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

using SixLabors.Fonts.Tables.AdvancedTypographic.Variations;

namespace SixLabors.Fonts.Tables.General.Colr {
  /// <summary>
  /// Represents a COLR v1 ClipBox format 2 subtable with variation-aware int16 bounding box edges.
  /// Each edge value is adjusted by a delta resolved from the ItemVariationStore.
  /// <see href="https://learn.microsoft.com/en-us/typography/opentype/spec/colr#clipbox"/>
  /// </summary>
  internal sealed class ClipBoxFormat2 : ClipBox
  {
      /// <summary>
      /// The minimum x-coordinate of the clip box.
      /// </summary>
      private readonly short xMin;

      /// <summary>
      /// The minimum y-coordinate of the clip box.
      /// </summary>
      private readonly short yMin;

      /// <summary>
      /// The maximum x-coordinate of the clip box.
      /// </summary>
      private readonly short xMax;

      /// <summary>
      /// The maximum y-coordinate of the clip box.
      /// </summary>
      private readonly short yMax;

      /// <summary>
      /// The base index into the ItemVariationStore delta sets for the four edge values.
      /// </summary>
      private readonly uint varIndexBase;

      /// <summary>
      /// Initializes a new instance of the <see cref="ClipBoxFormat2"/> class.
      /// </summary>
      /// <param name="xMin">The minimum x-coordinate.</param>
      /// <param name="yMin">The minimum y-coordinate.</param>
      /// <param name="xMax">The maximum x-coordinate.</param>
      /// <param name="yMax">The maximum y-coordinate.</param>
      /// <param name="varIndexBase">The base index into the ItemVariationStore delta sets.</param>
      public ClipBoxFormat2(short xMin, short yMin, short xMax, short yMax, uint varIndexBase)
      {
          this.xMin = xMin;
          this.yMin = yMin;
          this.xMax = xMax;
          this.yMax = yMax;
          this.varIndexBase = varIndexBase;
      }

      /// <inheritdoc/>
      public override Bounds GetBounds(ColrTable colr, GlyphVariationProcessor? processor)
      {
          float dx0 = colr.ResolveDelta(processor, this.varIndexBase + 0u);
          float dy0 = colr.ResolveDelta(processor, this.varIndexBase + 1u);
          float dx1 = colr.ResolveDelta(processor, this.varIndexBase + 2u);
          float dy1 = colr.ResolveDelta(processor, this.varIndexBase + 3u);

          float xMin = this.xMin + dx0;
          float yMin = this.yMin + dy0;
          float xMax = this.xMax + dx1;
          float yMax = this.yMax + dy1;

          return new Bounds(xMin, yMin, xMax, yMax);
      }
  }
}