#!/bin/bash

set -eu
set -o noglob

fatal() {
    local MSG="${1}"
    >&2 echo "[!] ${MSG}"
    exit 1
}

info() {
    local MSG="${1}"
    echo "[-] ${MSG}"
}

fetch() {
    local -r URL="$1"
    local -r OUTFILE="$2"

    local WGET_BINARY="/usr/bin/wget"
    local WGET_CMD="$WGET_BINARY -q --tries=3 --user-agent=PGA_installer"
    local CURL_BINARY="/usr/bin/curl"
    local CURL_CMD="$CURL_BINARY -sf -L --retry 3 --user-agent=PGA_installer"

    if [[ -x "${WGET_BINARY}" ]]
    then
        $WGET_CMD -O "$OUTFILE" "${URL}" || return 2
        return 0
    fi

    if [[ -x "${CURL_BINARY}" ]]
    then
        $CURL_CMD -o "$OUTFILE" "${URL}" || return 2
        return 0
    fi

    echo "Not found: $WGET_BINARY or $CURL_BINARY" >&2
    return 1
}

# Загрузка исполняемого файла гостевого агента и скрипта его обновления
install_pga_files() {
    local PGA_UPDATER="/etc/cron.daily/phoenix-ga-updater"
    local PGA_UPDATER_URL="http://updates.netangels.ru/phoenix-ga/updater"

    [[ -e "${PGA_UPDATER}" ]] && {
        fatal "${PGA_UPDATER} already exists"
    }

    info "Downloading ${PGA_UPDATER}"
    fetch ${PGA_UPDATER_URL} ${PGA_UPDATER} || {
        fatal "Failed to download ${PGA_UPDATER}"
    }
    chmod +x ${PGA_UPDATER}

    info "Downloading guest agent via ${PGA_UPDATER}"
    ${PGA_UPDATER} now
}

# Создание сервиса для systemd и его запуск
install_pga_systemd() {
    info "Systemd detected"

    info "Checking \`systemctl\` binary"
    local SYSTEMCTL_BINARY=$(which systemctl)
    [[ -n "$SYSTEMCTL_BINARY" ]] || {
        fatal "Can't find systemctl binary"
    }

    local PGA_SERVICE_FILE="/etc/systemd/system/phoenix-ga.service"

    info "Checking ${PGA_SERVICE_FILE}"
    [[ -e "${PGA_SERVICE_FILE}" ]] && {
        fatal "${PGA_SERVICE_FILE} already exists"
    }

    info "Creating ${PGA_SERVICE_FILE}"
    cat > ${PGA_SERVICE_FILE} <<EOF
[Unit]
Description=Phoenix Guest Agent
After=systemd-udevd.service

[Service]
Restart=always
RestartSec=0.5
ExecStart=/usr/sbin/phoenix-ga
StandardOutput=null

[Install]
WantedBy=multi-user.target
EOF

    info "Starting guest agent"
    ${SYSTEMCTL_BINARY} enable ${PGA_SERVICE_FILE}
    ${SYSTEMCTL_BINARY} start $( basename ${PGA_SERVICE_FILE} )
}

# Создание сервиса для upstart и его запуск
install_pga_upstart() {
    info "Upstart detected"

    info "Checking \`initctl\` binary"
    local INITCTL_BINARY=$(which initctl)
    [[ -n "${INITCTL_BINARY}" ]] || {
        fatal "Can't find initctl binary"
    }

    local PGA_INIT_FILE="/etc/init/phoenix-ga.conf"

    info "Checking ${PGA_INIT_FILE}"
    [[ -e "${PGA_INIT_FILE}" ]] && {
        fatal "${PGA_INIT_FILE} already exists"
    }

    info "Creating ${PGA_INIT_FILE}"
    cat > ${PGA_INIT_FILE} <<EOF
start on runlevel [2345]
stop on shutdown
respawn
exec /usr/sbin/phoenix-ga
EOF

    info "Starting guest agent"
    ${INITCTL_BINARY} start $( basename ${PGA_INIT_FILE%%.conf} )
}

# Настройка автозапуска гостевого агента для Sys-V init и его запуск
install_pga_sysvinit() {
    info "Sys-V Init detected"

    local INITTAB_FILE="/etc/inittab"

    info "Checking ${INITTAB_FILE}"
    [[ -e "${INITTAB_FILE}" ]] || {
        fatal "${INITTAB_FILE} does not exist"
    }
    grep -q '^PGA:' ${INITTAB_FILE} && {
        fatal "Guest agent already in ${INITTAB_FILE}"
    }

    info "Appending ${INITTAB_FILE}"
    cat >> ${INITTAB_FILE} <<EOF

#-- PGA begin
PGA:2345:respawn:/usr/sbin/phoenix-ga
#-- PGA end
EOF

    info "Starting guest agent"
    kill -1 1
}

[[ $UID -eq 0 ]] || {
    fatal "Must be started by superuser"
}

declare -r INIT_BINARY=$(readlink /proc/1/exe)

install_pga_files

case "${INIT_BINARY}" in
    "/lib/systemd/systemd")
        install_pga_systemd;;
    "/usr/lib/systemd/systemd")
        install_pga_systemd;;
    "/sbin/upstart")
        install_pga_upstart;;
    "/sbin/init")
        install_pga_sysvinit;;
esac

>/dev/null pgrep phoenix-ga || {
    fatal "Failed to start guest agent"
}

info "Guest agent succesfully started" 

exit 0