Create urlDecode function for redirects

src/date_fmt.zig

@@ -33,3 +33,20 @@ pub fn scrobbleToRow(allocator: std.mem.Allocator, scrobble: Data.Scrobble) !Dat
         .date = try dateFmt(allocator, scrobble.date),
     };
 }
+
+pub fn urlDecode(allocator: std.mem.Allocator, str: []const u8) ![]const u8 {
+    var decoded = std.ArrayList(u8).init(allocator);
+    var i: usize = 0;
+    while (i < str.len) : (i += 1) {
+        const v = str[i];
+        if (v == '%') {
+            if (i + 2 < str.len) {
+                const hex = str[i + 1 .. i + 3];
+                const char = try std.fmt.parseInt(u8, hex, 16);
+                try decoded.append(char);
+                i += 2;
+            } else return error.InvalidInput;
+        } else try decoded.append(v);
+    }
+    return decoded.toOwnedSlice();
+}