#!/usr/bin/env python3
import argparse
import csv
import json
import sys
import requests
from datetime import datetime
from pathlib import Path

api_url = "https://pi.hole/api"
verify = "/etc/pihole/tls_ca.crt"
default_password_file = "/etc/pihole/api_password"

parser = argparse.ArgumentParser(description="List non-static (dynamic) Pi-hole DHCP leases.")
parser.add_argument("-p", "--password-file", default=default_password_file,
                     help=f"Path to file containing the Pi-hole API password (default: {default_password_file})")
parser.add_argument("-t", "--table", action="store_true",
                     help="Print a human-readable aligned table (with local time expiry)")
parser.add_argument("-j", "--json", action="store_true",
                     help="Print machine-readable output as JSON instead of the default CSV")
args = parser.parse_args()

if args.table and args.json:
	parser.error("--table and --json are mutually exclusive")


def read_password(path):
	try:
		return Path(path).read_text().strip()
	except OSError as e:
		raise SystemExit(f"Could not read password file '{path}': {e}")


def format_expiry_human(value):
	try:
		return datetime.fromtimestamp(int(value)).strftime("%Y-%m-%d %H:%M:%S")
	except (TypeError, ValueError):
		return str(value)


auth_payload = {"password": read_password(args.password_file)}

with requests.post(f"{api_url}/auth", json=auth_payload, verify=verify) as auth:
	auth_json = auth.json()
	session = auth_json.get('session')
	if not session or not session.get('sid'):
		raise SystemExit(f"Authentication failed: {auth_json}")

	headers = {
		"X-FTL-SID": session.get('sid'),
		"X-FTL-CSRF": session.get('sid')
	}

	try:
		# Get static DHCP host mappings to know which MACs are static
		with requests.get(f"{api_url}/config", headers=headers, verify=verify) as config:
			config_json = config.json()
			static_macs = set()
			for entry in config_json.get('config').get('dhcp').get('hosts'):
				mac = entry.split(",")[0].lower()
				static_macs.add(mac)

		# Get current active DHCP leases
		with requests.get(f"{api_url}/dhcp/leases", headers=headers, verify=verify) as leases_resp:
			leases_json = leases_resp.json()
			leases = leases_json.get('leases', [])

			non_static = [l for l in leases if l.get('hwaddr', '').lower() not in static_macs]

			records = []
			for lease in non_static:
				records.append({
					"ip": lease.get('ip', '-'),
					"mac": lease.get('hwaddr', '-'),
					"hostname": lease.get('name') or '-',
					"expires": lease.get('expires', '-'),
				})

			if args.table:
				if not records:
					print("No non-static (dynamic) leases found.")
				else:
					rows = [(r["ip"], r["mac"], r["hostname"], format_expiry_human(r["expires"])) for r in records]
					ip_w = max(len(r[0]) for r in rows + [("IP", "", "", "")])
					mac_w = max(len(r[1]) for r in rows + [("", "MAC", "", "")])
					name_w = max(len(r[2]) for r in rows + [("", "", "Hostname", "")])

					print(f"{'IP':<{ip_w}}  {'MAC':<{mac_w}}  {'Hostname':<{name_w}}  Expires (local time)")
					print(f"{'-' * ip_w}  {'-' * mac_w}  {'-' * name_w}  {'-' * 19}")
					for ip, mac, name, expires in rows:
						print(f"{ip:<{ip_w}}  {mac:<{mac_w}}  {name:<{name_w}}  {expires}")

			elif args.json:
				print(json.dumps(records, indent=2))

			else:
				# Default: machine-readable CSV, raw (unix timestamp) expiry
				writer = csv.DictWriter(sys.stdout, fieldnames=["ip", "mac", "hostname", "expires"])
				writer.writeheader()
				writer.writerows(records)
	finally:
		requests.delete(f"{api_url}/auth", headers=headers, verify=verify)