/**
 * 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.explain.*;
import com.foundationdb.server.types.LazyList;
import com.foundationdb.server.types.TCustomOverloadResult;
import com.foundationdb.server.types.TExecutionContext;
import com.foundationdb.server.types.TInstance;
import com.foundationdb.server.types.TScalar;
import com.foundationdb.server.types.TOverloadResult;
import com.foundationdb.server.types.TPreptimeContext;
import com.foundationdb.server.types.TPreptimeValue;
import com.foundationdb.server.types.common.types.StringAttribute;
import com.foundationdb.server.types.mcompat.mtypes.MString;
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;
import com.foundationdb.server.types.texpressions.TPreparedExpression;

import java.util.List;

public class MConcat extends TScalarBase {
    public static final TScalar INSTANCE = new MConcat();
    
    private MConcat(){}
    
    @Override
    protected void buildInputSets(TInputSetBuilder builder) {
        builder.nextInputPicksWith(MString.VARCHAR.PICK_RIGHT_LENGTH).vararg(MString.VARCHAR, 0);
    }

    @Override
    protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < inputs.size(); ++i) {
            String inputStr = inputs.get(i).getString();
            assert inputStr != null;
            sb.append(inputStr);
        }
        output.putString(sb.toString(), null);
    }

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

    @Override
    public String[] registeredNames() {
        return new String[] { "concatenate", "concat" };
    }

    @Override
    public TOverloadResult resultType() {
        return TOverloadResult.custom(new TCustomOverloadResult() {
            @Override
            public TInstance resultInstance(List<TPreptimeValue> inputs, TPreptimeContext context) {
                int length = 0;
                for (TPreptimeValue ptv : inputs) {
                    length += ptv.type().attribute(StringAttribute.MAX_LENGTH);
                }
                return MString.VARCHAR.instance(length, anyContaminatingNulls(inputs));
            }
        });
    }

    @Override
    public CompoundExplainer getExplainer(ExplainContext context, List<? extends TPreparedExpression> inputs, TInstance resultType)
    {
        CompoundExplainer ex = super.getExplainer(context, inputs, resultType);
        ex.addAttribute(Label.INFIX_REPRESENTATION, PrimitiveExplainer.getInstance("||"));
        ex.addAttribute(Label.ASSOCIATIVE, PrimitiveExplainer.getInstance(true));
        return ex;
    }
}