Complete the implementation of returning cached data from the local disk cache

AS1024.GeoFeed/Controllers/GeofeedController.cs

@@ -4,6 +4,7 @@ using AS1024.GeoFeed.GeoFeedBuilder;
 using Microsoft.Extensions.Caching.Memory;
 using AS1024.GeoFeed.Models;
 using System.Text;
+using AS1024.GeoFeed.GeoFeedLocalCache;
 
 namespace AS1024.GeoFeed.Controllers
 {
@@ -17,13 +18,16 @@ namespace AS1024.GeoFeed.Controllers
         private readonly IMemoryCache memoryCache;
         private readonly IWebHostEnvironment environment;
         private readonly ILogger<GeofeedController> logger;
+        private readonly GeoFeedCacheDbContext dbContext;
         private const string GeoFeedCacheKey = "GeoFeedData";
 
         public GeofeedController(IGeoFeedProvider builder,
             IMemoryCache memoryCache,
             IWebHostEnvironment environment,
-            ILogger<GeofeedController> logger) {
+            ILogger<GeofeedController> logger,
+            GeoFeedCacheDbContext dbContext) {
             this.logger = logger;
+            this.dbContext = dbContext;
             this.builder = builder;
             this.memoryCache = memoryCache;
             this.environment = environment;
@@ -46,19 +50,36 @@ namespace AS1024.GeoFeed.Controllers
                     }
                 }
 
-                string csvContent = feed.ToGeoFeedCsv(); // Assuming ToGeoFeedCsv() returns a string in CSV format.
+                return ReturnFile(feed);
-                byte[] contentBytes = Encoding.UTF8.GetBytes(csvContent);
+            } catch (HttpRequestException ex)
-                string contentType = "text/csv";
+            {
+                logger.LogWarning($"Temporary failure of retrieving GeoData from upstream. {ex}");
+                var results = 
+                    dbContext.GeoFeedCacheEntries.ToList();
+                List<IPGeoFeed> cachedData = [];
+                results.ForEach(cachedData.Add);
+                return ReturnFile(cachedData);
+            }
 
-                return new FileContentResult(contentBytes, contentType)
+            catch (Exception ex)
-                {
-                    FileDownloadName = "geofeed.csv"
-                };
-            } catch (Exception ex)
             {
                 logger.LogError($"Geofeed generation failed. Exception: {ex}");
                 return StatusCode(500);
             }
+
+        }
+
+        [NonAction]
+        private IActionResult ReturnFile(List<IPGeoFeed>? feed)
+        {
+            string csvContent = feed.ToGeoFeedCsv(); // Assuming ToGeoFeedCsv() returns a string in CSV format.
+            byte[] contentBytes = Encoding.UTF8.GetBytes(csvContent);
+            string contentType = "text/csv";
+
+            return new FileContentResult(contentBytes, contentType)
+            {
+                FileDownloadName = "geofeed.csv"
+            };
         }
     }
 }