#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_ILI9341.h"

// Screen dimensions when split into 16x16 chunks is 15 by 20
// Max snake length is 100 - game is won at that point

// https://create.arduino.cc/projecthub/MisterBotBreak/how-to-use-a-tft-screen-8dbdaf

#define BLACK   0x0000
#define BLUE    0x001F
#define RED     0xF800
#define GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF
#define GREY     0xD6BA

#define TFT_DC 9
#define TFT_CS 10
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

#define JOY_VERT 0
#define JOY_HORIZ 1
#define JOY_SEL 2

#define NORTH 2
#define EAST 1
#define SOUTH -2
#define WEST -1

struct SnakeBody{
  int x;
  int y;
  
  int XMax;
  int XMin;

  int YMax;
  int YMin;
};

SnakeBody snake[100];
SnakeBody food[1];

// Size is 1 more then the length of the snake
unsigned int size = 3;
unsigned int score = 1;
unsigned int highScore = 0;
int direction = EAST;

void setup() {
  // Housekeeping
  tft.begin();
  Serial.begin(9600);
  randomSeed(analogRead(A4));
  pinMode(JOY_SEL, INPUT_PULLUP);
}

void home_screen()
{

}

void loop() 
{ 
  if (digitalRead(JOY_SEL) == LOW)
  {
    tft.fillScreen(BLACK);
    play_snake();
  }
}

void play_snake()
{
  // Initializng the position of the food
  food[0].x = 10;
  food[0].y = 10;
  food[0].XMax = 16 * food[0].x + 16;
  food[0].XMin = 16 * food[0].x;

  food[0].YMax = 16 * food[0].y + 16;
  food[0].YMin = 16 * food[0].y;

  // Initializing the starting postion of the snake
  snake[0].x = 6;
  snake[0].y = 10;
  snake[1].x = 6;
  snake[1].y = 10;

  // Draw boarders of the display (tft library won't let us use the whole screen)
 //TO DO

  for (int i = 0; i < size; i++)
  {
    snake[i].XMax = 16 * snake[i].x + 16;
    snake[i].XMin = 16 * snake[i].x;

    snake[i].YMax = 16 * snake[i].y + 16;
    snake[i].YMin = 16 * snake[i].y;
  }

  direction = EAST;
  size = 3;


  bool game_state = true;

  while (game_state == true)
  {
    // Prevents the snake from going in the exact opposite direction it is traveling in
    if (direction != -read_joystick())
    {
    // Changes direction to the direction of the joystick
      direction = read_joystick();
    }

    // Moves snake head in the direction of travel 
    snake_movement(direction);

    // Moves rest of snake body accordingly (func pear is inside that checks for food collision)
    update_snake();
    game_state = check_collision();
  }
  return;
}

// Moves the head of the snake in the specified direction
void snake_movement(int direction)
{
  if (direction == NORTH)
  {
    snake[0].y ++;
  }
  else if (direction == SOUTH)
  {
    snake[0].y --;
  }
  else if (direction == WEST)
  {
    snake[0].x --;
  }
  else if (direction == EAST)
  {
    snake[0].x ++;
  }
}

// ... Reads the joystick
int read_joystick()
{
    if(abs(analogRead(JOY_VERT) - 512) > 0)
    {
      if(analogRead(JOY_VERT) < 510)
      {
          return WEST;
      }
      else if(analogRead(JOY_VERT) > 520)
      {
          return EAST;
      }
    }

    else if(abs(analogRead(JOY_HORIZ) - 512) > 0)
    {
      if(analogRead(JOY_HORIZ) < 510)
      {
          return NORTH;
      }
      else if(analogRead(JOY_HORIZ) > 520)
      {
          return SOUTH;
      }
    }

    else 
    {
      return direction;
    }
}

// Checks for "pears" colision with snake
void pear()
{ 
  if (food[0].x == snake[0].x && food[0].y == snake[0].y)
  {
    size++;

    gen_cords();
    //food[0].x = random(0, 14);
    //food[0].y = random(0, 19);
    
    food[0].XMax = 16 * food[0].x + 16;
    food[0].XMin = 16 * food[0].x;

    food[0].YMax = 16 * food[0].y + 16;
    food[0].YMin = 16 * food[0].y;
  }
  tft.fillRect(food[0].XMin, food[0].YMin, 16, 16, RED);
}

// Generates valid random positions for the pear to spawn
void gen_cords()
{
  food[0].x = random(0, 14);
  food[0].y = random(0, 19); 

  for (int i = 0; i < size; i++)
  {
    if (food[0].x == snake[i].x && food[0].y == snake[i].y)
    {
      gen_cords();
      Serial.println("RECURSION!");
      break;
    }
  }  
}

// Moves the snake
void update_snake()
{
  for (int i = 0; i < size; i++)
  {
    tft.fillRect(snake[i].XMin, snake[i].YMin, 16, 16, BLACK);
  }

  for (int i = size; i > 0; i--)
  {
    snake[i].x = snake[i-1].x;
    snake[i].y = snake[i-1].y;
  }

  for (int i = 0; i < size; i++)
  {
    snake[i].XMax = 16 * snake[i].x + 16;
    snake[i].XMin = 16 * snake[i].x;

    snake[i].YMax = 16 * snake[i].y + 16;
    snake[i].YMin = 16 * snake[i].y;
  }

  for (int i = 1; i < size; i++)
  {
    tft.fillRect(snake[i].XMin, snake[i].YMin, 16, 16, GREEN);
  }
  tft.fillRect(snake[0].XMin, snake[0].YMin, 16, 16, YELLOW);

  pear();
  delay(300);
}

bool check_collision()
{
  // Check if the head leaves the screen
  if (snake[0].x > 14 || snake[0].x < 0)
  {
    lose();
    return false;
  }
  if (snake[0].y > 19 || snake[0].y < 0)
  {
    lose();
    return false;
  }
  
  for (int i = 2; i <= size; i++)
  {
    if (snake[0].x == snake[i].x && snake[0].y == snake[i].y)
    {
      lose();
      return false;
    }
  }

  return true;
}

void win()
{

}

void lose()
{
  // Save the score of the game
  score = size - 3;

  if (score > highScore)
  {
    highScore = score;
  }

  // Clear the game - alse end the game
  clear_snake();

  // Print the game over messages to the screen
  tft.setTextColor(RED);
  tft.setCursor(15, 75);
  tft.setTextSize(4);
  tft.println("GAME OVER");

  // Prints the score of the game to the screen
  tft.setTextColor(WHITE);
  tft.setCursor(40, 135);
  tft.setTextSize(3);
  tft.println("SCORE: ");
  tft.setCursor(150, 135);
  tft.println(score);

  tft.setTextSize(2);
  tft.setCursor(30, 175);
  tft.println("HIGH SCORE: ");
  tft.setCursor(175, 175);
  tft.println(highScore);

  tft.setTextColor(GREEN);
  tft.setTextSize(2);
  tft.setCursor(35, 220);
  tft.println("PRESS JOYSTICK");
  tft.setCursor(40, 240);
  tft.println("TO PLAY AGAIN");

  // Resets the score of the game
  score = 1;
}

void clear_snake()
{
  for (int i = 0; i < size; i++)
  {
    tft.fillRect(snake[i].XMin, snake[i].YMin, 16, 16, BLACK);
  } 

  tft.fillRect(food[0].XMin, food[0].YMin, 16, 16, BLACK);

  for (int i = 100; i > 3; i--)
  {
    snake[i].x = -1;
    snake[i].y= -1;
  }
}


/*
TODO:
 - Make home screen where you can select the game of your choice
 - Make end screen and start screen, pressing button sends you to home screen
 - Figure out how to use progmem to save high scores inbetween runs

 Move onto better and harder projects
 - Figure out a work around for memory that will give me the ability to 
 have more than one game (probably with a SD card)

  Use Arduino Mega, gives me 8x the flash memory so should be capable of
  running at least 4 games

*/