001/*-
002 * #%L
003 * HAPI FHIR JPA Model
004 * %%
005 * Copyright (C) 2014 - 2025 Smile CDR, Inc.
006 * %%
007 * Licensed under the Apache License, Version 2.0 (the "License");
008 * you may not use this file except in compliance with the License.
009 * You may obtain a copy of the License at
010 *
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 * #L%
019 */
020package ca.uhn.fhir.jpa.model.util;
021
022import ca.uhn.fhir.util.UrlUtil;
023import com.google.common.base.Charsets;
024import com.google.common.hash.HashCode;
025import com.google.common.hash.HashFunction;
026import com.google.common.hash.Hasher;
027import com.google.common.hash.Hashing;
028
029public class CodeSystemHash {
030        private static final HashFunction HASH_FUNCTION = Hashing.murmur3_128(0);
031        private static final byte[] DELIMITER_BYTES = "|".getBytes(Charsets.UTF_8);
032
033        public static long hashCodeSystem(String system, String code) {
034                Hasher hasher = HASH_FUNCTION.newHasher();
035                addStringToHasher(hasher, system);
036                addStringToHasher(hasher, code);
037
038                HashCode hashCode = hasher.hash();
039                return hashCode.asLong();
040        }
041
042        private static void addStringToHasher(Hasher hasher, String next) {
043                if (next == null) {
044                        hasher.putByte((byte) 0);
045                } else {
046                        next = UrlUtil.escapeUrlParam(next);
047                        byte[] bytes = next.getBytes(Charsets.UTF_8);
048                        hasher.putBytes(bytes);
049                }
050                hasher.putBytes(DELIMITER_BYTES);
051        }
052}