installer

#!/bin/bash
#
# blib installer
#
# Copyright (C) 2018  David Hobach  LGPLv3
# 0.6

function errorOut {
>&2 echo "ERROR: $1"
>&2 echo "Aborting..."
exit 1
}

#name of the directory this script resides in (hopefully)
SCRIPT_DIR="$(readlink -f "${BASH_SOURCE[0]}")" || errorOut "Failed to execute readlink."
SCRIPT_DIR="$(dirname "$SCRIPT_DIR")" || errorOut "Failed to execute dirname."

#name of this script
SCRIPT_NAME="${BASH_SOURCE[0]##*/}"

#default installation directory
DEFAULT_INSTALL_DIR="/usr/lib"

#name of the library
LIB_NAME="blib"

#where the binary link will be installed to
BINARY_INSTALL="/usr/bin/$LIB_NAME"

#path to the file where to install the manpage
MAN_INSTALL_PATH="/usr/share/man/man3/${LIB_NAME}.3"

function usage {
echo "Usage: $SCRIPT_NAME [install|uninstall|reinstall] [install dir]"
echo ""
echo "Installer for $LIB_NAME."
echo ""
echo "[install dir]: where to install the blib library to or remove it from (a blib subdirectory is created/removed there); default: $DEFAULT_INSTALL_DIR"
exit 1
}

function isInstalled {
local targetDir="$1"
#NOTE: -e doesn't work on dead symlinks (returns false)
[ -e "$targetDir" ] || [ -e "$BINARY_INSTALL" ] || [ -h "$BINARY_INSTALL" ]
}

function updateMan {
echo "Updating the mandb... "
mandb > /dev/null || errorOut "Failed to update the mandb."
}

#installR [install dir] [run man update]
function installR {
local installDir="$1"
local runMan="${2:-0}"
local targetDir="$installDir/$LIB_NAME"
local docDir="$targetDir/doc"
local generatedMan="$docDir/${LIB_NAME}.man"

#checks
[ ${BASH_VERSINFO[0]} -lt 4 ] && errorOut "blib only works with bash versions >= 4."
isInstalled "$targetDir" && errorOut "blib already appears to be installed. Please remove older installations first."
local blib="$SCRIPT_DIR/$LIB_NAME"
[ ! -f "$blib" ] && errorOut "Could not find $blib. Thus cannot install."

echo "Installing to ${targetDir} ..."
mkdir -p "$targetDir" || errorOut "Failed to create $targetDir."
cp -rT "$SCRIPT_DIR" "$targetDir" || errorOut "Failed to copy the blib files."

echo "Fixing access rights..."
chmod -R a+r "$targetDir" || errorOut "Failed to modify the access rights of $targetDir."
#gendoc must be able to write to $docDir:
chmod -R a+rw "$docDir" || errorOut "Failed to modify the access rights of $docDir."

echo "Creating a $LIB_NAME symlink to $BINARY_INSTALL ..."
ln -s "$targetDir/$LIB_NAME" "$BINARY_INSTALL" || errorOut "Failed to create the symlink."

if command -v pandoc &> /dev/null ; then
	blib gendoc html || exit $?
	blib gendoc pdf || exit $?
	blib gendoc man || exit $?

	ln -s "$generatedMan" "$MAN_INSTALL_PATH" || errorOut "Failed to install the $LIB_NAME manpage."
	[ $runMan -eq 0 ] && updateMan
else
	echo "Skipping doc installation as pandoc is not installed."
fi

return 0
}

#uninstallR [install dir] [run man update]
function uninstallR {
local installDir="$1"
local runMan="${2:-0}"
local targetDir="$installDir/blib"
[ ! -d "$targetDir" ] && errorOut "blib doesn't seem to be installed in $targetDir."

echo "Removing ${targetDir} ..."
rm -rf "$targetDir"
echo "Removing $BINARY_INSTALL ..."
rm -f "$BINARY_INSTALL"

if [ -h "$MAN_INSTALL_PATH" ] || [ -e "$MAN_INSTALL_PATH" ] ; then
	echo "Removing $MAN_INSTALL_PATH ..."
	rm -f "$MAN_INSTALL_PATH"
	[ $runMan -eq 0 ] && updateMan
fi

return 0
}

function reinstallR {
local installDir="$1"
uninstallR "$installDir" 1 || errorOut "Failed to uninstall."
installR "$installDir"
}

function main {
[ $# -lt 1 ] && usage
[ $# -gt 2 ] && usage

[ "$(whoami)" != "root" ] && errorOut "This script must be run as root."

#checks (otherwise we might remove /usr/lib/ ...)
command -v basename &> /dev/null || errorOut "basename is not installed."
command -v dirname &> /dev/null || errorOut "dirname is not installed."
command -v readlink &> /dev/null || errorOut "readlink is not installed."

#parse commands
local cmd="$1"
local installDir="$2"
[ -z "$installDir" ] && installDir="$DEFAULT_INSTALL_DIR"

case "$cmd" in
	install)
	installR "$installDir"
	;;

	uninstall)
	uninstallR "$installDir"
	;;
	
	reinstall)
	reinstallR "$installDir"
	;;

	*)
	usage
	;;
esac

echo "All done."
exit 0
}

main "$@"