import discord
from discord.ext import commands, tasks
import time

class TrackTimer():
    def __init__(self, duration, users, channel, author):
        self.end = time.time() + duration
        self.users = users
        self.channel = channel
        self.author = author
    def __str__(self):
        return str(self.end - time.time()) + "s remaining."
    def valid(self):
        return time.time() < (self.end)

class Timer(commands.Cog):
    """Timer commands."""
    def __init__(self, bot):
        self.bot = bot
        self.check_timers.start()
        self.timers = []

    @tasks.loop(seconds=2.0)
    async def check_timers(self):
        for timer in self.timers:
            if not timer.valid():
                msg = "Pencils down! "
                msg += timer.author.mention + " "
                for user in timer.users:
                    msg += user.mention + " "
                await timer.channel.send(msg)
                self.timers.remove(timer)

    @commands.command(pass_context=True, hidden=False)
    async def timer(self, ctx, minutes: int, mentions: str):
        """Starts a timer for a given number of minutes. 
        Tags mentioned users when timer expires.
        Always tags the user that called this function"""
        self.timers.append(TrackTimer(minutes*60, ctx.message.mentions, ctx.channel, ctx.author))
        msg = "Okay "
        for user in ctx.message.mentions:
            msg += user.display_name + ", "
        msg += ctx.author.display_name + "; "
        msg += "your " + str(minutes) + " minutes start now."
        await ctx.channel.send(msg)

def setup(bot):
    bot.add_cog(Timer(bot))