main.c

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <termios.h>

#define COLS 60
#define ROWS 30

int main() {
  // Hide cursor
  printf("\e[?25l");

  // Switch to canonical mode, disable echo
  struct termios oldt, newt;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);

  int x[1000], y[1000];
  int quit = 0;
  while (!quit) {
    // Render table
    printf("┌");
    for (int i = 0; i < COLS; i++)
      printf("─");
    printf("┐\n");

    for (int j = 0; j < ROWS; j++) {
      printf("│");
      for (int i = 0; i < COLS; i++)
        printf("·");
      printf("│\n");
    }

    printf("└");
    for (int i = 0; i < COLS; i++)
      printf("─");
    printf("┘\n");

    // Move cursor back to top
    printf("\e[%iA", ROWS + 2);

    int head = 0, tail = 0;
    x[head] = COLS / 2;
    y[head] = ROWS / 2;
    int gameover = 0;
    int xdir = 1, ydir = 0;
    int applex = -1, appley;

    while (!quit && !gameover) {
      if (applex < 0) {
        // Create new apple
        applex = rand() % COLS;
        appley = rand() % ROWS;

        for (int i = tail; i != head; i = (i + 1) % 1000)
          if (x[i] == applex && y[i] == appley)
            applex = -1;

        if (applex >= 0) {
          // Draw apple
          printf("\e[%iB\e[%iC❤", appley + 1, applex + 1);
          printf("\e[%iF", appley + 1);
        }
      }

      // Clear snake tail
      printf("\e[%iB\e[%iC·", y[tail] + 1, x[tail] + 1);
      printf("\e[%iF", y[tail] + 1);

      if (x[head] == applex && y[head] == appley) {
        applex = -1;
        printf("\a"); // Bell
      } else
        tail = (tail + 1) % 1000;

      int newhead = (head + 1) % 1000;
      x[newhead] = (x[head] + xdir + COLS) % COLS;
      y[newhead] = (y[head] + ydir + ROWS) % ROWS;
      head = newhead;

      for (int i = tail; i != head; i = (i + 1) % 1000)
        if (x[i] == x[head] && y[i] == y[head])
          gameover = 1;

      // Draw head
      printf("\e[%iB\e[%iC▓", y[head] + 1, x[head] + 1);
      printf("\e[%iF", y[head] + 1);
      fflush(stdout);

      usleep(5 * 1000000 / 60);

      // Read keyboard
      struct timeval tv;
      fd_set fds;
      tv.tv_sec = 0;
      tv.tv_usec = 0;

      FD_ZERO(&fds);
      FD_SET(STDIN_FILENO, &fds);
      select(STDIN_FILENO + 1, &fds, NULL, NULL, &tv);
      if (FD_ISSET(STDIN_FILENO, &fds)) {
        int ch = getchar();
        if (ch == 27 || ch == 'q') {
          quit = 1;
        } else if (ch == 'h' && xdir != 1) {
          xdir = -1;
          ydir = 0;
        } else if (ch == 'l' && xdir != -1) {
          xdir = 1;
          ydir = 0;
        } else if (ch == 'j' && ydir != -1) {
          xdir = 0;
          ydir = 1;
        } else if (ch == 'k' && ydir != 1) {
          xdir = 0;
          ydir = -1;
        } else if (ch == 'a' && xdir != 1) {
          xdir = -1;
          ydir = 0;
        } else if (ch == 'd' && xdir != -1) {
          xdir = 1;
          ydir = 0;
        } else if (ch == 's' && ydir != -1) {
          xdir = 0;
          ydir = 1;
        } else if (ch == 'w' && ydir != 1) {
          xdir = 0;
          ydir = -1;
        } 
      }
    }

    if (!quit) {
      // Show game over
      printf("\e[%iB\e[%iC Game Over! ", ROWS / 2, COLS / 2 - 5);
      printf("\e[%iF", ROWS / 2);
      fflush(stdout);
      getchar();
    }
  }

  // Show cursor
  printf("\e[?25h");

  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  return 0;
}