#!/usr/bin/env python3

import argparse
import datetime
import pytz
from typing import List

def list_timezones() -> List[str]:
    return pytz.all_timezones

def get_timezone_offset(tz: str) -> str:
    try:
        tz_obj = pytz.timezone(tz)
        offset = tz_obj.utcoffset(datetime.datetime.now())
        return f"{tz}: {offset}"
    except pytz.UnknownTimeZoneError:
        return f"Unknown timezone: {tz}"

def convert_timezones(source_tz: str, target_tz: str, time: str) -> str:
    try:
        source_tz_obj = pytz.timezone(source_tz)
        target_tz_obj = pytz.timezone(target_tz)
        time_obj = datetime.datetime.strptime(time, "%Y-%m-%d %H:%M")
        time_obj = source_tz_obj.localize(time_obj)
        converted_time = time_obj.astimezone(target_tz_obj)
        return f"{time} ({source_tz}) -> {converted_time.strftime('%Y-%m-%d %H:%M')} ({target_tz})"
    except (pytz.UnknownTimeZoneError, ValueError):
        return "Invalid input"

def schedule_meeting(timezones: List[str], time: str) -> str:
    try:
        time_obj = datetime.datetime.strptime(time, "%Y-%m-%d %H:%M")
        result = []
        for tz in timezones:
            tz_obj = pytz.timezone(tz)
            localized_time = tz_obj.localize(time_obj)
            result.append(f"{tz}: {localized_time.strftime('%Y-%m-%d %H:%M')}")
        return "\n".join(result)
    except ValueError:
        return "Invalid time format"

def main() -> None:
    parser = argparse.ArgumentParser(description="Chronozone: Time zone converter and scheduler")
    subparsers = parser.add_subparsers(dest="command")

    list_parser = subparsers.add_parser("list", help="List all timezones")
    list_parser.add_argument("-a", "--all", action="store_true", help="Show all timezones")

    offset_parser = subparsers.add_parser("offset", help="Get timezone offset")
    offset_parser.add_argument("timezone", help="Timezone name")

    convert_parser = subparsers.add_parser("convert", help="Convert time between timezones")
    convert_parser.add_argument("source_tz", help="Source timezone name")
    convert_parser.add_argument("target_tz", help="Target timezone name")
    convert_parser.add_argument("time", help="Time in YYYY-MM-DD HH:MM format")

    schedule_parser = subparsers.add_parser("schedule", help="Schedule a meeting across timezones")
    schedule_parser.add_argument("timezones", nargs="+", help="List of timezone names")
    schedule_parser.add_argument("time", help="Time in YYYY-MM-DD HH:MM format")

    args = parser.parse_args()

    if args.command == "list":
        if args.all:
            print("\n".join(list_timezones()))
        else:
            print("Use -a or --all to show all timezones")
    elif args.command == "offset":
        print(get_timezone_offset(args.timezone))
    elif args.command == "convert":
        print(convert_timezones(args.source_tz, args.target_tz, args.time))
    elif args.command == "schedule":
        print(schedule_meeting(args.timezones, args.time))
    else:
        parser.print_help()

if __name__ == "__main__":
    main()