Large refactor and project restructuring

PluralKit.API/Services/TokenAuthService.cs

@@ -0,0 +1,38 @@
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+
+using PluralKit.Core;
+
+namespace PluralKit.API
+{
+    public class TokenAuthService: IMiddleware
+    {
+        public PKSystem CurrentSystem { get; set; }
+
+        private IDataStore _data;
+
+        public TokenAuthService(IDataStore data)
+        {
+            _data = data;
+        }
+
+        public async Task InvokeAsync(HttpContext context, RequestDelegate next)
+        {
+            var token = context.Request.Headers["Authorization"].FirstOrDefault();
+            if (token != null)
+            {
+                CurrentSystem = await _data.GetSystemByToken(token);
+            }
+            
+            await next.Invoke(context);
+            CurrentSystem = null;
+        }
+
+        public LookupContext ContextFor(PKSystem system) => 
+            system.Id == CurrentSystem?.Id ? LookupContext.ByOwner : LookupContext.API;
+            
+        public LookupContext ContextFor(PKMember member) => 
+            member.System == CurrentSystem?.Id ? LookupContext.ByOwner : LookupContext.API;
+    }
+}