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1 files changed, 104 insertions, 0 deletions

diff --git a/CoreWiki/Utils/SafeUrl.cs b/CoreWiki/Utils/SafeUrl.cs
new file mode 100644
index 0000000..b2de803
--- /dev/null
+++ b/CoreWiki/Utils/SafeUrl.cs
@@ -0,0 +1,104 @@
+using System.Text;
+
+namespace CoreWiki.Utils;
+
+public class SafeUrl
+{
+    public static string Create(bool toLower, params string[] values)
+    {
+        return Create(toLower, String.Join("-", values));
+    }
+    
+    public static string Create(bool toLower, string value)
+    {
+        var normalised = value.Normalize(NormalizationForm.FormKD);
+
+        const int maxlen = 80;
+        int len = normalised.Length;
+        bool prevDash = false;
+        var sb = new StringBuilder(len);
+        char c;
+
+        for (int i = 0; i < len; i++)
+        {
+            c = normalised[i];
+            if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9'))
+            {
+                if (prevDash)
+                {
+                    sb.Append('-');
+                    prevDash = false;
+                }
+                sb.Append(c);
+            }
+            else if (c >= 'A' && c <= 'Z')
+            {
+                if (prevDash)
+                {
+                    sb.Append('-');
+                    prevDash = false;
+                }
+                // Tricky way to convert to lowercase
+                if (toLower)
+                    sb.Append((char)(c | 32));
+                else
+                    sb.Append(c);
+            }
+            else if (c == ' ' || c == ',' || c == '.' || c == '/' || c == '\\' || c == '-' || c == '_' || c == '=')
+            {
+                if (!prevDash && sb.Length > 0)
+                {
+                    prevDash = true;
+                }
+            }
+            else
+            {
+                string swap = ConvertEdgeCases(c, toLower);
+
+                if (swap != null)
+                {
+                    if (prevDash)
+                    {
+                        sb.Append('-');
+                        prevDash = false;
+                    }
+                    sb.Append(swap);
+                }
+            }
+
+            if (sb.Length == maxlen)
+                break;
+        }
+        return sb.ToString();
+    }
+
+    static string ConvertEdgeCases(char c, bool toLower)
+    {
+        string swap = null;
+        switch (c)
+        {
+            case 'ı':
+                swap = "i";
+                break;
+            case 'ł':
+                swap = "l";
+                break;
+            case 'Ł':
+                swap = toLower ? "l" : "L";
+                break;
+            case 'đ':
+                swap = "d";
+                break;
+            case 'ß':
+                swap = "ss";
+                break;
+            case 'ø':
+                swap = "o";
+                break;
+            case 'Þ':
+                swap = "th";
+                break;
+        }
+        return swap;
+    }
+}
\ No newline at end of file