# Environment variables:
#
# PS1_SHOWHOSTNAME
#       'auto' (default):       Only show hostname over SSH
#       'yes':                  Always show hostname
#       anything else:          Never show hostname


if [ "${TERM}" = dumb ]
then
    return
fi


__show-hostname ()
{
    case ${PS1_SHOWHOSTNAME} in
        (''|auto)
            [ "${SSH_CONNECTION}" ];;
        (yes)
            true;;
        (*)
            false;;
    esac
}

__have-gitprompt ()
{
    [ -f /usr/lib/git-core/git-sh-prompt ]
}

__set-title ()
{
    local title
    local git_root=$(git root 2> /dev/null)

    if [ ${git_root} ]
    then
        title=$(basename ${git_root})
    else
        local path=${PWD/~/\~}

        if __show-hostname
        then
            title="${USER}@${HOSTNAME}:${path}"
        else
            title="${USER}:${path}"
        fi
    fi

    # Cf. console_codes(4):
    #
    #   ESC ] 2 ; txt ST        Set window title to txt.
    #
    # ST is a "string terminator", either "ESC \" or "BEL".

    echo -ne "\E]2;${title}\a"
}

# In order to know how much space PS1 takes, Bash needs us to delimit
# non-printing characters with \[ and \].
__start-nonprinting ()
{
    if [ ${BUILDING_PS1} ]
    then
        echo -en '\['
    fi
}

__end-nonprinting ()
{
    if [ ${BUILDING_PS1} ]
    then
        echo -en '\]'
    fi
}

__fontify ()
{
    local -A codes=(
        [bold]=1
        [dim]=2
        [red]=31
        [green]=32
        [blue]=34
    )

    local text=$1
    shift

    __start-nonprinting
    echo -en '\E['

    for ((i=1; i<=$#; i++))
    do
        echo -en ${codes[${!i}]}

        if ((i<$#))
        then
            echo -en ';'
        else
            echo -en 'm'
        fi
    done

    __end-nonprinting

    echo -en "${text}"
    __start-nonprinting
    echo -en '\E[0m'
    __end-nonprinting
}

__set-prompt ()
{
    BUILDING_PS1=t
    PS1=''

    PS1+="$(__write-context)\n"
    PS1+=$(__fontify '\$' dim)
    PS1+=' '

    unset BUILDING_PS1
}

__current-column ()
{
    # Cf. console_codes(4) § ECMA-48 Status Report Commands

    local position
    read -sdR -p$'\E[6n' position

    local pattern='\[[0-9]+;([0-9]+)'

    if [[ ${position} =~ ${pattern} ]]
    then
        echo ${BASH_REMATCH[1]}
    else
        echo 0
    fi
}

__signal-no-newline ()
{
    local signal="/\n"
    __fontify ${signal} bold red
}

__draw-rule ()
{
    local line=''

    for ((i=$(__current-column); i<COLUMNS; i++))
    do
        line+=—
    done

    # If we do not add a newline, whatever comes after will be shoved
    # offscreen when autowrap is off.
    line+='\n'

    __fontify ${line} $@
}

__write-context ()
{
    local context=''

    context+=$(__fontify '\u' green)

    if __show-hostname
    then
        context+=$(__fontify @ dim)
        context+=$(__fontify '\h' bold green)
    fi

    context+=$(__fontify : dim)
    context+=$(__fontify '\w' bold blue)

    if [ ${PS1_SHOWGITSTATUS} ]
    then
        context+=$(__fontify "$(__git_ps1 '(%s)')" red)
    fi

    echo ${context}
}

__refresh-terminal ()
{
    local last_status=$?
    local last_column=$(__current-column)

    __set-title

    if [ ${last_column} -ne 1 ]
    then
        __signal-no-newline
    fi

    if [ ${last_status} -ne 0 ]
    then
        __fontify "${last_status} " bold red
        __draw-rule dim red
    else
        __draw-rule dim
    fi

    __set-prompt
}


if __have-gitprompt
then
    . /usr/lib/git-core/git-sh-prompt
    GIT_PS1_SHOWDIRTYSTATE=t
    GIT_PS1_SHOWUPSTREAM=auto

    PS1_SHOWGITSTATUS=t
fi

export PROMPT_COMMAND=__refresh-terminal