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//  * This file is part of the uutils coreutils package.
//  *
//  * (c) Martin Kysel <code@martinkysel.com>
//  *
//  * For the full copyright and license information, please view the LICENSE file
//  * that was distributed with this source code.

// spell-checker:ignore (ToDO) lflag ICANON tcgetattr tcsetattr TCSADRAIN

#[macro_use]
extern crate uucore;

use getopts::Options;
use std::fs::File;
use std::io::{stdout, Read, Write};

#[cfg(all(unix, not(target_os = "fuchsia")))]
extern crate nix;
#[cfg(all(unix, not(target_os = "fuchsia")))]
use nix::sys::termios;

#[cfg(target_os = "redox")]
extern crate redox_termios;
#[cfg(target_os = "redox")]
extern crate syscall;

#[derive(Clone, Eq, PartialEq)]
pub enum Mode {
    More,
    Help,
    Version,
}

static NAME: &str = "more";
static VERSION: &str = env!("CARGO_PKG_VERSION");

pub fn uumain(args: impl uucore::Args) -> i32 {
    let args = args.collect_str();

    let mut opts = Options::new();

    // FixME: fail without panic for now; but `more` should work with no arguments (ie, for piped input)
    if args.len() < 2 {
        println!("{}: incorrect usage", args[0]);
        return 1;
    }

    opts.optflag("h", "help", "display this help and exit");
    opts.optflag("v", "version", "output version information and exit");

    let matches = match opts.parse(&args[1..]) {
        Ok(m) => m,
        Err(e) => {
            show_error!("{}", e);
            panic!()
        }
    };
    let usage = opts.usage("more TARGET.");
    let mode = if matches.opt_present("version") {
        Mode::Version
    } else if matches.opt_present("help") {
        Mode::Help
    } else {
        Mode::More
    };

    match mode {
        Mode::More => more(matches),
        Mode::Help => help(&usage),
        Mode::Version => version(),
    }

    0
}

fn version() {
    println!("{} {}", NAME, VERSION);
}

fn help(usage: &str) {
    let msg = format!(
        "{0} {1}\n\n\
         Usage: {0} TARGET\n  \
         \n\
         {2}",
        NAME, VERSION, usage
    );
    println!("{}", msg);
}

#[cfg(all(unix, not(target_os = "fuchsia")))]
fn setup_term() -> termios::Termios {
    let mut term = termios::tcgetattr(0).unwrap();
    // Unset canonical mode, so we get characters immediately
    term.c_lflag.remove(termios::ICANON);
    // Disable local echo
    term.c_lflag.remove(termios::ECHO);
    termios::tcsetattr(0, termios::TCSADRAIN, &term).unwrap();
    term
}

#[cfg(any(windows, target_os = "fuchsia"))]
#[inline(always)]
fn setup_term() -> usize {
    0
}

#[cfg(target_os = "redox")]
fn setup_term() -> redox_termios::Termios {
    let mut term = redox_termios::Termios::default();
    let fd = syscall::dup(0, b"termios").unwrap();
    syscall::read(fd, &mut term).unwrap();
    term.c_lflag &= !redox_termios::ICANON;
    term.c_lflag &= !redox_termios::ECHO;
    syscall::write(fd, &term).unwrap();
    let _ = syscall::close(fd);
    term
}

#[cfg(all(unix, not(target_os = "fuchsia")))]
fn reset_term(term: &mut termios::Termios) {
    term.c_lflag.insert(termios::ICANON);
    term.c_lflag.insert(termios::ECHO);
    termios::tcsetattr(0, termios::TCSADRAIN, &term).unwrap();
}

#[cfg(any(windows, target_os = "fuchsia"))]
#[inline(always)]
fn reset_term(_: &mut usize) {}

#[cfg(any(target_os = "redox"))]
fn reset_term(term: &mut redox_termios::Termios) {
    let fd = syscall::dup(0, b"termios").unwrap();
    syscall::read(fd, term).unwrap();
    term.c_lflag |= redox_termios::ICANON;
    term.c_lflag |= redox_termios::ECHO;
    syscall::write(fd, &term).unwrap();
    let _ = syscall::close(fd);
}

fn more(matches: getopts::Matches) {
    let files = matches.free;
    let mut f = File::open(files.first().unwrap()).unwrap();
    let mut buffer = [0; 1024];

    let mut term = setup_term();

    let mut end = false;
    while let Ok(sz) = f.read(&mut buffer) {
        if sz == 0 {
            break;
        }
        stdout().write_all(&buffer[0..sz]).unwrap();
        for byte in std::io::stdin().bytes() {
            match byte.unwrap() {
                b' ' => break,
                b'q' | 27 => {
                    end = true;
                    break;
                }
                _ => (),
            }
        }

        if end {
            break;
        }
    }

    reset_term(&mut term);
    println!();
}