Added service level caching to IdentityService, Communication and Evidence

PostFundManagement.Application/Services/Shared/IdentityCacheService.cs

@@ -0,0 +1,31 @@
+using Microsoft.Extensions.Caching.Distributed;
+using PostFundManagement.Application.Abstractions.Services;
+using PostFundManagement.Domain.Errors;
+
+namespace PostFundManagement.Application.Services.Shared;
+
+public sealed class IdentityCacheService(IdentityService service, IDistributedCache cache) : IIdentityService
+{
+    public async ValueTask<Result> UserIsAuthorisedAsync(Guid userId, CancellationToken cancellationToken = default) =>
+        await Result.Try((Func<ValueTask<Result>>)(async () =>
+        {
+            var cacheKey = HashService.ToMd5Hash($"userisauthorised-{userId}").Value;
+
+            var cached = await cache.GetStringAsync(cacheKey);
+
+            if (string.IsNullOrWhiteSpace(cached))
+            {
+                var result = await service.UserIsAuthorisedAsync(userId, cancellationToken); ;
+
+                if (result.IsFailed) return result;
+
+                await cache.SetStringAsync(cacheKey, "true", cancellationToken);
+
+                return Result.Ok();
+            }
+
+            return cached.Equals("true", StringComparison.OrdinalIgnoreCase)
+                ? Result.Ok()
+                : Result.Fail(NotFoundError.New);
+        }));
+}