sopel/modules/watcher.py

#!/usr/bin/env python3
"""
A thread watcher module for 4chan.
"""
import time
import threading

import requests

from module import commands, example

def setup(bot):
	"""
	Establishes the bot's dictionary of watched threads.
	"""
	bot.memory["watcher"] = {}


def get_time():
	"""
	Returns the current time formatted in If-Modified-Since notation.
	"""
	return time.strftime("%a, %d %b %Y %H:%M:%S GMT", time.gmtime())


def get_num_posts(thread, name):
	"""
	Gets the number of OP posts from the thread JSON.
	"""
	num = 0
	for post in thread["posts"]:
		if post.get("name") == name:
			num += 1
	return num


def get_last_post(thread, name):
	"""
	Gets the last post made by name.
	"""
	for post in reversed(thread["posts"]):
		if post.get("name") == name:
			return post.get("no")


def get_api_url(url):
	"""
	Returns the API url for the provided thread url.
	"""
	return url.replace("boards.4chan", "a.4cdn") + ".json"


def get_thread_url(api_url):
	"""
	Returns the normal thread url for the provided API url.
	"""
	return api_url.replace("a.4cdn", "boards.4chan").replace(".json", "")


@commands("watch")
@example(".watch https://boards.4chan.org/qst/thread/2")
def watch(bot, trigger):
	"""
	A thread watcher for 4chan.
	"""
	url = trigger.group(3)
	op_name = trigger.group(4)

	if url in bot.memory["watcher"].keys():
		return bot.say("Error: I'm already watching that thread.")

	api_url = get_api_url(url)
	res = requests.get(api_url, verify=True)
	if res.status_code == 404:
		return bot.say("404: thread not found")

	thread = res.json()
	last_post = get_last_post(thread, op_name)
	time_since = get_time()

	t = WatcherThread(bot, api_url, op_name, last_post, time_since)
	t.start()
	bot.memory["watcher"][url] = t
	bot.say("[\x0304Watcher\x03] Watching thread: \x0307" + url)


@commands("unwatch")
@example(".unwatch https://boards.4chan.org/qst/thread/2")
def unwatch(bot, trigger):
	"""
	Stops the thread watcher thread for that thread.
	"""
	url = trigger.group(2)
	try:
		bot.memory["watcher"][url].stop.set()
		bot.memory["watcher"].pop(url)
	except KeyError:
		return bot.say("Error: I'm not watching that thread.")
	return bot.say("[\x0304Watcher\x03] No longer watching: \x0307" + url)


class WatcherThread(threading.Thread):
	def __init__(self, bot, api_url, op_name, last_post, time_since):
		threading.Thread.__init__(self)
		self.stop = threading.Event()
		self.period = 20

		self.bot = bot
		self.api_url = api_url
		self.op_name = op_name
		self.last_post = last_post
		self.time_since = time_since


	def run(self):
		while not self.stop.is_set():
			headers = {"If-Modified-Since": self.time_since}
			res = requests.get(self.api_url, headers=headers, verify=True)
			self.time_since = get_time()

			if res.status_code == 404:
				msg = "[\x0304Watcher\x03] Thread deleted: " \
				+ f"\x0307{get_thread_url(self.api_url)}"
				self.bot.say(msg)
				self.stop.set()
				continue

			if res.status_code == 304:
				self.stop.wait(self.period)
				continue

			thread = res.json()
			if thread["posts"][0].get("closed"):
				msg = "[\x0304Watcher\x03] Thread closed: " \
				+ f"\x0307{get_thread_url(self.api_url)}"
				self.bot.say(msg)
				self.stop.set()
				continue

			new_last_post = get_last_post(thread, self.op_name)
			if new_last_post > self.last_post:
				self.last_post = new_last_post
				msg = "[\x0304Watcher\x03] New post from \x0308" \
				+ f"{self.op_name}\x03 in \x0307{get_thread_url(self.api_url)}"
				self.bot.say(msg)
			self.stop.wait(self.period)