// SPDX-FileCopyrightText: edef <edef@unfathomable.blue>
// SPDX-License-Identifier: OSL-3.0

use {
	super::SyscallArg,
	std::fmt::{self, Debug},
};

#[derive(Clone, Copy, Eq, PartialEq)]
pub(crate) struct FileDesc(i32);

impl Debug for FileDesc {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "{}", self.0)
	}
}

impl SyscallArg for FileDesc {
	fn try_from_reg(reg: u64) -> Option<Self> {
		Some(match i32::try_from_reg(reg)? {
			fd @ 0..=i32::MAX => FileDesc(fd),
			_ => return None,
		})
	}
}

impl SyscallArg for Option<FileDesc> {
	fn try_from_reg(reg: u64) -> Option<Self> {
		Some(match i32::try_from_reg(reg)? {
			-1 => None,
			fd @ 0..=i32::MAX => Some(FileDesc(fd)),
			_ => return None,
		})
	}
}

#[derive(Clone, Copy, Eq, PartialEq)]
pub(crate) enum DirFd {
	Cwd,
	Fd(FileDesc),
}

const AT_FDCWD: i32 = -100;

impl Debug for DirFd {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		match *self {
			DirFd::Cwd => write!(f, "AT_FDCWD"),
			DirFd::Fd(FileDesc(fd)) => write!(f, "{fd}"),
		}
	}
}

impl SyscallArg for DirFd {
	fn try_from_reg(reg: u64) -> Option<Self> {
		Some(match i32::try_from_reg(reg)? {
			AT_FDCWD => Self::Cwd,
			fd @ 0..=i32::MAX => DirFd::Fd(FileDesc(fd)),
			_ => return None,
		})
	}
}