#!/bin/bash

function usage {
    local BASECMD
    BASECMD=$(basename "$0")
    echo "usage: $BASECMD <packages...>"
    echo 'idempotent debian package installation : update if necessary, install only if not yet done'
    exit 1
}

[ "$(id -u)" -ne 0 ] && echo 'root privilege required' && exit 2
[[ $# -lt 1 ]] && usage

if [ "$(date --date='-12 hours' +%s)" -gt "$(date -d "$(stat -c %y /var/lib/apt/lists/partial)" +%s)" ]; then
    echo "updating repositoring..."
    apt-get update
fi

for i in "$@"; do
    if ! dpkg -l "$i" 2>/dev/null | grep -q ^ii; then
        sudo apt-get install -y "$i"
    elif [ -n "${VERBOSE+x}" ] && $VERBOSE; then
        echo "apt package <$i> already installed!"
    fi
done