#pragma once

#include <string_view>
#include <vector>
#include <optional>
#include <span>
#include "util/string_lookup.hpp"

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

#include "assets/dynamic_data_stores/dynamic_shader_source_store.hpp"
#include "opengl/shading/shader_source_set.hpp"

namespace zgl {

class shader_preprocessor {

public:
	void preprocess(
		const dynamic_shader_source_store& shader_sources
	);

	void fetch_shader_sources(
		const dynamic_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
	);

private:
	inline static auto mesh_feature_defines = std::array{
		"#define FACE\n",
		"#define LINE\n",
		"#define POINT\n",
		"#define V_L\n",
		"#define V_RGB\n",
		"#define V_A\n",
		"#define LIGHTING\n",
		"#define TEXTURE\n",
		"#define U_RGBA\n",
	};

	inline static auto point_cloud_feature_defines = std::array{
		"#define SQUARE\n",
		"#define LIGHTING\n",
		"#define V_L\n",
		"#define V_RGB\n",
		"#define V_A\n",
		"#define U_RGBA\n",
		"#define RAINBOW\n"
	};

	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;

	using source_lookup_entry_type = std::pair<shader_source_metadata, dynamic_shader_source_store::id_type>;
	using source_lookup_type = std::vector<source_lookup_entry_type>;

	source_lookup_type m_shader_source_lookup;
};
}