/*
 * Copyright (c) 2016 Couchbase, Inc.
 *
 * Licensed 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 com.couchbase.client.core.metrics;

import java.util.concurrent.TimeUnit;

/**
 * The default configuration for the latency metrics collectors.
 *
 * @author Michael Nitschinger
 * @since 1.2.0
 */
public class DefaultLatencyMetricsCollectorConfig
    extends DefaultMetricsCollectorConfig
    implements LatencyMetricsCollectorConfig {

    public static final TimeUnit TARGET_UNIT = TimeUnit.MICROSECONDS;
    public static final Double[] TARGET_PERCENTILES = new Double[] { 50.0, 90.0, 95.0, 99.0, 99.9 };

    private final TimeUnit targetUnit;
    private final Double[] targetPercentiles;

    public static DefaultLatencyMetricsCollectorConfig disabled() {
        return create(0, TimeUnit.SECONDS);
    }

    public static DefaultLatencyMetricsCollectorConfig create() {
        return new DefaultLatencyMetricsCollectorConfig(builder());
    }

    public static DefaultLatencyMetricsCollectorConfig create(long emitFrequency, TimeUnit emitFrequencyUnit) {
        Builder builder = builder();
        builder.emitFrequency(emitFrequency);
        builder.emitFrequencyUnit(emitFrequencyUnit);
        return builder.build();
    }

    public static Builder builder() {
        return new Builder();
    }

    private DefaultLatencyMetricsCollectorConfig(Builder builder) {
        super(builder);

        this.targetUnit = builder.targetUnit;
        this.targetPercentiles = builder.targetPercentiles;
    }

    @Override
    public TimeUnit targetUnit() {
        return targetUnit;
    }

    @Override
    public Double[] targetPercentiles() {
        return targetPercentiles;
    }

    public static class Builder extends DefaultMetricsCollectorConfig.Builder {

        private TimeUnit targetUnit = TARGET_UNIT;
        private Double[] targetPercentiles = TARGET_PERCENTILES;

        protected Builder() {
        }

        /**
         * Overrides the target unit for the latencies recorded.
         *
         * Note that latencies are always recorded with nanosecond precision, but are converted before the
         * event is emitted based on the time unit provided here.
         *
         * @param targetUnit the target unit.
         */
        public Builder targetUnit(TimeUnit targetUnit) {
            this.targetUnit = targetUnit;
            return this;
        }

        /**
         * Overrides the emitted percentiles.
         *
         * Note that all kinds of percentiles between 0.1 and 99.999* can be provided, since all values are recorded
         * as part of the internal histogram.
         *
         * @param targetPercentiles the percentiles which should be emitted.
         */
        public Builder targetPercentiles(Double[] targetPercentiles) {
            this.targetPercentiles = targetPercentiles;
            return this;
        }

        @Override
        public Builder emitFrequency(long emitFrequency) {
            super.emitFrequency(emitFrequency);
            return this;
        }

        @Override
        public Builder emitFrequencyUnit(TimeUnit emitFrequencyUnit) {
            super.emitFrequencyUnit(emitFrequencyUnit);
            return this;
        }

        public DefaultLatencyMetricsCollectorConfig build() {
            return new DefaultLatencyMetricsCollectorConfig(this);
        }
    }

}