backport of public nsfw module

src/NadekoBot/Modules/Nsfw/Common/Downloaders/SafebooruImageDownloader.cs

@@ -0,0 +1,26 @@
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Net.Http.Json;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace NadekoBot.Modules.Nsfw.Common
+{
+    public class SafebooruImageDownloader : ImageDownloader<SafebooruElement>
+    {
+        public SafebooruImageDownloader(HttpClient http) : base(Booru.Safebooru, http)
+        {
+        }
+
+        public override async Task<List<SafebooruElement>> DownloadImagesAsync(string[] tags, int page, bool isExplicit = false, CancellationToken cancel = default)
+        {
+            var tagString = ImageDownloaderHelper.GetTagString(tags, isExplicit: false);
+            var uri = $"https://safebooru.org/index.php?page=dapi&s=post&q=index&limit=200&tags={tagString}&json=1&pid={page}";
+            var images = await _http.GetFromJsonAsync<List<SafebooruElement>>(uri, _serializerOptions, cancellationToken: cancel);
+            if (images is null)
+                return new();
+
+            return images;
+        }
+    }
+}