Automatically download and start xflux

flux.sh

#!/usr/bin/env bash

SCRIPT_NAME="${0##*/}"

TMP_DIR="$(mktemp -d)"
LAT="52.51"
LONG="13.39"
FLUX_URL="https://justgetflux.com/linux/xflux64.tgz"
STR_RUNNING="xflux is already running! If you want to stop it, use '${SCRIPT_NAME} stop'."
STR_STOPPED="xflux is not running! If you want to start it, use '${SCRIPT_NAME} start'."
STR_DL="Downloading xflux..."
STR_ASKDL="xflux is currently not installed. Do you want me to download it? [Y/n] "
STR_NODL="Neither wget nor curl is installed. Can not download xflux."
STR_DLERR="Uh-oh, something went wrong while downloading xflux..."
STR_USAGE="Usage: ${SCRIPT_NAME} start [--yes|-y] | stop | pid "

# Change to script's directory to ensure we're in the
# correct folder.
# http://stackoverflow.com/questions/3349105/how-to-set-current-working-directory-to-the-directory-of-the-script
cd "${0%/*}" || exit 1

_cleanup() {
    rm -rf "${TMP_DIR}"
}

command_exist() {
    command -v "${1}" > /dev/null
}

start_xflux() {
    if pgrep "xflux" > /dev/null; then
        echo "${STR_RUNNING}"
        exit 0
    else
        echo -n "Starting xflux for (${LAT}, ${LONG})..."
        if (command_exist "xflux"); then
            BIN="xflux"
        elif (command_exist "${HOME}/bin/xflux"); then
            BIN="${HOME}/bin/xflux"
        else
            download_xflux
        fi
        if [ ! -z "${BIN}" ]; then
            "${BIN}" -l "${LAT}" -g "${LONG}" > /dev/null && echo "OK"
        fi
        exit 0
    fi
}

stop_xflux() {
    if (pgrep "xflux" > /dev/null); then
        echo -n "Stopping xflux..."
        kill "$(pgrep -f xflux)"
        echo "OK"
    else
        echo "${STR_STOPPED}"
    fi
    exit 0
}

get_pid() {
    if (pgrep "xflux" > /dev/null); then
        pgrep -f xflux
    else
        echo "${STR_STOPPED}"
    fi
    exit 0
}

ask_download() {
    read -r -p "${STR_ASKDL}" RESPONSE
    case "${RESPONSE}" in
        [nN][oO]|[nN] ) exit 0 ;;
        *             ) download_xflux ;;
    esac
}

download_xflux() {
    if (command_exist wget); then
        echo -n "${STR_DL}"
        wget --directory-prefix="${TMP_DIR}" --quiet "${FLUX_URL}"
    elif (command_exist curl); then
        echo -n "${STR_DL}"
        curl --silent --output "${TMP_DIR}/xflux64.tgz" "${FLUX_URL}"
    else
        echo "${STR_NODL}"
        exit 1
    fi

    if [ -f "${TMP_DIR}/xflux64.tgz" ]; then
        echo "OK"
        mkdir -p "${HOME}/bin"
        tar -xzf "${TMP_DIR}/xflux64.tgz" -C "${HOME}/bin"
        rm -rf "${TMP_DIR}"
        start_xflux
    else
        echo "${STR_DLERR}"
        exit 1
    fi
}

case "${1}" in
    start )
        if (command_exist xflux || command_exist "${HOME}/bin/xflux"); then
            start_xflux
        else
            case "${2}" in
                --yes | -y )
                    download_xflux
                    ;;
                * )
                    ask_download
                    ;;
            esac
        fi
        ;;
    stop )
        stop_xflux
        ;;
    pid )
        get_pid
        ;;
    * )
        echo "${STR_USAGE}"
        exit 3
        ;;
esac

trap _cleanup EXIT