pub enum MetaCommand {
    Exit,
}

pub struct MetaCommandExecuteResult {
    pub should_exit: bool,
}

impl MetaCommand {
    pub fn execute(&self) -> MetaCommandExecuteResult {
        match self {
            MetaCommand::Exit => MetaCommandExecuteResult { should_exit: true },
        }
    }
}

pub enum MetaCommandParseError {
    Unrecognized { cmd: String },
}

impl std::fmt::Display for MetaCommandParseError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            MetaCommandParseError::Unrecognized { cmd } => {
                write!(f, "unrecognized meta-command {cmd:?}")
            }
        }
    }
}

impl std::str::FromStr for MetaCommand {
    type Err = MetaCommandParseError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s.trim() {
            ".exit" => Ok(MetaCommand::Exit),
            cmd => Err(MetaCommandParseError::Unrecognized {
                cmd: cmd.to_string(),
            }),
        }
    }
}