/*
 * Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see https://www.gnu.org/licenses/.
 */

use std::{
	env::args,
	process::ExitCode
};

extern crate getopt;
use getopt::GetOpt;

extern crate sysexits;
use sysexits::EX_USAGE;

fn usage(s: &str) -> ExitCode {
	eprintln!("Usage: {} [-egl] integer integer...", s);
	ExitCode::from(EX_USAGE as u8)
}

fn main() -> ExitCode {
	let argv = args().collect::<Vec<String>>();
	let mut can_eq = false;
	let mut can_gt = false;
	let mut can_lt = false;
	let mut optind = 0;

	if argv.len() < 3 { return usage(&argv[0]); }

	while let Some(opt) = argv.getopt("egl") {
		match opt.opt() {
			Ok("e") => can_eq = true,
			Ok("g") => can_gt = true,
			Ok("l") => can_lt = true,
			_ => { return usage(&argv[0]); },
		}
		optind = opt.ind();
	}

	if argv.len() - optind < 2 /* ref cmp */ { return usage(&argv[0]); }

	let mut reference: Option<usize> = None;
	let mut cmpn: usize;

	for arg in argv.iter().skip(optind) {
		match arg.parse::<usize>() {
			Ok(n) => cmpn = n,
			_ => {
				eprintln!("{}: {}: Invalid integer", &argv[0], arg);
				return ExitCode::from(EX_USAGE as u8);
			}
		}

		if let Some(refn) = reference {
			if (!can_eq && refn == cmpn)
					|| (!can_gt && refn > cmpn)
					|| (!can_lt && refn < cmpn)
				{ return ExitCode::FAILURE; }
		}

		reference = Some(cmpn);
	}

	ExitCode::SUCCESS
}