#pragma once

#include <filesystem>
#include <system_error>
#include <string_view>
#include "assets/data/mesh_data.hpp"
#include "assets/data_stores.hpp"
#include "assets/path_id_lookups.hpp"
#include <set>

namespace assets::obj_loader_error
{
enum class codes {
	ok = 0,
	cannot_open_file,
	malformed_vertex,
	malformed_texture_coordinate,
	malformed_normal,
	malformed_face,
	face_index_out_of_range,
	unknown_line_begin,
	use_material_without_material_library,
	unknown_material_name
};
} // namespace obj_loader_error

namespace assets
{

struct obj_loader
{
	static constexpr auto name = std::string_view("obj");
	using data_type = mesh_data;
	using store_type = mesh_store;
	using lookup_type = mesh_id_lookup;

	// TODO port this mess to the new interface
	[[nodiscard]] std::error_code prefetch(
		path_id_lookups& lookups
	);

	[[nodiscard]] std::error_code load(
		path_id_lookups& lookups,
		data_stores& stores,
		bool pedantic = false
	);

protected:
	struct indexed_vertex_type
	{
		z3d::index_triangle vertex;
		z3d::vertex_index buffer_index;

		friend auto operator<=>(const indexed_vertex_type& a, const indexed_vertex_type& b) {
			return a.vertex <=> b.vertex;
		}

		bool operator==(const indexed_vertex_type& other) const noexcept {
			return other.vertex == vertex;
		}
	};

	class parser_context
	{
	public:
		parser_context(
			const texture_id_lookup& texture_id_lookup,
			material_id_lookup& material_id_lookup,
			material_store& material_store,
			store_type& store
		);

		void operator()(lookup_type::const_pointer entry) noexcept;

	protected:
		void reset();

		[[nodiscard]] std::optional<texture_id> fetch_texture_id(
			const std::filesystem::path& mtl_dir,
			std::string_view filename,
			std::string_view texture_type_name
		);

	private:
		const path_id_lookups* m_id_lookups;
		data_stores* m_stores;
		data_type m_buffer{};
		data_type m_read_buffer{};
		std::set<indexed_vertex_type> vertex_ids{};
	};




	static void find_materials(
		std::span<char> buffer,
		std::filesystem::path& path_buffer,
		const std::filesystem::path& base_directory,
		std::ifstream& in,
		ztu::string_list& material_filenames
	);

	[[nodiscard]] static std::error_code obj_loader::parse_file(
		dynamic_mesh_buffer& read_buffer,
		dynamic_mesh_buffer& mesh_buffer,
		std::filesystem::path& path_buffer,
		const std::filesystem::path& base_directory,
		std::set<indexed_vertex_type>& vertex_ids,
		std::ifstream& in,
		prefetch_lookup& id_lookup,
		dynamic_shader_source_store& store,
		bool pedantic
	);
};
}