#pragma once

#include <filesystem>
#include <system_error>
#include <string_view>
#include "../data_loaders"
#include "../data_stores"
#include "assets/prefetch_lookup.hpp"
#include <set>

namespace 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

struct obj_loader {

	static constexpr auto name = std::string_view("obj");

	[[nodiscard]] static std::error_code prefetch(
		const file_dir_list& paths,
		prefetch_queue& queue
	);

	[[nodiscard]] static std::error_code load(
		dynamic_mesh_buffer& buffer,
		const file_dir_list& paths,
		prefetch_lookup& id_lookup,
		dynamic_shader_source_store& store,
		bool pedantic = false
	);

protected:
	using index_type = dynamic_mesh_buffer::index_type;
	using vertex_type = std::array<index_type, 3>;

	struct indexed_vertex_type
	{
		vertex_type vertex;
		index_type 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;
		}
	};

	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
	);
};