Implement zsh prompt indicator for 'nix shell'

Based on <https://discourse.nixos.org/t/using-zsh-with-grml-config-and-nix-shell-prompt-indicator/13838>

1 files changed, 21 insertions, 5 deletions

diff --git a/home/zshrc.nix b/home/zshrc.nix
index 134ee5a..68c3958 100644
--- a/home/zshrc.nix
+++ b/home/zshrc.nix
@@ -1,13 +1,10 @@
 { grml-zsh-config }: ''
   source ${grml-zsh-config}/etc/zsh/zshrc
 
-  #export PATH="$PATH:$HOME/.local/bin:$HOME/System/local/bin:$HOME/System/bin:$HOME/.cargo/bin"
+  export PATH="$PATH:$HOME/.cargo/bin"
 
   alias reset='tput reset'
   alias reload='exec zsh'
-  alias py=python
-  alias py2=python2
-  alias py3=python3
 
   function spawn() {
     if [ ! -x "$(command -v $1)" ]; then
@@ -39,7 +36,26 @@
   bindkey '\eOB' down-line-or-beginning-search
   bindkey '\e[B' down-line-or-beginning-search
 
-  zstyle ':prompt:grml:left:setup' items $([ ''${NO_USERATHOST:-0} -gt 0 ] || echo user at host) path percent
+  INSTALLABLES=()
+  while read -d: PATH_ITEM; do
+    if [[ "$PATH_ITEM" =~ "^/nix/store/[a-z0-9]+-([a-zA-Z][a-zA-Z0-9_]*(-[a-zA-Z][a-zA-Z0-9_]*)*)" ]]; then
+      INSTALLABLES+=("''${match[1]}")
+    fi
+  done <<<"$PATH"
+
+  if [ "''${#INSTALLABLES[@]}" -gt 0 ]; then
+    _GRML_NIX_SHELL="{''${INSTALLABLES[@]}} "
+  fi
+
+  unset INSTALLABLES PATH_ITEM
+
+  function grml_nix_shell() {
+    REPLY="$_GRML_NIX_SHELL"
+  }
+
+  grml_theme_add_token nix-shell -f grml_nix_shell '%F{red}' '%f'
+
+  zstyle ':prompt:grml:left:setup' items $([ ''${NO_USERATHOST:-0} -gt 0 ] || echo user at host) path nix-shell percent
   zstyle ':prompt:grml:right:setup' items sad-smiley vcs $([ ''${NO_BATTERY:-0} -gt 0 ] || echo battery) time
   zstyle ':prompt:grml:right:items:time' pre ' %F{yellow}'