#include <time.h>
#include <iostream>
#include <string>
#include <iomanip>
#include <cstdlib>

typedef unsigned int uint;
using namespace std;
enum movDir { UP, DOWN, LEFT, RIGHT };

class tile
{
public:
    tile() : val( 0 ), blocked( false ) {}
    uint val;
    bool blocked;
};

class g2048
{
public:
    g2048() : done( false ), win( false ), moved( true ), score( 0 ) {}
    void loop()
    {
	addTile();
	while( true )
	{
	    if( moved ) addTile();
	    drawBoard();
	    if( done ) break;
	    waitKey();
	}
	string s = "Game Over!";
	if( win ) s = "You've made it!";
	cout << s << endl << endl;
    }
private:
    void drawBoard()
    {
	system( "cls" );
	cout << "SCORE: " << score << endl << endl;
	for( int y = 0; y < 4; y++ )
	{
	    cout << "+------+------+------+------+" << endl << "| ";
	    for( int x = 0; x < 4; x++ )
	    {
		if( !board[x][y].val ) cout << setw( 4 ) << " ";
		else cout << setw( 4 ) << board[x][y].val;
		cout << " | ";
	    }
	    cout << endl;
	}
	cout << "+------+------+------+------+" << endl << endl;
    }
    void waitKey()
    {
	moved = false; char c;
	cout << "(W)Up (S)Down (A)Left (D)Right "; cin >> c; c &= 0x5F;
	switch( c )
	{
	    case 'W': move( UP );break;
	    case 'A': move( LEFT ); break;
	    case 'S': move( DOWN ); break;
	    case 'D': move( RIGHT );
	}
	for( int y = 0; y < 4; y++ )
	    for( int x = 0; x < 4; x++ )
		board[x][y].blocked = false;
    }
    void addTile()
    {
	for( int y = 0; y < 4; y++ )
	    for( int x = 0; x < 4; x++ )
		if( !board[x][y].val )
		{
		    uint a, b;
		    do
		    { a = rand() % 4; b = rand() % 4; }
		    while( board[a][b].val );

		    int s = rand() % 100;
		    if( s > 89 ) board[a][b].val = 4;
		    else board[a][b].val = 2;
		    if( canMove() ) return;
		}
	done = true;
    }
    bool canMove()
    {
	for( int y = 0; y < 4; y++ )
	    for( int x = 0; x < 4; x++ )
		if( !board[x][y].val ) return true;

	for( int y = 0; y < 4; y++ )
	    for( int x = 0; x < 4; x++ )
	    {
		if( testAdd( x + 1, y, board[x][y].val ) ) return true;
		if( testAdd( x - 1, y, board[x][y].val ) ) return true;
		if( testAdd( x, y + 1, board[x][y].val ) ) return true;
		if( testAdd( x, y - 1, board[x][y].val ) ) return true;
	    }
	return false;
    }
    bool testAdd( int x, int y, uint v )
    {
	if( x < 0 || x > 3 || y < 0 || y > 3 ) return false;
	return board[x][y].val == v;
    }
    void moveVert( int x, int y, int d )
    {
	if( board[x][y + d].val && board[x][y + d].val == board[x][y].val && !board[x][y].blocked && !board[x][y + d].blocked  )
	{
	    board[x][y].val = 0;
	    board[x][y + d].val *= 2;
	    score += board[x][y + d].val;
	    board[x][y + d].blocked = true;
	    moved = true;
	}
	else if( !board[x][y + d].val && board[x][y].val )
	{
	    board[x][y + d].val = board[x][y].val;
	    board[x][y].val = 0;
	    moved = true;
	}
	if( d > 0 ) { if( y + d < 3 ) moveVert( x, y + d,  1 ); }
	else        { if( y + d > 0 ) moveVert( x, y + d, -1 ); }
    }
    void moveHori( int x, int y, int d )
    {
	if( board[x + d][y].val && board[x + d][y].val == board[x][y].val && !board[x][y].blocked && !board[x + d][y].blocked  )
	{
	    board[x][y].val = 0;
	    board[x + d][y].val *= 2;
	    score += board[x + d][y].val;
	    board[x + d][y].blocked = true;
	    moved = true;
	}
	else if( !board[x + d][y].val && board[x][y].val )
	{
	    board[x + d][y].val = board[x][y].val;
	    board[x][y].val = 0;
	    moved = true;
	}
	if( d > 0 ) { if( x + d < 3 ) moveHori( x + d, y,  1 ); }
	else        { if( x + d > 0 ) moveHori( x + d, y, -1 ); }
    }
    void move( movDir d )
    {
	switch( d )
	{
	    case UP:
	    	for( int x = 0; x < 4; x++ )
		{
		    int y = 1;
		    while( y < 4 )
		    { if( board[x][y].val ) moveVert( x, y, -1 ); y++;}
		}
		break;
	    case DOWN:
		for( int x = 0; x < 4; x++ )
		{
		    int y = 2;
		    while( y >= 0 )
		    { if( board[x][y].val ) moveVert( x, y, 1 ); y--;}
		}
		break;
	    case LEFT:
		for( int y = 0; y < 4; y++ )
		{
		    int x = 1;
		    while( x < 4 )
		    { if( board[x][y].val ) moveHori( x, y, -1 ); x++;}
		}
		break;
	    case RIGHT:
		for( int y = 0; y < 4; y++ )
		{
		    int x = 2;
		    while( x >= 0 )
		    { if( board[x][y].val ) moveHori( x, y, 1 ); x--;}
		}
	}
    }
    tile board[4][4];
    bool win, done, moved;
    uint score;
};
int main( int argc, char* argv[] )
{
    srand( static_cast<uint>( time( NULL ) ) );
    g2048 g; g.loop();
    return system( "pause" );
}