// This source code is released into the public domain.
module;

#include <expected>
#include <filesystem>
#include <string>

#include <unistd.h>

export module nihil.posix:execv;

import nihil.error;
import :argv;
import :executor;

namespace nihil {

// execv: use a filename and an argument vector to call ::execv().
export struct execv final
{
	using tag = exec_tag;

	execv(std::filesystem::path path, argv &&args) noexcept
		: m_path(std::move(path))
		, m_args(std::move(args))
	{
	}

	~execv() = default;

	// Movable
	execv(execv &&) noexcept = default;
	auto operator=(execv &&) noexcept -> execv & = default;

	// Not copyable (because m_args isn't copyable).
	execv(execv const &) = delete;
	auto operator=(this execv &, execv const &) -> execv & = delete;

	// Perform the execv().  This only returns on failure.
	[[nodiscard]] auto exec(this execv &self) -> std::expected<void, error>
	{
		::execv(self.m_path.string().c_str(), self.m_args.data());
		return std::unexpected(error("execve failed", error(std::errc(errno))));
	}

private:
	std::filesystem::path m_path;
	argv m_args;
};

} // namespace nihil