Add avatars

NostrServices/Controllers/AvatarController.cs

@@ -0,0 +1,30 @@
+using System.Text;
+using Microsoft.AspNetCore.Mvc;
+
+namespace NostrServices.Controllers;
+
+[Route("/api/v1/avatar")]
+public class AvatarController : Controller
+{
+    /// <summary>
+    /// Robohash avatar endpoints
+    /// </summary>
+    /// <remarks>
+    /// Available sets: `cyberpunks`
+    /// </remarks>
+    /// <param name="set"></param>
+    /// <param name="value">Any value, can contain a file extension, response is only image/webp</param>
+    /// <returns></returns>
+    [HttpGet("{set}/{value}")]
+    [ResponseCache(Location = ResponseCacheLocation.Any, Duration = 86400)]
+    public IActionResult GetAvatar([FromRoute] string set, [FromRoute] string value)
+    {
+        var hash = System.Security.Cryptography.SHA256.HashData(
+            Encoding.UTF8.GetBytes(Path.GetFileNameWithoutExtension(value)));
+        var hashInt = BitConverter.ToInt32(hash);
+        var dir = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", set);
+        var fileList = Directory.EnumerateFiles(dir, "*.webp").ToList();
+        var pickImg = fileList[Math.Abs(hashInt % fileList.Count)];
+        return PhysicalFile(pickImg, "image/webp");
+    }
+}