001// --------------------------------------------------------------------------------
002// Copyright 2002-2025 Echo Three, LLC
003//
004// Licensed under the Apache License, Version 2.0 (the "License");
005// you may not use this file except in compliance with the License.
006// You may obtain a copy of the License at
007//
008//     http://www.apache.org/licenses/LICENSE-2.0
009//
010// Unless required by applicable law or agreed to in writing, software
011// distributed under the License is distributed on an "AS IS" BASIS,
012// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013// See the License for the specific language governing permissions and
014// limitations under the License.
015// --------------------------------------------------------------------------------
016
017package com.echothree.model.control.item.server.logic.checksum;
018
019import com.echothree.util.common.message.ExecutionErrors;
020import com.echothree.util.server.message.ExecutionErrorAccumulator;
021import javax.enterprise.context.ApplicationScoped;
022import javax.enterprise.inject.spi.CDI;
023
024@ApplicationScoped
025public class Isbn10ChecksumLogic
026        extends BaseChecksumLogic
027        implements ItemAliasChecksumInterface {
028
029    protected Isbn10ChecksumLogic() {
030        super();
031    }
032
033    public static Isbn10ChecksumLogic getInstance() {
034        return CDI.current().select(Isbn10ChecksumLogic.class).get();
035    }
036
037    private int getIsbn10CheckDigit(String alias, int offset) {
038        var result = -1;
039        var digit = alias.charAt(offset);
040
041        if(digit >= '0' && digit <= '9') {
042            result = digit - '0';
043        } else if(digit == 'X') {
044            result = 10;
045        }
046
047        return result;
048    }
049
050    @Override
051    public void checkChecksum(final ExecutionErrorAccumulator eea, final String alias) {
052        if(alias.length() == 10) {
053            var hasCharacterError = false;
054            var runningTotal = 0;
055            var checksum = 0;
056
057            for(var i = 0; i < 9; i++) {
058                var digit = getDigit(alias, i);
059
060                if(digit == -1) {
061                    hasCharacterError = true;
062                    break;
063                } else {
064                    runningTotal += digit;
065                    checksum += runningTotal;
066                }
067            }
068
069            if(!hasCharacterError) {
070                var checkDigit = getIsbn10CheckDigit(alias, 9);
071
072                hasCharacterError = checkDigit == -1;
073
074                if(!hasCharacterError) {
075                    runningTotal += checkDigit;
076                    checksum += runningTotal;
077
078                    if(checksum % 11 != 0) {
079                        eea.addExecutionError(ExecutionErrors.IncorrectIsbn10Checksum.name(), alias);
080                    }
081                }
082            }
083
084            if(hasCharacterError) {
085                eea.addExecutionError(ExecutionErrors.IncorrectIsbn10Character.name(), alias);
086            }
087        } else {
088            eea.addExecutionError(ExecutionErrors.IncorrectIsbn10Length.name(), alias);
089        }
090    }
091
092}