/*
 * 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.flink.test.windowing.sessionwindows;

import org.apache.flink.util.Preconditions;

/**
 * Configuration data for a session
 *
 * @param <K> type of session key
 * @param <E> type of session event
 */
public final class SessionConfiguration<K, E> {

	// key of the session
	private final K key;

	// id of the session w.r.t. key
	private final int sessionId;

	// allowed gap between events in one session
	private final long gap;

	// minimum event time among all events in the session
	private final long minEventTimestamp;

	// number of timely events in the session
	private final int numberOfTimelyEvents;

	// factory that produces the events for the session from metadata such as timestamps
	private final GeneratorEventFactory<K, E> eventFactory;

	public SessionConfiguration(
			K key,
			int sessionId,
			long gap,
			long minEventTimestamp,
			int numberOfTimelyEvents,
			GeneratorEventFactory<K, E> eventFactory) {

		Preconditions.checkNotNull(key);
		Preconditions.checkNotNull(eventFactory);
		Preconditions.checkArgument(numberOfTimelyEvents > 0);
		Preconditions.checkArgument(gap > 0);

		this.key = key;
		this.eventFactory = eventFactory;
		this.sessionId = sessionId;
		this.gap = gap;
		this.numberOfTimelyEvents = numberOfTimelyEvents;
		this.minEventTimestamp = minEventTimestamp;
	}

	public K getKey() {
		return key;
	}

	public GeneratorEventFactory<K, E> getEventFactory() {
		return eventFactory;
	}

	public long getGap() {
		return gap;
	}

	public long getMinEventTimestamp() {
		return minEventTimestamp;
	}

	public int getNumberOfTimelyEvents() {
		return numberOfTimelyEvents;
	}

	public int getSessionId() {
		return sessionId;
	}

	public static <K, E> SessionConfiguration<K, E> of(
			K key,
			int sessionId,
			long timeout,
			long startTimestamp,
			int numberOfEvents,
			GeneratorEventFactory<K, E> eventFactory) {
		return new SessionConfiguration<>(key, sessionId, timeout, startTimestamp, numberOfEvents, eventFactory);
	}

	@Override
	public String toString() {
		return "SessionConfiguration{" +
				"key=" + key +
				", sessionId=" + sessionId +
				", gap=" + gap +
				", minEventTimestamp=" + minEventTimestamp +
				", numberOfTimelyEvents=" + numberOfTimelyEvents +
				", eventFactory=" + eventFactory +
				'}';
	}

	public SessionConfiguration<K, E> getFollowupSessionConfiguration(long startTimestamp) {
		return SessionConfiguration.of(
				getKey(),
				getSessionId() + 1,
				getGap(),
				startTimestamp,
				getNumberOfTimelyEvents(),
				getEventFactory());
	}
}