TweetDuck/lib/TweetLib.Core/Features/Plugins/PluginLoader.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using TweetLib.Core.Features.Plugins.Enums;
using TweetLib.Utils.Data;

namespace TweetLib.Core.Features.Plugins {
	static class PluginLoader {
		private static readonly string[] EndTag = { "[END]" };

		public static IEnumerable<Result<Plugin>> AllInFolder(string pluginFolder, string pluginDataFolder, PluginGroup group) {
			string path = Path.Combine(pluginFolder, group.GetSubFolder());

			if (!Directory.Exists(path)) {
				yield break;
			}

			foreach (string fullDir in Directory.EnumerateDirectories(path, "*", SearchOption.TopDirectoryOnly)) {
				string name = Path.GetFileName(fullDir);
				string prefix = group.GetIdentifierPrefix();

				if (string.IsNullOrEmpty(name)) {
					yield return new Result<Plugin>(new DirectoryNotFoundException($"{prefix}(?): Could not extract directory name from path: {fullDir}"));
					continue;
				}

				Result<Plugin> result;

				try {
					result = new Result<Plugin>(FromFolder(name, fullDir, Path.Combine(pluginDataFolder, prefix, name), group));
				} catch (Exception e) {
					result = new Result<Plugin>(new Exception($"{prefix}{name}: {e.Message}", e));
				}

				yield return result;
			}
		}

		private static Plugin FromFolder(string name, string pathRoot, string pathData, PluginGroup group) {
			Plugin.Builder builder = new Plugin.Builder(group, name, pathRoot, pathData);

			foreach (var environment in Directory.EnumerateFiles(pathRoot, "*.js", SearchOption.TopDirectoryOnly).Select(Path.GetFileName).Select(EnvironmentFromFileName!)) {
				builder.AddEnvironment(environment);
			}

			string metaFile = Path.Combine(pathRoot, ".meta");

			if (!File.Exists(metaFile)) {
				throw new ArgumentException("Plugin is missing a .meta file.");
			}

			string? currentTag = null;
			string currentContents = string.Empty;

			foreach (string line in File.ReadAllLines(metaFile, Encoding.UTF8).Concat(EndTag).Select(static line => line.TrimEnd()).Where(static line => line.Length > 0)) {
				if (line[0] == '[' && line[^1] == ']') {
					if (currentTag != null) {
						SetProperty(builder, currentTag, currentContents);
					}

					currentTag = line.Substring(1, line.Length - 2).ToUpper();
					currentContents = string.Empty;

					if (line.Equals(EndTag[0])) {
						break;
					}
				}
				else if (currentTag != null) {
					currentContents = currentContents.Length == 0 ? line : currentContents + Environment.NewLine + line;
				}
				else {
					throw new FormatException($"Missing metadata tag before value: {line}");
				}
			}

			return builder.BuildAndSetup();
		}

		private static PluginEnvironment EnvironmentFromFileName(string file) {
			return PluginEnvironments.All.FirstOrDefault(env => file.Equals(env.GetPluginScriptFile(), StringComparison.Ordinal));
		}

		private static void SetProperty(Plugin.Builder builder, string tag, string value) {
			switch (tag) {
				case "NAME":
					builder.Name = value;
					break;
				case "DESCRIPTION":
					builder.Description = value;
					break;
				case "AUTHOR":
					builder.Author = value;
					break;
				case "VERSION":
					builder.Version = value;
					break;
				case "WEBSITE":
					builder.Website = value;
					break;
				case "CONFIGFILE":
					builder.ConfigFile = value;
					break;
				case "CONFIGDEFAULT":
					builder.ConfigDefault = value;
					break;
				case "REQUIRES":
					builder.RequiredVersion = Version.TryParse(value, out var version) ? version : throw new FormatException($"Invalid required minimum version: {value}");
					break;
				default:
					throw new FormatException($"Invalid metadata tag: {tag}");
			}
		}
	}
}