nvm: use `nvm current` in nvm_prompt_info and look in alternate install locations

This makes it work regardless of where nvm is loaded from. And it uses nvm's
version strings, which distinguish the "system" and "none" NVM environments,
instead of reporting the specific version of the system node.js or erroring,
respectively.

Fixes #4336
Closes #4338

lib/nvm.zsh

@@ -1,9 +1,8 @@
-# get the node.js version
+# get the nvm-controlled node.js version
 function nvm_prompt_info() {
-  [[ -f "$NVM_DIR/nvm.sh" ]] || return
   local nvm_prompt
-  nvm_prompt=$(node -v 2>/dev/null)
+  which nvm &>/dev/null || return
-  [[ "${nvm_prompt}x" == "x" ]] && return
+  nvm_prompt=$(nvm current)
-  nvm_prompt=${nvm_prompt:1}
+  nvm_prompt=${nvm_prompt#v}
   echo "${ZSH_THEME_NVM_PROMPT_PREFIX}${nvm_prompt}${ZSH_THEME_NVM_PROMPT_SUFFIX}"
 }

plugins/nvm/nvm.plugin.zsh

@@ -1,23 +1,45 @@
-# Set NVM_DIR if it isn't already defined
+# nvm
-[[ -z "$NVM_DIR" ]] && export NVM_DIR="$HOME/.nvm"
+#
+# This plugin locates and loads nvm, looking for it in well-known locations.
 
-# Don't try to load nvm if command already available
+() {
-type "nvm" &> /dev/null && return
+  emulate -L zsh
-
+  local nvm_install_dir="" dir install_locations
-# Load nvm if it exists in $NVM_DIR
+  if [[ -n $NVM_INSTALL_DIR ]]; then
-if [[ -f "$NVM_DIR/nvm.sh" ]]; then
+    # User-specified path
-    source "$NVM_DIR/nvm.sh"
+    nvm_install_dir=$NVM_INSTALL_DIR
-    return
+  else
+    # Well-known common installation locations for NVM
+    install_locations=( ~/.nvm )
+    [[ -n $NVM_DIR ]] && install_locations=($NVM_DIR $install_locations)
+    # Mac Homebrew sticks 
+    which brew &>/dev/null && install_locations+=$(brew --prefix nvm)
+    for dir ($install_locations); do
+      if [[ -s $dir/nvm.sh ]]; then
+        nvm_install_dir=$dir
+        break
+      fi
+    done
   fi
 
-# Otherwise try to load nvm installed via Homebrew
+  if [[ -n $nvm_install_dir ]]; then
+    source $nvm_install_dir/nvm.sh
+  else
+    # No NVM installation found
+    return 0
+  fi
 
-# User can set this if they have an unusual Homebrew setup
+  # Locate and use the completion file shipped with NVM, instead of this
-NVM_HOMEBREW="${NVM_HOMEBREW:-/usr/local/opt/nvm}"
+  # plugin's completion
-# Load nvm from Homebrew location if it exists
+  # (Their bash completion file has zsh portability support)
-[[ -f "$NVM_HOMEBREW/nvm.sh" ]] && source "$NVM_HOMEBREW/nvm.sh"
+  if [[ $ZSH_NVM_BUNDLED_COMPLETION == true ]]; then
-# Load nvm bash completion from Homebrew if it exists
+    local bash_comp_file
-if [[ -f "$NVM_HOMEBREW/etc/bash_completion.d/nvm" ]]; then
+    # Homebrew relocates the bash completion file, so look multiple places
-    autoload -U +X bashcompinit && bashcompinit
+    for bash_comp_file ( bash_completion etc/bash_completion.d/nvm ); do
-    source "$NVM_HOMEBREW/etc/bash_completion.d/nvm"
+      if [[ -s $nvm_install_dir/$bash_comp_file ]]; then
+        source $nvm_install_dir/$bash_comp_file
+        break;
+      fi
+    done
   fi
+}