#!/bin/bash
BASH_ARGV0=write-tty
echo -n "$0" >/proc/$BASHPID/comm

output_filter()
{
        tokenize | colorize | soft_cursor
}

chr()
{
        declare -i n="$*"
        printf "$(printf '\%o' "$n")"
}

colorize()
{
        BASH_ARGV0=colorize
        echo -n "$0" >/proc/$BASHPID/comm
        while read -r
        do
                case "$REPLY" in
                        \\[0-7][0-7][0-7] )
                                declare -i c=8#"${REPLY#?}"
                        ;;
                        \\U[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] )
                                declare -i c=16#"${REPLY#??}"
                        ;;
                        * )
                                printf '%s\n' "$REPLY"
                                continue
                                ;;
                esac
                if (( c > 128 + 127 ))
                then
                        :
                elif (( c > 128 + 32 ))
                then
                        REPLY=M-$(chr c - 128)
                elif (( c > 127 ))
                then
                        REPLY=M-^$(chr c - 128 + 64)
                elif (( c < 32 ))
                then
                        REPLY=^$(chr c + 64)
                fi
                printf $'\e[106m%s\e[m\n' "$REPLY"
        done
}

tokenize()
{
        BASH_ARGV0=tokenize
        echo -n "$0" >/proc/$BASHPID/comm
        while read -r -n1 -d ''
        do
                if [[ "$REPLY" =~ [[:print:]] ]]
                then
                        # Output one printable character per line. It may be a
                        # multibyte unicode character.
                        printf '%s\n' "$REPLY"
                        continue
                elif [ "$REPLY" ]
                then
                        # If it is a non-printable, then we output a
                        # multi-character line. In this case we colorize it
                        # later so that it won't be confused with multiple
                        # printable characters.
                        bytelen=$(LC_ALL=C; echo ${#REPLY})
                        if (( bytelen == 1 ))
                        then
                                printf '\\%.3o\n' "'$REPLY"
                        else
                                hexdigits=$(LC_ALL=C; for ((i=0; i<$bytelen; ++i))
                                do
                                        printf '%.2x' "'${REPLY:$i:1}"
                                        printf '%.2x\n' "'${REPLY:$i:1}" >&2
                                done)
                                printf '%s%.8x\n' '\U' 0x"$hexdigits"
                        fi
                else
                        printf '\\%.3o\n' 0
                fi
        done
}

soft_cursor()
{
        BASH_ARGV0=soft_cursor
        echo -n "$0" >/proc/$BASHPID/comm
        FMT=$'%s \b\e[%sm \e[m \b\b'
        REPLY=
        color=105
        while printf "$FMT" "$REPLY" "$color"
        do
                read -r || break
        done
}

output_filter