#!/bin/env python3
import datetime
from tkinter import Tk, CENTER, Label
import click
import typing as t
import os

DELTASECONDS = "+%Ss"
DELTAMINUTES = "+%Mm"
DELTAHOURS = "+%Hh"
HOURS = "%H:%M"
DATETIME_FORMAT = [
    "%Y-%m-%d",
    "%Y-%m-%dT%H:%M:%S",
    "%Y-%m-%d %H:%M:%S",
    "%Y-%m-%d %H:%M",
    HOURS,
    DELTAHOURS,
    DELTAMINUTES,
    DELTASECONDS,
]


class DateTime(click.DateTime):
    def _try_to_convert_date(self, value: t.Any, format: str) -> t.Optional[datetime]:
        try:
            if value[0] == "+":
                if format == DELTASECONDS and value[-1] == "s":
                    return datetime.datetime.now() + datetime.timedelta(
                        seconds=int(value[1:-1])
                    )
                if format == DELTAMINUTES and value[-1] == "m":
                    return datetime.datetime.now() + datetime.timedelta(
                        minutes=int(value[1:-1])
                    )
                if format == DELTAHOURS and value[-1] == "h":
                    return datetime.datetime.now() + datetime.timedelta(
                        hours=int(value[1:-1])
                    )
            if format == HOURS:
                return datetime.datetime.combine(
                    datetime.datetime.now().date(),
                    datetime.datetime.strptime(value, format).time(),
                )
            return datetime.datetime.strptime(value, format)
        except ValueError:
            return None


def start_app(enddate):
    root = Tk()
    root.geometry("300x100+200+200")
    root.configure(background="#000")
    tlbl = Label(root, text="", font=("Arial", -100), fg="#fff", bg="#000")
    tlbl.pack()
    tlbl.place(relx=0.5, rely=0.5, anchor=CENTER)

    def deltaStr(t):
        days, remainder = divmod(t.total_seconds(), 60 * 60 * 24)
        hours, remainder = divmod(remainder, 3600)
        minutes, seconds = divmod(remainder, 60)
        if days == 0:
            if hours == 0:
                if minutes == 0:
                    return f"{int(seconds):02d}"
                return f"{int(minutes):02d}:{int(seconds):02d}"
            return f"{int(hours):02d}:{int(minutes):02d}:{int(seconds):02d}"
        return f"{int(days):02d}:{int(hours):02d}:{int(minutes):02d}:{int(seconds):02d}"

    def resize(_):
        ratio = root.winfo_width() / 1920
        tlbl.configure(font=("Chicago", int(ratio * -200)))

    def update():
        delta = enddate - datetime.datetime.now()
        if delta.total_seconds() < 0:
            tlbl.configure(text="Now")
            tlbl.config(fg="red")
        else:
            tlbl.configure(text=deltaStr(delta))
        root.after(1000 - datetime.datetime.now().microsecond // 1000, update)

    root.bind("<Configure>", resize)
    root.bind("<Escape>", lambda x: root.destroy())
    root.after(1, update)
    if os.environ.get("XDG_CURRENT_DESKTOP", "") == "i3":
        root.wm_attributes("-type", "splash")
    root.mainloop()


@click.command()
@click.argument("enddate", type=DateTime(formats=DATETIME_FORMAT))
def main(enddate):
    start_app(enddate)


if __name__ == "__main__":
    main()