#!/usr/bin/env python3
"""Nagios plugin: report current memory usage.

Outputs a one-line status and perfdata and uses Nagios exit codes:
  0 OK, 1 WARNING, 2 CRITICAL, 3 UNKNOWN

Defaults: warning=80%%, critical=90%% (percent used).
"""

import argparse
import sys
import psutil


def human_mb(bytes_val):
	return bytes_val / (1024 * 1024)


def main():
	parser = argparse.ArgumentParser(description="Nagios memory usage check")
	parser.add_argument("-w", "--warning", type=int, default=80,
						help="warning threshold (percent used)")
	parser.add_argument("-c", "--critical", type=int, default=90,
						help="critical threshold (percent used)")
	args = parser.parse_args()

	if args.warning >= args.critical:
		print("UNKNOWN - warning threshold must be less than critical")
		sys.exit(3)

	try:
		vm = psutil.virtual_memory()
	except Exception as e:
		print(f"UNKNOWN - failed to read memory: {e}")
		sys.exit(3)

	total_mb = human_mb(vm.total)
	used_mb = human_mb(vm.total - vm.available)
	percent_used = vm.percent

	status = 0
	status_str = "OK"
	if percent_used >= args.critical:
		status = 2
		status_str = "CRITICAL"
	elif percent_used >= args.warning:
		status = 1
		status_str = "WARNING"

	# Perfdata: used and total in MiB, and percent
	perf = (
		f"used={used_mb:.1f}MiB;{args.warning};{args.critical};0;{total_mb:.1f}"
		f" total={total_mb:.1f}MiB"
	)

	print(f"MEMORY {status_str} - {used_mb:.1f}MiB used of {total_mb:.1f}MiB ({percent_used:.1f}%) | {perf}")
	sys.exit(status)


if __name__ == "__main__":
	main()