#!/bin/bash

colorize() {
    case "$1" in
        red)
            local color_start=$(tput setaf 1);;
        green)
            local color_start=$(tput setaf 2);;
        yellow)
            local color_start=$(tput setaf 3);;
        blue)
            local color_start=$(tput setaf 4);;
        purple)
            local color_start=$(tput setaf 5);;
        cyan)
            local color_start=$(tput setaf 6);;
    esac

    shift
    local color_reset='\033[0m'

    echo "${color_start}$*${color_reset}"
}

rnd_color() {
    arr=('red' 'green' 'yellow' 'blue' 'purple' 'cyan')
    printf "${arr[RANDOM % 6]}"
}

analysis() {
    sent="$1"
    re="$(printf "$sent" | tr -cs "[:alpha:]" "\n" | sed 's/^\(.\).*/\1/' | uniq -di)"

    if [ -z "$re" ]; then
        return
    fi

    while read -r smb; do
        smb_l=$(printf "$smb" | tr '[:upper:]' '[:lower:]')
        smb_u=$(printf "$smb" | tr '[:lower:]' '[:upper:]')
        color=$(rnd_color)
        color_smb=" $(colorize $color "$smb_l")"
        sent="${sent// "$smb_l"/$color_smb}"
        color_smb="-$(colorize $color "$smb_l")"
        sent="${sent//-"$smb_l"/$color_smb}"
        color_smb=" $(colorize $color "$smb_u")"
        sent="${sent// "$smb_u"/$color_smb}"
        color_smb="-$(colorize $color "$smb_u")"
        sent="${sent//-"$smb_u"/$color_smb}"
    done <<<"$re"

    printf "$sent\n"
}

while read -r line; do
    analysis "$line"
done <<<"$(cat -- "${1--}" | sed 's/\.\.\./…/g;s/\?\!/‽/g;s/[.…‽!?]/&\
/g;s/^[ \t]*//;s/[ \t]*$//;/^$/d')"