#! /bin/sh

# install_prereq: a script to install distribution-specific
# prerequirements

set -e

usage() {
  echo "$0: a script to install distribution-specific prerequirement"
  echo 'Revision: $Id$'
  echo ""
  echo "Usage: $0:         Shows this message."
  echo "Usage: $0 test     Prints commands it is about to run."
  echo "Usage: $0 install  Really install."
}

PACKAGES_DEBIAN="build-essential libnewt-dev libusb-dev modemp3d"
PACKAGES_RH="gcc newt-devel libusb-devel"
KVERS=`uname -r`

case "$1" in
test)    testcmd=test_cmd ;;
install) testcmd='' ;;
'') usage; exit 0 ;;
*) usage; exit 1 ;;
esac

NOTHING_TO_INSTALL=true
test_cmd() {
	NOTHING_TO_INSTALL=false
	echo "$@"
}

# Fixme: should be done by apt and not by dpkg?
check_installed_debs() {
	 dpkg-query -W --showformat '${Status} ${Package}\n' "$@" 2>/dev/null \
	 | awk '/ not-installed/{print $4}'
}

# parsing the output of yum is close to impossible.
# We'll use rpm and hope for the best:
check_installed_rpms() {
	for pack in "$@"
	do
		if ! rpm -q $pack >/dev/null 2>/dev/null
		then echo $pack
		fi
	done
}


has_kernel_source() {
	test -r /lib/modules/$KVERS/build/.config
}

in_test_mode() {
  test "$testcmd" != ''
}

handle_debian() {
	# echo "# Distribution is Debian or compatible"
	kernel_package=''
	extra_packs=`check_installed_debs $PACKAGES_DEBIAN`
	if ! has_kernel_source; then
		kernel_package="linux-headers-$KVERS"
		debian_release=`cat /etc/debian_version`
		case "$debian_release" in
		3.1) kernel_package="kernel-headers-$KVERS";;
		esac
		echo "# Kernel source not found. Installing $kernel_package"
	fi
	if [ "$extra_packs$kernel_package" = '' ]; then
		return
	fi
	$testcmd apt-get install -y $extra_packs $kernel_package
}

handle_rh() {
	# echo "# Distribution is RedHat or similar."
	kernel_package=''
	extra_packs=`check_installed_rpms $PACKAGES_RH`
	if ! has_kernel_source; then
		kern_str='' # extra "kernel version"
		case "$KVERS" in
		*smp*) kern_str='-smp';;
		*PAE*) kern_str='-PAE';;
		*xen*) kern_str='-xen';;
		esac
		kernel_package="kernel$kern_str-devel-$KVERS"
		echo "# Kernel source not found. Installing $kernel_package"

		echo "# if you get an error for the following command, consider"
		echo "#"
		echo "#yum install -y kernel$kern_str kernel$kern_str-devel"
		echo "#"
		echo "# and then reboot to upgrade to the newly installed kernel."
	fi
	if [ "$extra_packs$kernel_package" = '' ]; then
		return
	fi
	$testcmd yum install -y $extra_packs $kernel_package
}

if in_test_mode; then
	echo "#############################################"
	echo "## $1: test mode."
	echo "## Use the commands here to install your system."
	echo "#############################################"
fi

# handle the easy case of Debians first
if [ -r /etc/debian_version ]; then
  handle_debian
elif [ -r /etc/redhat-release ]; then
  handle_rh
fi

echo "#############################################"
if in_test_mode; then
  if $NOTHING_TO_INSTALL; then
    echo "## $1 completed successfully ((In test mode) "
  else
    echo "## $1: some extra packages are needed to build zaptel"
    exit 1
  fi
else
  echo "## $1 completed successfully"
fi
echo "#############################################"