python-info: add support for pyenv and only do extra work if the prompt needs it

modules/python/functions/python-info

@@ -13,29 +13,39 @@ local virtualenv_format
 local virtualenv_formatted
 local version_format
 local version_formatted
+local version
 
 # Clean up previous $python_info.
 unset python_info
 typeset -gA python_info
 
+# Grab the styling we might have to do
+zstyle -s ':prezto:module:python:info:virtualenv' format 'virtualenv_format'
+zstyle -s ':prezto:module:python:info:version' format 'version_format'
+
 # Format virtualenv.
+if [[ -n "$virtualenv_format" ]]; then
   if [[ -n "$VIRTUAL_ENV" ]]; then
-  zstyle -s ':prezto:module:python:info:virtualenv' format 'virtualenv_format'
     zformat -f virtualenv_formatted "$virtualenv_format" "v:${VIRTUAL_ENV:t}"
     python_info[virtualenv]="$virtualenv_formatted"
   fi
 
   # Do the same for Conda virtual environments
   if [[ -n "$CONDA_DEFAULT_ENV" ]]; then
-  zstyle -s ':prezto:module:python:info:virtualenv' format 'virtualenv_format'
     zformat -f virtualenv_formatted "$virtualenv_format" "v:${CONDA_DEFAULT_ENV:t}"
     python_info[virtualenv]="$virtualenv_formatted"
   fi
+fi
 
-if (( $+commands[python] )); then
-  zstyle -s ':prezto:module:python:info:version' format 'version_format'
 if [[ -n "$version_format" ]]; then
-    zformat -f version_formatted "$version_format" "v:${$(python3 --version)#Python }"
+  if (( $+commands[pyenv] )); then
+    version="${"$(pyenv version)"%% *}"
+  elif (( $+commands[python] )); then
+    version="${$(python3 --version)#Python }"
+  fi
+
+  if [[ -n "$version" && "$version" != "system" ]]; then
+    zformat -f version_formatted "$version_format" "v:$version"
     python_info[version]="$version_formatted"
   fi
 fi