#!/usr/bin/env zsh
  
  zmodload zsh/datetime
  
  function _current_epoch() {
    echo $(( $EPOCHSECONDS / 60 / 60 / 24 ))
  }
  
  function _update_zsh_update() {
    echo "LAST_EPOCH=$(_current_epoch)" >! ~/.zsh-update
  }
  
  function _upgrade_zsh() {
    env ZSH=$ZSH /bin/sh $ZSH/tools/upgrade.sh
    # update the zsh file
    _update_zsh_update
  }
  
  epoch_target=$UPDATE_ZSH_DAYS
  if [[ -z "$epoch_target" ]]; then
    # Default to old behavior
    epoch_target=13
  fi
  
  # Cancel upgrade if the current user doesn't have write permissions for the
  # oh-my-zsh directory.
  [[ -w "$ZSH" ]] || return 0

  # Cancel upgrade if git is unavailable on the system
  whence git >/dev/null || return 0

  if [ -f ~/.zsh-update ]
  then
    . ~/.zsh-update
  
    if [[ -z "$LAST_EPOCH" ]]; then
      _update_zsh_update && return 0;
    fi
  
    epoch_diff=$(($(_current_epoch) - $LAST_EPOCH))
    if [ $epoch_diff -gt $epoch_target ]
    then
      if [ "$DISABLE_UPDATE_PROMPT" = "true" ]
      then
        _upgrade_zsh
      else

        echo "[Oh My Zsh] Would you like to check for updates? [Y/n]: \c"

        read line

        if [[ "$line" == Y* ]] || [[ "$line" == y* ]] || [ -z "$line" ]; then

          _upgrade_zsh
        else
          _update_zsh_update
        fi
      fi
    fi
  else
    # create the zsh file
    _update_zsh_update
  fi