#
# This is OCF Linux distribution query support
# 
# Currently needed for the nfsserver RA which has some already
# released RH specific stuff (/etc/sysconfig/nfs editing)
#
# These functions are intended to be POSIX-compliant for portability.
# 

# systemd-based systems should all have an os-release file.
_ETC_OS_RELEASE_FILE="/etc/os-release"
_USR_OS_RELEASE_FILE="/usr/lib/os-release"

# Legacy distro-specific files
_DEBIAN_VERSION_FILE="/etc/debian_version"
_REDHAT_RELEASE_FILE="/etc/redhat-release"
_SUSE_RELEASE_FILE="/etc/SuSE-release"


# Converts OS release ID to a standard form regardless of source.
_process_os_release_id() {
	_os="$1"

	# Convert to lowercase, isolate distro name, remove whitespace
	_os=$(echo "$_os" \
		| tr "[:upper:]" "[:lower:]" \
		| sed -e "s|\(gnu/\)*linux||" -e "s/server//" \
			-e "s/release.*//" -e "s/[[:digit:]].*//" \
			-e "s/[[:blank:]]//")

	# Normalize known distros to os-release names
	case "$_os" in
	*alma*)
		_os="almalinux"
		;;
	*centos*)
		_os="centos"
		;;
	*debian*)
		_os="debian"
		;;
	*fedora*)
		_os="fedora"
		;;
	*ol*)
		_os="ol"
		;;
	*redhat*|*rhel*|*scientific*)
		_os="rhel"
		;;
	*rocky*)
		_os="rocky"
		;;
	*opensuse*)
		_os="opensuse"
		;;
	*suseenterprise*)
		_os="sles"
		;;
	*ubuntu*)
		_os="ubuntu"
		;;
	esac

	echo "$_os"
}

# Converts OS version ID to a form that ocf_version_cmp() can handle.
# Strips any garbage.
_process_os_version_id() {
	_ver="$1"
	_fmt="[[:digit:]][[:digit:].-]*[[:alnum:].\+-]*"

	echo "$_ver" | sed -e "s/[^[:digit:]]*\(${_fmt}\).*/\1/"
}

# Gets OS release ID (i.e., distro) or version ID from os-release file.
# $_ETC_OS_RELEASE_FILE takes precedence over $_USR_OS_RELEASE_FILE.
_get_val_from_os_release_file() {
	_key=""
	_value=""
	_func=""

	case "$1" in
	id)
		_key="ID"
		_func="_process_os_release_id"
		;;
	version_id)
		_key="VERSION_ID"
		_func="_process_os_version_id"
		;;
	esac

	if [ -n "$_key" ]; then
		if [ -f "$_ETC_OS_RELEASE_FILE" ]; then
			_value=$(awk -F "=" -v k="$_key" '$1 == k {print $2}' \
					"$_ETC_OS_RELEASE_FILE" | tr -d \")
		fi

		if [ -z "$_value" ] && [ -f "$_USR_OS_RELEASE_FILE" ]; then
			_value=$(awk -F "=" -v k="$_key" '$1 == k {print $2}' \
					"$_USR_OS_RELEASE_FILE" | tr -d \")
		fi
	fi

	# Ensure the value is in the correct format
	[ -n "$_func" ] && _value=$("$_func" "$_value")

	echo "$_value"
}

# Gets OS release ID from lsb_release command or legacy *-release files
_get_os_from_legacy_source() {
	_os=""

	if which lsb_release >/dev/null 2>&1; then
		_os=$(lsb_release -si)

	elif [ -f "$_DEBIAN_VERSION_FILE" ]; then
		_os="debian"

	elif [ -f "$_REDHAT_RELEASE_FILE" ]; then
		_os=$(head -n 1 "$_REDHAT_RELEASE_FILE")

	elif [ -f "$_SUSE_RELEASE_FILE" ]; then
		_os=$(head -n 1 "$_SUSE_RELEASE_FILE")

	else
		_os=$(uname -s)
	fi

	_process_os_release_id "$_os"
}

# Gets OS version from lsb_release command or legacy *-release files
_get_version_from_legacy_source() {
	_ver=""

	if which lsb_release >/dev/null 2>&1; then
		_ver=$(lsb_release -sr)

	elif [ -f "$_DEBIAN_VERSION_FILE" ]; then
		_ver=$(cat "$_DEBIAN_VERSION_FILE")

	elif [ -f "$_REDHAT_RELEASE_FILE" ]; then
		_ver=$(head -1 "$_REDHAT_RELEASE_FILE")

	elif [ -f "$_SUSE_RELEASE_FILE" ]; then
		_ver=$(awk '$1 == "VERSION" {print $3}' "$_SUSE_RELEASE_FILE")
		_patchlevel=$(awk '$1 == "PATCHLEVEL" {print $3}' \
				"$_SUSE_RELEASE_FILE")

		[ -n "$_patchlevel" ] && _ver="${_ver}.${_patchlevel}"

	else
		_ver=$(uname -r)
	fi

	_process_os_version_id "$_ver"
}

# Prints OS release ID (i.e., distro name)
get_release_id() {
	_os=$(_get_val_from_os_release_file id)

	if [ -z "$_os" ]; then
		_os=$(_get_os_from_legacy_source)
	fi

	echo "$_os"
}

# Prints OS version ID
get_os_version_id() {
	_ver=$(_get_val_from_os_release_file version_id)

	if [ -z "$_ver" ] || [ "$(get_release_id)" = "debian" ]; then
		# Debian only includes major release in os-release.
		# $_DEBIAN_VERSION_FILE has ${major}.${minor}.
		_ver=$(_get_version_from_legacy_source)
	fi

	echo "$_ver"
}

# Returns true if the OS is Debian-based, otherwise false
is_debian_based() {
	get_release_id | grep -i -e "debian" -e "ubuntu" >/dev/null 2>&1
}

# Returns true if the OS is Red Hat-based, otherwise false
is_redhat_based() {
	get_release_id | grep -i -e "almalinux" -e "centos" -e "fedora" -e "ol" \
		-e "redhat" -e "rhel" -e "rocky" -e "scientific" >/dev/null 2>&1
}

# Returns true if the OS is SUSE-based, otherwise false
is_suse_based() {
	get_release_id | grep -i -e "sles" -e "suse" >/dev/null 2>&1
}

# Sets global variables OS and VER.
# get_os_ver() is currently unused upstream; maintained for backwards
# compatibility.
get_os_ver() {
	OS=$(get_release_id)
	VER=$(get_os_version_id)
}