/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.pulsar.broker.stats.prometheus.metrics;

import com.google.common.base.Joiner;
import io.prometheus.client.Collector;
import org.apache.bookkeeper.stats.Counter;
import org.apache.bookkeeper.stats.Gauge;
import org.apache.bookkeeper.stats.OpStatsLogger;
import org.apache.bookkeeper.stats.StatsLogger;
import org.apache.bookkeeper.stats.prometheus.LongAdderCounter;

/**
 * A {@code Prometheus} based {@link StatsLogger} implementation.
 */
public class PrometheusStatsLogger implements StatsLogger {

    private final PrometheusMetricsProvider provider;
    private final String scope;

    PrometheusStatsLogger(PrometheusMetricsProvider provider, String scope) {
        this.provider = provider;
        this.scope = scope;
    }

    @Override
    public OpStatsLogger getOpStatsLogger(String name) {
        return provider.opStats.computeIfAbsent(completeName(name), x -> new DataSketchesOpStatsLogger());
    }

    @Override
    public Counter getCounter(String name) {
        return provider.counters.computeIfAbsent(completeName(name), x -> new LongAdderCounter());
    }

    @Override
    public <T extends Number> void registerGauge(String name, Gauge<T> gauge) {
        provider.gauges.computeIfAbsent(completeName(name), x -> new SimpleGauge<T>(gauge));
    }

    @Override
    public <T extends Number> void unregisterGauge(String name, Gauge<T> gauge) {
        // no-op
    }

    @Override
    public void removeScope(String name, StatsLogger statsLogger) {
        // no-op
    }

    @Override
    public StatsLogger scope(String name) {
        return new PrometheusStatsLogger(provider, completeName(name));
    }

    private String completeName(String name) {
        String completeName = scope.isEmpty() ? name : Joiner.on('_').join(scope, name);
        return Collector.sanitizeMetricName(completeName);
    }
}
