breed/src/main.rs

/*
 * Copyright (c) 2023 Marceline Cramer
 * Copyright (c) 2023 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,
    ffi::OsString,
    fs::File,
    io::{Read, Stdout, Write},
    os::fd::FromRawFd,
    path::Path,
};

use crossterm::{terminal, QueueableCommand, Result};
use yacexits::{exit, EX_DATAERR, EX_UNAVAILABLE};

mod actions;
mod buffer;
mod config;
mod keybinds;
mod state;
mod theme;

#[derive(Copy, Clone, Debug, Default)]
pub struct Cursor {
    pub column: usize,
    pub line: usize,
}

#[derive(Copy, Clone, Debug)]
pub enum Direction {
    Left,
    Down,
    Up,
    Right,
}

fn screen_main(stdout: &mut Stdout, mut state: state::State) -> Result<()> {
    let poll_timeout = std::time::Duration::from_millis(100);
    while !state.quit {
        state.draw(stdout)?;
        if let true = crossterm::event::poll(poll_timeout)? {
            let event = crossterm::event::read()?;
            state.on_event(event);
        }
    }

    Ok(())
}

fn main() -> Result<()> {
    let argv = args().collect::<Vec<String>>();
    let mut buf = Vec::new();
    let file_name: Option<OsString>;

    match argv.get(1).map(|s| s.as_str()) {
        Some("-") | None => {
            file_name = None;
            let stdin = 0; // get stdin as a file descriptor
            if unsafe { libc::isatty(stdin) } == 0 {
                unsafe { File::from_raw_fd(stdin) }
            } else {
                File::open("/dev/null")?
            }
        }
        Some(path) => {
            let input_file = Path::new(path);
            file_name = Some(OsString::from(&path));

            File::open(input_file).unwrap_or_else(|_| {
                let mut err = String::new();
                if !input_file.exists() {
                    err = "No such file or directory.".to_string();
                } else if input_file.is_dir() {
                    err = "Is a directory.".to_string();
                }
                eprintln!("{}: {}: {}", argv[0], path, err);
                exit(EX_UNAVAILABLE);
            })
        }
    }
    .read_to_end(&mut buf)?;

    let text = String::from_utf8(buf).unwrap_or_else(|_| {
        eprintln!(
            "{}: {}: File contents are not valid UTF-8.",
            argv[0], argv[1]
        );
        exit(EX_DATAERR);
    });

    let state = state::State::from_str(file_name, &text)?;

    // begin to enter alternate screen
    let mut stdout = std::io::stdout();
    terminal::enable_raw_mode()?;
    stdout.queue(terminal::EnterAlternateScreen)?;

    // register a panic handler to exit the alternate screen
    let old_panic_handler = std::panic::take_hook();
    std::panic::set_hook(Box::new(move |info| {
        let mut stdout = std::io::stdout();
        let _ = stdout.queue(terminal::LeaveAlternateScreen);
        let _ = terminal::disable_raw_mode();
        let _ = stdout.flush();
        old_panic_handler(info)
    }));

    // run inner event loop
    let result = screen_main(&mut stdout, state);

    // exit alternate screen
    stdout.queue(terminal::LeaveAlternateScreen)?;
    terminal::disable_raw_mode()?;

    result
}