#include "assets/file_parsers/threedtk_pose_loader.hpp"

#include <fstream>
#include <execution>
#include <glm/ext/matrix_transform.hpp>
#include <glm/gtx/euler_angles.hpp>
#include "util/logger.hpp"


std::error_code assets::threedtk_pose_loader::prefetch(
	path_id_lookups& lookups
) {
	return {};
}

std::error_code assets::threedtk_pose_loader::load(
	path_id_lookups& lookups,
	data_stores& stores,
	bool pedantic
) {
	m_path_buffer.clear();
	lookups.poses.by_extension(".pose", m_path_buffer);

	std::for_each(
		std::execution::parallel_unsequenced_policy{},
		m_path_buffer.begin(),
		m_path_buffer.end(),
		parser_context{
			lookups,
			stores
		}
	);

	return {};
}

assets::threedtk_pose_loader::parser_context::parser_context(
	path_id_lookups& m_id_lookups,
	data_stores& m_stores
) :
	m_id_lookups{ &m_id_lookups },
	m_stores{ &m_stores }
{
	m_line_buffer.reserve(64);
}

void assets::threedtk_pose_loader::parser_context::operator()(lookup_type::const_pointer entry) noexcept
{
	const auto& [ filename, id ] = *entry;

	if (const auto res = parse_file(filename, m_line_buffer))
	{
		m_stores->poses.insert(id, res.value());
	}
	else
	{
		const auto error = res.error();
		ztu::logger::error(
			"Error while parsing 3dtk pose file %: [%] %",
			filename,
			error.category().name(),
			error.message()
		);
	}
}

ztu::result<assets::pose_data> assets::threedtk_pose_loader::parse_file(
	const std::filesystem::path& filename,
	std::string& line_buffer
) {

	auto in = std::ifstream{ filename };
	if (not in.is_open())
	{
		return std::unexpected{ std::make_error_code(std::errc::no_such_file_or_directory) };
	}

	std::array<glm::vec3, 2> transform_vecs{};

	for (std::size_t row{}; row != 2; ++row) {

		std::getline(in, line_buffer);

		auto it = line_buffer.cbegin().base();
		auto end = line_buffer.cend().base();

		for (glm::vec3::length_type col{}; col != 3; ++col) {

			const auto [ ptr, ec ] = std::from_chars(
				it, end,
				transform_vecs[row][col],
				std::chars_format::general
			);

			if (ec != std::errc{}) {
				return std::unexpected{ std::make_error_code(ec) };
			}

			it = ptr + 1; // skip space in between components
		}
	}

	const auto& translation = transform_vecs[0];
	auto& angles = transform_vecs[1];
	angles *= static_cast<float>(M_PI / 180.0);

	return (
		glm::translate(glm::identity<glm::mat4>(), translation) *
		glm::eulerAngleXYZ(angles[0], angles[1], angles[2])
	);
}