/* Copyright (C) 2004-2026 Free Software Foundation, Inc.
   Author: Oliver Hitz

   This file is part of GNU Libidn.

   GNU Libidn is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at
       your option) any later version.

   or both in parallel, as here.

   GNU Libidn is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <https://www.gnu.org/licenses/>. */

package gnu.inet.encoding;

import java.util.Arrays;

/**
 * This class offers static methods for preparing internationalized
 * strings. It supports the following stringprep profiles:
 * <ul>
 * <li>RFC3491 nameprep
 * <li>RFC3920 XMPP nodeprep and resourceprep
 * </ul>
 * Note that this implementation only supports 16-bit Unicode code
 * points.
 */
public class Stringprep
{
  private static final RangeSet.Range[] NODEPREP_PASSTHROUGH_RANGES =
	  new RangeSet.Range[] { new RangeSet.Range(0x5B, 0x7E),
				 new RangeSet.Range(0x30, 0x39),
				 new RangeSet.Range(0x28, 0x2E)};

  private static final RangeSet.Range[] NAMEPREP_PASSTHROUGH_RANGES =
	  new RangeSet.Range[] { new RangeSet.Range(0x5B, 0x7F),
				 new RangeSet.Range(0x00, 0x40)};

  private static final RangeSet.Range[] RESOURCEPREP_PASSTHROUGH_RANGES =
	  new RangeSet.Range[] { new RangeSet.Range(0x20, 0x7E)};


  private static final RangeSet RANGE_A1 =
	  RangeSet.builder().addRanges(RFC3454.A1)
		  .build();

  private static final RangeSet RANGE_B1 =
	  RangeSet.builder().addRanges(RFC3454.B1)
		  .build();

  private static final RangeSet RANGE_D1 =
	  RangeSet.builder().addRanges(RFC3454.D1)
		  .build();

  private static final RangeSet RANGE_D2 =
	  RangeSet.builder().addRanges(RFC3454.D2)
		  .build();


  private static final RangeSet RANGE_C3_to_C8_C12_C22 =
	  RangeSet.builder().addRanges(RFC3454.C12)
		  .addRanges(RFC3454.C22)
		  .addRanges(RFC3454.C3)
		  .addRanges(RFC3454.C4)
		  .addRanges(RFC3454.C5)
		  .addRanges(RFC3454.C6)
		  .addRanges(RFC3454.C7)
		  .addRanges(RFC3454.C8)
		  // TODO Add C9 table now, proper unicode support now
		  // Temporary rejection of all "unsupported" in java 1.4
		  .addRange(new RangeSet.Range(0xffff, 0x10ffff))
		  .build();

  /**
   * Characters prohibited by RFC3920 nodeprep that aren't defined as
   * part of the RFC3454 tables.
   */
  private static final char [] RFC3920_NODEPREP_PROHIBIT = new char [] {
	  '\u0022', '\u0026', '\'',     '\u002F',
	  '\u003A', '\u003C', '\u003E', '\u0040'
  };

  private static final RangeSet RANGE_C3_TO_C8_C11_12_21_22_NP_PROHIB =
	  RangeSet.builder().addRanges(RFC3454.C3)
		  .addRanges(RFC3454.C4)
		  .addRanges(RFC3454.C5)
		  .addRanges(RFC3454.C6)
		  .addRanges(RFC3454.C7)
		  .addRanges(RFC3454.C8)
		  .addRanges(RFC3454.C11)
		  .addRanges(RFC3454.C12)
		  .addRanges(RFC3454.C21)
		  .addRanges(RFC3454.C22)
		  .addRanges(RFC3920_NODEPREP_PROHIBIT)
		  // TODO Add C9 table now, proper unicode support now
		  // Temporary rejection of all "unsupported" in java 1.4
		  .addRange(new RangeSet.Range(0xffff, 0x10ffff))
		  .build();

  private static final RangeSet RANGE_C3_to_C8_C12_C21_C22 =
	  RangeSet.builder().addRanges(RFC3454.C12)
		  .addRanges(RFC3454.C21)
		  .addRanges(RFC3454.C22)
		  .addRanges(RFC3454.C3)
		  .addRanges(RFC3454.C4)
		  .addRanges(RFC3454.C5)
		  .addRanges(RFC3454.C6)
		  .addRanges(RFC3454.C7)
		  .addRanges(RFC3454.C8)
		  // TODO Add C9 table now, proper unicode support now
		  // Temporary rejection of all "unsupported" in java 1.4
		  .addRange(new RangeSet.Range(0xffff, 0x10ffff))
		  .build();


  /**
   * Preps a name according to the Stringprep profile defined in
   * RFC3491. Unassigned code points are not allowed.
   *
   * @param input the name to prep.
   * @return the prepped name.
   * @throws StringprepException If the name cannot be prepped with
   * this profile.
   * @throws NullPointerException If the name is null.
   */
  public static String nameprep(String input)
    throws StringprepException,
	   NullPointerException
  {
    return nameprep(input, false);
  }

  /**
   * Preps a name according to the Stringprep profile defined in
   * RFC3491.
   *
   * @param input the name to prep.
   * @param allowUnassigned true if the name may contain unassigned
   * code points.
   * @return the prepped name.
   * @throws StringprepException If the name cannot be prepped with
   * this profile.
   * @throws NullPointerException If the name is null.
   */
  public static String nameprep(String input, boolean allowUnassigned)
    throws StringprepException,
	   NullPointerException
  {
    if (input == null) {
      throw new NullPointerException();
    }

    final RangeSet.Range inputRange = RangeSet.createTextRange(input);
    if (onlyPassThrough(NAMEPREP_PASSTHROUGH_RANGES, inputRange)) {
      return input;
    }
    if (!allowUnassigned && RANGE_A1.containsAnyCodePoint(input, inputRange)) {
      throw new StringprepException(StringprepException.CONTAINS_UNASSIGNED);
    }

    StringBuilder s = new StringBuilder(input);

    filter(s, RANGE_B1);
    map(s, RFC3454.B2search, RFC3454.B2replace);

    s = new StringBuilder(NFKC.normalizeNFKC(s.toString()));
    final RangeSet.Range normalizedRange = RangeSet.createTextRange(s);
    // B.3 is only needed if NFKC is not used, right?
    // map(s, RFC3454.B3search, RFC3454.B3replace);
    if (RANGE_C3_to_C8_C12_C22.containsAnyCodePoint(s, normalizedRange)) {
      // Table C.9 only contains code points > 0xFFFF which Java
      // doesn't handle
      throw new StringprepException(StringprepException.CONTAINS_PROHIBITED);
    }

    // Bidi handling
    boolean r = RANGE_D1.containsAnyCodePoint(s, normalizedRange);
    boolean l = RANGE_D2.containsAnyCodePoint(s, normalizedRange);

    // RFC 3454, section 6, requirement 1: already handled above (table C.8)

    // RFC 3454, section 6, requirement 2
    if (r && l) {
      throw new StringprepException(StringprepException.BIDI_BOTHRAL);
    }

    // RFC 3454, section 6, requirement 3
    if (r) {
      if (!RANGE_D1.contains(s.charAt(0)) ||
	  !RANGE_D1.contains(s.charAt(s.length()-1))) {
	throw new StringprepException(StringprepException.BIDI_LTRAL);
      }
    }

    return s.toString();
  }

  /**
   * Preps a node name according to the Stringprep profile defined in
   * RFC3920. Unassigned code points are not allowed.
   *
   * @param input the node name to prep.
   * @return the prepped node name.
   * @throws StringprepException If the node name cannot be prepped
   * with this profile.
   * @throws NullPointerException If the node name is null.
   */
  public static String nodeprep(String input)
    throws StringprepException,
	   NullPointerException
  {
    return nodeprep(input, false);
  }

  /**
   * Preps a node name according to the Stringprep profile defined in
   * RFC3920.
   *
   * @param input the node name to prep.
   * @param allowUnassigned true if the node name may contain
   * unassigned code points.
   * @return the prepped node name.
   * @throws StringprepException If the node name cannot be prepped
   * with this profile.
   * @throws NullPointerException If the node name is null.
   */
  public static String nodeprep(String input, boolean allowUnassigned)
    throws StringprepException,
	   NullPointerException
  {
    if (input == null) {
      throw new NullPointerException();
    }

    final RangeSet.Range inputRange = RangeSet.createTextRange(input);
    if (onlyPassThrough(NODEPREP_PASSTHROUGH_RANGES, inputRange)) {
      return input;
    }
    if (!allowUnassigned && RANGE_A1.containsAnyCodePoint(input, inputRange)) {
      throw new StringprepException(StringprepException.CONTAINS_UNASSIGNED);
    }

    StringBuilder s = new StringBuilder(input);

    filter(s, RANGE_B1);
    map(s, RFC3454.B2search, RFC3454.B2replace);

    s = new StringBuilder(NFKC.normalizeNFKC(s.toString()));
    final RangeSet.Range normalizedRange = RangeSet.createTextRange(s);
    if (RANGE_C3_TO_C8_C11_12_21_22_NP_PROHIB.containsAnyCodePoint(s, normalizedRange))
    {
      throw new StringprepException(StringprepException.CONTAINS_PROHIBITED);
    }

    // Bidi handling
    boolean r = RANGE_D1.containsAnyCodePoint(s, normalizedRange);
    boolean l = RANGE_D2.containsAnyCodePoint(s, normalizedRange);

    // RFC 3454, section 6, requirement 1: already handled above (table C.8)

    // RFC 3454, section 6, requirement 2
    if (r && l) {
      throw new	StringprepException(StringprepException.BIDI_BOTHRAL);
    }

    // RFC 3454, section 6, requirement 3
    if (r) {
      if (!RANGE_D1.contains(s.charAt(0)) ||
	  !RANGE_D1.contains(s.charAt(s.length() - 1))) {
	throw new StringprepException(StringprepException.BIDI_LTRAL);
      }
    }

    return s.toString();
  }

  /**
   * Preps a resource name according to the Stringprep profile defined
   * in RFC3920. Unassigned code points are not allowed.
   *
   * @param input the resource name to prep.
   * @return the prepped node name.
   * @throws StringprepException If the resource name cannot be prepped
   * with this profile.
   * @throws NullPointerException If the resource name is null.
   */
  public static String resourceprep(String input)
    throws StringprepException,
	   NullPointerException
  {
    return resourceprep(input, false);
  }

  /**
   * Preps a resource name according to the Stringprep profile defined
   * in RFC3920.
   *
   * @param input the resource name to prep.
   * @param allowUnassigned true if the resource name may contain
   * unassigned code points.
   * @return the prepped node name.
   * @throws StringprepException If the resource name cannot be prepped
   * with this profile.
   * @throws NullPointerException If the resource name is null.
   */
  public static String resourceprep(String input, boolean allowUnassigned)
    throws StringprepException,
	   NullPointerException
  {
    if (input == null) {
      throw new NullPointerException();
    }

    final RangeSet.Range inputRange = RangeSet.createTextRange(input);
    if (onlyPassThrough(RESOURCEPREP_PASSTHROUGH_RANGES, inputRange)) {
      return input;
    }
    if (!allowUnassigned && RANGE_A1.containsAnyCodePoint(input)) {
      throw new StringprepException(StringprepException.CONTAINS_UNASSIGNED);
    }

    StringBuilder s = new StringBuilder(input);

    filter(s, RANGE_B1);

    s = new StringBuilder(NFKC.normalizeNFKC(s.toString()));
    final RangeSet.Range normalizedRange = RangeSet.createTextRange(s);

    if (RANGE_C3_to_C8_C12_C21_C22.containsAnyCodePoint(s, normalizedRange)) {
      // Table C.9 only contains code points > 0xFFFF which Java
      // doesn't handle

      throw new StringprepException(StringprepException.CONTAINS_PROHIBITED);
    }

    // Bidi handling
    boolean r = RANGE_D1.containsAnyCodePoint(s, normalizedRange);
    boolean l = RANGE_D2.containsAnyCodePoint(s, normalizedRange);

    // RFC 3454, section 6, requirement 1: already handled above (table C.8)

    // RFC 3454, section 6, requirement 2
    if (r && l) {
      throw new	StringprepException(StringprepException.BIDI_BOTHRAL);
    }

    // RFC 3454, section 6, requirement 3
    if (r) {
      if (!RANGE_D1.contains(s.charAt(0)) ||
	  !RANGE_D1.contains(s.charAt(s.length() - 1))) {
	throw new StringprepException(StringprepException.BIDI_LTRAL);
      }
    }

    return s.toString();
  }

  private static boolean onlyPassThrough(final RangeSet.Range[] passThroughs,
					 final RangeSet.Range inputRange) {
    for (final RangeSet.Range passThrough : passThroughs) {
      if (passThrough.contains(inputRange)) {
	return true;
      }
    }
    return false;
  }

  static void filter(StringBuilder s, RangeSet f)
  {
    for (int j = 0; j < s.length(); ) {
      if (f.contains(s.charAt(j))) {
	s.deleteCharAt(j);
      } else {
	j++;
      }
    }
  }

  static void map(StringBuilder s, char[] search, String[] replace)
  {
    for (int i = 0; i < s.length(); i++) {
      char c = s.charAt(i);
      int mapIndex = Arrays.binarySearch(search, c);
      if (mapIndex >= 0) {
	String replacement = replace[mapIndex];
	s.replace(i, i + 1, replacement);
	i += replacement.length() - 1;
      }
    }
  }
}
