feat(backend): add create flag endpoint and job

Foxnouns.Backend/Jobs/CreateFlagInvocable.cs

@@ -0,0 +1,53 @@
+using System.Security.Cryptography;
+using Coravel.Invocable;
+using Foxnouns.Backend.Database;
+using Foxnouns.Backend.Database.Models;
+using Foxnouns.Backend.Extensions;
+using Foxnouns.Backend.Services;
+
+namespace Foxnouns.Backend.Jobs;
+
+public class CreateFlagInvocable(DatabaseContext db, ObjectStorageService objectStorageService, ILogger logger)
+    : IInvocable, IInvocableWithPayload<CreateFlagPayload>
+{
+    private readonly ILogger _logger = logger.ForContext<CreateFlagInvocable>();
+    public required CreateFlagPayload Payload { get; set; }
+
+    public async Task Invoke()
+    {
+        _logger.Information("Creating flag {FlagId} for user {UserId} with image data length {DataLength}", Payload.Id,
+            Payload.UserId, Payload.ImageData.Length);
+
+        try
+        {
+            var image = await Payload.ImageData.ConvertBase64UriToImage(size: 256, crop: false);
+            image.Seek(0, SeekOrigin.Begin);
+            var hash = Convert.ToHexString(await SHA256.HashDataAsync(image)).ToLower();
+            image.Seek(0, SeekOrigin.Begin);
+
+            await objectStorageService.PutObjectAsync(Path(hash), image, "image/webp");
+
+            var flag = new PrideFlag
+            {
+                Id = Payload.Id,
+                UserId = Payload.UserId,
+                Hash = hash,
+                Name = Payload.Name,
+                Description = Payload.Description
+            };
+            db.Add(flag);
+
+            await db.SaveChangesAsync();
+
+            _logger.Information("Uploaded flag {FlagId} with hash {Hash}", flag.Id, flag.Hash);
+        }
+        catch (ArgumentException ae)
+        {
+            _logger.Warning("Invalid data URI for flag {FlagId}: {Reason}", Payload.Id, ae.Message);
+        }
+
+        throw new NotImplementedException();
+    }
+
+    private static string Path(string hash) => $"flags/{hash}.webp";
+}