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

using System.IO;

namespace SixLabors.Fonts.Tables.AdvancedTypographic.GPos {
  /// <summary>
  /// Each LigatureAttach table consists of an array (componentRecords) and count (componentCount) of the component glyphs in a ligature.
  /// The array stores the ComponentRecords in the same order as the components in the ligature.
  /// The order of the records also corresponds to the writing direction — that is, the logical direction — of the text.
  /// For text written left to right, the first component is on the left; for text written right to left, the first component is on the right.
  /// </summary>
  internal class LigatureAttachTable
  {
      /// <summary>
      /// Initializes a new instance of the <see cref="LigatureAttachTable"/> class.
      /// </summary>
      /// <param name="reader">The big endian binary reader.</param>
      /// <param name="markClassCount">Number of defined mark classes.</param>
      /// <param name="offset">Offset from beginning of LigatureAttach table.</param>
      public LigatureAttachTable(BigEndianBinaryReader reader, ushort markClassCount, long offset)
      {
          // +-------------------+---------------------------------+--------------------------------------------------------------------------------------+
          // | Type              | Name                            | Description                                                                          |
          // +===================+=================================+======================================================================================+
          // | uint16            | componentCount                  | Number of ComponentRecords in this ligature.                                         |
          // +-------------------+---------------------------------+--------------------------------------------------------------------------------------+
          // | ComponentRecords  | componentRecords[componentCount]| Array of Component records, ordered in writing direction.                            |
          // +-------------------+---------------------------------+--------------------------------------------------------------------------------------+
          reader.Seek(offset, SeekOrigin.Begin);
          ushort componentCount = reader.ReadUInt16();
          this.ComponentRecords = new ComponentRecord[componentCount];
          for (int i = 0; i < componentCount; i++)
          {
              this.ComponentRecords[i] = new ComponentRecord(reader, markClassCount, offset);
          }
      }

      /// <summary>
      /// Gets the array of component records for this ligature, ordered in writing direction.
      /// </summary>
      public ComponentRecord[] ComponentRecords { get; }
  }
}