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package org.eclipse.xtend.backend.expr;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;

import org.eclipse.xtend.backend.common.BackendType;
import org.eclipse.xtend.backend.common.ExecutionContext;
import org.eclipse.xtend.backend.common.ExpressionBase;
import org.eclipse.xtend.backend.common.SourcePos;
import org.eclipse.xtend.backend.types.builtin.CollectionType;


/**
 * This class deals with the case where the middle end can not decide statically whether
 *  a property is to be resolved on a single object or on a collection
 *  
 * @author Arno Haase (http://www.haase-consulting.com)
 */
public final class PropertyOnWhateverExpression extends ExpressionBase {
    private final ExpressionBase _inner;
    private final String _propertyName;

    public PropertyOnWhateverExpression (ExpressionBase inner, String propertyName, SourcePos sourcePos) {
        super (sourcePos);
        
        _inner = inner;
        _propertyName = propertyName;
    }

    @Override
    public Object evaluateInternal(ExecutionContext ctx) {
        final Object o = _inner.evaluate(ctx);
        if (o == null) {
            ctx.logNullDeRef (getPos());
            return null;
        }

        final BackendType t = ctx.getTypesystem().findType (o);
        
        if (CollectionType.INSTANCE.isAssignableFrom(t)) {
            if (isProperty (t, _propertyName))
                return t.getProperty (ctx, o, _propertyName);
            
            final Collection<Object> result = (o instanceof List) ? new ArrayList<Object> () : new HashSet<Object> ();

            for (Object obj: (Collection<?>) o)
                result.add (ctx.getTypesystem().findType(obj).getProperty(ctx, obj, _propertyName));

            return result;
        }
        else
            return t.getProperty (ctx, o, _propertyName);
    }

    private boolean isProperty (BackendType t, String propName) {
        return t.getProperties().containsKey (propName);
    }
}