/**
 * Copyright (C) 2009-2013 FoundationDB, LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.foundationdb.server.types.mcompat.mfuncs;

import com.foundationdb.server.types.*;
import com.foundationdb.server.types.value.ValueSource;
import com.foundationdb.server.types.value.ValueTarget;
import com.foundationdb.server.types.texpressions.TInputSetBuilder;
import com.foundationdb.server.types.texpressions.TScalarBase;

public class MLog extends TScalarBase
{
    private final TClass argType;
    public MLog(TClass argType)
    {
        this.argType = argType;
    }
    
    @Override
    protected void buildInputSets(TInputSetBuilder builder)
    {
        builder.covers(argType, 0, 1);
    }

    @Override
    protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output)
    {
        double base = inputs.get(0).getDouble();
        double value = inputs.get(1).getDouble();
        if (0 < value && 0 < base && 1 != base)
            output.putDouble(Math.log(value)/Math.log(base));
        else
            output.putNull();
    }

    @Override
    public String displayName()
    {
        return "LOG";
    }

    @Override
    public TOverloadResult resultType()
    {
        return TOverloadResult.fixed(argType);
    }
}