#!/usr/bin/env python3
"""
Reminds of things.
"""
import os
import re
import time
import sqlite3
import threading
from datetime import datetime

import config
from module import commands, example

class MonitorThread(threading.Thread):
	"""
	A custom custom thread class for monitoring the time to announce
	reminders. It allows itself to be stopped when there are no reminders
	to look for.
	"""
	def __init__(self, bot):
		threading.Thread.__init__(self)
		self._bot = bot
		self.stop = threading.Event()

	def run(self):
		while not self._bot.stillConnected():
			time.sleep(1)
			# don't try to say anything if we're not fully connected yet
		while not self.stop.is_set():
			now = int(time.time())
			unixtimes = [int(key) for key in self._bot.memory["remind"].keys()]
			oldtimes = [t for t in unixtimes if t <= now]
			if oldtimes:
				for oldtime in oldtimes:
					for reminder in self._bot.memory["remind"][oldtime]:
						channel, nick, message = reminder
						if message:
							self._bot.msg(channel, nick + ': ' + message)
						else:
							self._bot.msg(channel, nick + '!')
					del self._bot.memory["remind"][oldtime]
					delete_reminder(self._bot, oldtime)
			if not self._bot.memory["remind"] or not self._bot.stillConnected():
				self.stop.set()
			self.stop.wait(2.5)
		del self._bot.memory["remind_monitor"]


def start_monitor(bot):
	"""
	Starts the monitor thread. Does nothing if one is already running.
	"""
	if bot.memory.get("remind_monitor"):
		return
	t = MonitorThread(bot)
	t.start()
	bot.memory["remind_monitor"] = t


def load_database(bot):
	"""
	Loads all entries from the 'remind' table in the bot's database and
	stores them in memory
	"""
	data = {}
	reminds = bot.db.execute("SELECT * FROM remind").fetchall()

	for remind in reminds:
		unixtime, channel, nick, message = remind
		reminder = (channel, nick, message)
		try:
			data[unixtime].append(reminder)
		except KeyError:
			data[unixtime] = [reminder]
	return data


def insert_reminder(bot, unixtime, reminder):
	"""
	Inserts a new reminder into the 'remind' table in the bot's database.
	reminder - a tuple containing (channel, nick, message)
	"""
	bot.db.execute("INSERT INTO remind (unixtime, channel, nick, message) "
		"VALUES(?,?,?,?)", (unixtime,) + reminder)


def delete_reminder(bot, unixtime):
	"""
	Deletes a reminder from the 'remind' table in the bot's database, using
	unixtime as the key.
	"""
	bot.db.execute("DELETE FROM remind WHERE unixtime = ?", (unixtime,))


def setup(bot):
	con = bot.db.connect()
	cur = con.cursor()
	try:
		cur.execute("SELECT * FROM remind").fetchone()
	except sqlite3.OperationalError:
		cur.execute("CREATE TABLE remind("
			"unixtime INTEGER DEFAULT (STRFTIME('%s', 'now')),"
			"channel TEXT,"
			"nick TEXT,"
			"message TEXT)")
		con.commit()
	con.close()
	bot.memory["remind"] = load_database(bot)
	start_monitor(bot)


regex = (
	"(?=\d+[ywdhms])"
	"(?:(\d+)y)?"
	"(?:(\d+)w)?"
	"(?:(\d+)d)?"
	"(?:(\d+)h)?"
	"(?:(\d+)m)?"
	"(?:(\d+)s)?"
)
multiplier = [
	60*60*24*365,
	60*60*24*7,
	60*60*24,
	60*60,
	60,
	1
]

@commands('remind')
@example('.remind 3h45m Go to class')
def remind(bot, trigger):
	"""Gives you a reminder in the given amount of time."""
	if len(trigger.args) == 1:
		return bot.msg("Missing arguments for reminder command.")
	if len(trigger.args) == 2:
		reminder = ''
	else:
		reminder = ' '.join(trigger.args[2:])

	duration = 0
	for n, group in enumerate(re.search(regex, trigger.args[1]).groups()):
		if not group:
			continue
		duration += int(group) * multiplier[n]
	create_reminder(bot, trigger, duration, reminder)


@commands('at')
@example('.at 2012-12-21 18:00:00 End the world.')
def at(bot, trigger):
	"""
	Gives you a reminder at the given time and date. Datetime must be in
	YYYY-MM-DD HH:MM:SS format. Only the bot's timezone is used.
	"""
	if len(trigger.args) < 3:
		return bot.msg("Missing arguments for reminder command.")
	if len(trigger.args) < 4:
		reminder = ''
	else:
		reminder = ' '.join(trigger.args[3:])

	try:
		at_time = datetime.strptime(' '.join(trigger.args[1:2]), 
				'%Y-%m-%d %H:%M:%S')
	except ValueError:
		return bot.msg("Datetime improperly formatted.")
	diff = at_time - datetime.now()
	duration = diff.seconds

	create_reminder(bot, trigger, duration, reminder)


def create_reminder(bot, trigger, duration, message):
	"""
	Inserts the reminder into the bot's memory and database so it can
	eventually announce for it.
	"""
	t = int(time.time()) + duration
	reminder = (trigger.channel, trigger.nick, message)
	try:
		bot.memory["remind"][t].append(reminder)
	except KeyError:
		bot.memory["remind"][t] = [reminder]
	start_monitor(bot)
	insert_reminder(bot, t, reminder)

	if duration >= 60:
		remind_at = datetime.fromtimestamp(t)
		t_format = config.default_time_format
		timef = datetime.strftime(remind_at, t_format)

		bot.reply('Okay, will remind at %s' % timef)
	else:
		bot.reply('Okay, will remind in %s secs' % duration)