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

using System.Numerics;

namespace SixLabors.Fonts {
  /// <summary>
  /// Encapsulates measured metrics for a single laid-out text line.
  /// </summary>
  public readonly struct LineMetrics
  {
      /// <summary>
      /// Initializes a new instance of the <see cref="LineMetrics"/> struct.
      /// </summary>
      /// <param name="ascender">The ascender line position within the line box.</param>
      /// <param name="baseline">The baseline position within the line box.</param>
      /// <param name="descender">The descender line position within the line box.</param>
      /// <param name="lineHeight">The total line-box size for this line.</param>
      /// <param name="start">The logical line box start position in pixel units.</param>
      /// <param name="extent">The logical line box extent in pixel units.</param>
      /// <param name="stringIndex">The UTF-16 index in the original text where this line begins.</param>
      /// <param name="graphemeIndex">The grapheme index in the original text where this line begins.</param>
      /// <param name="graphemeCount">The number of graphemes in the line.</param>
      /// <param name="graphemeOffset">The offset of this line's first grapheme metrics entry.</param>
      internal LineMetrics(
          float ascender,
          float baseline,
          float descender,
          float lineHeight,
          Vector2 start,
          Vector2 extent,
          int stringIndex,
          int graphemeIndex,
          int graphemeCount,
          int graphemeOffset)
      {
          this.Ascender = ascender;
          this.Baseline = baseline;
          this.Descender = descender;
          this.LineHeight = lineHeight;
          this.Start = start;
          this.Extent = extent;
          this.StringIndex = stringIndex;
          this.GraphemeIndex = graphemeIndex;
          this.GraphemeCount = graphemeCount;
          this.GraphemeOffset = graphemeOffset;
      }

      /// <summary>
      /// Gets the ascender line position within the line box.
      /// </summary>
      /// <remarks>
      /// This is a position value (not a baseline-relative distance).
      /// Use this value to draw the ascender guide line relative to the current line origin.
      /// </remarks>
      public float Ascender { get; }

      /// <summary>
      /// Gets the baseline position within the line box.
      /// </summary>
      /// <remarks>
      /// Use this value as the guide-line position for drawing a baseline relative to the current line origin.
      /// </remarks>
      public float Baseline { get; }

      /// <summary>
      /// Gets the descender line position within the line box.
      /// </summary>
      /// <remarks>
      /// This is a position value (not a baseline-relative distance).
      /// Use this value to draw the descender guide line relative to the current line origin.
      /// </remarks>
      public float Descender { get; }

      /// <summary>
      /// Gets the total line-box size for this line.
      /// </summary>
      public float LineHeight { get; }

      /// <summary>
      /// Gets the logical line box start position in pixel units.
      /// </summary>
      public Vector2 Start { get; }

      /// <summary>
      /// Gets the logical line box extent in pixel units.
      /// </summary>
      public Vector2 Extent { get; }

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

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

      /// <summary>
      /// Gets the number of graphemes in the line.
      /// </summary>
      public int GraphemeCount { get; }

      /// <summary>
      /// Gets the offset of this line's first entry in the flattened grapheme metrics buffer.
      /// </summary>
      internal int GraphemeOffset { get; }
  }
}