#
# System introspection script which defines variables for use in later dropins.
#
# Exposes system data as the SYSTEM_INFO associative array. Primarily pulls information via
# systemd-hostnamed if available; falls back to reading /etc/machine-info and /etc/hostname,
# or retrieving the system hostname with `uname`. Keys will always be the names of the D-Bus
# properties, not their corresponding fields in /etc/machine-info.
#
# Exposes OS release data as the OS_RELEASE associative array. Data is read directly from
# /etc/os-release if available, otherwise it is not provided.
#
# Exposes all /etc/machine-info fields, including those not defined by the spec, under MACHINE_INFO.
# Keys are the field names with no transforms applied.

_introspection--generate-file-parser() {
	awk 'match($0, /^([A-Za-z_][A-Za-z0-9_]*)=(.*)/, ary) { print "'"$1"'[" ary[1] "]='\''" ary[2] "'\''"}'
}

_introspection--parse-file() {
	local varname=$1
	while read line; do
		key=${${(LC)line%%=*}//_/}
		val=${line#*=}
		eval "${varname}[${key}]=\"${${val%\"}#\"}\""
	done
}

declare -A SYSTEM_INFO
declare -A OS_RELEASE
declare -A MACHINE_INFO
declare -A INTRO_STATE

refresh-system-info() {
	INTRO_STATE[SYSTEM_INFO]=none
	INTRO_STATE[OS_RELEASE]=none
	INTRO_STATE[MACHINE_INFO]=none
	INTRO_STATE[hostname]=none

	if [ -f /etc/machine-info ]; then
			# Populate MACHINE_INFO array
			_introspection--parse-file MACHINE_INFO </etc/machine-info
			INTRO_STATE[MACHINE_INFO]=present
	fi			

	# Parse OS release info, trying first from the new os-release file, then from the LSB standard. Variables should have more or less the same names between the two files.
	if [ -f /etc/os-release ]; then
		_introspection--parse-file OS_RELEASE </etc/os-release
		INTRO_STATE[OS_RELEASE]=present
	elif [ -f /etc/lsb_release ]; then
		_introspection--parse-file OS_RELEASE </etc/lsb_release
		INTRO_STATE[OS_RELEASE]=legacy_lsb_release
	fi

	# Parse detailed system info from hostnamectl, or synthesize what we can from /etc/machine-info and static and transient hostnames.
	if type hostnamectl &>/dev/null; then
		# We can get all relevant data from hostnamectl, so lets do that.
		eval $(hostnamectl --json=short | jq -r 'to_entries | .[] | select((.value | type) != "array" and (.value | type) != "object" and (.value | type) != "null") | "SYSTEM_INFO[\(.key)]=\(.value | @sh)"')
		INTRO_STATE[SYSTEM_INFO]=full
		INTRO_STATE[hostname]=full
	else
		# Parse machine info if available
		if [[ ${INTRO_STATE[MACHINE_INFO]} == present ]]; then
			# Populate SYSTEM_INFO array as best as possible (this will be missing a _lot_ of fields that hostnamed calculates)
			local shared_keys=(PrettyHostname IconName Chassis Deployment Location HardwareVendor HardwareModel HardwareVersion)
			for key val in "${(@kv)MACHINE_INFO}"; do
				case $key in
				HardwareSku)
					SYSTEM_INFO[HardwareSKU]=${MACHINE_INFO[HardwareSku]}
					;;
				*)
					if [[ ${${key:*shared_keys}:+x} == 'x' ]]; then
						SYSTEM_INFO[$key]=${MACHINE_INFO[$key]}
					fi
					;;
				esac
			done
			INTRO_STATE[SYSTEM_INFO]=limited
		fi
		# Read current (transient) hostname
		SYSTEM_INFO[Hostname]=$(uname -n)
		INTRO_STATE[hostname]=transient
		# Read static hostname if available
		if [ -f /etc/hostname ]; then
			SYSTEM_INFO[StaticHostname]=$(</etc/hostname)
			INTRO_STATE[hostname]=full
		fi
	fi
}

refresh-system-info