#!/bin/bash

OS_REQUIREMENTS_FILENAME="requirements.apt"

# Handle call with wrong command
function wrong_command()
{
  echo "${0##*/} - unknown command: '${1}'"
  usage_message
}

# Print help / script usage
function usage_message()
{
  echo "usage: ./${0##*/} <command>"
  echo "available commands are:"
  echo -e "\tlist\t\tPrint a list of all packages defined on ${OS_REQUIREMENTS_FILENAME} file"
  echo -e "\thelp\t\tPrint this help"
  echo -e "\n\tCommands that require superuser permission:"
  echo -e "\tinstall\t\tInstall packages defined on ${OS_REQUIREMENTS_FILENAME} file. Note: This\n\t\t\t   does not upgrade the packages already installed for new\n\t\t\t   versions, even if new version is available in the repository."
  echo -e "\tupgrade\t\tSame that install, but upgrate the already installed packages,\n\t\t\t   if new version is available."

}

# Read the requirements.apt file, and remove comments and blank lines
function list_packages(){
     grep -v "#" ${OS_REQUIREMENTS_FILENAME} | grep -v "^$";
}

function install()
{
    list_packages | xargs apt-get --no-upgrade install -y;
}

function upgrade()
{
    list_packages | xargs apt-get install -y;
}


function install_or_upgrade()
{
    P=${1}
    PARAN=${P:-"install"}

    if [[ $EUID -ne 0 ]]; then
        echo -e "\nYou must run this with root privilege" 2>&1
        echo -e "Please do:\n" 2>&1
        echo "sudo ./${0##*/} $PARAN" 2>&1
        echo -e "\n" 2>&1

        exit 1
    else

        apt-get update

        # Install the basic compilation dependencies and other required libraries of this project
        if [ "$PARAN" == "install" ]; then
            install;
        else
            upgrade;
        fi

        # cleaning downloaded packages from apt-get cache
        apt-get clean

        exit 0
    fi


}


# Handle command argument
case "$1" in
    install) install_or_upgrade;;
    upgrade) install_or_upgrade "upgrade";;
    list) list_packages;;
    help) usage_message;;
    *) wrong_command $1;;
esac
