Use nicer prompt in bash when outside a nix shell

m/common/base/env.nix

@@ -28,9 +28,22 @@
     VISUAL = "vim";
   };
 
-  programs.bash.promptInit = ''
-    PS1="\h\\$ "
-  '';
+  programs.bash.promptInit = # bash
+    ''
+      if echo "$PATH" | grep -qc '/nix/store'; then
+        # Inside a nix shell, dumb prompt
+        PS1="\h\\$ "
+      elif [ "$TERM" != "dumb" ] ; then
+        PROMPT_COLOR="1;31m"
+        ((UID)) && PROMPT_COLOR="1;32m"
+
+        PS1="\n\[\033[$PROMPT_COLOR\][\[\e]0;\u@\h: \w\a\]\u@\h:\w]\\$\[\033[0m\] "
+
+        if test "$TERM" = "xterm"; then
+          PS1="\[\033]2;\h:\u:\w\007\]$PS1"
+        fi
+      fi
+    '';
 
   time.timeZone = "Europe/Madrid";
   i18n.defaultLocale = "en_DK.UTF-8";