/// Helper functions, especially to reproduce C std/posix functions
use nix::errno::*;
use nix::Error as NixError;
use nix::sys::termios;
use nix::sys::termios::{
    ControlFlags,
    InputFlags,
    LocalFlags,
    OutputFlags,
    SpecialCharacterIndices,
    Termios
};

use std::io::Error;
use std::os::unix::io::RawFd;
use std::process::exit;

// Redefine the posix constants for rust land
pub const STDIN_FILENO: i32 = 0;
// pub const STDOUT_FILENO: i32 = 1;
// pub const STDERR_FILENO: i32 = 2;

/// Is this character an ASCII control character?
pub fn is_cntrl(c: char) -> bool {
    let code = c as u8;

    code < 32 || code == 127
}

pub fn die(code: &Errno, msg: &str) -> ! {
    eprintln!("{:?} ({})", code, msg);

    exit(1)
}

pub fn get_termios(fd: RawFd) -> Termios {
    termios::tcgetattr(fd).unwrap()
}

pub fn enable_raw_mode() -> Result<(), Error> {
    let mut raw = get_termios(STDIN_FILENO);

    raw.input_flags.remove(
        InputFlags::BRKINT &
            InputFlags::IGNCR &
            InputFlags::IGNBRK &
            InputFlags::ICRNL &
            InputFlags::INLCR &
            InputFlags::INPCK &
            InputFlags::ISTRIP &
            InputFlags::IXON &
            InputFlags::PARMRK
    );

    raw.output_flags.remove(OutputFlags::OPOST);

    raw.local_flags.remove(
        LocalFlags::ECHO &
            LocalFlags::ECHONL &
            LocalFlags::ICANON &
            LocalFlags::IEXTEN &
            LocalFlags::ISIG
    );

    raw.control_flags.remove(
        ControlFlags::CSIZE &
        ControlFlags::PARENB
    );

    // 8 bit characters
    raw.control_flags |= termios::ControlFlags::CS8;

    raw.control_chars[SpecialCharacterIndices::VMIN as usize] = 0;
    raw.control_chars[SpecialCharacterIndices::VTIME as usize] = 1;

    match termios::tcsetattr(STDIN_FILENO, termios::SetArg::TCSAFLUSH, &raw) {
        Ok(()) => Ok(()),
        Err(e) => match e.as_errno() {
            Some(errno) => die(&errno, "tcsetattr"),
            None => panic!("Failed to enable raw mode")
        }
    }
}

pub fn disable_raw_mode(original: &Termios) -> Result<(), Error> {
    match termios::tcsetattr(STDIN_FILENO, termios::SetArg::TCSAFLUSH, original) {
        Ok(()) => Ok(()),
        Err(E) => match E.as_errno() {
            Some(errno) => die(&errno, "tcsetattr"),
            None => panic!("Failed to disable raw mode")
        }
    }
}