/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the "Elastic License
 * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
 * Public License v 1"; you may not use this file except in compliance with, at
 * your election, the "Elastic License 2.0", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.rest.action.search;

import org.elasticsearch.telemetry.metric.LongCounter;
import org.elasticsearch.telemetry.metric.LongHistogram;
import org.elasticsearch.telemetry.metric.MeterRegistry;

import java.util.Map;

/**
 * Container class for aggregated metrics about search responses.
 */
public class SearchResponseMetrics {

    public enum ResponseCountTotalStatus {
        SUCCESS("success"),
        PARTIAL_FAILURE("partial_failure"),
        FAILURE("failure");

        private final String displayName;

        ResponseCountTotalStatus(String displayName) {
            this.displayName = displayName;
        }

        public String getDisplayName() {
            return displayName;
        }
    }

    public static final String RESPONSE_COUNT_TOTAL_STATUS_ATTRIBUTE_NAME = "response_status";

    public static final String TOOK_DURATION_TOTAL_HISTOGRAM_NAME = "es.search_response.took_durations.histogram";
    public static final String RESPONSE_COUNT_TOTAL_COUNTER_NAME = "es.search_response.response_count.total";

    private final LongHistogram tookDurationTotalMillisHistogram;
    private final LongCounter responseCountTotalCounter;

    public SearchResponseMetrics(MeterRegistry meterRegistry) {
        this(
            meterRegistry.registerLongHistogram(
                TOOK_DURATION_TOTAL_HISTOGRAM_NAME,
                "The SearchResponse.took durations in milliseconds, expressed as a histogram",
                "millis"
            ),
            meterRegistry.registerLongCounter(
                RESPONSE_COUNT_TOTAL_COUNTER_NAME,
                "The cumulative total of search responses with an attribute to describe "
                    + "success, partial failure, or failure, expressed as a single total counter and individual "
                    + "attribute counters",
                "count"
            )
        );
    }

    private SearchResponseMetrics(LongHistogram tookDurationTotalMillisHistogram, LongCounter responseCountTotalCounter) {
        this.tookDurationTotalMillisHistogram = tookDurationTotalMillisHistogram;
        this.responseCountTotalCounter = responseCountTotalCounter;
    }

    public long recordTookTime(long tookTime) {
        tookDurationTotalMillisHistogram.record(tookTime);
        return tookTime;
    }

    public void incrementResponseCount(ResponseCountTotalStatus responseCountTotalStatus) {
        responseCountTotalCounter.incrementBy(
            1L,
            Map.of(RESPONSE_COUNT_TOTAL_STATUS_ATTRIBUTE_NAME, responseCountTotalStatus.getDisplayName())
        );
    }
}