Initial commit

license-system-backend/src/License.Api/Services/IdempotencyService.cs

@@ -0,0 +1,49 @@
+using System.Security.Cryptography;
+using System.Text;
+using License.Api.Data;
+using License.Api.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace License.Api.Services;
+
+public class IdempotencyService
+{
+    private readonly AppDbContext _db;
+
+    public IdempotencyService(AppDbContext db)
+    {
+        _db = db;
+    }
+
+    public async Task<IdempotencyKeyRecord?> GetAsync(string key)
+    {
+        return await _db.IdempotencyKeys
+            .FirstOrDefaultAsync(x => x.IdempotencyKey == key && x.ExpiresAt > DateTime.UtcNow);
+    }
+
+    public async Task<IdempotencyKeyRecord> StoreAsync(string key, string path, string requestBodyHash, int responseCode, string responseBody)
+    {
+        var record = new IdempotencyKeyRecord
+        {
+            IdempotencyKey = key,
+            RequestPath = path,
+            RequestHash = requestBodyHash,
+            ResponseCode = responseCode,
+            ResponseBody = responseBody,
+            CreatedAt = DateTime.UtcNow,
+            ExpiresAt = DateTime.UtcNow.AddHours(24)
+        };
+
+        _db.IdempotencyKeys.Add(record);
+        await _db.SaveChangesAsync();
+        return record;
+    }
+
+    public static string ComputeRequestHash(string? body)
+    {
+        if (string.IsNullOrWhiteSpace(body))
+            return string.Empty;
+        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(body));
+        return Convert.ToHexString(hash).ToLowerInvariant();
+    }
+}