Add Generator command to generate emoji lookup table

resources/scripts/Generator/Commands/EmojiGeneratorCommand.cs

@@ -0,0 +1,83 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+using AngleSharp.Html.Parser;
+using Generator.Models;
+using Scriban;
+using Scriban.Runtime;
+using Spectre.Cli;
+using Spectre.IO;
+using Path = Spectre.IO.Path;
+
+namespace Generator.Commands
+{
+    public sealed class EmojiGeneratorCommand : AsyncCommand<GeneratorCommandSettings>
+    {
+        private readonly IFileSystem _fileSystem;
+
+        private readonly IHtmlParser _parser;
+
+        public EmojiGeneratorCommand()
+        {
+            _fileSystem = new FileSystem();
+            _parser = new HtmlParser();
+        }
+
+        public override async Task<int> ExecuteAsync(CommandContext context, GeneratorCommandSettings settings)
+        {
+            var output = new DirectoryPath(settings.Output);
+
+            if (!_fileSystem.Directory.Exists(settings.Output))
+            {
+                _fileSystem.Directory.Create(settings.Output);
+            }
+
+            var templatePath = new FilePath("Templates/Emoji.Generated.template");
+
+            var emojis = await FetchEmojis("http://www.unicode.org/emoji/charts/emoji-list.html");
+
+            var result = await RenderTemplate(templatePath, emojis);
+
+            var outputPath = output.CombineWithFilePath(templatePath.GetFilename().ChangeExtension(".cs"));
+
+            await File.WriteAllTextAsync(outputPath.FullPath, result);
+
+            return 0;
+        }
+
+        private async Task<IReadOnlyCollection<Emoji>> FetchEmojis(string url)
+        {
+            using var http = new HttpClient();
+
+            var htmlStream = await http.GetStreamAsync(url);
+
+            var document = await _parser.ParseDocumentAsync(htmlStream);
+
+            return Emoji.Parse(document).OrderBy(x => x.Name).ToList();
+        }
+
+        private static async Task<string> RenderTemplate(Path path, IReadOnlyCollection<Emoji> emojis)
+        {
+            var text = await File.ReadAllTextAsync(path.FullPath);
+
+            var template = Template.Parse(text);
+
+            var templateContext = new TemplateContext
+            {
+                // Because of the insane amount of Emojis,
+                // we need to get rid of some secure defaults :P
+                LoopLimit = int.MaxValue,
+            };
+
+            var scriptObject = new ScriptObject();
+
+            scriptObject.Import(new { Emojis = emojis });
+
+            templateContext.PushGlobal(scriptObject);
+
+            return await template.RenderAsync(templateContext);
+        }
+    }
+}