/*
    * 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
    *
    *      https://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.commons.validator.routines;
  
  import java.io.Serializable;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Locale;
  import java.util.Set;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.commons.validator.GenericValidator;
  
  /**
   * <p><strong>URL Validation</strong> routines.</p>
   * Behavior of validation is modified by passing in options:
   * <ul>
   * <li>ALLOW_2_SLASHES - [FALSE]  Allows double '/' characters in the path
   * component.</li>
   * <li>NO_FRAGMENT- [FALSE]  By default fragments are allowed, if this option is
   * included then fragments are flagged as illegal.</li>
   * <li>ALLOW_ALL_SCHEMES - [FALSE] By default only http, https, and ftp are
   * considered valid schemes.  Enabling this option will let any scheme pass validation.</li>
   * </ul>
   *
   * <p>Originally based in on php script by Debbie Dyer, validation.php v1.2b, Date: 03/07/02,
   * https://javascript.internet.com. However, this validation now bears little resemblance
   * to the php original.</p>
   * <pre>
   *   Example of usage:
   *   Construct a UrlValidator with valid schemes of "http", and "https".
   *
   *    String[] schemes = {"http","https"}.
   *    UrlValidator urlValidator = new UrlValidator(schemes);
   *    if (urlValidator.isValid("ftp://foo.bar.com/")) {
   *       System.out.println("URL is valid");
   *    } else {
   *       System.out.println("URL is invalid");
   *    }
   *
   *    prints "URL is invalid"
   *   If instead the default constructor is used.
   *
   *    UrlValidator urlValidator = new UrlValidator();
   *    if (urlValidator.isValid("ftp://foo.bar.com/")) {
   *       System.out.println("URL is valid");
   *    } else {
   *       System.out.println("URL is invalid");
   *    }
   *
   *   prints out "URL is valid"
   *  </pre>
   *
   * @see
   * <a href="https://www.ietf.org/rfc/rfc2396.txt">
   *  Uniform Resource Identifiers (URI): Generic Syntax
   * </a>
   *
   * @since 1.4
   */
  public class UrlValidator implements Serializable {
  
      private static final long serialVersionUID = 7557161713937335013L;
  
      private static final int MAX_UNSIGNED_16_BIT_INT = 0xFFFF; // port max
  
      /**
       * Allows all validly formatted schemes to pass validation instead of
       * supplying a set of valid schemes.
       */
      public static final long ALLOW_ALL_SCHEMES = 1 << 0;
  
      /**
       * Allow two slashes in the path component of the URL.
       */
      public static final long ALLOW_2_SLASHES = 1 << 1;
  
      /**
       * Enabling this options disallows any URL fragments.
       */
      public static final long NO_FRAGMENTS = 1 << 2;
  
     /**
      * Allow local URLs, such as https://localhost/ or https://machine/ .
      * This enables a broad-brush check, for complex local machine name
      *  validation requirements you should create your validator with
      *  a {@link RegexValidator} instead ({@link #UrlValidator(RegexValidator, long)})
      */
     public static final long ALLOW_LOCAL_URLS = 1 << 3; // CHECKSTYLE IGNORE MagicNumber
 
     /**
      * Protocol scheme (for example, http, ftp, https).
      */
     private static final String SCHEME_REGEX = "^\\p{Alpha}[\\p{Alnum}\\+\\-\\.]*";
     private static final Pattern SCHEME_PATTERN = Pattern.compile(SCHEME_REGEX);
 
     // Drop numeric, and  "+-." for now
     // TODO does not allow for optional userinfo.
     // Validation of character set is done by isValidAuthority
     private static final String AUTHORITY_CHARS_REGEX = "\\p{Alnum}\\-\\."; // allows for IPV4 but not IPV6
     // Allow for IPv4 mapped addresses: ::FFF:123.123.123.123
     private static final String IPV6_REGEX = "::FFFF:(?:\\d{1,3}\\.){3}\\d{1,3}|[0-9a-fA-F:]+"; // do this as separate match because : could cause ambiguity with port prefix
 
     // userinfo    = *( unreserved / pct-encoded / sub-delims / ":" )
     // unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
     // sub-delims    = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
     // We assume that password has the same valid chars as user info
     private static final String USERINFO_CHARS_REGEX = "[a-zA-Z0-9%-._~!$&'()*+,;=]";
 
     // since neither ':' nor '@' are allowed chars, we don't need to use non-greedy matching
     private static final String USERINFO_FIELD_REGEX =
             USERINFO_CHARS_REGEX + "+" + // At least one character for the name
             "(?::" + USERINFO_CHARS_REGEX + "*)?@"; // colon and password may be absent
 
     private static final String AUTHORITY_REGEX =
             "(?:\\[(" + IPV6_REGEX + ")\\]|(?:(?:" + USERINFO_FIELD_REGEX + ")?([" + AUTHORITY_CHARS_REGEX + "]*)))(?::(\\d*))?(.*)?";
     //             1                         for example, user:pass@           2                                       3       4
     private static final Pattern AUTHORITY_PATTERN = Pattern.compile(AUTHORITY_REGEX);
 
     private static final int PARSE_AUTHORITY_IPV6 = 1;
 
     private static final int PARSE_AUTHORITY_HOST_IP = 2; // excludes userinfo, if present
 
     private static final int PARSE_AUTHORITY_PORT = 3; // excludes leading colon
 
     /**
      * Should always be empty. The code currently allows spaces.
      */
     private static final int PARSE_AUTHORITY_EXTRA = 4;
 
     private static final String PATH_REGEX = "^(/[-\\w:@&?=+,.!/~*'%$_;\\(\\)]*)?$";
     private static final Pattern PATH_PATTERN = Pattern.compile(PATH_REGEX);
 
     private static final String QUERY_REGEX = "^(\\S*)$";
     private static final Pattern QUERY_PATTERN = Pattern.compile(QUERY_REGEX);
 
     /**
      * If no schemes are provided, default to this set.
      */
     private static final String[] DEFAULT_SCHEMES = {"http", "https", "ftp"}; // Must be lower-case
 
     /**
      * Singleton instance of this class with default schemes and options.
      */
     private static final UrlValidator DEFAULT_URL_VALIDATOR = new UrlValidator();
 
     /**
      * Returns the singleton instance of this class with default schemes and options.
      * @return singleton instance with default schemes and options
      */
     public static UrlValidator getInstance() {
         return DEFAULT_URL_VALIDATOR;
     }
 
     /**
      * Tests whether the given flag is on. If the flag is not a power of 2
      * (for example, 3) this tests whether the combination of flags is on.
      *
      * @param flag Flag value to check.
      * @param options what to check
      * @return whether the specified flag value is on.
      */
     private static boolean isOn(final long flag, final long options) {
         return (options & flag) > 0;
     }
 
     /**
      * Holds the set of current validation options.
      */
     private final long options;
 
     /**
      * The set of schemes that are allowed to be in a URL.
      */
     private final Set<String> allowedSchemes; // Must be lower-case
 
     /**
      * Regular expressions used to manually validate authorities if IANA
      * domain name validation isn't desired.
      */
     private final RegexValidator authorityValidator;
 
     /**
      * The domain validator.
      */
     private final DomainValidator domainValidator;
 
     /**
      * Constructs a new instance with default properties.
      */
     public UrlValidator() {
         this(null);
     }
 
     /**
      * Constructs a new instance with the given validation options.
      * @param options The options should be set using the public constants declared in
      * this class.  To set multiple options you simply add them together.  For example,
      * ALLOW_2_SLASHES + NO_FRAGMENTS enables both of those options.
      */
     public UrlValidator(final long options) {
         this(null, null, options);
     }
 
     /**
      * Constructs a new instance with the given validation options.
      * @param authorityValidator Regular expression validator used to validate the authority part
      * This allows the user to override the standard set of domains.
      * @param options Validation options. Set using the public constants of this class.
      * To set multiple options, simply add them together:
      * <p>{@code ALLOW_2_SLASHES + NO_FRAGMENTS}</p>
      * enables both of those options.
      */
     public UrlValidator(final RegexValidator authorityValidator, final long options) {
         this(null, authorityValidator, options);
     }
 
     /**
      * Behavior of validation is modified by passing in several strings options:
      * @param schemes Pass in one or more URL schemes to consider valid, passing in
      *        a null will default to "http,https,ftp" being valid.
      *        If a non-null schemes is specified then all valid schemes must
      *        be specified. Setting the ALLOW_ALL_SCHEMES option will
      *        ignore the contents of schemes.
      */
     public UrlValidator(final String[] schemes) {
         this(schemes, 0L);
     }
 
     /**
      * Behavior of validation is modified by passing in options:
      * @param schemes The set of valid schemes. Ignored if the ALLOW_ALL_SCHEMES option is set.
      * @param options The options should be set using the public constants declared in
      * this class.  To set multiple options you simply add them together.  For example,
      * ALLOW_2_SLASHES + NO_FRAGMENTS enables both of those options.
      */
     public UrlValidator(final String[] schemes, final long options) {
         this(schemes, null, options);
     }
 
     /**
      * Customizable constructor. Validation behavior is modified by passing in options.
      * @param schemes the set of valid schemes. Ignored if the ALLOW_ALL_SCHEMES option is set.
      * @param authorityValidator Regular expression validator used to validate the authority part
      * @param options Validation options. Set using the public constants of this class.
      * To set multiple options, simply add them together:
      * <p>{@code ALLOW_2_SLASHES + NO_FRAGMENTS}</p>
      * enables both of those options.
      */
     public UrlValidator(final String[] schemes, final RegexValidator authorityValidator, final long options) {
         this(schemes, authorityValidator, options, DomainValidator.getInstance(isOn(ALLOW_LOCAL_URLS, options)));
     }
 
     /**
      * Customizable constructor. Validation behavior is modified by passing in options.
      * @param schemes the set of valid schemes. Ignored if the ALLOW_ALL_SCHEMES option is set.
      * @param authorityValidator Regular expression validator used to validate the authority part
      * @param options Validation options. Set using the public constants of this class.
      * To set multiple options, simply add them together:
      * <p>{@code ALLOW_2_SLASHES + NO_FRAGMENTS}</p>
      * enables both of those options.
      * @param domainValidator the DomainValidator to use; must agree with ALLOW_LOCAL_URLS setting
      * @since 1.7
      */
     public UrlValidator(String[] schemes, final RegexValidator authorityValidator, final long options, final DomainValidator domainValidator) {
         this.options = options;
         if (domainValidator == null) {
             throw new IllegalArgumentException("DomainValidator must not be null");
         }
         if (domainValidator.isAllowLocal() != (options & ALLOW_LOCAL_URLS) > 0) {
             throw new IllegalArgumentException("DomainValidator disagrees with ALLOW_LOCAL_URLS setting");
         }
         this.domainValidator = domainValidator;
 
         if (isOn(ALLOW_ALL_SCHEMES)) {
             allowedSchemes = Collections.emptySet();
         } else {
             if (schemes == null) {
                 schemes = DEFAULT_SCHEMES;
             }
             allowedSchemes = new HashSet<>(schemes.length);
             for (final String scheme : schemes) {
                 allowedSchemes.add(scheme.toLowerCase(Locale.ENGLISH));
             }
         }
 
         this.authorityValidator = authorityValidator;
     }
 
     /**
      * Returns the number of times the token appears in the target.
      * @param token Token value to be counted.
      * @param target Target value to count tokens in.
      * @return the number of tokens.
      */
     protected int countToken(final String token, final String target) {
         int tokenIndex = 0;
         int count = 0;
         while (tokenIndex != -1) {
             tokenIndex = target.indexOf(token, tokenIndex);
             if (tokenIndex > -1) {
                 tokenIndex++;
                 count++;
             }
         }
         return count;
     }
 
     /**
      * Tests whether the given flag is off.  If the flag is not a power of 2
      * (for example, 3) this tests whether the combination of flags is off.
      *
      * @param flag Flag value to check.
      * @return whether the specified flag value is off.
      */
     private boolean isOff(final long flag) {
         return (options & flag) == 0;
     }
 
     /**
      * Tests whether the given flag is on.  If the flag is not a power of 2
      * (for example, 3) this tests whether the combination of flags is on.
      *
      * @param flag Flag value to check.
      * @return whether the specified flag value is on.
      */
     private boolean isOn(final long flag) {
         return (options & flag) > 0;
     }
 
     /**
      * <p>Checks if a field has a valid URL address.</p>
      *
      * Note that the method calls #isValidAuthority()
      * which checks that the domain is valid.
      *
      * @param value The value validation is being performed on.  A {@code null}
      * value is considered invalid.
      * @return true if the URL is valid.
      */
     public boolean isValid(final String value) {
         if (value == null) {
             return false;
         }
         final URI uri; // ensure value is a valid URI
         try {
             uri = new URI(value);
         } catch (final URISyntaxException e) {
             return false;
         }
         // OK, perform additional validation
         final String scheme = uri.getScheme();
         if (!isValidScheme(scheme)) {
             return false;
         }
         final String authority = uri.getRawAuthority();
         if ("file".equals(scheme) && GenericValidator.isBlankOrNull(authority)) { // Special case - file: allows an empty authority
             return true; // this is a local file - nothing more to do here
         }
         // Validate the authority
         if ("file".equals(scheme) && authority != null && authority.contains(":") || !isValidAuthority(authority)) {
             return false;
         }
         if (!isValidPath(uri.getRawPath()) || !isValidQuery(uri.getRawQuery()) || !isValidFragment(uri.getRawFragment())) {
             return false;
         }
         return true;
     }
 
     /**
      * Returns true if the authority is properly formatted.  An authority is the combination
      * of hostname and port.  A {@code null} authority value is considered invalid.
      * Note: this implementation validates the domain unless a RegexValidator was provided.
      * If a RegexValidator was supplied, and it matches, then the authority is regarded
      * as valid with no further checks, otherwise the method checks against the
      * AUTHORITY_PATTERN and the DomainValidator (ALLOW_LOCAL_URLS)
      * @param authority Authority value to validate, allows IDN
      * @return true if authority (hostname and port) is valid.
      */
     protected boolean isValidAuthority(final String authority) {
         if (authority == null) {
             return false;
         }
 
         // check manual authority validation if specified
         if (authorityValidator != null && authorityValidator.isValid(authority)) {
             return true;
         }
         // convert to ASCII if possible
         final String authorityASCII = DomainValidator.unicodeToASCII(authority);
 
         final Matcher authorityMatcher = AUTHORITY_PATTERN.matcher(authorityASCII);
         if (!authorityMatcher.matches()) {
             return false;
         }
 
         // We have to process IPV6 separately because that is parsed in a different group
         final String ipv6 = authorityMatcher.group(PARSE_AUTHORITY_IPV6);
         if (ipv6 != null) {
             final InetAddressValidator inetAddressValidator = InetAddressValidator.getInstance();
             if (!inetAddressValidator.isValidInet6Address(ipv6)) {
                 return false;
             }
         } else {
             final String hostLocation = authorityMatcher.group(PARSE_AUTHORITY_HOST_IP);
             // check if authority is hostname or IP address:
             // try a hostname first since that's much more likely
             if (!domainValidator.isValid(hostLocation)) {
                 // try an IPv4 address
                 final InetAddressValidator inetAddressValidator = InetAddressValidator.getInstance();
                 if (!inetAddressValidator.isValidInet4Address(hostLocation)) {
                     // isn't IPv4, so the URL is invalid
                     return false;
                 }
             }
             final String port = authorityMatcher.group(PARSE_AUTHORITY_PORT);
             if (!GenericValidator.isBlankOrNull(port)) {
                 try {
                     final int iPort = Integer.parseInt(port);
                     if (iPort < 0 || iPort > MAX_UNSIGNED_16_BIT_INT) {
                         return false;
                     }
                 } catch (final NumberFormatException nfe) {
                     return false; // this can happen for big numbers
                 }
             }
         }
 
         final String extra = authorityMatcher.group(PARSE_AUTHORITY_EXTRA);
         if (extra != null && !extra.trim().isEmpty()) {
             return false;
         }
 
         return true;
     }
 
     /**
      * Returns true if the given fragment is null or fragments are allowed.
      * @param fragment Fragment value to validate.
      * @return true if fragment is valid.
      */
     protected boolean isValidFragment(final String fragment) {
         if (fragment == null) {
             return true;
         }
 
         return isOff(NO_FRAGMENTS);
     }
 
     /**
      * Returns true if the path is valid.  A {@code null} value is considered invalid.
      * @param path Path value to validate.
      * @return true if path is valid.
      */
     protected boolean isValidPath(final String path) {
         if (path == null || !PATH_PATTERN.matcher(path).matches()) {
             return false;
         }
 
         try {
             // Don't omit host otherwise leading path may be taken as host if it starts with //
             final URI uri = new URI(null, "localhost", path, null);
             final String norm = uri.normalize().getPath();
             if (norm.startsWith("/../") // Trying to go via the parent dir
                     || norm.equals("/..")) { // Trying to go to the parent dir
                 return false;
             }
         } catch (final URISyntaxException e) {
             return false;
         }
 
         final int slash2Count = countToken("//", path);
         if (isOff(ALLOW_2_SLASHES) && slash2Count > 0) {
             return false;
         }
 
         return true;
     }
 
     /**
      * Returns true if the query is null, or it's a properly formatted query string.
      * @param query Query value to validate.
      * @return true if query is valid.
      */
     protected boolean isValidQuery(final String query) {
         if (query == null) {
             return true;
         }
         return QUERY_PATTERN.matcher(query).matches();
     }
 
     /**
      * Validate scheme. If schemes[] was initialized to a non-null,
      * then only those schemes are allowed.
      * Otherwise, the default schemes are "http", "https", "ftp".
      * Matching is case-blind.
      * @param scheme The scheme to validate.  A {@code null} value is considered
      * invalid.
      * @return true if valid.
      */
     protected boolean isValidScheme(final String scheme) {
         if (scheme == null || !SCHEME_PATTERN.matcher(scheme).matches()
                 || isOff(ALLOW_ALL_SCHEMES) && !allowedSchemes.contains(scheme.toLowerCase(Locale.ENGLISH))) {
             return false;
         }
 
         return true;
     }
 
 }