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

using System.Collections.Generic;
using System.Numerics;
using SixLabors.Fonts;
using SixLabors.Fonts.Rendering;

namespace SixLabors.ImageSharp.Drawing.Text {
  /// <summary>
  /// Builds vector shapes from text using the provided layout and rendering options.
  /// </summary>
  public static class TextBuilder
  {
      /// <summary>
      /// Generates the combined outline paths for all rendered glyphs in <paramref name="text"/>.
      /// The result merges per-glyph outlines into a single <see cref="IPathCollection"/> suitable for filling or stroking as one unit.
      /// </summary>
      /// <param name="text">The text to shape and render.</param>
      /// <param name="textOptions">The text rendering and layout options.</param>
      /// <returns>The combined <see cref="IPathCollection"/> for the rendered glyphs.</returns>
      public static IPathCollection GeneratePaths(string text, TextOptions textOptions)
      {
          GlyphBuilder glyphBuilder = new();
          TextRenderer renderer = new(glyphBuilder);

          renderer.RenderText(text, textOptions);

          return glyphBuilder.Paths;
      }

      /// <summary>
      /// Generates per-glyph path data and metadata for the rendered <paramref name="text"/>.
      /// Each entry contains the combined outline paths for a glyph and associated metadata that enables intelligent fill or stroke decisions at the glyph level.
      /// </summary>
      /// <param name="text">The text to shape and render.</param>
      /// <param name="textOptions">The text rendering and layout options.</param>
      /// <returns>A read-only list of <see cref="GlyphPathCollection"/> entries, one for each rendered glyph.</returns>
      public static IReadOnlyList<GlyphPathCollection> GenerateGlyphs(string text, TextOptions textOptions)
      {
          GlyphBuilder glyphBuilder = new();
          TextRenderer renderer = new(glyphBuilder);

          renderer.RenderText(text, textOptions);

          return glyphBuilder.Glyphs;
      }

      /// <summary>
      /// Generates the combined outline paths for all rendered glyphs in <paramref name="text"/>,
      /// laid out along the supplied <paramref name="path"/> baseline.
      /// The result merges per-glyph outlines into a single <see cref="IPathCollection"/>.
      /// </summary>
      /// <param name="text">The text to shape and render.</param>
      /// <param name="path">The path that defines the text baseline.</param>
      /// <param name="textOptions">The text rendering and layout options.</param>
      /// <returns>The combined <see cref="IPathCollection"/> for the rendered glyphs.</returns>
      public static IPathCollection GeneratePaths(string text, IPath path, TextOptions textOptions)
      {
          (IPath Path, TextOptions TextOptions) transformed = ConfigureOptions(textOptions, path);
          PathGlyphBuilder glyphBuilder = new(transformed.Path);
          TextRenderer renderer = new(glyphBuilder);

          renderer.RenderText(text, transformed.TextOptions);

          return glyphBuilder.Paths;
      }

      /// <summary>
      /// Generates per-glyph path data and metadata for the rendered <paramref name="text"/>,
      /// laid out along the supplied <paramref name="path"/> baseline.
      /// Each entry contains the combined outline paths for a glyph and associated metadata.
      /// </summary>
      /// <param name="text">The text to shape and render.</param>
      /// <param name="path">The path that defines the text baseline.</param>
      /// <param name="textOptions">The text rendering and layout options.</param>
      /// <returns>A read-only list of <see cref="GlyphPathCollection"/> entries, one for each rendered glyph.</returns>
      public static IReadOnlyList<GlyphPathCollection> GenerateGlyphs(string text, IPath path, TextOptions textOptions)
      {
          (IPath Path, TextOptions TextOptions) transformed = ConfigureOptions(textOptions, path);
          PathGlyphBuilder glyphBuilder = new(transformed.Path);
          TextRenderer renderer = new(glyphBuilder);

          renderer.RenderText(text, transformed.TextOptions);

          return glyphBuilder.Glyphs;
      }

      private static (IPath Path, TextOptions TextOptions) ConfigureOptions(TextOptions options, IPath path)
      {
          // When a path is specified we should explicitly follow that path
          // and not adjust the origin. Any translation should be applied to the path.
          if (options.Origin != Vector2.Zero)
          {
              TextOptions clone = new(options)
              {
                  Origin = Vector2.Zero
              };

              return (path.Translate(options.Origin), clone);
          }

          return (path, options);
      }
  }
}