/*
 * Copyright (c) 2011-2019 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 * which is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 */

package io.vertx.core.dns;

import io.vertx.codegen.annotations.DataObject;
import io.vertx.core.buffer.Buffer;
import io.vertx.core.impl.AddressResolver;
import io.vertx.core.json.JsonObject;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

Configuration options for Vert.x hostname resolver. The resolver uses the local hosts file and performs
DNS A and AAAA queries.
Author:
Julien Viet/**
 * Configuration options for Vert.x hostname resolver. The resolver uses the local <i>hosts</i> file and performs
 * DNS <i>A</i> and <i>AAAA</i> queries.
 *
 * @author <a href="mailto:julien@julienviet.com">Julien Viet</a>
 */
@DataObject(generateConverter = true, publicConverter = false)
public class AddressResolverOptions {

  
The default list of DNS servers = null (uses system name server's list like resolve.conf otherwise Google Public DNS)
/**
   * The default list of DNS servers = null (uses system name server's list like resolve.conf otherwise Google Public DNS)
   */
  public static final List<String> DEFAULT_SERVERS = null;

  
The default value for setOptResourceEnabled = false /**
   * The default value for {@link #setOptResourceEnabled} = false
   */
  public static final boolean DEFAULT_OPT_RESOURCE_ENABLED = false;

  
The default value for the negative cache min TTL = 0
/**
   * The default value for the negative cache min TTL = 0
   */
  public static final int DEFAULT_CACHE_MIN_TIME_TO_LIVE = 0;

  
The default value for the negative cache max TTL = 0x7fffffff
/**
   * The default value for the negative cache max TTL = 0x7fffffff
   */
  public static final int DEFAULT_CACHE_MAX_TIME_TO_LIVE = Integer.MAX_VALUE;

  
The default value for the negative cache TTL = 0
/**
   * The default value for the negative cache TTL = 0
   */
  public static final int DEFAULT_CACHE_NEGATIVE_TIME_TO_LIVE = 0;

  
The default value for the query timeout in millis = 5000
/**
   * The default value for the query timeout in millis = 5000
   */
  public static final int DEFAULT_QUERY_TIMEOUT = 5000;

  
The default value for the max dns queries per query = 4
/**
   * The default value for the max dns queries per query = 4
   */
  public static final int DEFAULT_MAX_QUERIES = 4;

  
The default value of the rd flag = true
/**
   * The default value of the rd flag = true
   */
  public static final boolean DEFAULT_RD_FLAG = true;

  
The default value of search domains = null
/**
   * The default value of search domains = null
   */
  public static final List<String> DEFAULT_SEACH_DOMAINS = null;

  
The default ndots value = loads the value from the OS on Linux otherwise use the value 1
/**
   * The default ndots value = loads the value from the OS on Linux otherwise use the value 1
   */
  public static final int DEFAULT_NDOTS = AddressResolver.DEFAULT_NDOTS_RESOLV_OPTION;

  
The default servers rotate value = loads the value from the OS on Linux otherwise use the value false
/**
   * The default servers rotate value = loads the value from the OS on Linux otherwise use the value false
   */
  public static final boolean DEFAULT_ROTATE_SERVERS = AddressResolver.DEFAULT_ROTATE_RESOLV_OPTION;

  private String hostsPath;
  private Buffer hostsValue;
  private List<String> servers;
  private boolean optResourceEnabled;
  private int cacheMinTimeToLive;
  private int cacheMaxTimeToLive;
  private int cacheNegativeTimeToLive;
  private long queryTimeout;
  private int maxQueries;
  private boolean rdFlag;
  private List<String> searchDomains;
  private int ndots;
  private boolean rotateServers;

  public AddressResolverOptions() {
    servers = DEFAULT_SERVERS;
    optResourceEnabled = DEFAULT_OPT_RESOURCE_ENABLED;
    cacheMinTimeToLive = DEFAULT_CACHE_MIN_TIME_TO_LIVE;
    cacheMaxTimeToLive = DEFAULT_CACHE_MAX_TIME_TO_LIVE;
    cacheNegativeTimeToLive = DEFAULT_CACHE_NEGATIVE_TIME_TO_LIVE;
    queryTimeout = DEFAULT_QUERY_TIMEOUT;
    maxQueries = DEFAULT_MAX_QUERIES;
    rdFlag = DEFAULT_RD_FLAG;
    searchDomains = DEFAULT_SEACH_DOMAINS;
    ndots = DEFAULT_NDOTS;
    rotateServers = DEFAULT_ROTATE_SERVERS;
  }

  public AddressResolverOptions(AddressResolverOptions other) {
    this.hostsPath = other.hostsPath;
    this.hostsValue = other.hostsValue != null ? other.hostsValue.copy() : null;
    this.servers = other.servers != null ? new ArrayList<>(other.servers) : null;
    this.optResourceEnabled = other.optResourceEnabled;
    this.cacheMinTimeToLive = other.cacheMinTimeToLive;
    this.cacheMaxTimeToLive = other.cacheMaxTimeToLive;
    this.cacheNegativeTimeToLive = other.cacheNegativeTimeToLive;
    this.queryTimeout = other.queryTimeout;
    this.maxQueries = other.maxQueries;
    this.rdFlag = other.rdFlag;
    this.searchDomains = other.searchDomains != null ? new ArrayList<>(other.searchDomains) : null;
    this.ndots = other.ndots;
    this.rotateServers = other.rotateServers;
  }

  public AddressResolverOptions(JsonObject json) {
    this();
    AddressResolverOptionsConverter.fromJson(json, this);
  }

  
Returns:
the path to the alternate hosts configuration file/**
   * @return the path to the alternate hosts configuration file
   */
  public String getHostsPath() {
    return hostsPath;
  }

  
Set the path of an alternate hosts configuration file to use instead of the one provided by the os.

The default value is null, so the operating system hosts config is used.
Params:
hostsPath – the hosts path
Returns:
a reference to this, so the API can be used fluently/**
   * Set the path of an alternate hosts configuration file to use instead of the one provided by the os.
   * <p/>
   * The default value is null, so the operating system hosts config is used.
   *
   * @param hostsPath the hosts path
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setHostsPath(String hostsPath) {
    this.hostsPath = hostsPath;
    return this;
  }

  
Returns:
the hosts configuration file value/**
   * @return the hosts configuration file value
   */
  public Buffer getHostsValue() {
    return hostsValue;
  }

  
Set an alternate hosts configuration file to use instead of the one provided by the os.

The value should contain the hosts content literaly, for instance 127.0.0.1 localhost

The default value is null, so the operating system hosts config is used.
Params:
hostsValue – the hosts content
Returns:
a reference to this, so the API can be used fluently/**
   * Set an alternate hosts configuration file to use instead of the one provided by the os.
   * <p/>
   * The value should contain the hosts content literaly, for instance <i>127.0.0.1 localhost</i>
   * <p/>
   * The default value is null, so the operating system hosts config is used.
   *
   * @param hostsValue the hosts content
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setHostsValue(Buffer hostsValue) {
    this.hostsValue = hostsValue;
    return this;
  }

  
Returns:
the list of dns server/**
   * @return the list of dns server
   */
  public List<String> getServers() {
    return servers;
  }

  
Set the list of DNS server addresses, an address is the IP of the dns server, followed by an optional colon and a port, e.g 8.8.8.8 or {code 192.168.0.1:40000}. When the list is empty, the resolver will use the list of the system DNS server addresses from the environment, if that list cannot be retrieved it will use Google's public DNS servers "8.8.8.8" and "8.8.4.4". 
Params:
servers – the list of DNS servers
Returns:
a reference to this, so the API can be used fluently/**
   * Set the list of DNS server addresses, an address is the IP  of the dns server, followed by an optional
   * colon and a port, e.g {@code 8.8.8.8} or {code 192.168.0.1:40000}. When the list is empty, the resolver
   * will use the list of the system DNS server addresses from the environment, if that list cannot be retrieved
   * it will use Google's public DNS servers {@code "8.8.8.8"} and {@code "8.8.4.4"}.
   *
   * @param servers the list of DNS servers
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setServers(List<String> servers) {
    this.servers = servers;
    return this;
  }

  
Add a DNS server address.
Params:
server – the server to add
Returns:
a reference to this, so the API can be used fluently/**
   * Add a DNS server address.
   *
   * @param server the server to add
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions addServer(String server) {
    if (servers == null) {
      servers = new ArrayList<>();
    }
    servers.add(server);
    return this;
  }

  
Returns:
true if an optional record is automatically included in DNS queries/**
   * @return true if an optional record is automatically included in DNS queries
   */
  public boolean isOptResourceEnabled() {
    return optResourceEnabled;
  }

  
Set to true to enable the automatic inclusion in DNS queries of an optional record that hints
the remote DNS server about how much data the resolver can read per response.
Params:
optResourceEnabled – true to enable, false otherwise
Returns:
a reference to this, so the API can be used fluently/**
   * Set to true to enable the automatic inclusion in DNS queries of an optional record that hints
   * the remote DNS server about how much data the resolver can read per response.
   *
   * @param optResourceEnabled true to enable, false otherwise
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setOptResourceEnabled(boolean optResourceEnabled) {
    this.optResourceEnabled = optResourceEnabled;
    return this;
  }

  
Returns:
the cache min TTL in seconds/**
   * @return the cache min TTL in seconds
   */
  public int getCacheMinTimeToLive() {
    return cacheMinTimeToLive;
  }

  
Set the cache minimum TTL value in seconds. After resolution successful IP addresses are cached with their DNS response TTL,
use this to set a minimum value to all responses TTL.
Params:
cacheMinTimeToLive – the cache min TTL in seconds
Returns:
a reference to this, so the API can be used fluently/**
   * Set the cache minimum TTL value in seconds. After resolution successful IP addresses are cached with their DNS response TTL,
   * use this to set a minimum value to all responses TTL.
   *
   * @param cacheMinTimeToLive the cache min TTL in seconds
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setCacheMinTimeToLive(int cacheMinTimeToLive) {
    if (cacheMinTimeToLive < 0) {
      throw new IllegalArgumentException("cacheMinTimeToLive must be >= 0");
    }
    this.cacheMinTimeToLive = cacheMinTimeToLive;
    return this;
  }

  
Returns:
the cache max TTL in seconds/**
   * @return the cache max TTL in seconds
   */
  public int getCacheMaxTimeToLive() {
    return cacheMaxTimeToLive;
  }

  
Set the cache maximum TTL value in seconds. After successful resolution IP addresses are cached with their DNS response TTL,
use this to set a maximum value to all responses TTL.
Params:
cacheMaxTimeToLive – the cache max TTL in seconds
Returns:
a reference to this, so the API can be used fluently/**
   * Set the cache maximum TTL value in seconds. After successful resolution IP addresses are cached with their DNS response TTL,
   * use this to set a maximum value to all responses TTL.
   *
   * @param cacheMaxTimeToLive the cache max TTL in seconds
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setCacheMaxTimeToLive(int cacheMaxTimeToLive) {
    if (cacheMaxTimeToLive < 0) {
      throw new IllegalArgumentException("cacheMaxTimeToLive must be >= 0");
    }
    this.cacheMaxTimeToLive = cacheMaxTimeToLive;
    return this;
  }

  
Returns:
the cache negative TTL in seconds/**
   * @return the cache negative TTL in seconds
   */
  public int getCacheNegativeTimeToLive() {
    return cacheNegativeTimeToLive;
  }

  
Set the negative cache TTL value in seconds. After a failed hostname resolution, DNS queries won't be retried
for a period of time equals to the negative TTL. This allows to reduce the response time of negative replies
and reduce the amount of messages to DNS servers.
Params:
cacheNegativeTimeToLive – the cache negative TTL in seconds
Returns:
a reference to this, so the API can be used fluently/**
   * Set the negative cache TTL value in seconds. After a failed hostname resolution, DNS queries won't be retried
   * for a period of time equals to the negative TTL. This allows to reduce the response time of negative replies
   * and reduce the amount of messages to DNS servers.
   *
   * @param cacheNegativeTimeToLive the cache negative TTL in seconds
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setCacheNegativeTimeToLive(int cacheNegativeTimeToLive) {
    if (cacheNegativeTimeToLive < 0) {
      throw new IllegalArgumentException("cacheNegativeTimeToLive must be >= 0");
    }
    this.cacheNegativeTimeToLive = cacheNegativeTimeToLive;
    return this;
  }

  
Returns:
the query timeout in milliseconds/**
   * @return the query timeout in milliseconds
   */
  public long getQueryTimeout() {
    return queryTimeout;
  }

  
Set the query timeout in milliseconds, i.e the amount of time after a query is considered to be failed.
Params:
queryTimeout – the query timeout in milliseconds
Returns:
a reference to this, so the API can be used fluently/**
   * Set the query timeout in milliseconds, i.e the amount of time after a query is considered to be failed.
   *
   * @param queryTimeout the query timeout in milliseconds
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setQueryTimeout(long queryTimeout) {
    if (queryTimeout < 1) {
      throw new IllegalArgumentException("queryTimeout must be > 0");
    }
    this.queryTimeout = queryTimeout;
    return this;
  }

  
Returns:
the maximum number of queries to be sent during a resolution/**
   * @return the maximum number of queries to be sent during a resolution
   */
  public int getMaxQueries() {
    return maxQueries;
  }

  
Set the maximum number of queries when an hostname is resolved.
Params:
maxQueries – the max number of queries to be sent
Returns:
a reference to this, so the API can be used fluently/**
   * Set the maximum number of queries when an hostname is resolved.
   *
   * @param maxQueries the max number of queries to be sent
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setMaxQueries(int maxQueries) {
    if (maxQueries < 1) {
      throw new IllegalArgumentException("maxQueries must be > 0");
    }
    this.maxQueries = maxQueries;
    return this;
  }

  
Returns:
the DNS queries Recursion Desired flag value/**
   * @return the DNS queries <i>Recursion Desired</i> flag value
   */
  public boolean getRdFlag() {
    return rdFlag;
  }

  
Set the DNS queries Recursion Desired flag value.
Params:
rdFlag – the flag value
Returns:
a reference to this, so the API can be used fluently/**
   * Set the DNS queries <i>Recursion Desired</i> flag value.
   *
   * @param rdFlag the flag value
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setRdFlag(boolean rdFlag) {
    this.rdFlag = rdFlag;
    return this;
  }

  
Returns:
the list of search domains/**
   * @return the list of search domains
   */
  public List<String> getSearchDomains() {
    return searchDomains;
  }

  
Set the lists of DNS search domains.

When the search domain list is null, the effective search domain list will be populated using
the system DNS search domains.
Params:
searchDomains – the search domains/**
   * Set the lists of DNS search domains.
   * <p/>
   * When the search domain list is null, the effective search domain list will be populated using
   * the system DNS search domains.
   *
   * @param searchDomains the search domains
   */
  public AddressResolverOptions setSearchDomains(List<String> searchDomains) {
    this.searchDomains = searchDomains;
    return this;
  }

  
Add a DNS search domain.
Params:
searchDomain – the search domain to add
Returns:
a reference to this, so the API can be used fluently/**
   * Add a DNS search domain.
   *
   * @param searchDomain the search domain to add
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions addSearchDomain(String searchDomain) {
    if (searchDomains == null) {
      searchDomains = new ArrayList<>();
    }
    searchDomains.add(searchDomain);
    return this;
  }

  
Returns:
the ndots value/**
   * @return the ndots value
   */
  public int getNdots() {
    return ndots;
  }

  
Set the ndots value used when resolving using search domains, the default value is -1 which determines the value from the OS on Linux or uses the value 1. 
Params:
ndots – the new ndots value
Returns:
a reference to this, so the API can be used fluently/**
   * Set the ndots value used when resolving using search domains, the default value is {@code -1} which
   * determines the value from the OS on Linux or uses the value {@code 1}.
   *
   * @param ndots the new ndots value
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setNdots(int ndots) {
    if (ndots < -1) {
      throw new IllegalArgumentException("ndots must be >= -1");
    }
    this.ndots = ndots;
    return this;
  }

  
Returns:
the value true when the dns server selection uses round robin/**
   * @return the value {@code true} when the dns server selection uses round robin
   */
  public boolean isRotateServers() {
    return rotateServers;
  }

  
Set to true to enable round-robin selection of the dns server to use. It spreads the query load among the servers and avoids all lookup to hit the first server of the list. 
Returns:
a reference to this, so the API can be used fluently/**
   * Set to {@code true} to enable round-robin selection of the dns server to use. It spreads the query load
   * among the servers and avoids all lookup to hit the first server of the list.
   *
   * @return a reference to this, so the API can be used fluently
   */
  public AddressResolverOptions setRotateServers(boolean rotateServers) {
    this.rotateServers = rotateServers;
    return this;
  }

  public JsonObject toJson() {
    JsonObject json = new JsonObject();
    AddressResolverOptionsConverter.toJson(this, json);
    return json;
  }
}