/*
 * 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
 *
 *     http://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.
 */

package org.apache.jena.sparql.expr;

import java.util.ArrayList;
import java.util.List;
import org.apache.jena.sparql.engine.binding.Binding;
import org.apache.jena.sparql.function.FunctionEnv;
import org.apache.jena.sparql.graph.NodeTransform;

/** A function which takes N arguments (N may be variable e.g. regex) */

public abstract class ExprFunctionN extends ExprFunction
{
    protected ExprList args = null;

    protected ExprFunctionN(String fName, Expr...args) {
        this(fName, argList(args));
    }

    protected ExprFunctionN(String fName, ExprList args) {
        super(fName);
        this.args = args;
    }

    private static ExprList argList(Expr[] args) {
        ExprList exprList = new ExprList();
        for ( Expr e : args )
            if ( e != null )
                exprList.add(e);
        return exprList;
    }

    @Override
    public Expr getArg(int i) {
        i = i-1;
        if ( i >= args.size() )
            return null;
        return args.get(i);
    }

    @Override
    public int numArgs() { return args.size(); }

    @Override
    public List<Expr> getArgs() { return args.getList(); }

    @Override
    public Expr copySubstitute(Binding binding) {
        ExprList newArgs = new ExprList();
        for ( int i = 1; i <= numArgs(); i++ )
        {
            Expr e = getArg(i);
            e = e.copySubstitute(binding);
            newArgs.add(e);
        }
        return copy(newArgs);
    }

    @Override
    public Expr applyNodeTransform(NodeTransform transform) {
        ExprList newArgs = new ExprList();
        for ( int i = 1 ; i <= numArgs() ; i++ ) {
            Expr e = getArg(i);
            e = e.applyNodeTransform(transform);
            newArgs.add(e);
        }
        return copy(newArgs);
    }

    /** Special form evaluation (example, don't eval the arguments first) */
    protected NodeValue evalSpecial(Binding binding, FunctionEnv env) { return null; }

    @Override
    final public NodeValue eval(Binding binding, FunctionEnv env) {
        NodeValue s = evalSpecial(binding, env);
        if ( s != null )
            return s;

        List<NodeValue> argsEval = new ArrayList<>();
        for ( int i = 1 ; i <= numArgs() ; i++ ) {
            NodeValue x = eval(binding, env, getArg(i));
            argsEval.add(x);
        }
        return eval(argsEval, env);
    }

    public NodeValue eval(List<NodeValue> args, FunctionEnv env) { return eval(args); }

    public abstract NodeValue eval(List<NodeValue> args);

    public abstract Expr copy(ExprList newArgs);

    @Override
    public void visit(ExprVisitor visitor) { visitor.visit(this); }
    public Expr apply(ExprTransform transform, ExprList exprList) { return transform.transform(this, exprList); }

}
