echo-with-color

#!/usr/bin/env bash

set -euo pipefail

function buffer() {
    BUFFER="${BUFFER}${BUFFER:+ }${@}"
}

function buffer_with_color() {
    [ "${1}" == "${COLOR}" ] && buffer "${2}" || buffer "${1:-${DEFAULT}}${2}"
    [ "${1}" == "${DEFAULT}" ] && COLOR= || COLOR="${1}"
}

function help() {
    echo -e "$(cat << EOF
Usage:
    ${0} [OPTION]... [--] [STRING]...

Generic options:
    -h          show help
    -n          do not output the trailing new line

Color options:
    -0 STRING   output with default color (default)
    -B STRING   output with bold blue (${BOLD_BLUE}sample${DEFAULT})
    -C STRING   output with bold cyan (${BOLD_CYAN}sample${DEFAULT})
    -G STRING   output with bold green (${BOLD_GREEN}sample${DEFAULT})
    -K STRING   output with bold black (${BOLD_BLACK}sample${DEFAULT})
    -M STRING   output with bold magenta (${BOLD_MAGENTA}sample${DEFAULT})
    -R STRING   output with bold red (${BOLD_RED}sample${DEFAULT})
    -W STRING   output with bold white (${BOLD_WHITE}sample${DEFAULT})
    -Y STRING   output with bold yellow (${BOLD_YELLOW}sample${DEFAULT})
    -b STRING   output with blue (${BLUE}sample${DEFAULT})
    -c STRING   output with cyan (${CYAN}sample${DEFAULT})
    -g STRING   output with green (${GREEN}sample${DEFAULT})
    -k STRING   output with black (${BLACK}sample${DEFAULT})
    -m STRING   output with magenta (${MAGENTA}sample${DEFAULT})
    -r STRING   output with red (${RED}sample${DEFAULT})
    -w STRING   output with white (${WHITE}sample${DEFAULT})
    -y STRING   output with yellow (${YELLOW}sample${DEFAULT})
EOF
)"
}

DEFAULT="\033[0m"

BLACK="\033[0;30m"
RED="\033[0;31m"
GREEN="\033[0;32m"
YELLOW="\033[0;33m"
BLUE="\033[0;34m"
MAGENTA="\033[0;35m"
CYAN="\033[0;36m"
WHITE="\033[0;37m"

BOLD_BLACK="\033[1;30m"
BOLD_RED="\033[1;31m"
BOLD_GREEN="\033[1;32m"
BOLD_YELLOW="\033[1;33m"
BOLD_BLUE="\033[1;34m"
BOLD_MAGENTA="\033[1;35m"
BOLD_CYAN="\033[1;36m"
BOLD_WHITE="\033[1;37m"

BUFFER=
COLOR=
NO_NEWLINE=

while getopts '0:B:C:G:K:M:R:W:Y:b:c:g:hk:m:nr:w:y:' OPT
do
    case "${OPT}" in
        0)
            buffer_with_color "" "${OPTARG}"
            ;;
        B)
            buffer_with_color "${BOLD_BLUE}" "${OPTARG}"
            ;;
        C)
            buffer_with_color "${BOLD_CYAN}" "${OPTARG}"
            ;;
        G)
            buffer_with_color "${BOLD_GREEN}" "${OPTARG}"
            ;;
        K)
            buffer_with_color "${BOLD_BLACK}" "${OPTARG}"
            ;;
        M)
            buffer_with_color "${BOLD_MAGENTA}" "${OPTARG}"
            ;;
        R)
            buffer_with_color "${BOLD_RED}" "${OPTARG}"
            ;;
        W)
            buffer_with_color "${BOLD_WHITE}" "${OPTARG}"
            ;;
        Y)
            buffer_with_color "${BOLD_YELLOW}" "${OPTARG}"
            ;;
        b)
            buffer_with_color "${BLUE}" "${OPTARG}"
            ;;
        c)
            buffer_with_color "${CYAN}" "${OPTARG}"
            ;;
        g)
            buffer_with_color "${GREEN}" "${OPTARG}"
            ;;
        h)
            help
            exit 1
            ;;
        k)
            buffer_with_color "${BLACK}" "${OPTARG}"
            ;;
        m)
            buffer_with_color "${MAGENTA}" "${OPTARG}"
            ;;
        n)
            NO_NEWLINE=yes
            ;;
        r)
            buffer_with_color "${RED}" "${OPTARG}"
            ;;
        w)
            buffer_with_color "${WHITE}" "${OPTARG}"
            ;;
        y)
            buffer_with_color "${YELLOW}" "${OPTARG}"
            ;;
        *)
            exit 1
            ;;
    esac
done

shift $(($OPTIND - 1))

buffer "${@}"
[ -n "${COLOR}" ] && BUFFER="${BUFFER}${DEFAULT}"
echo -e ${NO_NEWLINE:+-n} "${BUFFER}"