package solver;

/**
 * @author mohsen
 *
 */

public class Relation {
	
	static public int reduce(int relationNumber,int variableNumber,int value){
		int r,m; // new relation number
		m = getMagicNumber(variableNumber, value);
		r = (relationNumber&m);
		if (value==0){
			r = r|(r<<(1<<variableNumber));
		}else{
			r = r|(r>>(1<<variableNumber));
		}
		return r; 
		 
	}
	static public int rename(int relationNumber,int variableNumber){
		int m0,m1;
		m0 = getMagicNumber(variableNumber, 0);
		m1 = getMagicNumber(variableNumber, 1);
		int s = (1<<variableNumber);
		int r = ((relationNumber&m0)<<s)|((relationNumber&m1)>>s);
		return r;
	}

	static public boolean isVariableNotInRelation(int relationNumber, int variableNumber){
		int m = getMagicNumber(variableNumber, 1);
		return ((relationNumber&m)>>(1<<variableNumber))==(relationNumber&(~m));

/*		int r0 = reduce(relationNumber,variableNumber,0);
		int r1 = reduce(relationNumber,variableNumber,1);
		return (r0==r1);
*/	}
	
	static public int rank(int relationNumber){
		int rank =3;
		for (int i=0;i<3;i++){
			if (isVariableNotInRelation(relationNumber, i)) rank--;
		}
		return rank;
	}
	
	static public int q(int relationNumber,int sub/*0,1,2,3*/){
		int m;
		switch (sub){
		case 0:
			m=1;
			break;
		case 1:
			m=22;
			break;
		case 2:
			m=104;
			break;
		case 3:
			m=128;
			break;
		default:
				m=0;
				System.out.println("Sub can be 0,1,2,or 3");
		}
		return ones((relationNumber&m));
	}
	
	static public int ones(int relationNumber){
		int c=0;
		for(int i=0;i<8;i++){
			if ((relationNumber&(1<<i))!=0) c++;
		}
		return c;
	}
	
	static public int getMagicNumber(int variableNumber,int value){
		//ToDo: use xor, see if there is a default return value 
		if(value==0){
			if(variableNumber==0) return 85; /*1st var (Least Significant), value 0*/
			if(variableNumber==1) return 51;
			if(variableNumber==2) return 15; /*last var (Most Significant), value 0*/
			System.out.println("Only 3 variable Numbers are allowed 0,1,2");
		}else if(value ==1){
			if(variableNumber==0) return 170; /*1st var (Least Significant), value 1*/
			if(variableNumber==1) return 204;
			if(variableNumber==2) return 240; /*last var (Most Significant), value 1*/
			System.out.println("Only 3 variable Numbers are allowed 0,1,2");
		}else{
			System.out.println("Only 0 or 1 are allowed as values");
		}
		return -1;
	}
	
	static public int isForced(int relationNumber, int variableNumber){
		if (isVariableNotInRelation(relationNumber, variableNumber)){
			return -1;
		}else{
			int m = getMagicNumber(variableNumber, 1);
			int rm = relationNumber&m;
			if(rm== 0){
				return 0;
			}else if (rm==relationNumber){
				return 1;
			}else{
				return -1;
			}
		}		
	}
}