/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

#include <err.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sysexits.h>
#include <unistd.h>

static struct {
    int read;
    int write;
} winch;

static void sigwinch() {
    struct winsize localWindow;
    int error = ioctl(STDERR_FILENO, TIOCGWINSZ, &localWindow);
    if (error) err(EX_IOERR, "ioctl(%d, TIOCGWINSZ, ...)", STDERR_FILENO);

    ssize_t size = write(winch.write, &localWindow, sizeof(localWindow));
    if (size < 0) err(EX_IOERR, "write(%d)", winch.write);
    if ((size_t)size < sizeof(localWindow)) {
        errx(EX_IOERR, "short write(%d)", winch.write);
    }
}

int main(int argc, char *argv[]) {
    if (argc < 2) return EX_USAGE;
    const char *path = argv[1];

    int fd = open(path, O_RDONLY);
    if (fd < 0) err(EX_NOINPUT, "%s", path);

    struct winsize remoteWindow;
    ssize_t size = read(fd, &remoteWindow, sizeof(remoteWindow));
    if (size < 0) err(EX_IOERR, "%s", path);
    if ((size_t)size < sizeof(remoteWindow)) errx(EX_IOERR, "%s: short read", path);

    int error = pipe((int *)&winch);
    if (error) err(EX_OSERR, "pipe");

    signal(SIGWINCH, sigwinch);
    sigwinch();
    for (;;) {
        struct winsize localWindow;
        ssize_t size = read(winch.read, &localWindow, sizeof(localWindow));
        if (size < 0) err(EX_IOERR, "read(%d)", winch.read);
        if ((size_t)size < sizeof(localWindow)) {
            errx(EX_IOERR, "short read(%d)", winch.read);
        }

        if (
            localWindow.ws_col == remoteWindow.ws_col
            && localWindow.ws_row == remoteWindow.ws_row
        ) break;

        printf(
            "%hux%hu -> %hux%hu\n",
            localWindow.ws_col, localWindow.ws_row,
            remoteWindow.ws_col, remoteWindow.ws_row
        );
    }
}