/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.sparql.expr.aggregate;

import org.apache.jena.atlas.logging.Log;
import org.apache.jena.graph.Node;
import org.apache.jena.sparql.engine.binding.Binding;
import org.apache.jena.sparql.expr.Expr;
import org.apache.jena.sparql.expr.ExprList;
import org.apache.jena.sparql.expr.NodeValue;
import org.apache.jena.sparql.function.FunctionEnv;
import org.apache.jena.sparql.graph.NodeConst;
import org.apache.jena.sparql.serializer.SerializationContext;

public class AggCount extends AggregatorBase
{
    // ---- COUNT(*)

    public AggCount() { super("COUNT", false, (ExprList)null); }
    @Override
    public Aggregator copy(ExprList expr)
    { 
        if ( expr != null )
            Log.warn(this, "Copying non-null expression for COUNT(*)");
        return new AggCount(); }

    @Override
    public Expr getExpr()       { return null; }
    
    @Override
    public Accumulator createAccumulator()
    { 
        return new AggCount.AccCount();
    }

    @Override
    public String asSparqlExpr(SerializationContext sCxt)       { return "count(*)"; }
    @Override
    public String toString()        { return "count(*)"; }
    @Override
    public String toPrefixString()  { return "(count)"; }

    @Override
    public Node getValueEmpty()     { return NodeConst.nodeZero; } 
    
    @Override
    public int hashCode()   { return HC_AggCount; }

    @Override
    public boolean equals(Aggregator other, boolean bySyntax) {
        if ( other == null ) return false;
        if ( this == other ) return true;
        if ( ! ( other instanceof AggCount ) ) return false;
        return true;
    }

    static class AccCount implements Accumulator
    {
        private long count = 0;
        public AccCount()   { }
        @Override
        public void accumulate(Binding binding, FunctionEnv functionEnv)
        { count++; }
        // Errors can't occur.
        @Override
        public NodeValue getValue()             { return NodeValue.makeInteger(count); }
    }
}
