#pragma once

#include <string_view>
#include <vector>
#include <optional>
#include <span>

#include "assets/data_stores.hpp"
#include "util/string_lookup.hpp"

#include "opengl/metadata/shader_source_metadata.hpp"
#include "opengl/shading/requirements/shader_source_requirements.hpp"
#include "opengl/metadata/preprocessed_shader_source_metadata.hpp"

#include "assets/data_stores/shader_source_store.hpp"
#include "opengl/shading/shader_source_set.hpp"

namespace zgl {

class shader_source_manager {

public:
	using store_type = assets::shader_source_store;
	using store_id_type = store_type::id_type;
	using metadata_type = shader_source_metadata;
	using data_type = char*;
	using handle_type = const char*;
	using entry_type = std::pair<metadata_type, store_id_type>;
	using entry_view_type = std::pair<preprocessed_shader_source_metadata, handle_type>;

	void process(const assets::data_stores& stores);

	void get_shader_sources(
		const assets::shader_source_store& shader_sources,
		std::span<const shading::shader_source_requirements> requirements,
		std::span<preprocessed_shader_source_metadata> metadata,
		std::vector<const char*>& shader_strings
	);

protected:

	void tokenize_declarations(std::string_view source);

	std::optional<shader_source_metadata> parse_metadata_from_tokens();

	[[nodiscard]] static bool parse_stage_declaration(
		std::span<const std::string_view> values,
		shader_source_metadata& metadata
	);

	[[nodiscard]] static bool parse_geometry_declaration(
		std::span<const std::string_view> tokens,
		shader_source_metadata& metadata
	);

	[[nodiscard]] static bool parse_features_declaration(
		std::span<const std::string_view> values,
		shader_source_metadata& metadata
	);

	[[nodiscard]] static bool parse_static_enable_declaration(
		std::span<const std::string_view> values,
		shader_source_metadata& metadata
	);

	[[nodiscard]] static bool parse_dynamic_enable_declaration(
		std::span<const std::string_view> values,
		shader_source_metadata& metadata
	);

	template<typename T>
	static void parse_feature_tokens(
		std::span<const std::string_view> values,
		const ztu::string_lookup<T>& feature_lookup,
		T& features
	);

	static void get_define_strings(
		shading::model_geometry::types geometry,
		shading::features::generic::type features,
		shading::features::generic::type& feature_count,
		std::vector<const char*>& defines
	);


	std::vector<entry_type> m_shader_source_lookup;

private:
	std::vector<std::string_view> m_value_token_buffer;
	std::vector<std::size_t> m_declaration_token_count_buffer;
	std::array<std::size_t, 4> m_declaration_type_index_buffer;
};
}