#!/usr/bin/env python3

"""
Author: Gian Segato

Usage:

tz 15 to pt

tz: exec name
to: either to, or from
pt: the desidered timezone
15: the desidered time (accepted values: now, +/-x, 15) in the CURRENT timezone if "to", otherwise in the DEST timezone

"""

import sys
import os
from datetime import datetime, timedelta
import pytz

local = pytz.timezone('Europe/Berlin')
fmt = '%m-%d %H:%M'

if len(sys.argv) != 4:
    print("Not enough args")
    os._exit(-1)

delta_arg = sys.argv[1]  # "16"
dir_arg = sys.argv[2].lower()  # "to".lower()
tz_arg = sys.argv[3].lower()  # "pt".lower()


tz = None
if tz_arg == "pt":
    tz = "US/Pacific"
elif tz_arg == "ct":
    tz = "US/Central"
elif tz_arg == "et":
    tz = "US/Eastern"
elif tz_arg == "uk":
    tz = "Europe/London"
else:
    raise Exception("Unkonwn timezone")

tz = pytz.timezone(tz)


to = None
if dir_arg == "to":
    ref = local.localize(datetime.now())
    to = tz
else:
    ref = tz.localize(datetime.now())
    to = local

if delta_arg == "now":
    delta = 0
elif delta_arg[0] == "+" or delta_arg[0] == "-":
    delta = int(delta_arg[1:])
    if delta_arg[0] == "-":
        delta *= -1
else:
    delta = 0
    ref = ref.replace(hour=int(delta_arg), minute=0, second=0)

ref += timedelta(hours=delta)

r = ref.astimezone(to).strftime(fmt)

result = "{} ({}) → {} ({})".format(ref.strftime(fmt), tz if to != tz else local, r, local if to != tz else tz)
print(result)