ZSH_NVM_DIR=${0:a:h}

[[ -z "$NVM_DIR" ]] && export NVM_DIR="$HOME/.nvm"

_zsh_nvm_rename_function() {
  test -n "$(declare -f $1)" || return
  eval "${_/$1/$2}"
  unset -f $1
}

_zsh_nvm_has() {
  type "$1" > /dev/null 2>&1
}

_zsh_nvm_latest_release_tag() {
  echo $(cd "$NVM_DIR" && git fetch --quiet origin && git describe --abbrev=0 --tags --match "v[0-9]*" origin)
}

_zsh_nvm_install() {
  echo "Installing nvm..."
  git clone https://github.com/creationix/nvm.git "$NVM_DIR"
  $(cd "$NVM_DIR" && git checkout --quiet "$(_zsh_nvm_latest_release_tag)")
}

_zsh_nvm_global_binaries() {

  # Look for global binaries
  local global_binary_paths="$(echo "$NVM_DIR"/v0*/bin/*(N) "$NVM_DIR"/versions/*/*/bin/*(N))"

  # If we have some, format them
  if [[ -n "$global_binary_paths" ]]; then
    echo "$NVM_DIR"/v0*/bin/*(N) "$NVM_DIR"/versions/*/*/bin/*(N) |
      xargs -n 1 basename |
      sort |
      uniq
  fi
}

_zsh_nvm_load() {

  # Source nvm (check if `nvm use` should be ran after load)
  if [[ "$NVM_NO_USE" == true ]]; then
    source "$NVM_DIR/nvm.sh" --no-use
  else
    source "$NVM_DIR/nvm.sh"
  fi

  # Rename main nvm function
  _zsh_nvm_rename_function nvm _zsh_nvm_nvm

  # Wrap nvm in our own function
  nvm() {
    case $1 in
      'upgrade')
        _zsh_nvm_upgrade
        ;;
      'revert')
        _zsh_nvm_revert
        ;;
      *)
        _zsh_nvm_nvm "$@"
        ;;
    esac
  }
}

_zsh_nvm_lazy_load() {

  # Get all global node module binaries including node
  # (only if NVM_NO_USE is off)
  local global_binaries
  if [[ "$NVM_NO_USE" == true ]]; then
    global_binaries=()
  else
    global_binaries=($(_zsh_nvm_global_binaries))
  fi

  # Add yarn lazy loader if it's been installed by something other than npm
  _zsh_nvm_has yarn && global_binaries+=('yarn')

  # Add nvm
  global_binaries+=('nvm')

  # Remove any binaries that conflict with current aliases
  local cmds
  cmds=()
  for bin in $global_binaries; do
    [[ "$(which $bin)" = "$bin: aliased to "* ]] || cmds+=($bin)
  done

  # Create function for each command
  for cmd in $cmds; do

    # When called, unset all lazy loaders, load nvm then run current command
    eval "$cmd(){
      unset -f $cmds
      _zsh_nvm_load
      $cmd \"\$@\"
    }"
  done
}

nvm_update() {
  echo 'Deprecated, please use `nvm upgrade`'
}
_zsh_nvm_upgrade() {

  # Use default upgrade if it's built in
  if [[ -n "$(_zsh_nvm_nvm help | grep 'nvm upgrade')" ]]; then
    _zsh_nvm_nvm upgrade
    return
  fi

  # Otherwise use our own
  local installed_version=$(cd "$NVM_DIR" && git describe --tags)
  echo "Installed version is $installed_version"
  echo "Checking latest version of nvm..."
  local latest_version=$(_zsh_nvm_latest_release_tag)
  if [[ "$installed_version" = "$latest_version" ]]; then
    echo "You're already up to date"
  else
    echo "Updating to $latest_version..."
    echo "$installed_version" > "$ZSH_NVM_DIR/previous_version"
    $(cd "$NVM_DIR" && git fetch --quiet && git checkout "$latest_version")
    _zsh_nvm_load
  fi
}

_zsh_nvm_previous_version() {
  cat "$ZSH_NVM_DIR/previous_version" 2>/dev/null
}

_zsh_nvm_revert() {
  local previous_version="$(_zsh_nvm_previous_version)"
  if [[ -n "$previous_version" ]]; then
    local installed_version=$(cd "$NVM_DIR" && git describe --tags)
    if [[ "$installed_version" = "$previous_version" ]]; then
      echo "Already reverted to $installed_version"
      return
    fi
    echo "Installed version is $installed_version"
    echo "Reverting to $previous_version..."
    $(cd "$NVM_DIR" && git checkout "$previous_version")
    _zsh_nvm_load
  else
    echo "No previous version found"
  fi
}

autoload -U add-zsh-hook
_zsh_nvm_auto_use() {
  _zsh_nvm_has nvm_find_nvmrc || return

  local node_version="$(nvm version)"
  local nvmrc_path="$(nvm_find_nvmrc)"

  if [ -n "$nvmrc_path" ]; then
    local nvmrc_node_version=$(nvm version "$(cat "${nvmrc_path}")")

    if [ "$nvmrc_node_version" != "N/A" ] && [ "$nvmrc_node_version" != "$node_version" ]; then
      nvm use
    fi
  elif [ "$node_version" != "$(nvm version default)" ]; then
    echo "Reverting to nvm default version"
    nvm use default
  fi
}

# Don't init anything if this is true (debug/testing only)
if [[ "$ZSH_NVM_NO_LOAD" != true ]]; then

  # Install nvm if it isn't already installed
  [[ ! -f "$NVM_DIR/nvm.sh" ]] && _zsh_nvm_install

  # If nvm is installed
  if [[ -f "$NVM_DIR/nvm.sh" ]]; then

    # Load it
    [[ "$NVM_LAZY_LOAD" == true ]] && _zsh_nvm_lazy_load || _zsh_nvm_load

    # Auto use nvm on chpwd
    [[ "$NVM_AUTO_USE" == true ]] && add-zsh-hook chpwd _zsh_nvm_auto_use && _zsh_nvm_auto_use
  fi

fi