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//! Application (sub)command(s), i.e. app entry points

#[doc(hidden)]
pub use abscissa_derive::Command;

use crate::{runnable::Runnable, terminal};
use clap::{FromArgMatches, Parser};
use std::{env, ffi::OsString, fmt::Debug};
use termcolor::ColorChoice;

/// Subcommand of an application: derives or otherwise implements the `Options`
/// trait, but also has a `run()` method which can be used to invoke the given
/// (sub)command.
pub trait Command: Debug + FromArgMatches + Runnable {
    /// Name of this program as a string
    fn name() -> &'static str;

    /// Description of this program
    fn description() -> &'static str;

    /// Authors of this program
    fn authors() -> &'static str;

    /// Parse command-line arguments from an iterator
    fn parse_args<T, I>(into_args: I) -> Self
    where
        Self: Parser,
        I: IntoIterator<Item = T>,
        T: Into<OsString> + Clone,
    {
        let args: Vec<OsString> = into_args.into_iter().map(|s| s.into()).collect();

        Self::try_parse_from(args.as_slice()).unwrap_or_else(|err| {
            terminal::init(ColorChoice::Auto);
            err.exit()
        })
    }

    /// Parse command-line arguments from the environment
    fn parse_env_args() -> Self
    where
        Self: Parser,
    {
        Self::parse_args(env::args())
    }
}

#[cfg(test)]
mod tests {
    use crate::{Command, Runnable};
    use clap::Parser;

    #[derive(Command, Debug, Parser)]
    pub struct DummyCommand {}

    impl Runnable for DummyCommand {
        fn run(&self) {
            panic!("unimplemented");
        }
    }

    #[test]
    fn derived_command_test() {
        assert_eq!(DummyCommand::name(), "abscissa_core");
    }
}