function precmd {

    local TERMWIDTH
    (( TERMWIDTH = ${COLUMNS} - 1 ))


    ###
    # Truncate the path if it's too long.
    
    PR_FILLBAR=""
    PR_PWDLEN=""
    
    local promptsize=${#${(%):---(%n@%m:%l)---()--}}
    local pwdsize=${#${(%):-%~}}
    
    if [[ "$promptsize + $pwdsize" -gt $TERMWIDTH ]]; then
	    ((PR_PWDLEN=$TERMWIDTH - $promptsize))
    else
        PR_FILLBAR="\${(l.(($TERMWIDTH - ($promptsize + $pwdsize)))..${PR_HBAR}.)}"
    fi
}


setopt extended_glob
preexec () {
    if [[ "$TERM" == "screen" ]]; then
	local CMD=${1[(wr)^(*=*|sudo|-*)]}
	echo -n "\ek$CMD\e\\"
    fi
}


setprompt () {
    # Allow for functions in the prompt.
    setopt prompt_subst

    # See if we can use colors.
    autoload colors zsh/terminfo
    if [[ "$terminfo[colors]" -ge 8 ]]; then
	colors
    fi
    for color in RED GREEN YELLOW BLUE MAGENTA CYAN WHITE; do
	eval PR_$color='%{$terminfo[bold]$fg[${(L)color}]%}'
	eval PR_LIGHT_$color='%{$fg[${(L)color}]%}'
	(( count = $count + 1 ))
    done
    PR_NO_COLOUR="%{$terminfo[sgr0]%}"

    # Autoload zsh functions.
    fpath=(~/.zsh/functions $fpath)
    autoload -U ~/.zsh/functions/*(:t)

    # Enable auto-execution of functions.
    typeset -ga preexec_functions
    typeset -ga precmd_functions
    typeset -ga chpwd_functions

    # Append git functions needed for prompt.
    preexec_functions+='preexec_update_git_vars'
    precmd_functions+='precmd_update_git_vars'
    chpwd_functions+='chpwd_update_git_vars'


    ###
    # See if we can use extended characters to look nicer.
    
    typeset -A altchar
    set -A altchar ${(s..)terminfo[acsc]}
    PR_SET_CHARSET="%{$terminfo[enacs]%}"
    PR_SHIFT_IN="%{$terminfo[smacs]%}"
    PR_SHIFT_OUT="%{$terminfo[rmacs]%}"
    PR_HBAR=${altchar[q]:--}
    PR_ULCORNER=${altchar[l]:--}
    PR_LLCORNER=${altchar[m]:--}
    PR_LRCORNER=${altchar[j]:--}
    PR_URCORNER=${altchar[k]:--}

    
    ###
    # Decide if we need to set titlebar text.
    
    case $TERM in
	?term*|screen)
	    PR_TITLEBAR=$'%{\e]0;%(!.-=*[ROOT]*=- | .)%n@%m:%~ | ${COLUMNS}x${LINES} | %y\a%}'
	    ;;
	screeningplopp)
	    PR_TITLEBAR=$'%{\e_screen \005 (\005t) | %(!.-=[ROOT]=- | .)%n@%m:%~ | ${COLUMNS}x${LINES} | %y\e\\%}'
	    ;;
	*)
	    PR_TITLEBAR=''
	    ;;
    esac
    
    
    ###
    # Decide whether to set a screen title
    if [[ "$TERM" == "screen" ]]; then
	PR_STITLE=$'%{\ekzsh\e\\%}'
    else
	PR_STITLE=''
    fi
    
    
    ###
    # APM detection
    
    if which ibam > /dev/null; then
	PR_APM='$PR_RED${${PR_APM_RESULT[(f)1]}[(w)-2]}%%(${${PR_APM_RESULT[(f)3]}[(w)-1]})$PR_LIGHT_BLUE:'
    elif which apm > /dev/null; then
	PR_APM='$PR_RED${PR_APM_RESULT[(w)5,(w)6]/\% /%%}$PR_LIGHT_BLUE:'
    else
	PR_APM=''
    fi
    
    
    ###
    # Finally, the prompt.

#    PROMPT='$PR_SET_CHARSET$PR_STITLE${(e)PR_TITLEBAR}\
#    $PR_CYAN$PR_SHIFT_IN$PR_ULCORNER$PR_BLUE$PR_HBAR$PR_SHIFT_OUT(\
#    $PR_GREEN%(!.$PR_RED%SROOT%s.%n)$PR_GREEN@%m:%l\
#    $PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_CYAN$PR_HBAR${(e)PR_FILLBAR}$PR_BLUE$PR_HBAR$PR_SHIFT_OUT(\
#    $PR_MAGENTA%$PR_PWDLEN<...<%~%<<\
#    $PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_CYAN$PR_URCORNER$PR_SHIFT_OUT\
#    
#    $PR_CYAN$PR_SHIFT_IN$PR_LLCORNER$PR_BLUE$PR_HBAR$PR_SHIFT_OUT(\
#    %(?..$PR_LIGHT_RED%?$PR_BLUE:)\
#    ${(e)PR_APM}$PR_YELLOW%D{%H:%M}\
#    $PR_LIGHT_BLUE:%(!.$PR_RED.$PR_WHITE)%#$PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT\
#    $PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_SHIFT_OUT\
#    $PR_NO_COLOUR ' 
#
#    RPROMPT=' $PR_CYAN$PR_SHIFT_IN$PR_HBAR$PR_BLUE$PR_HBAR$PR_SHIFT_OUT\
#($PR_YELLOW%D{%a,%b%d}$PR_BLUE)$PR_SHIFT_IN$PR_HBAR$PR_CYAN$PR_LRCORNER$PR_SHIFT_OUT$PR_NO_COLOUR'


    PROMPT='$PR_SET_CHARSET$PR_NO_COLOUR\
%(?..($PR_LIGHT_RED%?$PR_NO_COLOUR%))\
%(!.$PR_RED.$PR_GREEN)%n$PR_GREEN@%m \
%(!.$PR_RED.$PR_NO_COLOUR)$(prompt_git_info)\
$PR_NO_COLOUR%#$PR_BLUE>\
$PR_NO_COLOUR '

    RPROMPT=' ($PR_WHITE%$PR_PWDLEN<...<%~%<<$PR_NO_COLOUR)'

    #PS2='$PR_WHITE%_>$PR_NO_COLOUR '
    PS2='$PR_NO_COLOUR%_$PR_WHITE> '
}

setprompt