package org.simantics.scl.compiler.elaboration.query;

import java.util.Collection;
import java.util.Set;

import org.simantics.scl.compiler.elaboration.contexts.ReplaceContext;
import org.simantics.scl.compiler.elaboration.contexts.TypingContext;
import org.simantics.scl.compiler.elaboration.expressions.EVariable;
import org.simantics.scl.compiler.elaboration.expressions.QueryTransformer;
import org.simantics.scl.compiler.elaboration.expressions.Variable;
import org.simantics.scl.compiler.elaboration.query.compilation.ConstraintCollectionContext;
import org.simantics.scl.compiler.elaboration.query.compilation.DerivateException;
import org.simantics.scl.compiler.elaboration.query.compilation.UnsolvableQueryException;
import org.simantics.scl.compiler.elaboration.relations.LocalRelation;
import org.simantics.scl.compiler.elaboration.relations.SCLRelation;
import org.simantics.scl.compiler.types.Types;
import org.simantics.scl.compiler.types.kinds.Kinds;

import gnu.trove.map.hash.THashMap;
import gnu.trove.set.hash.THashSet;

public class QExists extends QAbstractModifier {
    Variable[] variables;
    
    public QExists(Variable[] variables, Query query) {
        super(query);
        this.variables = variables;
    }
    
    public QExists(Collection<Variable> variables, Query query) {
        this(variables.toArray(new Variable[variables.size()]), query);
    }

    @Override
    public void collectFreeVariables(THashSet<Variable> vars) {
        super.collectFreeVariables(vars);
        for(Variable variable : variables)
            vars.remove(variable);
    }

    @Override
    public void checkType(TypingContext context) {
        for(Variable var : variables)
            var.setType(Types.metaVar(Kinds.STAR));
        super.checkType(context);
    }

    @Override
    public void collectConstraints(ConstraintCollectionContext context) throws UnsolvableQueryException {
        for(Variable variable : variables)
            context.addVariable(variable);
        query.collectConstraints(context);
    }
    
    @Override
    public Diff[] derivate(THashMap<LocalRelation, Diffable> diffables) throws DerivateException {
        Diff[] result = query.derivate(diffables);
        for(int i=0;i<result.length;++i)
            result[i].query = new QExists(variables, result[i].query);
        return result;
    }

    @Override
    public Query replace(ReplaceContext context) {
        Variable[] newVariables = new Variable[variables.length];
        for(int i=0;i<variables.length;++i) {
            Variable variable = variables[i];
            Variable newVariable = new Variable(variable.getName(), variable.getType().replace(context.tvarMap)); 
            newVariables[i] = newVariable;
            context.varMap.put(variable, new EVariable(newVariable));
        }
        Query result = new QExists(newVariables, query.replace(context));
        for(Variable v : variables)
            context.varMap.remove(v);
        return result;
    }
    
    @Override
    public Query removeRelations(Set<SCLRelation> relations) {
        Query newQuery = query.removeRelations(relations);
        if(newQuery == query)
            return this;
        else if(newQuery == EMPTY_QUERY)
            return EMPTY_QUERY;
        else
            return new QExists(variables, newQuery);
    }
    
    @Override
    public void accept(QueryVisitor visitor) {
        visitor.visit(this);
    }
    
    @Override
    public Query accept(QueryTransformer transformer) {
        return transformer.transform(this);
    }

}