Expose LND's other macaroon if possible

BTCPayServer/Controllers/Macaroons.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace BTCPayServer.Controllers
+{
+    public class Macaroons
+    {
+        public class Macaroon
+        {
+            public Macaroon(byte[] bytes)
+            {
+                Bytes = bytes;
+                Hex = NBitcoin.DataEncoders.Encoders.Hex.EncodeData(bytes);
+            }
+
+            public string Hex { get; set; }
+            public byte[] Bytes { get; set; }
+        }
+        public static async Task<Macaroons> GetFromDirectoryAsync(string directoryPath)
+        {
+            if (directoryPath == null)
+                throw new ArgumentNullException(nameof(directoryPath));
+            Macaroons macaroons = new Macaroons();
+            if (!Directory.Exists(directoryPath))
+                return macaroons;
+            foreach(var file in Directory.GetFiles("*.macaroon"))
+            {
+                try
+                {
+                    switch (Path.GetFileName(file))
+                    {
+                        case "admin.macaroon":
+                            macaroons.AdminMacaroon = new Macaroon(await File.ReadAllBytesAsync(file));
+                            break;
+                        case "readonly.macaroon":
+                            macaroons.ReadonlyMacaroon = new Macaroon(await File.ReadAllBytesAsync(file));
+                            break;
+                        case "invoice.macaroon":
+                            macaroons.InvoiceMacaroon = new Macaroon(await File.ReadAllBytesAsync(file));
+                            break;
+                        default:
+                            break;
+                    }
+                }
+                catch { }
+            }
+            return macaroons;
+        }
+        public Macaroon ReadonlyMacaroon { get; set; }
+
+        public Macaroon InvoiceMacaroon { get; set; }
+        public Macaroon AdminMacaroon { get; set; }
+    }
+}