/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed 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.kie.dmn.feel.runtime.functions;

import org.kie.dmn.api.feel.runtime.events.FEELEvent;
import org.kie.dmn.api.feel.runtime.events.FEELEvent.Severity;
import org.kie.dmn.feel.runtime.events.InvalidParametersEvent;
import org.kie.dmn.feel.runtime.functions.FEELFnResult;

public class SubstringAfterFunction
        extends BaseFEELFunction {

    public SubstringAfterFunction() {
        super( "substring after" );
    }

    public FEELFnResult<String> invoke(@ParameterName( "string" ) String string, @ParameterName( "match" ) String match) {
        if ( string == null ) {
            return FEELFnResult.ofError(new InvalidParametersEvent(Severity.ERROR, "string", "cannot be null"));
        }
        if ( match == null ) {
            return FEELFnResult.ofError(new InvalidParametersEvent(Severity.ERROR, "match", "cannot be null"));
        }
        
        int index = string.indexOf( match );
        if( index >= 0 ) {
            return FEELFnResult.ofResult( string.substring( index+match.length() ) );
        } else if( index < 0 ) {
            return FEELFnResult.ofResult( string );
        }
        
        // unreachable code.
        return FEELFnResult.ofError(new InvalidParametersEvent(Severity.ERROR, "was an unreachable condition for this function"));
    }

}