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

namespace SixLabors.Fonts {
  /// <summary>
  /// Represents a hit-tested grapheme position in laid-out text.
  /// </summary>
  public readonly struct TextHit
  {
      /// <summary>
      /// Initializes a new instance of the <see cref="TextHit"/> struct.
      /// </summary>
      /// <param name="lineIndex">The zero-based line index.</param>
      /// <param name="graphemeIndex">The grapheme index in the original text.</param>
      /// <param name="stringIndex">The UTF-16 index in the original text.</param>
      /// <param name="isTrailing">Whether the hit is on the trailing side of the grapheme.</param>
      internal TextHit(int lineIndex, int graphemeIndex, int stringIndex, bool isTrailing)
      {
          this.LineIndex = lineIndex;
          this.GraphemeIndex = graphemeIndex;
          this.StringIndex = stringIndex;
          this.IsTrailing = isTrailing;
      }

      /// <summary>
      /// Gets the zero-based line index.
      /// </summary>
      public int LineIndex { get; }

      /// <summary>
      /// Gets the zero-based grapheme index in the original text.
      /// </summary>
      public int GraphemeIndex { get; }

      /// <summary>
      /// Gets the zero-based UTF-16 code unit index in the original text.
      /// </summary>
      public int StringIndex { get; }

      /// <summary>
      /// Gets the grapheme insertion index represented by this hit.
      /// </summary>
      public int GraphemeInsertionIndex => this.GraphemeIndex + (this.IsTrailing ? 1 : 0);

      /// <summary>
      /// Gets a value indicating whether the hit is on the trailing side of the grapheme.
      /// </summary>
      public bool IsTrailing { get; }
  }
}