/* 
 * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 * SPDX-License-Identifier: LGPL-3.0-or-later
 *
 * This file is part of SPD.
 *
 * SPD 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.
 *
 * SPD 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 SPD. If not, see <https://www.gnu.org/licenses/>.
 *
 * This file incorporates work covered by the following copyright and permission
 * notice:
 *
 *     Copyright 2023 Douman
 *
 *     Boost Software License - Version 1.0 - August 17th, 2003
 *
 *     Permission is hereby granted, free of charge, to any person or
 *     organization obtaining a copy of the software and accompanying
 *     documentation covered by this license (the "Software") to use, reproduce,
 *     display, distribute, execute, and transmit the Software, and to prepare
 *     derivative works of the Software, and to permit third-parties to whom the
 *     Software is furnished to do so, all subject to the following:
 *
 *     The copyright notices in the Software and this entire statement,
 *     including the above license grant, this restriction and the following 
 *     disclaimer, must be included in all copies of the Software, in whole or 
 *     in part, and all derivative works of the Software, unless such copies or
 *     derivative works are solely in the form of machine-executable object code
 *     generated by a source language processor.
 *
 *     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
 *     OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND 
 *     NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR ANYONE
 *     DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR OTHER LIABILITY,
 *     WHETHER IN CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 *     CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 *     SOFTWARE.
 */

//! C main entry point with nice wrapper for arguments.
//!
//!```rust
//!#![no_main]
//!
//!#[no_mangle]
//!pub fn rust_main(args: c_main::Args) -> isize {
//!    for arg in args.into_iter().skip(1) {
//!        println!("arg={:?}", arg);
//!    }
//!    0
//!}
//!```

#![cfg_attr(feature = "cargo-clippy", allow(clippy::style))]
#![cfg_attr(rustfmt, rustfmt_skip)]

mod args;
use args::*;

#[allow(unused)]
#[cold]
#[inline(never)]
unsafe fn invalid_cli_args_error() -> libc::c_int {
    libc::printf("Unable to parse C argv as utf-8 string\n\0".as_ptr() as _);
    255
}

///Converts C string to Rust's, verifying it is UTF-8
///
///It is UB to pass non-C string as it requires \0
pub unsafe fn c_str_to_rust(ptr: *const u8) -> Result<&'static str, core::str::Utf8Error> {
    let len = libc::strlen(ptr as *const i8);
    let parts = core::slice::from_raw_parts(ptr, len);
    core::str::from_utf8(parts)
}

///Converts C string to Rust's one assuming it is UTF-8
///
///It is UB to pass non-C string as it requires \0
pub unsafe fn c_str_to_rust_unchecked(ptr: *const u8) -> &'static str {
    let len = libc::strlen(ptr as *const i8);
    let parts = core::slice::from_raw_parts(ptr, len);
    core::str::from_utf8_unchecked(parts)
}

extern "Rust" {
    fn rust_main(args: Args) -> isize;
}

#[doc(hidden)]
#[cfg(not(test))]
#[no_mangle]
pub unsafe extern fn main(argc: libc::c_int, argv: *const *const u8) -> libc::c_int {
    match Args::new(argc as isize, argv) {
        Ok(args) => rust_main(args) as _,
        Err(_) => invalid_cli_args_error(),
    }
}