/*
 * Copyright (c) 2026 James Maes (KofTwentyTwo)
 * SPDX-License-Identifier: MIT
 */

using System.Globalization;
using System.IO;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using KofTwentyTwo.AppKit;


namespace BrandTool;

/// <summary>
/// brandtool --out &lt;dir&gt; [--start #RRGGBB] [--end #RRGGBB] [--glyph "&lt;svg path data&gt;"] [--stroke 56]
/// Writes app-icon.svg and app.ico (16..256 px PNG frames) into &lt;dir&gt;.
/// </summary>
internal static class Program
{
   private const double Box = 512;
   private const double TileInset = 48;
   private const double TileRadius = 104;
   private static readonly int[] s_iconSizes = [16, 20, 24, 32, 40, 48, 64, 128, 256];



   /// <summary>Entry point: reads the options, then writes app-icon.svg and a multi-size app.ico to the output folder.</summary>
   [STAThread]
   private static int Main(string[] args)
   {
      Dictionary<string, string> options = Parse(args);
      if(!options.TryGetValue("out", out string? outDir))
      {
         Console.Error.WriteLine("usage: brandtool --out <dir> [--start #RRGGBB] [--end #RRGGBB] [--glyph \"<path data>\"] [--stroke <width>]");
         return 2;
      }

      var spec = new MarkSpec(
          options.GetValueOrDefault("start", "#3B4CCA"),
          options.GetValueOrDefault("end", "#2A2F8F"),
          options.GetValueOrDefault("glyph", "M 200 152 L 312 256 L 200 360"),
          double.Parse(options.GetValueOrDefault("stroke", "56"), CultureInfo.InvariantCulture));

      Directory.CreateDirectory(outDir);
      File.WriteAllText(Path.Combine(outDir, "app-icon.svg"), Svg(spec));
      WriteIco(Path.Combine(outDir, "app.ico"), s_iconSizes.Select(size => Png(spec, size)).ToList(), s_iconSizes);
      Console.WriteLine($"Wrote app-icon.svg and app.ico to {Path.GetFullPath(outDir)}");
      return 0;
   }



   /// <summary>Parses --name value pairs into a case-insensitive dictionary.</summary>
   private static Dictionary<string, string> Parse(string[] args)
   {
      var options = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
      for(int i = 0; i + 1 < args.Length; i += 2)
      {
         options[args[i].TrimStart('-')] = args[i + 1];
      }
      return options;
   }



   /// <summary>The mark as SVG text: the rounded gradient tile and the white stroked glyph.</summary>
   private static string Svg(MarkSpec spec)
       => $"""
            <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" width="512" height="512">
              <!-- Generated by AppKit BrandTool. Transparent outside the rounded tile. -->
              <defs>
                <linearGradient id="tile" x1="0" y1="0" x2="1" y2="1">
                  <stop offset="0" stop-color="{spec.Start}" />
                  <stop offset="1" stop-color="{spec.End}" />
                </linearGradient>
              </defs>
              <rect x="{TileInset}" y="{TileInset}" width="{Box - 2 * TileInset}" height="{Box - 2 * TileInset}" rx="{TileRadius}" fill="url(#tile)" />
              <path d="{spec.Glyph}" fill="none" stroke="#FFFFFF" stroke-width="{spec.Stroke.ToString(CultureInfo.InvariantCulture)}" stroke-linecap="round" stroke-linejoin="round" />
            </svg>

            """;



   /// <summary>Renders the mark with WPF as a PNG of the given pixel size.</summary>
   private static byte[] Png(MarkSpec spec, int size)
   {
      var visual = new DrawingVisual();
      using(DrawingContext context = visual.RenderOpen())
      {
         double scale = size / Box;
         context.PushTransform(new ScaleTransform(scale, scale));
         var gradient = new LinearGradientBrush(ToColor(spec.Start), ToColor(spec.End), new Point(0, 0), new Point(1, 1));
         context.DrawRoundedRectangle(gradient, null, new Rect(TileInset, TileInset, Box - 2 * TileInset, Box - 2 * TileInset), TileRadius, TileRadius);
         var pen = new Pen(Brushes.White, spec.Stroke) { StartLineCap = PenLineCap.Round, EndLineCap = PenLineCap.Round, LineJoin = PenLineJoin.Round };
         context.DrawGeometry(null, pen, Geometry.Parse(spec.Glyph));
      }

      var bitmap = new RenderTargetBitmap(size, size, 96, 96, PixelFormats.Pbgra32);
      bitmap.Render(visual);
      var encoder = new PngBitmapEncoder();
      encoder.Frames.Add(BitmapFrame.Create(bitmap));
      using var stream = new MemoryStream();
      encoder.Save(stream);
      return stream.ToArray();
   }



   /// <summary>Writes an .ico whose frames are embedded PNGs (supported since Windows Vista).</summary>
   private static void WriteIco(string path, List<byte[]> pngs, int[] sizes)
   {
      using var writer = new BinaryWriter(File.Create(path));
      writer.Write((ushort)0);           // reserved
      writer.Write((ushort)1);           // type: icon
      writer.Write((ushort)pngs.Count);
      int offset = 6 + 16 * pngs.Count;
      for(int i = 0; i < pngs.Count; i++)
      {
         writer.Write((byte)(sizes[i] >= 256 ? 0 : sizes[i])); // 0 means 256
         writer.Write((byte)(sizes[i] >= 256 ? 0 : sizes[i]));
         writer.Write((byte)0);         // palette
         writer.Write((byte)0);         // reserved
         writer.Write((ushort)1);       // planes
         writer.Write((ushort)32);      // bits per pixel
         writer.Write(pngs[i].Length);
         writer.Write(offset);
         offset += pngs[i].Length;
      }
      foreach(byte[] png in pngs)
      {
         writer.Write(png);
      }
   }



   /// <summary>Parses a #RRGGBB or #AARRGGBB string into a WPF color.</summary>
   private static Color ToColor(string hex)
   {
      var color = ArgbColor.Parse(hex);
      return Color.FromArgb(color.A, color.R, color.G, color.B);
   }



   /// <summary>The mark definition: gradient colors, the glyph's SVG path data, and its stroke width.</summary>
   private sealed record MarkSpec(string Start, string End, string Glyph, double Stroke);
}