// snake.cpp - classic Nokia-style Snake for Bananarchy (Sxmo/dwm, 240x296)
// Standalone X11 application in C++. Self-contained: uses a built-in 5x7
// bitmap font so it has no font-file dependency.
//
// Controls (Nokia keypad + D-pad):
//   2 / Up        -> turn up        8 / Down      -> turn down
//   4 / Left       -> turn left      6 / Right     -> turn right
//   5 / OK / Enter -> pause / restart (after game over)
//   Back / Esc     -> quit
//
// Build: g++ -O2 snake.cpp -lX11 -o snake

#include <X11/Xlib.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <unistd.h>
#include <sys/select.h>
#include <sys/time.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>
#include <X11/Xatom.h>

static const int WIN_W = 239;
static const int WIN_H = 295;
static const int COLS = 24;
static const int ROWS = 28;

// ---- 5x7 bitmap font (rows are 5-bit patterns, MSB = leftmost pixel) ----
struct Glyph { char ch; unsigned char r[7]; };
static const Glyph GLYPHS[] = {
  {' ', {0,0,0,0,0,0,0}},
  {'!', {0b00100,0b00100,0b00100,0b00100,0b00100,0,0b00100}},
  {'.', {0,0,0,0,0,0b00100,0b00100}},
  {'-', {0,0,0,0b11111,0,0,0}},
  {':', {0,0b00100,0b00100,0,0b00100,0b00100,0}},
  {'?', {0b01110,0b10001,0b00001,0b00110,0b00100,0,0b00100}},
  {'A', {0b01110,0b10001,0b10001,0b11111,0b10001,0b10001,0b10001}},
  {'B', {0b11110,0b10001,0b10001,0b11110,0b10001,0b10001,0b11110}},
  {'C', {0b01110,0b10001,0b10000,0b10000,0b10000,0b10001,0b01110}},
  {'D', {0b11110,0b10001,0b10001,0b10001,0b10001,0b10001,0b11110}},
  {'E', {0b11111,0b10000,0b10000,0b11110,0b10000,0b10000,0b11111}},
  {'F', {0b11111,0b10000,0b10000,0b11110,0b10000,0b10000,0b10000}},
  {'G', {0b01110,0b10001,0b10000,0b10111,0b10001,0b10001,0b01111}},
  {'H', {0b10001,0b10001,0b10001,0b11111,0b10001,0b10001,0b10001}},
  {'I', {0b01110,0b00100,0b00100,0b00100,0b00100,0b00100,0b01110}},
  {'K', {0b10001,0b10010,0b10100,0b11000,0b10100,0b10010,0b10001}},
  {'L', {0b10000,0b10000,0b10000,0b10000,0b10000,0b10000,0b11111}},
  {'M', {0b10001,0b11011,0b10101,0b10101,0b10001,0b10001,0b10001}},
  {'N', {0b10001,0b10001,0b11001,0b10101,0b10011,0b10001,0b10001}},
  {'O', {0b01110,0b10001,0b10001,0b10001,0b10001,0b10001,0b01110}},
  {'P', {0b11110,0b10001,0b10001,0b11110,0b10000,0b10000,0b10000}},
  {'R', {0b11110,0b10001,0b10001,0b11110,0b10100,0b10010,0b10001}},
  {'S', {0b01111,0b10000,0b10000,0b01110,0b00001,0b00001,0b11110}},
  {'T', {0b11111,0b00100,0b00100,0b00100,0b00100,0b00100,0b00100}},
  {'V', {0b10001,0b10001,0b10001,0b10001,0b10001,0b01010,0b00100}},
  {'W', {0b10001,0b10001,0b10001,0b10101,0b10101,0b11011,0b10001}},
  {'Y', {0b10001,0b10001,0b01010,0b00100,0b00100,0b00100,0b00100}},
  {'J', {0b00010,0b00010,0b00010,0b00010,0b10010,0b10010,0b01100}},
  {'Q', {0b01110,0b10001,0b10001,0b10001,0b10101,0b10010,0b01101}},
  {'U', {0b10001,0b10001,0b10001,0b10001,0b10001,0b10001,0b01110}},
  {'Z', {0b11111,0b00010,0b00100,0b01000,0b10000,0b10000,0b11111}},
  {'0', {0b01110,0b10011,0b10101,0b10101,0b11001,0b10001,0b01110}},
  {'1', {0b00100,0b01100,0b00100,0b00100,0b00100,0b00100,0b01110}},
  {'2', {0b01110,0b10001,0b00001,0b00110,0b01000,0b10000,0b11111}},
  {'3', {0b11110,0b00001,0b00001,0b01110,0b00001,0b00001,0b11110}},
  {'4', {0b00010,0b00110,0b01010,0b10010,0b11111,0b00010,0b00010}},
  {'5', {0b11111,0b10000,0b11110,0b00001,0b00001,0b10001,0b01110}},
  {'6', {0b00110,0b01000,0b10000,0b11110,0b10001,0b10001,0b01110}},
  {'7', {0b11111,0b00001,0b00010,0b00100,0b01000,0b01000,0b01000}},
  {'8', {0b01110,0b10001,0b10001,0b01110,0b10001,0b10001,0b01110}},
  {'9', {0b01110,0b10001,0b10001,0b01111,0b00001,0b00010,0b01100}},
};
static const int NGLYPH = int(sizeof(GLYPHS) / sizeof(GLYPHS[0]));

static const unsigned char* glyph(char c) {
  for (int i = 0; i < NGLYPH; i++)
    if (GLYPHS[i].ch == c) return GLYPHS[i].r;
  return GLYPHS[0].r; // space
}

// ---- X11 state ----
static Display* dpy = nullptr;
static Window win;
static GC gc;
static Pixmap back;
static int screen;
static int winW = WIN_W, winH = WIN_H;
static int cell, gx0, gy0, gw, gh;

// ---- colors (Nokia green monochrome) ----
static unsigned long C_BG, C_FG, C_HEAD, C_FOOD, C_DIM;

// ---- game state ----
enum State { PLAYING, PAUSED, GAMEOVER };
static State state = PLAYING;
static int snake[COLS * ROWS][2]; // x,y per segment (0 = tail)
static int snakelen = 4;
static int dirx = 1, diry = 0;     // current direction
static int ndirx = 1, ndiry = 0;   // buffered next direction
static int foodx, foody;
static int score = 0;
static int best = 0;
static int speed = 130;            // ms per step (speeds up with score)
static unsigned long nextTick = 0;
static bool running = true;
static unsigned long now_ms() {
  struct timeval tv;
  gettimeofday(&tv, nullptr);
  return (unsigned long)(tv.tv_sec * 1000 + tv.tv_usec / 1000);
}

static void compute_grid() {
  int m = 4;
  int topH = 16; // reserved status strip for SCORE/BEST
  int aw = winW - 2 * m;
  int ah = winH - topH - m;
  cell = aw / COLS;
  if ((ah / ROWS) < cell) cell = ah / ROWS;
  if (cell < 4) cell = 4;
  gw = cell * COLS;
  gh = cell * ROWS;
  gx0 = (winW - gw) / 2;
  gy0 = topH + (ah - gh) / 2;
}

static void place_food() {
  bool occ[COLS * ROWS];
  for (int i = 0; i < COLS * ROWS; i++) occ[i] = false;
  for (int i = 0; i < snakelen; i++) occ[snake[i][0] + snake[i][1] * COLS] = true;
  int freecnt = 0;
  for (int i = 0; i < COLS * ROWS; i++) if (!occ[i]) freecnt++;
  if (freecnt == 0) { foodx = -1; foody = -1; return; }
  int pick = (int)(rand() % freecnt);
  int idx = 0;
  for (int i = 0; i < COLS * ROWS; i++) {
    if (!occ[i]) {
      if (idx == pick) { foodx = i % COLS; foody = i / COLS; return; }
      idx++;
    }
  }
}

static void reset_game() {
  snakelen = 4;
  int cx = COLS / 2, cy = ROWS / 2;
  for (int i = 0; i < snakelen; i++) {
    snake[i][0] = cx - (snakelen - 1 - i); // head at cx, tail to the left
    snake[i][1] = cy;
  }
  dirx = 1; diry = 0;
  ndirx = 1; ndiry = 0;
  score = 0;
  speed = 130;
  place_food();
  state = PLAYING;
  nextTick = now_ms() + speed;
}

static void step() {
  // apply buffered direction (no reversing)
  if (!(ndirx == -dirx && ndiry == -diry) && !(ndirx == 0 && ndiry == 0)) {
    dirx = ndirx; diry = ndiry;
  }
  int hx = snake[snakelen - 1][0] + dirx;
  int hy = snake[snakelen - 1][1] + diry;
  if (hx < 0 || hx >= COLS || hy < 0 || hy >= ROWS) { state = GAMEOVER; return; }
  // self collision (ignore current tail cell since it will move, unless growing)
  for (int i = 0; i < snakelen - 1; i++) {
    if (snake[i][0] == hx && snake[i][1] == hy) { state = GAMEOVER; return; }
  }
  bool ate = (hx == foodx && hy == foody);
  if (!ate) {
    // shift body toward tail
    for (int i = 0; i < snakelen - 1; i++) {
      snake[i][0] = snake[i + 1][0];
      snake[i][1] = snake[i + 1][1];
    }
  } else {
    if (snakelen < COLS * ROWS) snakelen++;
  }
  snake[snakelen - 1][0] = hx;
  snake[snakelen - 1][1] = hy;
  if (ate) {
    score += 10;
    if (score > best) best = score;
    int ns = 130 - (score / 50) * 8;
    if (ns < 60) ns = 60;
    speed = ns;
    place_food();
  }
  nextTick = now_ms() + speed;
}

static void draw_text(int x, int y, int scale, unsigned long col, const char* s) {
  int cx = x;
  for (const char* p = s; *p; p++) {
    const unsigned char* g = glyph(*p);
    for (int r = 0; r < 7; r++) {
      unsigned char row = g[r];
      for (int b = 0; b < 5; b++) {
        if (row & (1 << (4 - b))) {
          XSetForeground(dpy, gc, col);
          XFillRectangle(dpy, back, gc, cx + b * scale, y + r * scale, scale, scale);
        }
      }
    }
    cx += 6 * scale;
  }
}

static void render() {
  XSetForeground(dpy, gc, C_BG);
  XFillRectangle(dpy, back, gc, 0, 0, winW, winH);

  // playfield border (single clean frame around the grid)
  XSetForeground(dpy, gc, C_DIM);
  XDrawRectangle(dpy, back, gc, gx0 - 1, gy0 - 1, gw + 2, gh + 2);

  // food
  if (foodx >= 0) {
    XSetForeground(dpy, gc, C_FOOD);
    XFillRectangle(dpy, back, gc, gx0 + foodx * cell, gy0 + foody * cell, cell, cell);
  }
  // snake
  for (int i = 0; i < snakelen; i++) {
    XSetForeground(dpy, gc, (i == snakelen - 1) ? C_HEAD : C_FG);
    XFillRectangle(dpy, back, gc, gx0 + snake[i][0] * cell, gy0 + snake[i][1] * cell, cell, cell);
  }

  // score (top status strip, clear of the playfield border)
  char buf[32];
  snprintf(buf, sizeof(buf), "SCORE %d", score);
  draw_text(gx0, 4, 1, C_DIM, buf);
  if (best > 0) {
    snprintf(buf, sizeof(buf), "BEST %d", best);
    draw_text(gx0 + gw - 11 * 6, 4, 1, C_DIM, buf);
  }

  if (state == PAUSED || state == GAMEOVER) {
    XSetForeground(dpy, gc, C_BG);
    XFillRectangle(dpy, back, gc, 0, 0, winW, winH);
  }
  if (state == PAUSED) {
    draw_text(winW / 2 - 5 * 6, winH / 2 - 7 * 2, 2, C_FG, "PAUSE");
    draw_text(winW / 2 - 4 * 6, winH / 2 + 7 * 2, 1, C_DIM, "5 RESUME");
  } else if (state == GAMEOVER) {
    draw_text(winW / 2 - 9 * 6, winH / 2 - 14, 2, C_FG, "GAME OVER");
    snprintf(buf, sizeof(buf), "SCORE %d", score);
    draw_text(winW / 2 - 5 * 6, winH / 2 + 4, 1, C_DIM, buf);
    draw_text(winW / 2 - 5 * 6, winH / 2 + 4 + 9, 1, C_DIM, "5 NEW GAME");
  }

  XCopyArea(dpy, back, win, gc, 0, 0, winW, winH, 0, 0);
  XFlush(dpy);
}

static void handle_key(KeySym ks) {
  switch (ks) {
    case XK_Up: case XK_w: case XK_KP_Up: case XK_2:
      ndirx = 0; ndiry = -1; break;
    case XK_Down: case XK_s: case XK_KP_Down: case XK_8: case XK_x:
      ndirx = 0; ndiry = 1; break;
    case XK_Left: case XK_a: case XK_KP_Left: case XK_4:
      ndirx = -1; ndiry = 0; break;
    case XK_Right: case XK_d: case XK_KP_Right: case XK_6:
      ndirx = 1; ndiry = 0; break;
    case XK_5: case XK_Return: case XK_KP_Enter: case XK_space: case XK_p:
      if (state == PLAYING) state = PAUSED;
      else if (state == PAUSED) { state = PLAYING; nextTick = now_ms() + speed; }
      else if (state == GAMEOVER) reset_game();
      break;
    case XK_Escape: case XK_BackSpace: case XK_Delete: case XK_End:
    case XK_Menu:
      // quit is handled by the caller via a flag
      running = false;
      break;
    default:
      if (state == GAMEOVER) reset_game();
      break;
  }
}

static void setup_window() {
  dpy = XOpenDisplay(nullptr);
  if (!dpy) { fprintf(stderr, "snake: cannot open display\n"); exit(1); }
  screen = DefaultScreen(dpy);
  win = XCreateWindow(dpy, RootWindow(dpy, screen), 0, 0, winW, winH, 0,
                       CopyFromParent, InputOutput, CopyFromParent, 0, nullptr);
  XStoreName(dpy, win, "Snake");
  XClassHint* ch = XAllocClassHint();
  if (ch) { ch->res_name = (char*)"snake"; ch->res_class = (char*)"snake"; XSetClassHint(dpy, win, ch); XFree(ch); }

  // float as a dialog so dwm doesn't tile it
  Atom wtype = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE", False);
  Atom dialog = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE_DIALOG", False);
  XChangeProperty(dpy, win, wtype, XA_ATOM, 32, PropModeReplace, (unsigned char*)&dialog, 1);

  // fixed size hints
  XSizeHints sh;
  sh.flags = PMinSize | PMaxSize | PSize;
  sh.min_width = sh.max_width = winW;
  sh.min_height = sh.max_height = winH;
  XSetWMNormalHints(dpy, win, &sh);

  Atom wm_del = XInternAtom(dpy, "WM_DELETE_WINDOW", False);
  XSetWMProtocols(dpy, win, &wm_del, 1);

  gc = XCreateGC(dpy, win, 0, nullptr);
  back = XCreatePixmap(dpy, win, winW, winH, DefaultDepth(dpy, screen));

  C_BG = BlackPixel(dpy, screen);
  // Nokia green monochrome
  C_FG = 0x33ff33;
  C_HEAD = 0x99ff99;
  C_FOOD = 0x66ff66;
  C_DIM = 0x2f9f2f;

  XSelectInput(dpy, win, KeyPressMask | StructureNotifyMask | ExposureMask);
  XMapWindow(dpy, win);
  compute_grid();
}

static void handle_event(XEvent& e) {
  if (e.type == ClientMessage) {
    Atom wm_del = XInternAtom(dpy, "WM_DELETE_WINDOW", False);
    if ((Atom)e.xclient.data.l[0] == wm_del) running = false;
  } else if (e.type == ConfigureNotify) {
    if (e.xconfigure.width != winW || e.xconfigure.height != winH) {
      winW = e.xconfigure.width; winH = e.xconfigure.height;
      compute_grid();
    }
  } else if (e.type == Expose) {
    render();
  } else if (e.type == KeyPress) {
    char buf[8];
    KeySym ks = 0;
    XLookupString(&e.xkey, buf, sizeof(buf), &ks, nullptr);
    if (ks == NoSymbol) ks = XLookupKeysym(&e.xkey, 0);
    if (ks == XK_q) { running = false; return; }
    handle_key(ks);
  }
}

int main() {
  srand((unsigned)time(nullptr) ^ (unsigned)getpid());
  setup_window();
  reset_game();
  render();

  int xfd = ConnectionNumber(dpy);
  while (running) {
    long until = (long)nextTick - (long)now_ms();
    if (until < 0) until = 0;
    struct timeval tv;
    tv.tv_sec = until / 1000;
    tv.tv_usec = (until % 1000) * 1000;
    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(xfd, &fds);
    int r = select(xfd + 1, &fds, nullptr, nullptr, &tv);
    bool dirty = false;
    if (r > 0) {
      XEvent e;
      while (XPending(dpy)) {
        XNextEvent(dpy, &e);
        handle_event(e);
        if (!running) break;
      }
      if (!running) break;
      dirty = true;
    }
    if (running && now_ms() >= nextTick) {
      if (state == PLAYING) step();
      if (state == PLAYING) nextTick = now_ms() + speed;
      else nextTick = now_ms() + 80; // keep loop responsive while paused/over
      dirty = true;
    }
    if (dirty) render();
  }

  XFreeGC(dpy, gc);
  XFreePixmap(dpy, back);
  XDestroyWindow(dpy, win);
  XCloseDisplay(dpy);
  return 0;
}