// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

namespace SixLabors.Fonts.Unicode {
  /// <summary>
  /// Unicode Grapheme_Cluster_Break property values and local rule sentinels.
  /// <see href="https://www.unicode.org/reports/tr29/#Grapheme_Cluster_Break_Property_Values"/>
  /// </summary>
  /// <remarks>
  /// UAX #29 uses these classes in ordered boundary rules to determine extended
  /// grapheme clusters. Some members are rule sentinels rather than Unicode property
  /// values exposed by the standard.
  /// </remarks>
  public enum GraphemeClusterClass
  {
      /// <summary>
      /// Rule sentinel that matches any code point.
      /// </summary>
      /// <remarks>
      /// This is not a Unicode property value; it represents the "any" operand in
      /// UAX #29 boundary rules.
      /// </remarks>
      Any = 0,

      /// <summary>
      /// U+000D CARRIAGE RETURN (CR).
      /// </summary>
      CarriageReturn = 1,

      /// <summary>
      /// U+000A LINE FEED (LF).
      /// </summary>
      LineFeed = 2,

      /// <summary>
      /// Controls, separators, formats, and default-ignorable unassigned code points
      /// that form hard grapheme cluster boundaries.
      /// </summary>
      /// <remarks>
      /// This class excludes CR, LF, U+200C ZERO WIDTH NON-JOINER, U+200D ZERO
      /// WIDTH JOINER, and prepended concatenation marks because those participate
      /// in more specific UAX #29 rules.
      /// </remarks>
      Control = 3,

      /// <summary>
      /// Extending code points that remain in the same extended grapheme cluster as
      /// the preceding base.
      /// </summary>
      /// <remarks>
      /// This includes Grapheme_Extend code points, emoji modifiers, U+200C ZERO
      /// WIDTH NON-JOINER, and a small number of spacing marks needed for canonical
      /// equivalence.
      /// </remarks>
      Extend = 4,

      /// <summary>
      /// Regional indicator symbols used to build flag emoji pairs.
      /// </summary>
      RegionalIndicator = 5,

      /// <summary>
      /// Code points that prepend to the following grapheme cluster.
      /// </summary>
      /// <remarks>
      /// This includes Indic_Syllabic_Category values Consonant_Preceding_Repha and
      /// Consonant_Prefixed, plus Prepended_Concatenation_Mark code points.
      /// </remarks>
      Prepend = 6,

      /// <summary>
      /// Spacing marks that extend the previous grapheme cluster.
      /// </summary>
      /// <remarks>
      /// This includes spacing marks whose Grapheme_Cluster_Break value is not
      /// Extend, plus U+0E33 THAI CHARACTER SARA AM and U+0EB3 LAO VOWEL SIGN AM.
      /// </remarks>
      SpacingMark = 7,

      /// <summary>
      /// Hangul leading consonant Jamo (Hangul_Syllable_Type = L).
      /// </summary>
      HangulLead = 8,

      /// <summary>
      /// Hangul vowel Jamo (Hangul_Syllable_Type = V).
      /// </summary>
      HangulVowel = 9,

      /// <summary>
      /// Hangul trailing consonant Jamo (Hangul_Syllable_Type = T).
      /// </summary>
      HangulTail = 10,

      /// <summary>
      /// Hangul LV syllables.
      /// </summary>
      HangulLeadVowel = 11,

      /// <summary>
      /// Hangul LVT syllables.
      /// </summary>
      HangulLeadVowelTail = 12,

      /// <summary>
      /// Extended pictographic code points used by GB11 emoji ZWJ sequence handling.
      /// </summary>
      /// <remarks>
      /// This is not itself a Grapheme_Cluster_Break property value; UAX #29 uses
      /// it when matching emoji ZWJ sequences.
      /// </remarks>
      ExtendedPictographic = 13,

      /// <summary>
      /// U+200D ZERO WIDTH JOINER.
      /// </summary>
      ZeroWidthJoiner = 14,

      /// <summary>
      /// Other.
      /// </summary>
      /// <remarks>
      /// This is the Unicode <c>Other</c> / <c>XX</c> fallback for code points
      /// without an explicit grapheme cluster break class.
      /// </remarks>
      Other = 0xFF
  }
}