/* Copyright (c) 2018, June 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 <linux/fb.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sysexits.h>
#include <termios.h>
#include <unistd.h>

extern int init(int argc, char *argv[]);
extern const char *status(void);
extern void draw(uint32_t *buf, size_t xres, size_t yres);
extern bool input(char in);

static struct termios saveTerm;
static void restoreTerm(void) {
    tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
}

int main(int argc, char *argv[]) {
    int error;

    error = init(argc, argv);
    if (error) return error;

    const char *path = getenv("FRAMEBUFFER");
    if (!path) path = "/dev/fb0";

    int fb = open(path, O_RDWR);
    if (fb < 0) err(EX_OSFILE, "%s", path);

    struct fb_var_screeninfo info;
    error = ioctl(fb, FBIOGET_VSCREENINFO, &info);
    if (error) err(EX_IOERR, "%s", path);

    size_t size = 4 * info.xres * info.yres;
    uint32_t *buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fb, 0);
    if (buf == MAP_FAILED) err(EX_IOERR, "%s", path);

    error = tcgetattr(STDERR_FILENO, &saveTerm);
    if (error) err(EX_IOERR, "tcgetattr");
    atexit(restoreTerm);

    struct termios term = saveTerm;
    term.c_lflag &= ~(ICANON | ECHO);
    error = tcsetattr(STDERR_FILENO, TCSADRAIN, &term);
    if (error) err(EX_IOERR, "tcsetattr");

    uint32_t saveBg = buf[0];

    uint32_t back[info.xres * info.yres];
    for (;;) {
        draw(back, info.xres, info.yres);
        memcpy(buf, back, size);

        char in;
        ssize_t len = read(STDERR_FILENO, &in, 1);
        if (len < 0) err(EX_IOERR, "read");
        if (!len) return EX_DATAERR;

        if (!input(in)) {
            for (uint32_t i = 0; i < info.xres * info.yres; ++i) {
                buf[i] = saveBg;
            }
            fprintf(stderr, "%s\n", status());
            return EX_OK;
        }
    }
}