lints 0.2.0

use super::{
    ExitCode,
    io::{self, Write as _},
};
use std::ffi::OsString;
/// Error from parsing CLI arguments.
#[cfg_attr(test, derive(Debug, PartialEq))]
pub(crate) enum E {
    /// No arguments exist including the name of the program which is assumed to be the first argument.
    NoArgs,
    /// The contained string is not an argument that is supported.
    UnknownArg(OsString),
}
impl E {
    /// Writes `self` to `stderr`.
    pub(crate) fn into_exit_code(self) -> ExitCode {
        let mut stderr = io::stderr().lock();
        match self {
            Self::NoArgs => writeln!(
                stderr,
                "No arguments were passed including the first argument which is assumed to be the name of the program. See lints help for more information."
            ),
            Self::UnknownArg(arg) => writeln!(
                stderr,
                "Unrecognized argument '{}' was passed. See lints help for more information.",
                arg.display()
            ),
        }.map_or(ExitCode::FAILURE, |()| ExitCode::FAILURE)
    }
}
/// The command passed.
#[cfg_attr(test, derive(Debug, PartialEq))]
#[derive(Clone, Copy)]
pub(crate) enum Cmd {
    /// `"allow"` all lints.
    Allow(Opts),
    /// `"deny"`.
    Deny(Opts),
    /// `"help"`.
    Help,
    /// `"version"`.
    Version,
}
/// Options to process lints.
#[cfg_attr(test, derive(Debug, PartialEq))]
#[derive(Clone, Copy, Default)]
pub(crate) struct Opts {
    /// `--all` was passed.
    pub all_lints: bool,
    /// `--allow-undefined-lints` was passed.
    pub allow_undefined_lints: bool,
    /// `-` was passed.
    pub read_stdin: bool,
}
impl Opts {
    /// Add options from `opts` to `self`.
    ///
    /// Returns `None` iff successful; otherwise returns the problematic argument.
    fn add<I: Iterator<Item = OsString>>(
        &mut self,
        mut opts: I,
        arg: OsString,
    ) -> Option<OsString> {
        /// `b'-'`.
        const DASH: u8 = b'-';
        /// `b"--all"`.
        const ALL: &[u8] = b"--all".as_slice();
        /// `b"--allow-undefined-lints"`.
        const ALLOW_UNDEFINED_LINTS: &[u8] = b"--allow-undefined-lints".as_slice();
        match arg.as_encoded_bytes() {
            &[DASH] => {
                if self.read_stdin {
                    Err(())
                } else {
                    self.read_stdin = true;
                    Ok(())
                }
            }
            ALL => {
                if self.all_lints || self.read_stdin {
                    Err(())
                } else {
                    self.all_lints = true;
                    Ok(())
                }
            }
            ALLOW_UNDEFINED_LINTS => {
                if self.allow_undefined_lints || self.read_stdin {
                    Err(())
                } else {
                    self.allow_undefined_lints = true;
                    Ok(())
                }
            }
            _ => Err(()),
        }
        .map_or(Some(arg), |()| {
            opts.next().and_then(|opt| self.add(opts, opt))
        })
    }
}
impl Cmd {
    /// Parses the CLI arguments.
    pub(crate) fn try_from_args<I: IntoIterator<Item = OsString>>(iter: I) -> Result<Self, E> {
        let mut args = iter.into_iter();
        args.next().ok_or(E::NoArgs).and_then(|_| {
            args.next().map_or_else(
                || Ok(Self::Deny(Opts::default())),
                |cmd| match cmd.as_encoded_bytes() {
                    b"allow" => args.next().map_or_else(
                        || Ok(Self::Allow(Opts::default())),
                        |arg| {
                            let mut opts = Opts::default();
                            opts.add(args, arg)
                                .map_or(Ok(Self::Allow(opts)), |opt| Err(E::UnknownArg(opt)))
                        },
                    ),
                    b"deny" => args.next().map_or_else(
                        || Ok(Self::Deny(Opts::default())),
                        |arg| {
                            let mut opts = Opts::default();
                            opts.add(args, arg)
                                .map_or(Ok(Self::Deny(opts)), |opt| Err(E::UnknownArg(opt)))
                        },
                    ),
                    b"help" => args
                        .next()
                        .map_or(Ok(Self::Help), |opt| Err(E::UnknownArg(opt))),
                    b"version" => args
                        .next()
                        .map_or(Ok(Self::Version), |opt| Err(E::UnknownArg(opt))),
                    _ => {
                        let mut opts = Opts::default();
                        opts.add(args, cmd)
                            .map_or(Ok(Self::Deny(opts)), |opt| Err(E::UnknownArg(opt)))
                    }
                },
            )
        })
    }
}
#[cfg(test)]
mod tests {
    use super::{Cmd, E, Opts};
    #[expect(clippy::too_many_lines, reason = "a lot of permutations to test")]
    #[test]
    fn successes() {
        assert_eq!(
            Cmd::try_from_args(["".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--all".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--allow-undefined-lints".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "-".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--all".into(), "--allow-undefined-lints".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--all".into(), "-".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: false,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--allow-undefined-lints".into(), "-".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: true,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "--all".into(),
                "--allow-undefined-lints".into(),
                "-".into()
            ]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into()]),
            Ok(Cmd::Allow(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into(), "--all".into()]),
            Ok(Cmd::Allow(Opts {
                all_lints: true,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into(), "--allow-undefined-lints".into()]),
            Ok(Cmd::Allow(Opts {
                all_lints: false,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into(), "-".into()]),
            Ok(Cmd::Allow(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "allow".into(),
                "--allow-undefined-lints".into(),
                "--all".into()
            ]),
            Ok(Cmd::Allow(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into(), "--all".into(), "-".into(),]),
            Ok(Cmd::Allow(Opts {
                all_lints: true,
                allow_undefined_lints: false,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "allow".into(),
                "--all".into(),
                "--allow-undefined-lints".into(),
                "-".into(),
            ]),
            Ok(Cmd::Allow(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into(), "--all".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: false,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into(), "--allow-undefined-lints".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into(), "-".into()]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: false,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "deny".into(),
                "--all".into(),
                "--allow-undefined-lints".into()
            ]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: false,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "deny".into(),
                "--allow-undefined-lints".into(),
                "-".into(),
            ]),
            Ok(Cmd::Deny(Opts {
                all_lints: false,
                allow_undefined_lints: true,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "deny".into(),
                "--allow-undefined-lints".into(),
                "--all".into(),
                "-".into(),
            ]),
            Ok(Cmd::Deny(Opts {
                all_lints: true,
                allow_undefined_lints: true,
                read_stdin: true,
            }))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "help".into()]),
            Ok(Cmd::Help)
        );
        assert_eq!(
            Cmd::try_from_args(["doesn't matter what this is".into(), "version".into()]),
            Ok(Cmd::Version)
        );
    }
    #[test]
    fn errs() {
        assert_eq!(Cmd::try_from_args([]), Err(E::NoArgs));
        assert_eq!(
            Cmd::try_from_args(["".into(), "".into()]),
            Err(E::UnknownArg("".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "foo".into()]),
            Err(E::UnknownArg("foo".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "help".into(), "version".into()]),
            Err(E::UnknownArg("version".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "version".into(), "allow".into()]),
            Err(E::UnknownArg("allow".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "allow".into(), "allow".into()]),
            Err(E::UnknownArg("allow".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into(), "allow".into()]),
            Err(E::UnknownArg("allow".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--all".into(), "allow".into()]),
            Err(E::UnknownArg("allow".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "--allow-undefined-lints".into(), "deny".into()]),
            Err(E::UnknownArg("deny".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "deny".into(), "--all".into(), "".into()]),
            Err(E::UnknownArg("".into()))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "--all".into(),
                "--allow-undefined-lints".into(),
                "--all".into()
            ]),
            Err(E::UnknownArg("--all".into()))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "deny".into(),
                "--all".into(),
                "--allow-undefined-lints".into(),
                "foo".into()
            ]),
            Err(E::UnknownArg("foo".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "-".into(), "deny".into(),]),
            Err(E::UnknownArg("deny".into()))
        );
        assert_eq!(
            Cmd::try_from_args(["".into(), "-".into(), "--all".into(),]),
            Err(E::UnknownArg("--all".into()))
        );
        assert_eq!(
            Cmd::try_from_args([
                "".into(),
                "allow".into(),
                "-".into(),
                "--allow-undefined-lints".into()
            ]),
            Err(E::UnknownArg("--allow-undefined-lints".into()))
        );
    }
}