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

using System;

namespace SixLabors.Fonts {
  /// <summary>
  /// Extension methods for <see cref="IFontCollection"/>.
  /// </summary>
  public static class FontCollectionExtensions
  {
      /// <summary>
      /// Adds the fonts from the <see cref="SystemFonts"/> collection to this <see cref="FontCollection"/>.
      /// </summary>
      /// <param name="collection">The font collection.</param>
      /// <returns>The <see cref="FontCollection"/> containing the system fonts.</returns>
      public static FontCollection AddSystemFonts(this FontCollection collection)
      {
          // This cast is safe because our underlying SystemFontCollection implements
          // both interfaces separately.
          foreach (FontMetrics metric in (IReadOnlyFontMetricsCollection)SystemFonts.Collection)
          {
              ((IFontMetricsCollection)collection).AddMetrics(metric);
          }

          collection.AddSearchDirectories(SystemFonts.Collection.SearchDirectories);

          return collection;
      }

      /// <summary>
      /// Adds the fonts from the <see cref="SystemFonts"/> collection to this <see cref="FontCollection"/>.
      /// </summary>
      /// <param name="collection">The font collection.</param>
      /// <param name="match">The <see cref="Predicate{T}"/> delegate that defines the conditions of <see cref="FontMetrics"/> to add into the font collection.</param>
      /// <returns>The <see cref="FontCollection"/> containing the system fonts.</returns>
      public static FontCollection AddSystemFonts(this FontCollection collection, Predicate<FontMetrics> match)
      {
          bool isMatch = false;
          foreach (FontMetrics metric in (IReadOnlyFontMetricsCollection)SystemFonts.Collection)
          {
              bool currentMatch = match(metric);
              isMatch |= currentMatch;
              if (currentMatch)
              {
                  ((IFontMetricsCollection)collection).AddMetrics(metric);
              }
          }

          if (isMatch)
          {
              collection.AddSearchDirectories(SystemFonts.Collection.SearchDirectories);
          }

          return collection;
      }
  }
}