Update the sqlite provider to say it was retrieved from the persistent cache

AS1024.GeoFeed.Core.SqliteGeoFeedCache/GeoFeedSqliteCache.cs

@@ -58,7 +58,7 @@ namespace AS1024.GeoFeed.Core.GeoFeedSqliteLocalCache
             List<IPGeoFeed> cachedData = [];
             results.ForEach(cachedData.Add);
 
-            return cachedData.ToGeoFeedCsv();
+            return cachedData.ToGeoFeedCsv(true, true);
         }
 
         private async Task DBContextMigrate()

AS1024.GeoFeed.Core/Tools/GeoFeedTools.cs

@@ -5,10 +5,23 @@ namespace AS1024.GeoFeed.Core.Tools
 {
     public static class GeoFeedTools
     {
-        public static string ToGeoFeedCsv(this List<IPGeoFeed> geoFeeds)
+        /// <summary>
+        /// Returns a CSV string for a given GeoFeed retreived from various sources
+        /// </summary>
+        /// <param name="geoFeeds">GeoFeed returned from the source of truth</param>
+        /// <param name="timeStamp">If a timestamp should be appended at the header</param>
+        /// <param name="isCached">If the result is cached</param>
+        /// <returns></returns>
+        public static string ToGeoFeedCsv(this List<IPGeoFeed> geoFeeds, bool timeStamp = false, bool isCached = false)
         {
             StringBuilder csvContent = new();
 
+            if (timeStamp)
+                csvContent.AppendLine($"# GeoFeed generated on {DateTime.UtcNow:R}");
+
+            if (isCached)
+                csvContent.AppendLine($"# Geofeed data is returned from local in memory cache");
+
             foreach (IPGeoFeed feed in geoFeeds)
             {
                 csvContent.AppendLine($"{feed.Prefix},{feed.GeolocCountry},{feed.GeolocRegion},{feed.GeolocCity},{feed.GeolocPostalCode}");

AS1024.GeoFeed.MinimalAPI/Program.cs

@@ -55,10 +55,12 @@ namespace AS1024.GeoFeed.MinimalAPI
                 IMemoryCache memoryCache,
                 IWebHostEnvironment environment)
         {
+            bool isCached = true;
             try
             {
                 if (!memoryCache.TryGetValue("Geofeed", out List<IPGeoFeed>? feed))
                 {
+                    isCached = false;
                     feed = await provider.GetGeoFeedData();
                     if (environment.IsProduction())
                     {
@@ -68,7 +70,7 @@ namespace AS1024.GeoFeed.MinimalAPI
                     }
                 }
 
-                return Results.File(Encoding.UTF8.GetBytes(feed.ToGeoFeedCsv()),
+                return Results.File(Encoding.UTF8.GetBytes(feed.ToGeoFeedCsv(true, isCached)),
                     "text/csv",
                     "geofeed.csv");
 

AS1024.GeoFeed/Controllers/GeofeedController.cs

@@ -36,10 +36,12 @@ namespace AS1024.GeoFeed.Controllers
         [Route("")]
         public async Task<IActionResult> Get()
         {
+            bool isCached = true;
             try
             {
                 if (!memoryCache.TryGetValue(GeoFeedCacheKey, out List<IPGeoFeed>? feed))
                 {
+                    isCached = false;
                     feed = await builder.GetGeoFeedData();
                     if (environment.IsProduction())
                     {
@@ -49,7 +51,7 @@ namespace AS1024.GeoFeed.Controllers
                     }
                 }
 
-                return ReturnFile(feed);
+                return ReturnFile(feed, isCached);
             } catch (HttpRequestException ex)
             {
                 logger.LogWarning($"Temporary failure of retrieving GeoData from upstream. {ex}");
@@ -66,9 +68,9 @@ namespace AS1024.GeoFeed.Controllers
         }
 
         [NonAction]
-        private IActionResult ReturnFile(List<IPGeoFeed>? feed)
+        private IActionResult ReturnFile(List<IPGeoFeed>? feed, bool isCached = false)
         {
-            string csvContent = feed.ToGeoFeedCsv(); // Assuming ToGeoFeedCsv() returns a string in CSV format.
+            string csvContent = feed.ToGeoFeedCsv(true, isCached); // Assuming ToGeoFeedCsv() returns a string in CSV format.
             return ReturnFile(csvContent);
         }