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Elasticsearch Java API Client
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/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. licenses this file to you 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 co.elastic.clients.json;

import jakarta.json.stream.JsonGenerator;
import jakarta.json.stream.JsonParser;
import jakarta.json.stream.JsonParsingException;

import javax.annotation.Nullable;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Map;
import java.util.NoSuchElementException;

/**
 * Base interface for enumerations in API types. Members have a JSON representation and also accept
 * aliases when parsed from a string value.
 */
public interface JsonEnum extends JsonpSerializable {
    String jsonValue();

    @Nullable
    default String[] aliases() {
        return null;
    }

    @Override
    default void serialize(JsonGenerator generator, JsonpMapper params) {
        generator.write(jsonValue());
    }

    class Deserializer extends JsonpDeserializerBase {
        private final Map lookupTable;

        public Deserializer(T[] values) {
            super(
                EnumSet.of(JsonParser.Event.VALUE_STRING, JsonParser.Event.KEY_NAME),
                EnumSet.of(JsonParser.Event.VALUE_STRING)
            );

            // Use the same size calculation as in java.lang.Enum.enumConstantDirectory
            this.lookupTable = new HashMap<>((int)(values.length / 0.75f) + 1);
            for (T member : values) {
                this.lookupTable.put(member.jsonValue(), member);
                String[] aliases = member.aliases();
                if (aliases != null) {
                    for (String alias: aliases) {
                        this.lookupTable.put(alias, member);
                    }
                }
            }
        }

        @Override
        public T deserialize(JsonParser parser, JsonpMapper mapper, JsonParser.Event event) {
            String value = parser.getString();
            return deserialize(value, parser);
        }

        /**
         * Get the enum member for a JSON string value
         *
         * @param value the JSON value
         * @param parser parsing context
         * @return the enum member
         * @throws JsonParsingException if no matching enum was found
         */
        public T deserialize(String value, JsonParser parser) {
            T result = this.lookupTable.get(value);
            if (result == null) {
                throw new JsonpMappingException("Invalid enum '" + value + "'", parser.getLocation());
            }
            return result;
        }

        /**
         * Get the enum member for a JSON string value
         *
         * @param value the JSON value
         * @return the enum member
         * @throws IllegalArgumentException if no matching enum was found
         */
        public T parse(String value) {
            T result = this.lookupTable.get(value);
            if (result == null) {
                throw new NoSuchElementException("Invalid enum '" + value + "'");
            }
            return result;
        }
    }
}