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

import java.util.Arrays;

import org.simantics.scl.compiler.elaboration.contexts.TranslationContext;
import org.simantics.scl.compiler.elaboration.contexts.TypingContext;
import org.simantics.scl.compiler.elaboration.expressions.EApply;
import org.simantics.scl.compiler.elaboration.expressions.EVar;
import org.simantics.scl.compiler.elaboration.expressions.Expression;
import org.simantics.scl.compiler.elaboration.query.pre.QPreExists;
import org.simantics.scl.compiler.elaboration.query.pre.QPreGuard;
import org.simantics.scl.compiler.errors.Locations;

public abstract class QAbstractCombiner extends Query {
    public Query[] queries;
    
    public QAbstractCombiner(Query[] queries) {
        this.queries = queries;
    }
    
    @Override
    public Query resolve(TranslationContext context) {
        Query modifiedQuery = handleExistsStatement(context);
        if(modifiedQuery != null)
            return modifiedQuery.resolve(context);
            
        for(int i=0;i<queries.length;++i)
            queries[i] = queries[i].resolve(context);
        return this;
    }
    
    private QPreExists handleExistsStatement(TranslationContext context) {
        if(queries.length == 0)
            return null;
        if(!(queries[0] instanceof QPreGuard))
            return null;
        Expression exp = ((QPreGuard)queries[0]).guard;
        if(!(exp instanceof EApply))
            return null;
        EApply apply = (EApply)exp;
        if(!(apply.getFunction() instanceof EVar))
            return null;
        if(!((EVar)apply.getFunction()).name.equals("exists"))
            return null;
        
        queries = Arrays.copyOfRange(queries, 1, queries.length);
        
        Expression[] pars = apply.getParameters();
        String[] variableNames = new String[pars.length];
        for(int i=0;i<pars.length;++i) {
            if(pars[i] instanceof EVar)
                variableNames[i] = ((EVar)pars[i]).name;
            else {
                context.getErrorLog().log(pars[i].getLocation(), "Exists statement may only contain variables as parameters.");
                return null;
            }
        }
        return new QPreExists(variableNames, this);
    }

    @Override
    public void checkType(TypingContext context) {
        for(Query query : queries)
            query.checkType(context);
    }
    
    @Override
    public void setLocationDeep(long loc) {
        if(location == Locations.NO_LOCATION) {
            location = loc;
            for(Query query : queries)
                query.setLocationDeep(loc);
        }
    }
}