Started implementing modular payment gateways. Implemented a basic plugin system

TODO: Add capability for plugins to modify the kestrel pipeline

Moonlight/App/Services/PluginService.cs

@@ -0,0 +1,120 @@
+using System.Reflection;
+using Moonlight.App.Helpers;
+using Moonlight.App.Plugins;
+using Moonlight.App.Plugins.Contexts;
+
+namespace Moonlight.App.Services;
+
+public class PluginService
+{
+    private readonly List<MoonlightPlugin> Plugins = new();
+
+    public async Task Load(IServiceCollection services)
+    {
+        var path = PathBuilder.Dir("storage", "plugins");
+        Directory.CreateDirectory(path);
+
+        var files = FindFiles(path)
+            .Where(x => x.EndsWith(".dll"))
+            .ToArray();
+
+        foreach (var file in files)
+        {
+            try
+            {
+                var assembly = Assembly.LoadFile(PathBuilder.File(Directory.GetCurrentDirectory(), file));
+
+                int plugins = 0;
+                foreach (var type in assembly.GetTypes())
+                {
+                    if (type.IsSubclassOf(typeof(MoonlightPlugin)))
+                    {
+                        try
+                        {
+                            var plugin = (Activator.CreateInstance(type) as MoonlightPlugin)!;
+
+                            // Create environment
+                            plugin.Context = new PluginContext()
+                            {
+                                Services = services
+                            };
+
+                            try
+                            {
+                                await plugin.Enable();
+                                
+                                // After here we can treat the plugin as successfully loaded
+                                plugins++;
+                                Plugins.Add(plugin);
+                            }
+                            catch (Exception e)
+                            {
+                                Logger.Fatal($"Unhandled exception while enabling plugin '{type.Name}'");
+                                Logger.Fatal(e);
+                            }
+                        }
+                        catch (Exception e)
+                        {
+                            Logger.Fatal($"Failed to create plugin environment for '{type.Name}'");
+                            Logger.Fatal(e);
+                        }
+                    }
+                }
+                
+                if(plugins == 0) // If 0, we can assume that it was a library dll
+                    Logger.Info($"Loaded {file} as a library");
+                else
+                    Logger.Info($"Loaded {plugins} plugin(s) from {file}");
+            }
+            catch (Exception e)
+            {
+                Logger.Fatal($"Unable to load assembly from file '{file}'");
+                Logger.Fatal(e);
+            }
+        }
+        
+        Logger.Info($"Loaded {Plugins.Count} plugin(s)");
+    }
+
+    public async Task RunPreInit()
+    {
+        foreach (var plugin in Plugins)
+        {
+            Logger.Info($"Running pre init tasks for {plugin.GetType().Name}");
+
+            foreach (var preInitTask in plugin.Context.PreInitTasks)
+                await Task.Run(preInitTask);
+        }
+    }
+    
+    public async Task RunPrePost(IServiceProvider provider)
+    {
+        foreach (var plugin in Plugins)
+        {
+            // Pass through the dependency injection
+            var scope = provider.CreateScope();
+            plugin.Context.Provider = scope.ServiceProvider;
+            plugin.Context.Scope = scope;
+            
+            Logger.Info($"Running post init tasks for {plugin.GetType().Name}");
+
+            foreach (var postInitTask in plugin.Context.PostInitTasks)
+                await Task.Run(postInitTask);
+        }
+    }
+
+    private string[] FindFiles(string dir)
+    {
+        var result = new List<string>();
+
+        foreach (var file in Directory.GetFiles(dir))
+            result.Add(file);
+
+        foreach (var directory in Directory.GetDirectories(dir))
+        {
+            result.AddRange(FindFiles(directory));
+        }
+
+        return result.ToArray();
+    }
+}