Arbitrary Webhook for NotificationConnectors

Backend only deals in REST Webhooks
The API has custom Endpoints for Ntfy, Gotify, Lunasea that create pre-formatted Webhooks
#297 #259

API/Schema/NotificationConnectors/NotificationConnector.cs

@@ -1,20 +1,65 @@
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
+using System.Text;
 using Microsoft.EntityFrameworkCore;
 using Newtonsoft.Json;
 
 namespace API.Schema.NotificationConnectors;
 
-[PrimaryKey("NotificationConnectorId")]
-public abstract class NotificationConnector(string notificationConnectorId, NotificationConnectorType notificationConnectorType)
+[PrimaryKey("Name")]
+public class NotificationConnector(string name, string url, Dictionary<string, string> headers, string httpMethod, string body)
 {
     [MaxLength(64)]
-    public string NotificationConnectorId { get; } = notificationConnectorId;
-    public NotificationConnectorType NotificationConnectorType { get; init; } = notificationConnectorType;
+    public string Name { get; init; } = name;
     
+    public string Url { get; internal set; } = url;
+
+    public Dictionary<string, string> Headers { get; internal set; } = headers;
+
+    public string HttpMethod { get; internal set; } = httpMethod;
+
+    public string Body { get; internal set; } = body;
+
     [JsonIgnore]
     [NotMapped]
-    protected readonly HttpClient _client = new();
-    
-    public abstract void SendNotification(string title, string notificationText);
+    private readonly HttpClient Client = new()
+    {
+        DefaultRequestHeaders = { { "User-Agent", TrangaSettings.userAgent } }
+    };
+
+    public void SendNotification(string title, string notificationText)
+    {
+        CustomWebhookFormatProvider formatProvider = new CustomWebhookFormatProvider(title, notificationText);
+        string formattedUrl = string.Format(formatProvider, Url);
+        string formattedBody = string.Format(formatProvider, Body, title, notificationText);
+        Dictionary<string, string> formattedHeaders = Headers.ToDictionary(h => h.Key, 
+            h => string.Format(formatProvider, h.Value, title, notificationText));
+
+        HttpRequestMessage request = new(System.Net.Http.HttpMethod.Parse(HttpMethod), formattedUrl);
+        foreach (var (key, value) in formattedHeaders)
+            request.Headers.Add(key, value);
+        request.Content = new StringContent(formattedBody);
+
+        HttpResponseMessage response = Client.Send(request);
+    }
+
+    private class CustomWebhookFormatProvider(string title, string text) : IFormatProvider
+    {
+        public object? GetFormat(Type? formatType)
+        {
+            return this;
+        }
+
+        public string Format(string fmt, object arg, IFormatProvider provider)
+        {
+            if(arg.GetType() != typeof(string))
+                return arg.ToString() ?? string.Empty;
+
+            StringBuilder sb = new StringBuilder(fmt);
+            sb.Replace("%title", title);
+            sb.Replace("%text", text);
+            
+            return sb.ToString();
+        }
+    }
 }