#include <iostream>
#include <string>

using namespace std;

class playfair
{
public:
    void doIt( string k, string t, bool ij, bool e )
    {
	createGrid( k, ij ); getTextReady( t, ij, e );
	if( e ) doIt( 1 ); else doIt( -1 );
	display();
    }

private:
    void doIt( int dir )
    {
	int a, b, c, d; string ntxt;
	for( string::const_iterator ti = _txt.begin(); ti != _txt.end(); ti++ )
	{
	    if( getCharPos( *ti++, a, b ) )
		if( getCharPos( *ti, c, d ) )
		{
		    if( a == c )     { ntxt += getChar( a, b + dir ); ntxt += getChar( c, d + dir ); }
		    else if( b == d ){ ntxt += getChar( a + dir, b ); ntxt += getChar( c + dir, d ); }
		    else             { ntxt += getChar( c, b ); ntxt += getChar( a, d ); }
		}
	}
	_txt = ntxt;
    }

    void display()
    {
	cout << "\n\n OUTPUT:\n=========" << endl;
	string::iterator si = _txt.begin(); int cnt = 0;
	while( si != _txt.end() )
	{
	    cout << *si; si++; cout << *si << " "; si++;
	    if( ++cnt >= 26 ) cout << endl, cnt = 0;
	}
	cout << endl << endl;
    }

    char getChar( int a, int b )
    {
	return _m[ (b + 5) % 5 ][ (a + 5) % 5 ];
    }

    bool getCharPos( char l, int &a, int &b )
    {
	for( int y = 0; y < 5; y++ )
	    for( int x = 0; x < 5; x++ )
		if( _m[y][x] == l )
		{ a = x; b = y; return true; }

	return false;
    }

    void getTextReady( string t, bool ij, bool e )
    {
	for( string::iterator si = t.begin(); si != t.end(); si++ )
	{
	    *si = toupper( *si ); if( *si < 65 || *si > 90 ) continue;
	    if( *si == 'J' && ij ) *si = 'I';
	    else if( *si == 'Q' && !ij ) continue;
	    _txt += *si;
	}
	if( e )
	{
	    string ntxt = ""; size_t len = _txt.length();
	    for( size_t x = 0; x < len; x += 2 )
	    {
		ntxt += _txt[x];
		if( x + 1 < len )
		{
		    if( _txt[x] == _txt[x + 1] ) ntxt += 'X';
		    ntxt += _txt[x + 1];
		}
	    }
	    _txt = ntxt;
	}
	if( _txt.length() & 1 ) _txt += 'X';
    }

    void createGrid( string k, bool ij )
    {
	if( k.length() < 1 ) k = "KEYWORD";
	k += "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; string nk = "";
	for( string::iterator si = k.begin(); si != k.end(); si++ )
	{
	    *si = toupper( *si ); if( *si < 65 || *si > 90 ) continue;
	    if( ( *si == 'J' && ij ) || ( *si == 'Q' && !ij ) )continue;
	    if( nk.find( *si ) == -1 ) nk += *si;
	}
	copy( nk.begin(), nk.end(), &_m[0][0] );
    }

    string _txt; char _m[5][5];
};

int main( int argc, char* argv[] )
{
    string key, i, txt; bool ij, e;
    cout << "(E)ncode or (D)ecode? "; getline( cin, i ); e = ( i[0] == 'e' || i[0] == 'E' );
    cout << "Enter a en/decryption key: "; getline( cin, key );
    cout << "I <-> J (Y/N): "; getline( cin, i ); ij = ( i[0] == 'y' || i[0] == 'Y' );
    cout << "Enter the text: "; getline( cin, txt );
    playfair pf; pf.doIt( key, txt, ij, e ); return system( "pause" );
}