/*
 * Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
 * 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;
extern crate sysexits;

use getopt::GetOpt;
use sysexits::{ EX_DATAERR, EX_USAGE };

#[cfg(target_os="openbsd")] use sysexits::EX_OSERR;
#[cfg(target_os="openbsd")] extern crate openbsd;
#[cfg(target_os="openbsd")] extern crate strerror;
#[cfg(target_os="openbsd")] use openbsd::{ Promises, pledge, unveil };
#[cfg(target_os="openbsd")] use strerror::StrError;

fn err(argv0: &String, e: String, code: u8) -> ExitCode {
	eprintln!("{}: {}", argv0, e);
	ExitCode::from(code)
}

fn usage(argv0: &String) -> ExitCode {
	eprintln!("Usage: {} [-egl] integer integer...", argv0);
	ExitCode::from(EX_USAGE)
}

fn main() -> ExitCode {
	let argv = args().collect::<Vec<String>>();

	#[cfg(target_os="openbsd")] {
		let promises = Promises::new("stdio unveil");
		if let Err(e) = pledge(Some(promises), Some(Promises::default())) {
			return err(&argv[0], e.strerror(), EX_OSERR);
		}

		if let Err(e) = unveil(None, None) {
			return err(&argv[0], e.strerror(), EX_OSERR);
		}
	}

	let mut e = false; /* args can be == */
	let mut g = false; /* args can be > */
	let mut l = false; /* args can be < */
	let mut optind = 0;

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

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

	if !e & !g & !l { return usage(&argv[0]); }

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

	let mut prev: Option<usize> = None; /* no previous operand */
	let mut currn: usize;

	for arg in argv.iter().skip(optind) { /* iterate operands */
		match arg.parse::<usize>() { /* parse current operand */
			Ok(n) => currn = n,
			Err(e) => {
				let error = arg.to_owned() + ": " + &e.to_string();
				return err(&argv[0], error, EX_DATAERR);
			}
		}

		if let Some(prevn) = prev { /* if there was a previous opr., test */
			if (!e && prevn == currn)
					|| (!g && prevn > currn)
					|| (!l && prevn < currn)
				{ return ExitCode::FAILURE; }
		}

		prev = Some(currn); /* there is a previous operand */
	}

	ExitCode::SUCCESS
}