/*
 * 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.Severity;
import org.kie.dmn.feel.runtime.events.InvalidParametersEvent;

public class SubstringFunction
        extends BaseFEELFunction {

    public SubstringFunction() {
        super( "substring" );
    }

    public FEELFnResult<String> invoke(@ParameterName("string") String string, @ParameterName("start position") Number start) {
        if ( string == null ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "string", "cannot be null" ) );
        }
        if ( start == null ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "start position", "cannot be null" ) );
        }
        if ( Math.abs( start.intValue() ) > string.length() ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "parameter 'start position' inconsistent with parameter 'string' length" ) );
        }

        if ( start.intValue() > 0 ) {
            return FEELFnResult.ofResult( string.substring( start.intValue() - 1 ) );
        } else if ( start.intValue() < 0 ) {
            return FEELFnResult.ofResult( string.substring( string.length() + start.intValue() ) );
        } else {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "start position", "cannot be zero" ) );
        }
    }

    public FEELFnResult<String> invoke(@ParameterName("string") String string, @ParameterName("start position") Number start, @ParameterName("length") Number length) {
        if ( string == null ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "string", "cannot be null" ) );
        }
        if ( start == null ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "start position", "cannot be null" ) );
        }
        if ( Math.abs( start.intValue() ) > string.length() ) {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "parameter 'start position' inconsistent with parameter 'string' length" ) );
        }

        if ( start.intValue() > 0 ) {
            return FEELFnResult.ofResult( string.substring( start.intValue() - 1, Math.min( string.length(), start.intValue() + length.intValue() - 1 ) ) );
        } else if ( start.intValue() < 0 ) {
            return FEELFnResult.ofResult( string.substring( string.length() + start.intValue(), Math.min( string.length(), string.length() + start.intValue() + length.intValue() ) ) );
        } else {
            return FEELFnResult.ofError( new InvalidParametersEvent( Severity.ERROR, "start position", "cannot be zero" ) );
        }
    }
}