1 files changed, 81 insertions, 0 deletions
diff --git a/users/sterni/nix/url/default.nix b/users/sterni/nix/url/default.nix
new file mode 100644
index 000000000000..37bd0de66ac9
--- /dev/null
+++ b/users/sterni/nix/url/default.nix
@@ -0,0 +1,81 @@
+{ depot, lib, ... }:
+
+let
+
+  inherit (depot.users.sterni.nix)
+    char
+    int
+    string
+    flow
+    ;
+
+  reserved = c: builtins.elem c [
+    "!" "#" "$" "&" "'" "(" ")"
+    "*" "+" "," "/" ":" ";" "="
+    "?" "@" "[" "]"
+  ];
+
+  unreserved = c: char.asciiAlphaNum c
+    || builtins.elem c [ "-" "_" "." "~" ];
+
+  percentEncode = c:
+    if unreserved c
+    then c
+    else "%" + (string.fit {
+      width = 2;
+      char = "0";
+      side = "left";
+    } (int.toHex (char.ord c)));
+
+  encode = { leaveReserved ? false }: s:
+    let
+      chars = lib.stringToCharacters s;
+      tr = c:
+        if leaveReserved && reserved c
+        then c
+        else percentEncode c;
+    in lib.concatStrings (builtins.map tr chars);
+
+  decode = s:
+    let
+      tokens = builtins.split "%" s;
+      decodeStep =
+        { result ? ""
+        , inPercent ? false
+        }: s:
+        flow.cond [
+          [
+            (builtins.isList s)
+            {
+              inherit result;
+              inPercent = true;
+            }
+          ]
+          [
+            inPercent
+            {
+              inPercent = false;
+              # first two characters came after an %
+              # the rest is the string until the next %
+              result = result
+                + char.chr (int.fromHex (string.take 2 s))
+                + (string.drop 2 s);
+            }
+          ]
+          [
+            (!inPercent)
+            {
+              result = result + s;
+            }
+          ]
+        ];
+
+    in
+      (builtins.foldl' decodeStep {} tokens).result;
+
+in {
+  inherit
+    encode
+    decode
+    ;
+}