/*
 * 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 com.epam.dlab.backendapi.domain;

import com.epam.dlab.backendapi.resources.dto.LibraryAutoCompleteDTO;
import com.epam.dlab.backendapi.resources.dto.LibraryDTO;
import com.epam.dlab.exceptions.DlabException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.MoreObjects;
import io.dropwizard.util.Duration;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.stream.Collectors;

/**
 * Class to store the info about libraries.
 */
@Slf4j
public class ExploratoryLibList {

	/**
	 * Timeout in milliseconds when the info is out of date.
	 */
	private static final long EXPIRED_TIMEOUT_MILLIS = Duration.hours(2).toMilliseconds();

	/**
	 * Timeout in milliseconds until the is out of date.
	 */
	private static final long UPDATE_TIMEOUT_MILLIS = Duration.minutes(30).toMilliseconds();

	/**
	 * Timeout in milliseconds for request to update lib.
	 */
	protected static final long UPDATE_REQUEST_TIMEOUT_MILLIS = Duration.minutes(15).toMilliseconds();

	/**
	 * Group name.
	 */
	private String group;

	/**
	 * List of libraries group:libraries:version.
	 */
	private Map<String, Map<String, String>> libs = new HashMap<>();

	/**
	 * Time in milliseconds when the info is out of date.
	 */
	private long expiredTimeMillis = 0;

	/**
	 * Last access time in milliseconds to the info.
	 */
	private long accessTimeMillis = 0;

	/**
	 * Update start time in milliseconds.
	 */
	private long updateStartTimeMillis = 0;

	/**
	 * Update in progress.
	 */
	private boolean updating = false;


	/**
	 * Instantiate the list of libraries.
	 *
	 * @param group   the name of docker's image.
	 * @param content JSON string.
	 */
	ExploratoryLibList(String group, String content) {
		this.group = group;
		if (content != null) {
			setLibs(content);
		}
	}

	/**
	 * Return the list of all groups.
	 */
	public List<String> getGroupList() {
		List<String> list = new ArrayList<>(libs.keySet());
		Collections.sort(list);
		return list;
	}

	/**
	 * Return the name of docker image;
	 */
	public String getGroup() {
		return group;
	}

	/**
	 * Return the full list of libraries for group.
	 *
	 * @param group the name of group.
	 */
	public Map<String, String> getLibs(String group) {
		return libs.get(group);
	}

	/**
	 * Return the full list of libraries for group.
	 *
	 * @param content JSON string.
	 */
	private void setLibs(String content) {
		ObjectMapper mapper = new ObjectMapper();
		try {
			synchronized (this) {
				@SuppressWarnings("unchecked")
				Map<String, Map<String, String>> map = mapper.readValue(content, Map.class);
				for (Map.Entry<String, Map<String, String>> entry : map.entrySet()) {
					Map<String, String> group = entry.getValue();
					String groupName = entry.getKey();
					libs.remove(groupName);
					log.info("Update {} group with lib group {} with {} libraries", this.group, groupName, (group != null) ? group.size() : null);
					libs.put(groupName, new TreeMap<>(group));
				}
				setExpiredTime();
				updating = false;
			}
		} catch (IOException e) {
			throw new DlabException("Cannot deserialize the list of libraries. " + e.getLocalizedMessage(), e);
		}
	}

	public void setExpiredTime() {
		expiredTimeMillis = System.currentTimeMillis() + EXPIRED_TIMEOUT_MILLIS;
		accessTimeMillis = System.currentTimeMillis();
	}

	/**
	 * Search and return the list of libraries for name's prefix <b>startWith</b>.
	 *
	 * @param group     the name of group.
	 * @param startWith the prefix for library name.
	 * @return LibraryAutoCompleteDTO dto
	 */
	public LibraryAutoCompleteDTO getLibs(String group, String startWith) {
		final String startsWithLower = startWith.toLowerCase();
		Map<String, String> libMap = getLibs(group);
		if (libMap == null) {
			return LibraryAutoCompleteDTO.builder()
					.autoComplete(isUpdating() ? AutoCompleteEnum.UPDATING : AutoCompleteEnum.NONE)
					.libraries(Collections.emptyList())
					.build();
		}
		List<LibraryDTO> libraries = libMap.entrySet()
				.stream()
				.filter(e -> e.getKey().toLowerCase().startsWith(startsWithLower))
				.map(e -> new LibraryDTO(e.getKey(), e.getValue()))
				.collect(Collectors.toList());

		return LibraryAutoCompleteDTO.builder()
				.autoComplete(AutoCompleteEnum.ENABLED)
				.libraries(libraries)
				.build();
	}

	/**
	 * Set last access time.
	 */
	private void touch() {
		accessTimeMillis = System.currentTimeMillis();
	}

	/**
	 * Return <b>true</b> if the info is out of date.
	 */
	public boolean isExpired() {
		touch();
		return (expiredTimeMillis < System.currentTimeMillis());
	}

	/**
	 * Return <b>true</b> if the info needs to update.
	 */
	public boolean isUpdateNeeded() {
		touch();
		return (accessTimeMillis > expiredTimeMillis - UPDATE_TIMEOUT_MILLIS);
	}

	/**
	 * Set updating in progress.
	 */
	public void setUpdating() {
		updateStartTimeMillis = System.currentTimeMillis();
		updating = true;
	}

	/**
	 * Set updating to false.
	 */
	public void setNotUpdating() {
		updating = Boolean.FALSE;
	}

	/**
	 * Return <b>true</b> if the update in progress.
	 */
	public boolean isUpdating() {
		if (updating &&
				updateStartTimeMillis + UPDATE_REQUEST_TIMEOUT_MILLIS < System.currentTimeMillis()) {
			updating = false;
		}
		return updating;
	}


	@Override
	public String toString() {
		return MoreObjects.toStringHelper(this)
				.add("group", group)
				.add("expiredTimeMillis", expiredTimeMillis)
				.add("accessTimeMillis", accessTimeMillis)
				.add("updateStartTimeMillis", updateStartTimeMillis)
				.add("isUpdating", updating)
				.add("libs", (libs == null ? "null" : "..."))
				.toString();
	}
}