zsh: add just completion

nix/home-manager/programs/zsh.nix

@@ -7,6 +7,40 @@ let
   channelSources = (import ../../default.nix {
       versionsPath = ../../variables/versions.nix;
     }).channelSources;
+
+  just-plugin =
+    let
+      plugin_file = pkgs.writeText "_just" ''
+        #compdef just
+        #autload
+
+        alias justl="\just --list"
+        alias juste="\just --evaluate"
+
+        local subcmds=()
+
+        while read -r line ; do
+           if [[ ! $line == Available* ]] ;
+           then
+              subcmds+=(''${line/[[:space:]]*\#/:})
+           fi
+        done < <(just --list)
+
+        _describe 'command' subcmds
+      '';
+
+    in pkgs.stdenv.mkDerivation {
+      name = "just-completions";
+      version = "0.1.0";
+      phases = "installPhase";
+      installPhase = ''
+        PLUGIN_PATH=$out/share/oh-my-zsh/plugins/just
+        mkdir -p $PLUGIN_PATH
+        cp ${plugin_file} $PLUGIN_PATH/_just
+        chmod --recursive a-w $out
+      '';
+  };
+
 in {
   programs.zsh = {
     enable = true;
@@ -78,6 +112,10 @@ in {
         name = "minikube";
         src = "${pkgs.oh-my-zsh}/share/oh-my-zsh/plugins/minikube";
       }
+      {
+        name = "just";
+        src = "${just-plugin}/share/oh-my-zsh/plugins/just";
+      }
     ];
     oh-my-zsh = {
       enable = true;