shortening pwd

precmd.zsh

autoload -U colors && colors
precmd() {
	red_at="%{$fg[red]}@%{$reset_color%}"
	red_dollar="%{$fg[red]%}$%{$reset_color%}"
	typeset host_info
	[[ -n $SSH_CONNECTION ]] && host_info="$USER${red_at}$HOST "

	if [[ $USER == "CC" ]]; then
		# number of chracters of the path of the prompt is less 30
		# use '~' to represent $HOME as long as possible
		if [[ $PWD =~ $HOME ]]; then
		 	pwd="${PWD[@]//$HOME/~}"
			prefix_slash=
		else
			pwd=$PWD
			prefix_slash=/
		fi

		# ugly work around
		# IFS=/ read -A pwdarr <<< "$pwd"
		pwdarr=(${(ps:/:)pwd})

		if [[ ${#pwd[@]} -le 30 ]]; then
			prompt="%~ ${red_dollar} "
		else
			prompt="${prefix_slash}${host_info}${pwdarr[1]}/.../${pwdarr[-1]} ${red_dollar} "
		fi
	else  # other user
		prompt=${red_at}'%c % '
	fi
}