package org.simantics.scl.compiler.elaboration.chr.plan;

import java.util.ArrayList;

import org.simantics.scl.compiler.compilation.CompilationContext;
import org.simantics.scl.compiler.constants.Constant;
import org.simantics.scl.compiler.constants.JavaComparisonOperation;
import org.simantics.scl.compiler.constants.singletons.NullCheck;
import org.simantics.scl.compiler.elaboration.chr.relations.CHRConstraint;
import org.simantics.scl.compiler.elaboration.expressions.Expression;
import org.simantics.scl.compiler.elaboration.expressions.Variable;
import org.simantics.scl.compiler.internal.codegen.continuations.ICont;
import org.simantics.scl.compiler.internal.codegen.references.IVal;
import org.simantics.scl.compiler.internal.codegen.writer.CodeWriter;

public class IterateConstraintOp extends PlanOp {
    
    public CHRConstraint constraint;
    public Variable[] variables;
    public Expression[] expressions;
    public int boundMask;
    public boolean killAfterMatch;
    public boolean passive;
    
    public IterateConstraintOp(long location, CHRConstraint constraint, Variable[] variables, Expression[] expressions,
            int boundMask, boolean killAfterMatch, boolean passive) {
        super(location);
        this.constraint = constraint;
        this.variables = variables;
        this.expressions = expressions;
        this.boundMask = boundMask;
        this.killAfterMatch = killAfterMatch;
        this.passive = passive;
        
    }

    @Override
    public void toString(StringBuilder b) {
        b.append("ITERATE ").append(constraint);
        for(int i=0;i<expressions.length;++i)
            if((boundMask & (1 << i)) != 0) {
                b.append(" (").append(expressions[i]).append(")");
            }
            else {
                b.append(" ").append(variables[i]);
            }
    }

    @Override
    public void generateCode(CompilationContext context, PlanContext planContext, CodeWriter w) {
        CodeWriter body = w.createBlock(constraint.factType);
        CodeWriter nextFact = w.createBlock();
        ICont bodyContinuation = body.getContinuation();
        CodeWriter end = w.createBlock();
        IVal fact = body.getParameters()[0];

        ArrayList<IVal> parameters = new ArrayList<IVal>(expressions.length+1);
        parameters.add(planContext.storeVar);
        for(int i=0;i<expressions.length;++i)
            if(((boundMask>>i)&1)==1)
                parameters.add(expressions[i].toVal(context.environment, w));
        w.jump(bodyContinuation, w.apply(location,
                constraint.fetchFromIndex(context, boundMask), parameters.toArray(new IVal[parameters.size()])));

        body.branchAwayIf(body.apply(location, NullCheck.INSTANCE.createSpecialization(constraint.factType), fact),
                end.getContinuation());
        IVal id = body.apply(location, constraint.accessId, fact);
        for(PartnerFact partnerFact : planContext.partnerFacts)
            if(partnerFact.active && !passive) {
                body.branchAwayUnless(body.apply(location, JavaComparisonOperation.ILESS, id, partnerFact.id),
                        nextFact.getContinuation());
            }
            else if(partnerFact.constraint == constraint) {
                body.branchAwayIf(body.apply(location, JavaComparisonOperation.IEQUAL, id, partnerFact.id),
                        nextFact.getContinuation());
            }

        for(int i=0;i<variables.length;++i)
            if(((boundMask>>i)&1)==0)
                variables[i].setVal(constraint.accessComponent(location, body, fact, i));
        Constant nextElement = constraint.nextElement(context, boundMask);
        planContext.partnerFacts.add(new PartnerFact(false, id, constraint, fact, constraint.mayBeRemoved(), killAfterMatch, nextElement, bodyContinuation, end.getContinuation()));
        planContext.nextOp(body);
        if(body.isUnfinished()) 
            body.jump(nextFact.getContinuation());
        nextFact.jump(bodyContinuation, nextFact.apply(location, nextElement, fact));

        w.continueAs(end);
    }   
}