Add the Issue Reporting functionality (#1811)

* Added issuesreporting and the ability to add categories to the UI
* Added lazy loading!

src/Ombi.Helpers/CacheService.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Caching.Memory;
+using Nito.AsyncEx;
+
+namespace Ombi.Helpers
+{
+    public class CacheService : ICacheService
+    {
+        private readonly IMemoryCache _memoryCache;
+        private readonly AsyncLock _mutex = new AsyncLock();
+        public CacheService(IMemoryCache memoryCache)
+        {
+            _memoryCache = memoryCache ?? throw new ArgumentNullException(nameof(memoryCache));
+        }
+
+        public async Task<T> GetOrAdd<T>(string cacheKey, Func<Task<T>> factory, DateTime absoluteExpiration = default(DateTime))
+        {
+            if (absoluteExpiration == default(DateTime))
+            {
+                absoluteExpiration = DateTime.Now.AddHours(1);
+            }
+            // locks get and set internally
+            if (_memoryCache.TryGetValue<T>(cacheKey, out var result))
+            {
+                return result;
+            }
+
+            using (await _mutex.LockAsync())
+            {
+                if (_memoryCache.TryGetValue(cacheKey, out result))
+                {
+                    return result;
+                }
+
+                result = await factory();
+                _memoryCache.Set(cacheKey, result, absoluteExpiration);
+
+                return result;
+            }
+        }
+
+        public void Remove(string key)
+        {
+            _memoryCache.Remove(key);
+        }
+
+        
+           
+            public T GetOrAdd<T>(string cacheKey, Func<T> factory, DateTime absoluteExpiration)
+            {
+                // locks get and set internally
+                if (_memoryCache.TryGetValue<T>(cacheKey, out var result))
+                {
+                    return result;
+                }
+
+                lock (TypeLock<T>.Lock)
+                {
+                    if (_memoryCache.TryGetValue(cacheKey, out result))
+                    {
+                        return result;
+                    }
+
+                    result = factory();
+                    _memoryCache.Set(cacheKey, result, absoluteExpiration);
+
+                    return result;
+                }
+            }
+
+            private static class TypeLock<T>
+            {
+                public static object Lock { get; } = new object();
+            }
+        
+    }
+}