Move SyncPlay api to Jellyfin.Api

Jellyfin.Api/Controllers/TimeSyncController.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Globalization;
+using MediaBrowser.Model.SyncPlay;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Jellyfin.Api.Controllers
+{
+    /// <summary>
+    /// The time sync controller.
+    /// </summary>
+    [Route("/GetUtcTime")]
+    public class TimeSyncController : BaseJellyfinApiController
+    {
+        /// <summary>
+        /// Gets the current utc time.
+        /// </summary>
+        /// <response code="200">Time returned.</response>
+        /// <returns>An <see cref="UtcTimeResponse"/> to sync the client and server time.</returns>
+        [HttpGet]
+        [ProducesResponseType(statusCode: StatusCodes.Status200OK)]
+        public ActionResult<UtcTimeResponse> GetUtcTime()
+        {
+            // Important to keep the following line at the beginning
+            var requestReceptionTime = DateTime.UtcNow.ToUniversalTime().ToString("o", DateTimeFormatInfo.InvariantInfo);
+
+            var response = new UtcTimeResponse();
+            response.RequestReceptionTime = requestReceptionTime;
+
+            // Important to keep the following two lines at the end
+            var responseTransmissionTime = DateTime.UtcNow.ToUniversalTime().ToString("o", DateTimeFormatInfo.InvariantInfo);
+            response.ResponseTransmissionTime = responseTransmissionTime;
+
+            // Implementing NTP on such a high level results in this useless
+            // information being sent. On the other hand it enables future additions.
+            return response;
+        }
+    }
+}