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

namespace SixLabors.Fonts.Unicode {
  /// <summary>
  /// Unicode East_Asian_Width property values.
  /// <see href="https://www.unicode.org/reports/tr11/"/>
  /// </summary>
  /// <remarks>
  /// East_Asian_Width is a Unicode character property used when interoperating with
  /// East Asian legacy encodings and typography. The property has six default values,
  /// but any operation that needs a display-cell width must still resolve those values
  /// to a context-specific narrow or wide result.
  /// </remarks>
  public enum EastAsianWidthClass
  {
      /// <summary>
      /// Neutral (N): characters that are not East Asian for this property.
      /// </summary>
      /// <remarks>
      /// Neutral characters are not normally found in legacy East Asian character sets or
      /// traditional East Asian typography. UAX #11 recommends treating them like narrow
      /// characters for practical resolved-width decisions, but the property value itself
      /// is distinct from <see cref="Narrow"/>.
      /// </remarks>
      Neutral = 0,

      /// <summary>
      /// Ambiguous (A): characters that can be either wide or narrow depending on context.
      /// </summary>
      /// <remarks>
      /// Ambiguous characters need extra information, such as language, script, font,
      /// source encoding, or explicit markup, before they can be resolved to a display
      /// width. In East Asian legacy contexts they may be treated as wide;
      /// otherwise UAX #11 recommends treating them as narrow by default.
      /// </remarks>
      Ambiguous = 1,

      /// <summary>
      /// Fullwidth (F): explicitly encoded fullwidth compatibility characters.
      /// </summary>
      /// <remarks>
      /// Fullwidth characters have a compatibility decomposition of type <c>&lt;wide&gt;</c>
      /// to another Unicode character that is implicitly narrow. They exist to preserve
      /// round-tripping with mixed-width East Asian legacy encodings.
      /// </remarks>
      Fullwidth = 2,

      /// <summary>
      /// Halfwidth (H): explicitly encoded halfwidth compatibility characters.
      /// </summary>
      /// <remarks>
      /// Halfwidth characters have a compatibility decomposition of type <c>&lt;narrow&gt;</c>
      /// to another Unicode character that is implicitly wide, with the special case of
      /// U+20A9 WON SIGN. They are distinct from ordinary narrow characters because they
      /// can still behave like East Asian compatibility forms for font selection and some
      /// punctuation behavior.
      /// </remarks>
      Halfwidth = 3,

      /// <summary>
      /// Narrow (Na): characters that are always narrow and have explicit wide or fullwidth counterparts.
      /// </summary>
      /// <remarks>
      /// Narrow characters are implicitly narrow in East Asian typography and legacy
      /// character sets. ASCII is the common example: the ordinary ASCII code points are
      /// Narrow, while their compatibility forms are Fullwidth.
      /// </remarks>
      Narrow = 4,

      /// <summary>
      /// Wide (W): characters that are always wide in East Asian typography.
      /// </summary>
      /// <remarks>
      /// Wide characters behave like ideographs for East Asian layout. This includes
      /// many Han, Kana, Hangul, and emoji-presentation characters that are not encoded
      /// as explicit Fullwidth compatibility forms.
      /// </remarks>
      Wide = 5
  }
}