#include <vector>
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

#include "SDL.h"
#include "SDL_ttf.h"

const short BLOCK_WIDTH  = 100;
const short BLOCK_HEIGHT = 100;

const short BOARD_WIDTH  = 4;
const short BOARD_HEIGHT = 4;

const short FONT_SIZE    = 20;

void draw_board( vector<vector<int> > *board, SDL_Surface *screen )
{
	TTF_Font    *font   = NULL;
	SDL_Surface *number = NULL;
	Uint32       color  = SDL_MapRGB( screen->format, 0, 0, 125 );
	SDL_Color    textColor;
	textColor.r = 0; textColor.g = 0; textColor.b = 0;

	font    = TTF_OpenFont("font.ttf", FONT_SIZE);
	
	if( font == NULL )
		return;

	SDL_Rect dstrect;
	dstrect.w = BLOCK_WIDTH;
	dstrect.h = BLOCK_HEIGHT;
	SDL_Rect fontrect;

	SDL_FillRect( screen, NULL, SDL_MapRGB( screen->format, 0,0,0 ) );
	
	int count = 1;
	for( short i = 0; i < BOARD_WIDTH; i++ )
	{
		for( short j = 0; j < BOARD_HEIGHT; j++)
		{
			dstrect.y = i * BLOCK_WIDTH;
			dstrect.x = j * BLOCK_HEIGHT;
			fontrect.x = dstrect.x + ( dstrect.w / 2 );
			fontrect.y = dstrect.y + ( dstrect.h / 2 );
			
			if( number != NULL )
				SDL_FreeSurface(number);

			std::stringstream s;
			s << (*board)[i][j];

			number = TTF_RenderText_Solid( font, s.str().c_str() , textColor );

			if( (*board)[i][j] != -1 ){
				SDL_FillRect( screen, &dstrect, color );
				SDL_BlitSurface( number, NULL, screen, &fontrect );
			}
		}
	}

	if( number != NULL )
		SDL_FreeSurface(number);

	SDL_Flip(screen);

	return;
}

int round_to_nth(int num, int nth)
{
	return num - num % nth;
}

void make_swap(int &n1, int &n2)
{
	int t = n1;
	n1 = n2;
	n2 = t;

	return;
}

// Return true if player clicked on a movable piece
bool click_event(int x, int y, vector<vector<int> > *board)
{
	x = round_to_nth(x, BLOCK_WIDTH)  / BLOCK_WIDTH;
	y = round_to_nth(y, BLOCK_HEIGHT) / BLOCK_HEIGHT;

	// Check Left
	if( x > 0 )
	{
		if( (*board)[y][x-1] == -1 )
			make_swap( (*board)[y][x], (*board)[y][x-1] );
	}

	// Check Right
	if( x < BOARD_WIDTH - 1 )
	{
		if( (*board)[y][x+1] == -1 )
			make_swap( (*board)[y][x], (*board)[y][x+1] );
	}

	// Check Above
	if( y > 0 )
	{
		if( (*board)[y-1][x] == -1 )
			make_swap( (*board)[y][x], (*board)[y-1][x] );
	}

	// Check Below
	if( y < BOARD_HEIGHT - 1 )
	{
		if( (*board)[y+1][x] == -1 )
			make_swap( (*board)[y][x], (*board)[y+1][x] );
	}
	
	return false;
}

int main( int argc, char **argv )
{
	/**** SDL INITIALIZATION ****/
	SDL_Surface *screen = NULL;

	if( SDL_Init(SDL_INIT_EVERYTHING ) == -1 )
		return 1;

	if( TTF_Init() == -1 )
		return 1;

	screen = SDL_SetVideoMode( BLOCK_WIDTH * BOARD_WIDTH, BLOCK_HEIGHT * BOARD_HEIGHT, 
							   32, SDL_SWSURFACE );

	if( screen == NULL )
		return 1;

	SDL_WM_SetCaption("NPuzzle written in C++ and SDL", NULL);

	/**** BOARD INITIALIZATION ****/
	vector< vector<int> > board;
	int count = 1;
	for( short i = 0; i < BOARD_WIDTH; i++){
		vector<int> t;
		board.push_back(t);
		
		for( short j = 0; j < BOARD_HEIGHT; j++){
			board[i].push_back( count++ );
		}
	}

	// -1 represents the empty square
	board[BOARD_WIDTH-1][BOARD_HEIGHT-1] = -1;

	/*** GAME LOGIC ***/
	SDL_Event ev;
	bool game = true;
	while(game)
	{
		SDL_Delay(1);
		while( SDL_PollEvent(&ev) )
		{
			if( ev.type == SDL_QUIT )
				game = false;
			if( ev.type == SDL_MOUSEBUTTONDOWN )
			{
				click_event( ev.button.x, ev.button.y, &board ); 	
			}
		}

		draw_board(&board,screen);
	}


	// Free resources and exit
	SDL_FreeSurface(screen);
	SDL_Quit();
	return 0;
}