// Including the required Arduino libraries
#include <MD_MAX72xx.h>
#include <SPI.h>
#include <string.h>

#define MAX_DEVICES 1
#define ISPRESSED LOW

struct tile {
  bool is_on;
  bool is_wall;
  bool is_apple;
  bool is_snake;
  int time_placed;
};

// MD_MAX72XX main_display = MD_MAX72XX(MD_MAX72XX::GENERIC_HW, DIN, CLK, CS, 1);
MD_MAX72XX main_display = MD_MAX72XX(MD_MAX72XX::GENERIC_HW, 11, 13, 10, 1);

unsigned int board[8][8];
bool buttons[4];
unsigned int time_passed = 0;
unsigned int frames_passed = 0;
unsigned int n_apples = 0;
unsigned int snake_length = 3;
unsigned int game_state = 0;
const unsigned int FPS = 60;
const unsigned int MS_PER_FRAME = 1000 / FPS;

// Bit representation: 00000000 / Time placed % 64 000000 / 00 is wall (0 = off, 1 = wall, 2 = apple, 3 = snake)
void set_bits_at(unsigned int x, unsigned int y, unsigned int start, unsigned int stop, unsigned int new_value) {
  // Serial.print("Old = ");
  // Serial.println(board[x][y]);
  unsigned int value = board[x][y];
  unsigned int temp = (1 << (stop - start + 1)) - 1;
  temp <<= start;
  // Serial.print("Temp = ");
  // Serial.println(temp);
  value &= value ^ temp;
  // Serial.print("Erased = ");
  // Serial.println(value);
  value |= new_value << start;
  board[x][y] = value;
  // Serial.print("new = ");
  // Serial.println(board[x][y]);
}
unsigned int get_bits_at(unsigned int x, unsigned int y, unsigned int start, unsigned int stop) {
  unsigned int value = board[x][y];
  value <<= (15 - stop);
  value >>= (15 - stop + start);
  return value;
}

tile convert_to_tile(unsigned int x, unsigned int y) {
  tile new_tile;
  new_tile.is_on = get_bits_at(x, y, 0, 1) ? true : false;
  new_tile.is_wall = get_bits_at(x, y, 0, 1) == 1 ? true : false;
  new_tile.is_apple = get_bits_at(x, y, 0, 1) == 2 ? true : false;
  new_tile.is_snake = get_bits_at(x, y, 0, 1) == 3 ? true : false;
  new_tile.time_placed = get_bits_at(x, y, 2, 7);
  return new_tile;
}

void draw_board() {
  for (unsigned int y = 0; y < 8; y++) {
    for (unsigned int x = 0; x < 8; x++) {
      if (get_bits_at(x, y, 0, 1) == 0) main_display.setPoint(x, y, false);
      else if (get_bits_at(x, y, 0, 1) == 3 && (get_bits_at(x, y, 2, 7) + 1) % 64 == frames_passed) main_display.setPoint(x, y, time_passed % 12 > 2);
      else if (get_bits_at(x, y, 0, 1) == 2) main_display.setPoint(x, y, (time_passed / 12) % 4 == 0);
      else main_display.setPoint(x, y, true);
    }
  }
  // for (unsigned int y = 0; y < 8; y++) {
  //   for (unsigned int x = 0; x < 8; x++) {
  //     Serial.print(get_bits_at(x, y, 0, 1));
  //     Serial.print(" ");
  //   }
  //   Serial.println("");
  // }
}


void update_buttons(bool check_on) {
  // Serial.println(digitalRead(4));
  // Serial.println(digitalRead(5));
  // Serial.println(digitalRead(6));
  // Serial.println(digitalRead(7));
  if (check_on) {
    if (digitalRead(4) == ISPRESSED) buttons[0] = true;
    if (digitalRead(5) == ISPRESSED) buttons[1] = true;
    if (digitalRead(6) == ISPRESSED) buttons[2] = true;
    if (digitalRead(7) == ISPRESSED) buttons[3] = true;

  } else {
    if (digitalRead(4) != ISPRESSED) buttons[0] = false;
    if (digitalRead(5) != ISPRESSED) buttons[1] = false;
    if (digitalRead(6) != ISPRESSED) buttons[2] = false;
    if (digitalRead(7) != ISPRESSED) buttons[3] = false;

  }
  if (buttons[0] + buttons[1] + buttons[2] + buttons[3] != 0 && game_state == 0) {
    randomSeed(millis());
    create_apple();
    create_apple();
    create_apple();
    game_state = 1;
  }
}

void reset_game() {
  for (int y = 0; y < 8; y++) {
    for (int x = 0; x < 8; x ++) {
      board[x][y] = 0;
    }
  }
  snake_length = 3;
  n_apples = 0;
  game_state = 0;
}

unsigned int cur_x = 0, cur_y = 0, cur_dir = 0;
// 0 = left, 1 = down, 2 == right, 3 = up

void update_direction() {
  if (buttons[0] && cur_dir != 2) cur_dir = 0;
  if (buttons[1] && cur_dir != 1) cur_dir = 3;
  if (buttons[2] && cur_dir != 3) cur_dir = 1;
  if (buttons[3] && cur_dir != 0) cur_dir = 2;
}

void update_pos() {
  if (cur_dir == 0) cur_x += 1;
  else if (cur_dir == 1) cur_y += 7;
  else if (cur_dir == 2) cur_x += 7;
  else if (cur_dir == 3) cur_y += 1;
  cur_x %= 8;
  cur_y %= 8;
}

void update_game() {
  update_direction();
  update_pos();
  update_snake();
  // Serial.print("Moved to ");
  // Serial.print(cur_x);
  // Serial.print(" ");
  // Serial.println(cur_y);
}

void create_apple() {
  unsigned int next_apple_x = random(8);
  unsigned int next_apple_y = random(8);
  while (get_bits_at(next_apple_x, next_apple_y, 0, 1) != 0) {
    next_apple_x = random(8);
    next_apple_y = random(8);
  }
  
  set_bits_at(next_apple_x, next_apple_y, 0, 1, 2);
  
  Serial.println("set apple at");
  Serial.println(next_apple_x);
  Serial.println(next_apple_y);
  n_apples += 1;
}

void update_snake() {


  tile next_tile = convert_to_tile(cur_x, cur_y);
  if (next_tile.is_apple) {
    n_apples -= 1;
    snake_length += 1;
    create_apple();
  }

  if (next_tile.is_snake && (next_tile.time_placed + snake_length) % 64 != frames_passed) {
    reset_game();
  }

  for (int y = 0; y < 8; y++) {
    for (int x = 0; x < 8; x++) {
      if (get_bits_at(x, y, 0, 1) != 3) continue;
      if ((get_bits_at(x, y, 2, 7) + snake_length) % 64 != frames_passed) continue;
      set_bits_at(x, y, 0, 7, 0);
    }
  }

  set_bits_at(cur_x, cur_y, 0, 1, 3);
  set_bits_at(cur_x, cur_y, 2, 7, frames_passed);



  // Serial.print("Current frame = ");
  // Serial.println(frames_passed);
  // Serial.print("Frame to delete = ");
  // Serial.println(frames_passed + snake_length);
  // for (unsigned int y = 0; y < 8; y++) {
  //   for (unsigned int x = 0; x < 8; x++) {
  //     Serial.print(get_bits_at(x, y, 2, 7));
  //     Serial.print(" ");
  //   }
  //   Serial.println("");
  // }
}

void setup() {
	// Intialize the object
  main_display.begin();
  main_display.control(MD_MAX72XX::INTENSITY, 0);
  main_display.clear();
  Serial.begin(9600);

  pinMode(7, INPUT_PULLUP);
  pinMode(6, INPUT_PULLUP);
  pinMode(5, INPUT_PULLUP);
  pinMode(4, INPUT_PULLUP);

  for (unsigned int x = 0; x < 8; x++) {
    for (unsigned int y = 0; y < 8; y++) {
      board[x][y] = 0;
    }
  }


  set_bits_at(0, 0, 0, 1, 3);
  set_bits_at(0, 0, 2, 7, 0);
  // board[7][7] = 0;
  // set_bits_at(7, 7, 0, 1, 2);
  // set_bits_at(7, 7, 2, 7, 35);
  // Serial.println(get_bits_at(7, 7, 2, 7));
  // Serial.println(get_bits_at(7, 7, 0, 1));
}

void loop() {
  draw_board();
  update_buttons(true);

  time_passed += 1;
  if (time_passed >= MS_PER_FRAME && game_state == 1) {
    update_game();
    update_buttons(false);
    frames_passed += 1;
    frames_passed %= 64;
    time_passed = 0;
  }

}