Added first implementation of subscriptions

Moonlight/App/Services/OneTimeJwtService.cs

@@ -0,0 +1,109 @@
+using System.Text;
+using JWT.Algorithms;
+using JWT.Builder;
+using Moonlight.App.Exceptions;
+using Moonlight.App.Helpers;
+using Moonlight.App.Repositories;
+
+namespace Moonlight.App.Services;
+
+public class OneTimeJwtService
+{
+    private readonly ConfigService ConfigService;
+    private readonly RevokeRepository RevokeRepository;
+
+    public OneTimeJwtService(ConfigService configService, RevokeRepository revokeRepository)
+    {
+        ConfigService = configService;
+        RevokeRepository = revokeRepository;
+    }
+
+    public string Generate(Action<Dictionary<string, string>> options, TimeSpan? validTime = null)
+    {
+        var opt = new Dictionary<string, string>();
+        options.Invoke(opt);
+
+        string secret = ConfigService
+            .GetSection("Moonlight")
+            .GetSection("Security")
+            .GetValue<string>("Token");
+
+        var id = StringHelper.GenerateString(16);
+        
+        var builder = JwtBuilder.Create()
+            .WithAlgorithm(new HMACSHA256Algorithm())
+            .WithSecret(secret)
+            .AddClaim("unique_id", id)
+            .AddClaim("iat", DateTimeOffset.Now.ToUnixTimeSeconds())
+            .AddClaim("nbf", DateTimeOffset.Now.AddSeconds(-10).ToUnixTimeSeconds())
+            .MustVerifySignature();
+
+        if (validTime == null)
+            builder = builder.AddClaim("exp", DateTimeOffset.Now.AddMinutes(10).ToUnixTimeSeconds());
+        else
+            builder = builder.AddClaim("exp", DateTimeOffset.Now.Add(validTime.Value));
+
+        foreach (var o in opt)
+        {
+            builder = builder.AddClaim(o.Key, o.Value);
+        }
+
+        return builder.Encode();
+    }
+
+    public Dictionary<string, string>? Validate(string token)
+    {
+        string secret = ConfigService
+            .GetSection("Moonlight")
+            .GetSection("Security")
+            .GetValue<string>("Token");
+
+        string json;
+        
+        try
+        {
+            json = JwtBuilder.Create()
+                .WithAlgorithm(new HMACSHA256Algorithm())
+                .WithSecret(secret)
+                .Decode(token);
+            
+            //TODO: Error handling, report signature errors
+        }
+        catch (Exception e)
+        {
+            return null;
+        }
+
+        var data = new ConfigurationBuilder().AddJsonStream(
+            new MemoryStream(Encoding.ASCII.GetBytes(json))
+        ).Build();
+
+        var id = data.GetValue<string>("unique_id");
+
+        if (RevokeRepository
+                .Get()
+                .FirstOrDefault(x => x.Identifier == id) != null)
+        {
+            throw new DisplayException("This token has been already used");
+        }
+
+        var opt = new Dictionary<string, string>();
+
+        foreach (var child in data.GetChildren())
+        {
+            opt.Add(child.Key, child.Value!);
+        }
+
+        return opt;
+    }
+
+    public void Revoke(string token)
+    {
+        var values = Validate(token);
+
+        RevokeRepository.Add(new()
+        {
+            Identifier = values["unique_id"]
+        });
+    }
+}