more work on api & rename to Pilz.Net

Pilz.Net/Api/ApiServer.cs

@@ -0,0 +1,176 @@
+using Pilz.Extensions.Reflection;
+using System.Net;
+using System.Reflection;
+using static Pilz.Net.Api.IApiServer;
+
+namespace Pilz.Net.Api;
+
+public class ApiServer(string apiUrl) : IApiServer
+{
+    protected readonly Dictionary<string, Delegate> handlers = [];
+    protected readonly Dictionary<Type, IMessageSerializer> serializers = [];
+    protected readonly HttpListener httpListener = new();
+
+    public event OnCheckAuthenticationEventHandler? OnCheckAuthentication;
+
+    protected record PrivateApiResult(ApiResult Original, string? ResultJson);
+
+    public string ApiUrl { get; } = apiUrl;
+
+    public virtual bool EnableAuth { get; set; }
+
+    public IMessageSerializer Serializer { get; set; } = new DefaultMessageSerializer();
+
+    public virtual void Start()
+    {
+        httpListener.Start();
+        Listen();
+    }
+
+    public virtual void Stop()
+    {
+        httpListener.Stop();
+    }
+
+    public virtual void RegisterHandler<T>(T instance) where T : class
+    {
+        // Get all public instance methods
+        var methods = typeof(T).GetMethods(BindingFlags.Instance | BindingFlags.Public);
+
+        // Register each method
+        foreach (var method in methods)
+            RegisterHandler(method.CreateDelegate(instance));
+    }
+
+    public virtual void RegisterHandler(Delegate handler)
+    {
+        var method = handler.Method;
+
+        // Sanity checks
+        if (method.GetCustomAttribute<MessageHandlerAttribute>() is not MessageHandlerAttribute attribute
+            || method.GetParameters().FirstOrDefault() is not ParameterInfo parameter
+            || !parameter.ParameterType.IsAssignableTo(typeof(ApiMessage))
+            || !method.ReturnType.IsAssignableTo(typeof(ApiResult)))
+            throw new NotSupportedException("The first parameter needs to be of type ApiMessage and must return an ApiResult object and the method must have the MessageHandlerAttribute.");
+
+        // Add handler
+        handlers.Add(ApiUrl + attribute.Route, handler);
+    }
+
+    protected virtual void Listen()
+    {
+        while (httpListener.IsListening)
+            CheckContext();
+    }
+
+    protected virtual void CheckContext()
+    {
+        var context = httpListener.GetContext();
+        void close() => context.Response.OutputStream.Close();
+
+        if (context.Request.HttpMethod != HttpMethod.Post.Method
+            || context.Request.ContentType is not string contentType
+            || !contentType.Contains("application/json"))
+        {
+            close();
+            return;
+        }
+
+        // Parse url
+        var path = context.Request.Url?.PathAndQuery.Replace(ApiUrl, string.Empty);
+        if (string.IsNullOrWhiteSpace(path) || context.Request.ContentLength64 <= 0)
+        {
+            close();
+            return;
+        }
+
+        // Read input content
+        using StreamReader input = new(context.Request.InputStream);
+        var contentJson = input.ReadToEnd();
+
+        // Get auth key
+        if (context.Request.Headers.Get("API-AUTH-KEY") is not string authKey)
+            authKey = null!;
+
+        // Handle message
+        if (HandleMessage(path, contentJson, authKey) is not PrivateApiResult result)
+        {
+            close();
+            return;
+        }
+
+        // Set response parameters
+        context.Response.StatusCode = (int)result.Original.StatusCode;
+
+        // Write response content
+        if (result.ResultJson is not null)
+        {
+            context.Response.ContentType = "application/json";
+            using StreamWriter output = new(context.Response.OutputStream);
+            output.Write(result);
+        }
+
+        close();
+    }
+
+    protected virtual PrivateApiResult? HandleMessage(string url, string json, string? authKey)
+    {
+        // Get handler
+        if (!handlers.TryGetValue(url, out var handler)
+            || handler.Method.GetCustomAttribute<MessageHandlerAttribute>() is not MessageHandlerAttribute attribute)
+            return null;
+
+        // Check authentication
+        if (attribute.RequiesAuth && (string.IsNullOrWhiteSpace(authKey) || !CheckAuthentication(authKey)))
+            return null;
+
+        // Get required infos
+        var targetType = handler.Method.GetParameters().First().ParameterType;
+        var serializer = GetSerializer(attribute.Serializer);
+
+        // Deserialize
+        if (serializer.Deserialize(json, targetType) is not ApiMessage message)
+            return null;
+
+        // Invoke handler
+        if (handler.DynamicInvoke(message) is not ApiResult result)
+            return null;
+
+        // Return result without message
+        if (result.Message is null)
+            return new(result, null);
+
+        // Serializer
+        if (serializer.Serialize(result.Message) is not string resultStr)
+            return null;
+
+        // Return result with message
+        return new(result, resultStr);
+    }
+
+    protected virtual IMessageSerializer GetSerializer(Type? t)
+    {
+        if (t is not null)
+        {
+            if (serializers.TryGetValue(t, out var s) && s is not null)
+                return s;
+            else if (Activator.CreateInstance(t) is IMessageSerializer ss)
+            {
+                serializers.Add(t, ss);
+                return ss;
+            }
+        }
+        return Serializer;
+    }
+
+    protected virtual bool CheckAuthentication(string authKey)
+    {
+        if (OnCheckAuthentication != null)
+        {
+            var args = new ApiAuthCheckEventArgs(authKey);
+            OnCheckAuthentication?.Invoke(this, args);
+            return args.Valid;
+        }
+        return false;
+    }
+}