001package ca.uhn.fhir.jpa.model.util;
002
003/*-
004 * #%L
005 * HAPI FHIR JPA Model
006 * %%
007 * Copyright (C) 2014 - 2022 Smile CDR, Inc.
008 * %%
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *      http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 * #L%
021 */
022
023import ca.uhn.fhir.util.UrlUtil;
024import com.google.common.base.Charsets;
025import com.google.common.hash.HashCode;
026import com.google.common.hash.HashFunction;
027import com.google.common.hash.Hasher;
028import com.google.common.hash.Hashing;
029
030public class CodeSystemHash {
031    private static final HashFunction HASH_FUNCTION = Hashing.murmur3_128(0);
032    private static final byte[] DELIMITER_BYTES = "|".getBytes(Charsets.UTF_8);
033
034    static public long hashCodeSystem( String system, String code ) {
035        Hasher hasher = HASH_FUNCTION.newHasher();
036        addStringToHasher(hasher, system);
037        addStringToHasher(hasher, code);
038
039        HashCode hashCode = hasher.hash();
040        return hashCode.asLong();
041    }
042
043    static private void addStringToHasher(Hasher hasher, String next) {
044        if (next == null) {
045            hasher.putByte((byte) 0);
046        } else {
047            next = UrlUtil.escapeUrlParam(next);
048            byte[] bytes = next.getBytes(Charsets.UTF_8);
049            hasher.putBytes(bytes);
050        }
051        hasher.putBytes(DELIMITER_BYTES);
052    }
053}