/*
 * Copyright (C) 2011 The Guava Authors
 *
 * 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.google.common.net;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Objects;
import com.google.common.base.Strings;
import com.google.errorprone.annotations.Immutable;
import java.io.Serializable;
import org.checkerframework.checker.nullness.qual.Nullable;

An immutable representation of a host and port.
Example usage:
HostAndPort hp = HostAndPort.fromString("[2001:db8::1]")
    .withDefaultPort(80)
    .requireBracketsForIPv6();
hp.getHost();   // returns "2001:db8::1"
hp.getPort();   // returns 80
hp.toString();  // returns "[2001:db8::1]:80"

Here are some examples of recognized formats:

  
example.com
  
example.com:80
  
192.0.2.1
  
192.0.2.1:80
  
[2001:db8::1] - getHost() omits brackets 
[2001:db8::1]:80 - getHost() omits brackets 
2001:db8::1 - Use requireBracketsForIPv6() to prohibit this 
Note that this is not an exhaustive list, because these methods are only concerned with
brackets, colons, and port numbers. Full validation of the host field (if desired) is the
caller's responsibility.
Author:
Paul Marks
Since:
10.0/**
 * An immutable representation of a host and port.
 *
 * <p>Example usage:
 *
 * <pre>
 * HostAndPort hp = HostAndPort.fromString("[2001:db8::1]")
 *     .withDefaultPort(80)
 *     .requireBracketsForIPv6();
 * hp.getHost();   // returns "2001:db8::1"
 * hp.getPort();   // returns 80
 * hp.toString();  // returns "[2001:db8::1]:80"
 * </pre>
 *
 * <p>Here are some examples of recognized formats:
 *
 * <ul>
 *   <li>example.com
 *   <li>example.com:80
 *   <li>192.0.2.1
 *   <li>192.0.2.1:80
 *   <li>[2001:db8::1] - {@link #getHost()} omits brackets
 *   <li>[2001:db8::1]:80 - {@link #getHost()} omits brackets
 *   <li>2001:db8::1 - Use {@link #requireBracketsForIPv6()} to prohibit this
 * </ul>
 *
 * <p>Note that this is not an exhaustive list, because these methods are only concerned with
 * brackets, colons, and port numbers. Full validation of the host field (if desired) is the
 * caller's responsibility.
 *
 * @author Paul Marks
 * @since 10.0
 */
@Beta
@Immutable
@GwtCompatible
public final class HostAndPort implements Serializable {
  
Magic value indicating the absence of a port number. /** Magic value indicating the absence of a port number. */
  private static final int NO_PORT = -1;

  
Hostname, IPv4/IPv6 literal, or unvalidated nonsense. /** Hostname, IPv4/IPv6 literal, or unvalidated nonsense. */
  private final String host;

  
Validated port number in the range [0..65535], or NO_PORT /** Validated port number in the range [0..65535], or NO_PORT */
  private final int port;

  
True if the parsed host has colons, but no surrounding brackets. /** True if the parsed host has colons, but no surrounding brackets. */
  private final boolean hasBracketlessColons;

  private HostAndPort(String host, int port, boolean hasBracketlessColons) {
    this.host = host;
    this.port = port;
    this.hasBracketlessColons = hasBracketlessColons;
  }

  
Returns the portion of this HostAndPort instance that should represent the hostname or IPv4/IPv6 literal. 
A successful parse does not imply any degree of sanity in this field. For additional validation, see the HostSpecifier class. 
Since:
20.0 (since 10.0 as getHostText)/**
   * Returns the portion of this {@code HostAndPort} instance that should represent the hostname or
   * IPv4/IPv6 literal.
   *
   * <p>A successful parse does not imply any degree of sanity in this field. For additional
   * validation, see the {@link HostSpecifier} class.
   *
   * @since 20.0 (since 10.0 as {@code getHostText})
   */
  public String getHost() {
    return host;
  }

  
Return true if this instance has a defined port. /** Return true if this instance has a defined port. */
  public boolean hasPort() {
    return port >= 0;
  }

  
Get the current port number, failing if no port is defined.
Throws:
IllegalStateException – if no port is defined. You can use withDefaultPort(int) to prevent this from occurring.
Returns:
a validated port number, in the range [0..65535]/**
   * Get the current port number, failing if no port is defined.
   *
   * @return a validated port number, in the range [0..65535]
   * @throws IllegalStateException if no port is defined. You can use {@link #withDefaultPort(int)}
   *     to prevent this from occurring.
   */
  public int getPort() {
    checkState(hasPort());
    return port;
  }

  
Returns the current port number, with a default if no port is defined. /** Returns the current port number, with a default if no port is defined. */
  public int getPortOrDefault(int defaultPort) {
    return hasPort() ? port : defaultPort;
  }

  
Build a HostAndPort instance from separate host and port values.
Note: Non-bracketed IPv6 literals are allowed. Use requireBracketsForIPv6() to prohibit these. 
Params:
host – the host string to parse. Must not contain a port number.
port – a port number from [0..65535]
Throws:
IllegalArgumentException – if host contains a port number, or port is out of range.
Returns:
if parsing was successful, a populated HostAndPort object./**
   * Build a HostAndPort instance from separate host and port values.
   *
   * <p>Note: Non-bracketed IPv6 literals are allowed. Use {@link #requireBracketsForIPv6()} to
   * prohibit these.
   *
   * @param host the host string to parse. Must not contain a port number.
   * @param port a port number from [0..65535]
   * @return if parsing was successful, a populated HostAndPort object.
   * @throws IllegalArgumentException if {@code host} contains a port number, or {@code port} is out
   *     of range.
   */
  public static HostAndPort fromParts(String host, int port) {
    checkArgument(isValidPort(port), "Port out of range: %s", port);
    HostAndPort parsedHost = fromString(host);
    checkArgument(!parsedHost.hasPort(), "Host has a port: %s", host);
    return new HostAndPort(parsedHost.host, port, parsedHost.hasBracketlessColons);
  }

  
Build a HostAndPort instance from a host only.
Note: Non-bracketed IPv6 literals are allowed. Use requireBracketsForIPv6() to prohibit these. 
Params:
host – the host-only string to parse. Must not contain a port number.
Throws:
IllegalArgumentException – if host contains a port number.
Returns:
if parsing was successful, a populated HostAndPort object.
Since:
17.0/**
   * Build a HostAndPort instance from a host only.
   *
   * <p>Note: Non-bracketed IPv6 literals are allowed. Use {@link #requireBracketsForIPv6()} to
   * prohibit these.
   *
   * @param host the host-only string to parse. Must not contain a port number.
   * @return if parsing was successful, a populated HostAndPort object.
   * @throws IllegalArgumentException if {@code host} contains a port number.
   * @since 17.0
   */
  public static HostAndPort fromHost(String host) {
    HostAndPort parsedHost = fromString(host);
    checkArgument(!parsedHost.hasPort(), "Host has a port: %s", host);
    return parsedHost;
  }

  
Split a freeform string into a host and port, without strict validation.
Note that the host-only formats will leave the port field undefined. You can use withDefaultPort(int) to patch in a default value. 
Params:
hostPortString – the input string to parse.
Throws:
IllegalArgumentException – if nothing meaningful could be parsed.
Returns:
if parsing was successful, a populated HostAndPort object./**
   * Split a freeform string into a host and port, without strict validation.
   *
   * <p>Note that the host-only formats will leave the port field undefined. You can use {@link
   * #withDefaultPort(int)} to patch in a default value.
   *
   * @param hostPortString the input string to parse.
   * @return if parsing was successful, a populated HostAndPort object.
   * @throws IllegalArgumentException if nothing meaningful could be parsed.
   */
  public static HostAndPort fromString(String hostPortString) {
    checkNotNull(hostPortString);
    String host;
    String portString = null;
    boolean hasBracketlessColons = false;

    if (hostPortString.startsWith("[")) {
      String[] hostAndPort = getHostAndPortFromBracketedHost(hostPortString);
      host = hostAndPort[0];
      portString = hostAndPort[1];
    } else {
      int colonPos = hostPortString.indexOf(':');
      if (colonPos >= 0 && hostPortString.indexOf(':', colonPos + 1) == -1) {
        // Exactly 1 colon. Split into host:port.
        host = hostPortString.substring(0, colonPos);
        portString = hostPortString.substring(colonPos + 1);
      } else {
        // 0 or 2+ colons. Bare hostname or IPv6 literal.
        host = hostPortString;
        hasBracketlessColons = (colonPos >= 0);
      }
    }

    int port = NO_PORT;
    if (!Strings.isNullOrEmpty(portString)) {
      // Try to parse the whole port string as a number.
      // JDK7 accepts leading plus signs. We don't want to.
      checkArgument(!portString.startsWith("+"), "Unparseable port number: %s", hostPortString);
      try {
        port = Integer.parseInt(portString);
      } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Unparseable port number: " + hostPortString);
      }
      checkArgument(isValidPort(port), "Port number out of range: %s", hostPortString);
    }

    return new HostAndPort(host, port, hasBracketlessColons);
  }

  
Parses a bracketed host-port string, throwing IllegalArgumentException if parsing fails.
Params:
hostPortString – the full bracketed host-port specification. Post might not be specified.
Throws:
IllegalArgumentException – if parsing the bracketed host-port string fails.
Returns:
an array with 2 strings: host and port, in that order./**
   * Parses a bracketed host-port string, throwing IllegalArgumentException if parsing fails.
   *
   * @param hostPortString the full bracketed host-port specification. Post might not be specified.
   * @return an array with 2 strings: host and port, in that order.
   * @throws IllegalArgumentException if parsing the bracketed host-port string fails.
   */
  private static String[] getHostAndPortFromBracketedHost(String hostPortString) {
    int colonIndex = 0;
    int closeBracketIndex = 0;
    checkArgument(
        hostPortString.charAt(0) == '[',
        "Bracketed host-port string must start with a bracket: %s",
        hostPortString);
    colonIndex = hostPortString.indexOf(':');
    closeBracketIndex = hostPortString.lastIndexOf(']');
    checkArgument(
        colonIndex > -1 && closeBracketIndex > colonIndex,
        "Invalid bracketed host/port: %s",
        hostPortString);

    String host = hostPortString.substring(1, closeBracketIndex);
    if (closeBracketIndex + 1 == hostPortString.length()) {
      return new String[] {host, ""};
    } else {
      checkArgument(
          hostPortString.charAt(closeBracketIndex + 1) == ':',
          "Only a colon may follow a close bracket: %s",
          hostPortString);
      for (int i = closeBracketIndex + 2; i < hostPortString.length(); ++i) {
        checkArgument(
            Character.isDigit(hostPortString.charAt(i)),
            "Port must be numeric: %s",
            hostPortString);
      }
      return new String[] {host, hostPortString.substring(closeBracketIndex + 2)};
    }
  }

  
Provide a default port if the parsed string contained only a host.
You can chain this after fromString(String) to include a port in case the port was omitted from the input string. If a port was already provided, then this method is a no-op. 
Params:
defaultPort – a port number, from [0..65535]
Returns:
a HostAndPort instance, guaranteed to have a defined port./**
   * Provide a default port if the parsed string contained only a host.
   *
   * <p>You can chain this after {@link #fromString(String)} to include a port in case the port was
   * omitted from the input string. If a port was already provided, then this method is a no-op.
   *
   * @param defaultPort a port number, from [0..65535]
   * @return a HostAndPort instance, guaranteed to have a defined port.
   */
  public HostAndPort withDefaultPort(int defaultPort) {
    checkArgument(isValidPort(defaultPort));
    if (hasPort()) {
      return this;
    }
    return new HostAndPort(host, defaultPort, hasBracketlessColons);
  }

  
Generate an error if the host might be a non-bracketed IPv6 literal.
URI formatting requires that IPv6 literals be surrounded by brackets, like "[2001:db8::1]". Chain this call after fromString(String) to increase the strictness of the parser, and disallow IPv6 literals that don't contain these brackets. 
Note that this parser identifies IPv6 literals solely based on the presence of a colon. To perform actual validation of IP addresses, see the InetAddresses.forString(String) method. 
Throws:
IllegalArgumentException – if bracketless IPv6 is detected.
Returns:
this, to enable chaining of calls./**
   * Generate an error if the host might be a non-bracketed IPv6 literal.
   *
   * <p>URI formatting requires that IPv6 literals be surrounded by brackets, like "[2001:db8::1]".
   * Chain this call after {@link #fromString(String)} to increase the strictness of the parser, and
   * disallow IPv6 literals that don't contain these brackets.
   *
   * <p>Note that this parser identifies IPv6 literals solely based on the presence of a colon. To
   * perform actual validation of IP addresses, see the {@link InetAddresses#forString(String)}
   * method.
   *
   * @return {@code this}, to enable chaining of calls.
   * @throws IllegalArgumentException if bracketless IPv6 is detected.
   */
  public HostAndPort requireBracketsForIPv6() {
    checkArgument(!hasBracketlessColons, "Possible bracketless IPv6 literal: %s", host);
    return this;
  }

  @Override
  public boolean equals(@Nullable Object other) {
    if (this == other) {
      return true;
    }
    if (other instanceof HostAndPort) {
      HostAndPort that = (HostAndPort) other;
      return Objects.equal(this.host, that.host)
          && this.port == that.port
          && this.hasBracketlessColons == that.hasBracketlessColons;
    }
    return false;
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(host, port, hasBracketlessColons);
  }

  
Rebuild the host:port string, including brackets if necessary. /** Rebuild the host:port string, including brackets if necessary. */
  @Override
  public String toString() {
    // "[]:12345" requires 8 extra bytes.
    StringBuilder builder = new StringBuilder(host.length() + 8);
    if (host.indexOf(':') >= 0) {
      builder.append('[').append(host).append(']');
    } else {
      builder.append(host);
    }
    if (hasPort()) {
      builder.append(':').append(port);
    }
    return builder.toString();
  }

  
Return true for valid port numbers. /** Return true for valid port numbers. */
  private static boolean isValidPort(int port) {
    return port >= 0 && port <= 65535;
  }

  private static final long serialVersionUID = 0;
}