backport of public nsfw module

src/NadekoBot/Modules/Nsfw/Common/ImageData.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace NadekoBot.Modules.Nsfw.Common
+{
+    public class ImageData : IComparable<ImageData>
+    {
+        public Booru SearchType { get; }
+        public string FileUrl { get; }
+        public HashSet<string> Tags { get; }
+        public string Rating { get; }
+
+        public ImageData(string url, Booru type, string[] tags, string rating)
+        {
+            if (type == Booru.Danbooru && !Uri.IsWellFormedUriString(url, UriKind.Absolute))
+            {
+                this.FileUrl = "https://danbooru.donmai.us" + url;
+            }
+            else
+            {
+                this.FileUrl = url.StartsWith("http", StringComparison.InvariantCulture) ? url : "https:" + url;
+            }
+            
+            this.SearchType = type;
+            this.FileUrl = url;
+            this.Tags = tags.ToHashSet();
+            this.Rating = rating;
+        }
+
+        public override string ToString()
+        {
+            return FileUrl;
+        }
+
+        public override int GetHashCode() => FileUrl.GetHashCode();
+        public override bool Equals(object obj)
+            => obj is ImageData ico && ico.FileUrl == this.FileUrl;
+
+        public int CompareTo(ImageData other)
+            => string.Compare(FileUrl, other.FileUrl, StringComparison.InvariantCulture);
+    }
+}