feat(cloud): add script for browsing mega

.bin/toposort.nix

@@ -0,0 +1,50 @@
+let
+  lib = import <nixpkgs/lib>;
+in rec {
+  inherit lib;
+
+  input = [
+    {
+      x = ["pool" "zfs"];
+      y = ["mdadm" "raid1"];
+    }
+    {
+      x = ["pool" "zfs"];
+      y = ["disk" "sda"];
+    }
+    {
+      x = ["mdadm" "raid1"];
+      y = ["disk" "sdb"];
+    }
+    {
+      x = ["mdadm" "raid1"];
+      y = ["disk" "sdc"];
+    }
+  ];
+
+  outNodes = node: graph:
+    lib.unique
+    (builtins.map (e: e.y)
+      (builtins.filter (v: v.x == node) graph));
+
+  vertices = graph:
+    lib.unique
+    (builtins.map (x: x.y) graph ++ builtins.map (x: x.x) graph);
+
+  deleteVertex = node: graph: (builtins.filter (v: v.x != node && v.y != node) graph);
+
+  findSink = graph:
+    lib.findFirst
+    (v: outNodes v graph == [])
+    (lib.trace graph (builtins.abort "No sink found"))
+    (vertices graph);
+
+  topSort = graph:
+    if graph == []
+    then []
+    else if builtins.length graph == 1
+    then let only = builtins.head graph; in [only.y only.x]
+    else let sink = findSink graph; in [sink] ++ topSort (deleteVertex sink graph);
+
+  output = topSort input;
+}