backport of public nsfw module

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

@@ -0,0 +1,34 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using NadekoBot.Extensions;
+
+namespace NadekoBot.Modules.Nsfw.Common
+{
+    public sealed class SankakuImageDownloader : ImageDownloader<SankakuImageObject>
+    {
+        private readonly string _baseUrl;
+
+        public SankakuImageDownloader(HttpClient http)
+            : base(Booru.Sankaku, http)
+        {
+            _baseUrl = "https://capi-v2.sankakucomplex.com";
+            _http.AddFakeHeaders();
+        }
+        
+        public override async Task<List<SankakuImageObject>> DownloadImagesAsync(string[] tags, int page, bool isExplicit = false, CancellationToken cancel = default)
+        {
+            // explicit probably not supported
+            var tagString = ImageDownloaderHelper.GetTagString(tags, false);
+
+            var uri = $"{_baseUrl}/posts?tags={tagString}&limit=50";
+            var data = await _http.GetStringAsync(uri).ConfigureAwait(false);
+            return JsonSerializer.Deserialize<SankakuImageObject[]>(data, _serializerOptions)
+                .Where(x => !string.IsNullOrWhiteSpace(x.FileUrl) && x.FileType.StartsWith("image"))
+                .ToList();
+        }
+    }
+}