#include <stdio.h>
#include <conio.h>

//Binary logic
#define TRUE  1
#define FALSE 0

//Snake directions
#define STOP  0	//snake is not moving (in the beginning or when game is paused)
#define LEFT  1 //snake is moving left
#define RIGHT 2 //snake is moving right
#define UP    3 //snake is moving up
#define DOWN  4 //snake is moving down

//Snake, Fruit, Boundary
#define SNAKE_HEAD "O"  //printf(SNAKE_HEAD) will draw the snake head
#define SNAKE_TAIL "x"  //printf(SNAKE_TAIL) will draw a segment of the snake tail
#define FRUIT      "F"  //printf(FRUIT) will draw the fruit
#define MOUSE      "M"  //printf(FRUIT) will draw the fruit

#define BOUNDARY   "#"  //printf(BOUNDARY) will draw the boundary
#define SPACE      " "  //printf(SPACE) will draw an empty space

//Escape key
#define ESC_KEY 27   //ASCII code for escape ESC key

// global variables
int gameOver;			    //to indicate game over
int mapWidth = 20;         //width of map
int mapHeight = 20;         //height of map
int snakeHeadX, snakeHeadY;         //X, Y coordinates of snake head
int fruitX, fruitY;         //X, Y coordinates of fruit
int mouseX, mouseY;         //X, Y coordinates of fruit

int dir;                    //direction of snake
int tailX[400], tailY[400]; //snake tail X Y coordinates arrays ; maximum length of snake is 400
int tailLength;             //length of snake tail

int lives = 0;
bool gameclose;
int score;
int scoremod;
bool pause;

							// function prototypes
void displayWelcome();  //display welcome screen with welcome message and instructions
void initializeGame();  //initialize the snake game
void drawScreen();      //draw display screen with map boundary, snake and fruit
void readInput();       //read input from keyboard
void updateSnake();     //update snake head and tail positions to move by one step
void checkConditions(); //check if snake hit boundary, bites its own tail or eats the fruit
void displayGameOver(); //display game over screen

void main()
{
	gameclose = false;
	pause = false;
	while (!gameclose)
	{
		system("cls");
		fseek(stdin, 0, SEEK_END);
		displayWelcome(); //display welcome screen with welcome message and instructions
		initializeGame(); //initialize the snake game
		while (!gameOver) { //if not yet game over
			if (pause)
			{
				if (getch() == 'p')
					pause = false;
				continue;
			}
			drawScreen(); //draw display screen with map boundary, snake and fruit
			readInput();  //read input from keyboard
			updateSnake();//update snake head and tail positions to move by one step
			checkConditions();//check if snake hit boundary, bites its own tail or eats the fruit
			Sleep(100);    //delay by 50ms to slow down the snake's movement
		}
		displayGameOver(); //display game over screen
	}
}

void displayWelcome()
{
	// Part 1 : Complete the welcome screen
	printf("\n\t\t\t\t\t Welcome to snake game\n\n\n");
	printf("\t\t Control the snake to eat the fruits that appear at random locations\n\n");
	printf("\n\n\t\t\t The snake will grow longer when it has eaten a fruit");
	printf("\n\n\n\n\t\t\t\t\t GOOD LUCK!!!\n\n\n");
	printf("Directions:\n");
	printf("Left- Press'a'\n");
	printf("Right- Press'd'\n");
	printf("Up- Press'w'\n");
	printf("Down- Press's'\n");
	printf("Quit- Press'Esc'\n\n");
	printf("Press any key to start.");
	fseek(stdin, 0, SEEK_END);
	while (true)
	{
		if(getch())
		{
				break;
		}
	}
	Sleep(1000);
	fseek(stdin, 0, SEEK_END);

}

void initializeGame() {
	gameOver = FALSE;  // gameOver is false at beginning of the game
	srand(NULL); // initialize seed for random number generator
	dir = STOP;        //  snake has not yet started moving

					   // Part 2: initialize the X and Y coordinates of snake head and fruit



					   // place the head of the snake at the centre of the map at the beginning of the game
					   // use variables : snakeX, snakeY
	snakeHeadX = mapWidth / 2;
	snakeHeadY = mapHeight / 2;

	score = 0;
	scoremod = 5;
	lives = 3;

	// place the fruit at random location inside the map
	// use variables : fruitX, fruitY and rand() function
	fruitX = rand() % (mapWidth - 1);
	fruitY = rand() % (mapHeight - 1);
	while (fruitX == 0) {
		fruitX = rand() % (mapWidth - 1);
	}
	while (fruitY == 0) {
		fruitY = rand() % (mapHeight - 1);
	}

	mouseX = rand() % (mapWidth - 1);
	mouseY = rand() % (mapHeight - 1);
	while (mouseX == 0) {
		mouseX = rand() % (mapWidth - 1);
	}
	while (mouseY == 0) {
		mouseY = rand() % (mapHeight - 1);
	}

}

void drawScreen() {
	//This function draws display screen with map boundary, snake and fruit
	int x;     // loop counter for x axis
	int y;     // loop counter for y axis
	int k;     // loop counter to count length of snake tail
	int drawTail = FALSE; //draw is set to TRUE when a tail is drawn at the coordinates

	system("cls"); // clears the entire screen
	printf("\n");

	//draw left and right boundary, top and bottom boundary, snake and fruit

	// Part 3: Complete the nested for loops
	for (y = 0; y < mapHeight; y++) { //loop from top to bottom, y=0 to y=mapHeight-1
		for (x = 0; x < mapWidth; x++) {  //loop from left to right, x=0 to x=mapWidth-1
										  // Insert your code below
			if (y == 0 || y == mapHeight - 1)
			{
				printf(BOUNDARY);
			}
			else if (x == 0 || x == mapWidth - 1)
			{
				printf(BOUNDARY);
			}
			else if (x == snakeHeadX && y == snakeHeadY)
			{
				switch(dir)
				{
				case RIGHT:
					printf(">");
					break;
				case LEFT:
					printf("<");
					break;
				case UP:
					printf("^");
					break;
				case DOWN:
					printf("v");
					break;
				default:
					printf(SNAKE_HEAD);
					break;
				}
			}
			else if (x == fruitX && y == fruitY)
			{
				printf(FRUIT);
			}
			else if (x == mouseX && y == mouseY)
			{
				printf(MOUSE);
			}
			else
			{
				drawTail = FALSE;
				for (k = tailLength; k >= 0; k--)
				{
					if (x == tailX[k] && y == tailY[k])
					{
						printf(SNAKE_TAIL);
						drawTail = TRUE;
					}

				}
				if (drawTail == FALSE)
				{
					printf(SPACE);
				}
			}
		}//end of inner for loop
		printf("\n");

	}//end of outer for loop
	printf("Score: %d\n", score);
	printf("Lives: %d\n", lives);

	printf("Press 'p' to pause/unpause\n");
}

void readInput() {
	// Part 4: Complete the switch-case structure
	// This function reads input from keyboard and determine direction of snake's movement
	if (kbhit()) { //detect whether a key is pressed
		switch (getch()) {  //read in a character and determine the direction of the snake
		case 'a':
		{
			if (dir == RIGHT)
				break;
			dir = LEFT;
			break;
		}
		case 'd':
		{
			if (dir == LEFT)
				break;
			dir = RIGHT;
			break;
		}
		case 'w':
		{
			if (dir == DOWN)
				break;
			dir = UP;
			break;
		}
		case 's':
		{
			if (dir == UP)
				break;
			dir = DOWN;
			break;
		}
		case 'p':
			pause = true;
			break;










		}
	}
}

void updateSnake() {
	//This function update the coordinates of the snake head, and snake tail segments
	//Update from the final segment of the snake to the snake head

	int i;   //loop counter

			 //loop to the move all the segments of the snake tail
			 //The final segment of the tail will move to the 2nd last segment of the tail
			 //The 2nd last segment of the tail will move to the 3rd last segment of the tail
			 //...and so on
			 //The second segment of the tail will move to the first segment of the tail
	for (i = tailLength - 1; i >0; i--) {
		tailX[i] = tailX[i - 1];
		tailY[i] = tailY[i - 1];
	}

	// move the first segment of tail to the snake head's position
	tailX[0] = snakeHeadX;
	tailY[0] = snakeHeadY;

	//check snake direction and update coordinates of snake head
	switch (dir) {
	case LEFT:       //if snake moves to the left
		snakeHeadX--;  //x coordinate decreases by 1; no change in y coordinates
		break;
	case RIGHT:      //if snake moves to the right
		snakeHeadX++;  //x coordinate increases by 1; no change in y coordinates
		break;
	case UP:         //if snake moves up
		snakeHeadY--;  //y coordinate decreases by 1; no change in x coordinates
		break;
	case DOWN:       //if snake moves down
		snakeHeadY++;  //y coordinate increases by 1; no change in x coordinates
		break;
	default:
		break;
	}
	static int counter = 0;
	++counter;
	if (counter > 5)
	{
		//check snake direction and update coordinates of snake head
		switch (rand() % 5) {
		case LEFT:       //if snake moves to the left
			if (mouseX <= 1)
				break;
			mouseX--;  //x coordinate decreases by 1; no change in y coordinates
			break;
		case RIGHT:      //if snake moves to the right
			if (mouseX >= 17)
				break;
			mouseX++;  //x coordinate increases by 1; no change in y coordinates
			break;
		case UP:         //if snake moves up
			if (mouseY <= 1)
				break;
			mouseY--;  //y coordinate decreases by 1; no change in x coordinates
			break;
		case DOWN:       //if snake moves down
			if (mouseY >= 17)
				break;
			mouseY++;  //y coordinate increases by 1; no change in x coordinates
			break;
		default:
			break;
		}
		counter = 0;
	}
}

void checkConditions()
{
	// Part 5 : Complete the if statements
	//This function checks whether the snake hits the boundary, bites its own tail or eats the fruit
	// if the snake head hits or crosses the boundary
	//    game over !
	bool hit = false;
	int i;
	if (snakeHeadX <= 0 || snakeHeadX > 18 || snakeHeadY <= 0 || snakeHeadY >= 18)
		hit = true;


	// if the snake head bites any part of its tail
	//    game over !
	for (i = tailLength; i>0; i--) {
		if (snakeHeadX == tailX[i] && snakeHeadY == tailY[i])
			hit = false;
	}


	// if the snake eats the fruit
	//    then regenerates a new fruit at random locations
	if (snakeHeadX == fruitX && snakeHeadY == fruitY) {
		score += scoremod;
		tailLength++;
		fruitX = rand() % (mapWidth - 1);
		fruitX = rand() % (mapHeight - 1);
		while (fruitX == 0) {
			fruitX = rand() % (mapWidth - 1);
		}
		while (fruitY == 0) {
			fruitY = rand() % (mapHeight - 1);
		}
	}

	if (snakeHeadX == mouseX && snakeHeadY == mouseY) {
		score += scoremod;
		tailLength++;
		mouseX = rand() % (mapWidth - 1);
		mouseY = rand() % (mapHeight - 1);
		while (mouseX == 0) {
			mouseX = rand() % (mapWidth - 1);
		}
		while (mouseY == 0) {
			mouseY = rand() % (mapHeight - 1);
		}
	}
	if (hit)
	{
		tailLength = 0;
		lives--;
		snakeHeadX = mapWidth / 2;
		snakeHeadY = mapHeight / 2;
		for (int i = 0; i < 400; ++i)
		{
			tailX[i] = tailY[i] = 0;
		}
	}

	if (lives < 0)
	{
		gameOver = true;
	}
}
void displayGameOver()
{
	fseek(stdin,0,SEEK_END);
	//This function discplays the game over screen
	system("cls");  //clear screen
	printf("\n\n\t\t\t Game Over! \n\n\n\n"); //display Game Over message
	printf("\n \n \n \n Press any key to return to main menu.");// prompt user to press a key
	printf("\n \n \n \n Press any 'X' to End.");// prompt user to press a key

	while (!gameclose)
	{
		if (kbhit())
		{
			char key = getch();
			if (key == 'x')
				gameclose = true;
			else
				break;
		}
	}
	fseek(stdin,0,SEEK_END);
}