	using value_type = std::pair<id_type, shader_source_view>;

	using id_iterator_type = id_type const*;
	using string_iterator_type = Char*;
	using length_iterator_type = const length_type*;
	using metadata_iterator_type = const metadata_type*;

	using offset_type = size_type;
	using difference_type = std::ptrdiff_t;
	using pointer = value_type*;
	using reference = value_type;
	using iterator_category = std::random_access_iterator_tag;

private:
	friend shader_source_store;

	shader_source_store_iterator(
		id_iterator_type ids,
		string_iterator_type strings,
		length_iterator_type lengths,
		metadata_iterator_type metadata,
		std::size_t index,
		const offset_type& offset
	);

public:
	constexpr shader_source_store_iterator() noexcept = default;

	constexpr shader_source_store_iterator(const shader_source_store_iterator&) noexcept = default;
	constexpr shader_source_store_iterator(shader_source_store_iterator&&) noexcept = default;

	constexpr shader_source_store_iterator& operator=(const shader_source_store_iterator&) noexcept = default;
	constexpr shader_source_store_iterator& operator=(shader_source_store_iterator&&) noexcept = default;

	reference operator*() const;

	shader_source_store_iterator& operator++();
	shader_source_store_iterator operator++(int);
	shader_source_store_iterator& operator--();
	shader_source_store_iterator operator--(int);

	shader_source_store_iterator& operator+=(difference_type n);
	shader_source_store_iterator& operator-=(difference_type n);
	shader_source_store_iterator operator+(difference_type n) const;
	shader_source_store_iterator operator-(difference_type n) const;
	difference_type operator-(const shader_source_store_iterator& other) const;

	reference operator[](difference_type n) const;

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

protected:

	void calc_offset(difference_type n);

	reference dereference() const;

private:
	id_iterator_type m_ids{};
	string_iterator_type m_strings{};
	length_iterator_type m_lengths{};
	metadata_iterator_type m_metadata{};
	size_type m_index{};
	offset_type m_offset{};
};


class shader_source_store
{
public:
	using size_type = std::size_t;
	using count_type = ztu::u32;

	using iterator = shader_source_store_iterator<char>;
	using const_iterator = shader_source_store_iterator<const char>;
	using view_type = std::ranges::subrange<iterator>;
	using const_view_type = std::ranges::subrange<const_iterator>;
	using id_type = shader_source_id;
	using data_type = shader_source_data;

	bool insert(id_type id, const data_type& data);

	bool insert(iterator it, id_type id, const data_type& data);

	[[nodiscard]] std::pair<iterator, bool> find(id_type id);

	[[nodiscard]] std::pair<const_iterator, bool> find(id_type id) const;

	inline void remove(const iterator& it);

	inline void clear();

	[[nodiscard]] inline std::shared_lock<std::shared_mutex> acquire_read_lock() const;

	[[nodiscard]] inline std::unique_lock<std::shared_mutex> acquire_write_lock();

	[[nodiscard]] inline iterator begin();

	[[nodiscard]] inline iterator end();

	[[nodiscard]] inline const_iterator begin() const;

	[[nodiscard]] inline const_iterator end() const;

	[[nodiscard]] inline const_iterator cbegin() const;

	[[nodiscard]] inline const_iterator cend() const;

protected:
	bool unsafe_insert(iterator it, id_type id, const data_type& data);

	[[nodiscard]] std::pair<iterator, bool> unsafe_find(id_type id);

	[[nodiscard]] std::pair<const_iterator, bool> unsafe_find(id_type id) const;

private:
	std::vector<id_type> m_ids;
	std::vector<char> m_strings;
	std::vector<count_type> m_lengths;
	std::vector<shader_source_data::metadata> m_metadata;
	mutable std::shared_mutex m_mutex;
};

}

#define INCLUDE_SHADER_SOURCE_STORE_IMPLEMENTATION
#include "assets/data_stores/shader_source_store.ipp"
#undef INCLUDE_SHADER_SOURCE_STORE_IMPLEMENTATION