/*
 * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
 * SPDX-License-Identifier: LGPL-3.0-or-later
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser 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 Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see https://www.gnu.org/licenses/.
 */

use std::ffi::{ c_int, c_char, CString, CStr };

pub struct Opt {
	pub arg: Option<String>,
	pub ind: i32,
	pub opt: i32,
}

pub enum OptError {
	MissingArg,
	UnknownOpt,
}

// Function signature
pub trait GetOpt {
	fn getopt(&self, optstring: &str) -> Option<Result<Opt, OptError>>;
}

impl GetOpt for Vec<String> {
    fn getopt(&self, optstring: &str) -> Option<Result<Opt, OptError>> {
        let c_strings: Vec<_> = self
			.iter()
			.cloned()
			.map(CString::new)
			.map(Result::unwrap)
			.collect();

        let argv: Vec<_> = c_strings.iter().map(|x| x.as_ptr()).collect();
        let argv_ptr = argv.as_ptr() as *const *mut c_char;
        let optstring_c = CString::new(optstring).unwrap();
        let opts = optstring_c.into_raw();
        let len = self.len() as c_int;

        unsafe {
            let a = match getopt(len, argv_ptr, opts) {
				/* From getopt(3p):
				 *
				 * The getopt() function shall return the next option character
				 * specified on the command line.
				 *
				 * A <colon> (':') shall be returned if getopt() detects a
				 * missing argument and the first character of optstring was a
				 * <colon> (':').
				 *
				 * A <question-mark> ('?') shall be returned if getopt()
				 * encounters an option character not in optstring or detects a
				 * missing argument and the first character of optstring was not
				 * a <colon> (':').
				 *
				 * Otherwise, getopt() shall return -1 when all command line
				 * options are parsed. */
                58 => { /* ASCII value for ':' */
					return Some(Err(OptError::MissingArg));
				},
                63 => { /* ASCII value for '?' */
					return Some(Err(OptError::UnknownOpt))
				},
				/* From getopt(3p):
				 *
				 * If, when getopt() is called:
				 *
				 * argv[optind]  is a null pointer
				 * *argv[optind]  is not the character -
				 * argv[optind]  points to the string "-"
				 *
				 * getopt() shall return -1 without changing optind.  If:
				 *
				 * argv[optind]   points to the string "--"
				 *
				 * getopt() shall return -1 after incrementing optind. */
                -1 => return None,
                _ => CStr::from_ptr(optarg).to_string_lossy().into_owned(),
            };

            Some(Ok(Opt { arg: Some(a), ind: optind, opt: optopt }))
        }
    }
}
/* binding to getopt(3p) */
extern "C" {
	static mut optarg: *mut c_char;
	static mut _opterr: c_int;
	static mut optind: c_int;
	static mut optopt: c_int;

	fn getopt(
		___argc: c_int,
		___argv: *const *mut c_char,
		__shortopts: *const c_char,
	) -> c_int;
}