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

using System.IO;

namespace SixLabors.Fonts.Tables.AdvancedTypographic.GPos {
  /// <summary>
  /// Represents the BaseArray table used in MarkToBase attachment positioning (GPOS LookupType 4).
  /// The BaseArray table contains an array of BaseRecords, one for each base glyph, ordered by the base Coverage index.
  /// <see href="https://learn.microsoft.com/en-us/typography/opentype/spec/gpos#mark-to-base-attachment-positioning-format-1-mark-to-base-attachment-point"/>
  /// </summary>
  internal class BaseArrayTable
  {
      /// <summary>
      /// Initializes a new instance of the <see cref="BaseArrayTable"/> class.
      /// </summary>
      /// <param name="reader">The big endian binary reader.</param>
      /// <param name="offset">The offset to the beginning of the base array table.</param>
      /// <param name="classCount">The class count.</param>
      public BaseArrayTable(BigEndianBinaryReader reader, long offset, ushort classCount)
      {
          // +--------------+------------------------+--------------------------------------------------------------------------------------+
          // | Type         | Name                   | Description                                                                          |
          // +==============+========================+======================================================================================+
          // | uint16       | baseCount              | Number of BaseRecords                                                                |
          // +--------------+------------------------+--------------------------------------------------------------------------------------+
          // | BaseRecord   | baseRecords[baseCount] | Array of BaseRecords, in order of baseCoverage Index.                                |
          // +--------------+------------------------+--------------------------------------------------------------------------------------+
          reader.Seek(offset, SeekOrigin.Begin);
          ushort baseCount = reader.ReadUInt16();
          this.BaseRecords = new BaseRecord[baseCount];
          for (int i = 0; i < baseCount; i++)
          {
              this.BaseRecords[i] = new BaseRecord(reader, classCount, offset);
          }
      }

      /// <summary>
      /// Gets the base records.
      /// </summary>
      public BaseRecord[] BaseRecords { get; }
  }
}