/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.hc.client5.http.impl;

import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

import org.apache.hc.core5.annotation.Contract;
import org.apache.hc.core5.annotation.ThreadingBehavior;
import org.apache.hc.core5.concurrent.DefaultThreadFactory;
import org.apache.hc.core5.pool.ConnPoolControl;
import org.apache.hc.core5.util.Args;
import org.apache.hc.core5.util.TimeValue;
import org.apache.hc.core5.util.Timeout;

/**
 * This class maintains a background thread to enforce an eviction policy for expired / idle
 * persistent connections kept alive in the connection pool.
 *
 * @since 4.4
 */
@Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
public final class IdleConnectionEvictor {

    private static final TimeValue ONE_SECOND = TimeValue.ofSeconds(1L);
    private static final TimeValue ONE_MINUTE = TimeValue.ofMinutes(1L);

    private final ThreadFactory threadFactory;
    private final Thread thread;

    public IdleConnectionEvictor(final ConnPoolControl<?> connectionManager, final ThreadFactory threadFactory,
                                 final TimeValue sleepTime, final TimeValue maxIdleTime) {
        Args.notNull(connectionManager, "Connection manager");
        this.threadFactory = threadFactory != null ? threadFactory : new DefaultThreadFactory("idle-connection-evictor", true);
        final TimeValue localSleepTime = sleepTime != null ? sleepTime : calculateSleepTime(maxIdleTime);
        this.thread = this.threadFactory.newThread(() -> {
            try {
                while (!Thread.currentThread().isInterrupted()) {
                    localSleepTime.sleep();
                    connectionManager.closeExpired();
                    if (maxIdleTime != null) {
                        connectionManager.closeIdle(maxIdleTime);
                    }
                }
            } catch (final InterruptedException ex) {
                Thread.currentThread().interrupt();
            } catch (final Exception ignore) {
            }

        });
    }

    public IdleConnectionEvictor(final ConnPoolControl<?> connectionManager, final TimeValue sleepTime, final TimeValue maxIdleTime) {
        this(connectionManager, null, sleepTime, maxIdleTime);
    }

    public IdleConnectionEvictor(final ConnPoolControl<?> connectionManager, final TimeValue maxIdleTime) {
        this(connectionManager, null, null, maxIdleTime);
    }

    public void start() {
        thread.start();
    }

    public void shutdown() {
        thread.interrupt();
    }

    public boolean isRunning() {
        return thread.isAlive();
    }

    public void awaitTermination(final Timeout timeout) throws InterruptedException {
        thread.join(timeout != null ? timeout.toMilliseconds() : Long.MAX_VALUE);
    }

    static TimeValue calculateSleepTime(final TimeValue maxIdleTime) {
        if (maxIdleTime == null) {
            return ONE_MINUTE;
        } else {
            final TimeValue sleepTime = maxIdleTime.divide(10, TimeUnit.NANOSECONDS);
            return sleepTime.compareTo(ONE_SECOND) < 0 ? ONE_SECOND : sleepTime;
        }
    }

}
