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/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.script.expression;

import org.apache.lucene.search.DoubleValuesSource;
import org.opensearch.index.fielddata.IndexFieldData;
import org.opensearch.search.MultiValueMode;

/**
 * Expressions API for numeric fields.
 */
final class NumericField {
    // no instance
    private NumericField() {}

    // supported variables
    static final String VALUE_VARIABLE = "value";
    static final String EMPTY_VARIABLE = "empty";
    static final String LENGTH_VARIABLE = "length";

    // supported methods
    static final String GETVALUE_METHOD = "getValue";
    static final String ISEMPTY_METHOD = "isEmpty";
    static final String SIZE_METHOD = "size";
    static final String MINIMUM_METHOD = "min";
    static final String MAXIMUM_METHOD = "max";
    static final String AVERAGE_METHOD = "avg";
    static final String MEDIAN_METHOD = "median";
    static final String SUM_METHOD = "sum";
    static final String COUNT_METHOD = "count";

    static DoubleValuesSource getVariable(IndexFieldData fieldData, String fieldName, String variable) {
        switch (variable) {
            case VALUE_VARIABLE:
                return new FieldDataValueSource(fieldData, MultiValueMode.MIN);
            case EMPTY_VARIABLE:
                return new EmptyMemberValueSource(fieldData);
            case LENGTH_VARIABLE:
                return new CountMethodValueSource(fieldData);
            default:
                throw new IllegalArgumentException(
                    "Member variable [" + variable + "] does not exist for " + "numeric field [" + fieldName + "]."
                );
        }
    }

    static DoubleValuesSource getMethod(IndexFieldData fieldData, String fieldName, String method) {
        switch (method) {
            case GETVALUE_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.MIN);
            case ISEMPTY_METHOD:
                return new EmptyMemberValueSource(fieldData);
            case SIZE_METHOD:
                return new CountMethodValueSource(fieldData);
            case MINIMUM_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.MIN);
            case MAXIMUM_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.MAX);
            case AVERAGE_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.AVG);
            case MEDIAN_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.MEDIAN);
            case SUM_METHOD:
                return new FieldDataValueSource(fieldData, MultiValueMode.SUM);
            case COUNT_METHOD:
                return new CountMethodValueSource(fieldData);
            default:
                throw new IllegalArgumentException("Member method [" + method + "] does not exist for numeric field [" + fieldName + "].");
        }
    }
}