#include <limits.h>
#include "safeops.h"

SafeInt SafeInt::operator +( SafeInt other )
{
	if( good() && other.good() ) {
		int onum = other.num;

		if( num > 0 && onum > 0 ) {
			if( num > INT_MAX - onum ) {
				// overflow.
				return SafeInt();
			}
		} else if( num < 0 && onum < 0 ) {
			if( num < INT_MIN - onum ) {
				// underflow.
				return SafeInt();
			}
		}

		return SafeInt( num + onum ); 
	} else {
		return SafeInt();
	}
}

SafeInt SafeInt::operator *( SafeInt other )
{
	if( good() && other.good() ) {
		int onum = other.num;

		if( num == 0 || onum == 0 ) {
			return SafeInt( 0 );
		}

		bool neg = (num < 0) != (onum < 0);

		if( neg ) {
			if( num < INT_MIN / onum ) {
				return SafeInt();
			}
		} else {
			if( num > INT_MAX / onum ) {
				return SafeInt();
			}
		}

		return SafeInt( num * onum );
	} else {
		return SafeInt();
	}
}

SafeInt SafeInt::operator /( SafeInt other )
{
	if( good() && other.good() ) {
		int onum = other.num;

		if( onum == 0 ) {
			return SafeInt();
		} else {
			return SafeInt( num / onum );
		}
	}

	return SafeInt();
}

SafeInt gcd( SafeInt a, SafeInt b )
{
	if( a.good() && b.good() ) {
		return GreatestCommonDivisor( a.getValue(), b.getValue() );
	} else {
		return SafeInt();
	}
}

int sign( SafeInt a )
{
	if( a.good() ) {
		int x = a.getValue();
		if( x < 0 ) {
			return -1;
		} else if( x > 0 ) {
			return 1;
		}
	}

	return 0;
}

double ratio( SafeInt a, SafeInt b )
{
	if( a.good() && b.good() ) {
		return (double)(a.getValue()) / (double)(b.getValue());
	}

	return 0.0;
}

bool divide( SafeInt a, SafeInt b, SafeInt& q, SafeInt& r )
{
	if( a.good() && b.good() ) {
		int aa = a.getValue();
		int bb = b.getValue();

		int qq = aa / bb;
		int rr = aa - qq * bb;

		q = SafeInt( qq );
		r = SafeInt( rr );

		return true;
	}

	return false;
}

bool good( SafeInt& m )
{
	return m.good();
}

ostream& operator <<( ostream& os, SafeInt& si )
{
	if( si.good() ) {
		return os << si.getValue();
	} else {
		return os << "???";
	}
}