#!/usr/bin/env python3

import sys
import os
from collections import defaultdict
import datetime
import threading
from time import sleep
import json
import mattermost
import mattermost.ws

SERVER = "mattermost.zeus.gent"
TEAM_NAME = "zeus"
CHAN_NAME = "pannenkoeken"
EMOJI_NAME = "pancakes"
SINCE = datetime.datetime.strptime("2020-11-01 00:00", "%Y-%m-%d %H:%M") \
	.astimezone(datetime.timezone.utc)
TAGGERS = [
	# Board
	"flynn",
	"bobby",
	"pcassima",
	"redfast00",
	"francis.",
	"hannes",
	"arnhoudt",
	"mel",

	# Sneaky backdoor (actually just for testing and if you read this, nobody has removed it)
	"midgard",
]

TOKEN = os.getenv("MM_ACCESS_TOKEN")
USER = os.getenv("MM_USERNAME")
PASSWORD = os.getenv("MM_PASSWORD")


def first(iterable, default=None):
	for x in iterable:
		return x
	return default


def get_posts_for_channel(mmapi, channel_id, since, **kwargs):
	after = None
	while True:
		data_page = mmapi._get("/v4/channels/"+channel_id+"/posts", params=(
			{ "after": after }
			if after else
			{ "since": to_mm_timestamp(since) }
		), **kwargs)

		order = list(reversed(data_page["order"]))
		for post_id in order:
			yield data_page["posts"][post_id]

		if not order:
			return
		after = order[-1]


##################################
# Log in
mm = mattermost.MMApi(f"https://{SERVER}/api")

if TOKEN:
	mm.login(bearer=TOKEN)
else:
	assert USER
	assert PASSWORD
	mm.login(USER, PASSWORD)


##################################
# Get channel
team_data = first(filter(lambda team: team["name"] == TEAM_NAME, mm.get_teams()))
assert team_data, "Team should exist"

channel_data = first(filter(lambda chan: chan["name"] == CHAN_NAME, mm.get_team_channels(team_data["id"])))
assert channel_data, "Channel should exist"
channel = channel_data["id"]


##################################
# Get users

# People who are authorized to grant pancakes
tagger_ids = {u["id"]: u["username"] for u in mm.get_users_by_usernames_list(TAGGERS)}


users = {u["id"]: u for u in mm.get_users(in_channel=channel)}

for user in users.values():
	assert user["username"].find(" ") == -1, f"{user['username']} shouldn't have spaces in username"

def get_username(userid):
	# When someone joined later
	if userid not in users:
		users[userid] = mm.get_user(userid)

	return users[userid]["username"]


##################################
# Get posts
posts = {}
def get_post(postid):
	if postid not in posts:
		posts[postid] = mm.get_post(postid)

	return posts[postid]


def parse_mm_timestamp(mm_timestamp):
	return datetime.datetime.fromtimestamp(mm_timestamp / 1000, datetime.timezone.utc)

def to_mm_timestamp(dt):
	return int(dt.timestamp() * 1000)


def reaction_qualifies(reaction):
	return reaction["emoji_name"] == EMOJI_NAME and reaction["user_id"] in tagger_ids


awarded = defaultdict(set)
def award_if_appropriate(reaction):
	if not reaction_qualifies(reaction):
		return

	post = get_post(reaction["post_id"])
	if parse_mm_timestamp(post["create_at"]) < SINCE:
		return

	awarder_id = reaction["user_id"]
	if awarder_id in awarded[post["id"]]:
		return
	awarded[post["id"]].add(awarder_id)

	reaction_time = parse_mm_timestamp(reaction["create_at"]).isoformat(timespec="microseconds")
	post_time = parse_mm_timestamp(reaction["create_at"]).isoformat(timespec="microseconds")
	awardee = get_username(post["user_id"])
	awarder = get_username(awarder_id)
	print(f"{awardee} {post['id']} at {post_time} verified by {awarder} at {reaction_time}", flush=True)


def retract_if_appropriate(reaction):
	if not reaction_qualifies(reaction):
		return

	post = get_post(reaction["post_id"])
	if parse_mm_timestamp(post["create_at"]) < SINCE:
		return

	awarder_id = reaction["user_id"]
	awarded[post["id"]].discard(awarder_id)

	awardee = get_username(post["user_id"])
	awarder = get_username(awarder_id)
	print(f"{awardee} {post['id']} verification removed by {awarder}", flush=True)


def handle_backlog(since):
	for post in get_posts_for_channel(mm, channel, since):
		for reaction in post.get("metadata", {}).get("reactions", []):
			award_if_appropriate(reaction)


def handle_live():
	def ws_handler(mmws, event_data):
		if event_data["broadcast"]["channel_id"] != channel:
			return

		if event_data["event"] == "reaction_added":
			award_if_appropriate(json.loads(event_data["data"]["reaction"]))
		elif event_data["event"] == "reaction_removed":
			retract_if_appropriate(json.loads(event_data["data"]["reaction"]))

	ws = mattermost.ws.MMws(ws_handler, mm, f"wss://{SERVER}/api/v4/websocket")
	while True:
		sleep(60 * 1000)


live = "--live" in sys.argv[1:]

# Note: skipping this step and updating an existing file would be dangerous: you would miss revocations that happened while not listening.
handle_backlog(SINCE)

if sys.stdout.isatty():
	print("To use this data, redirect stdout to a file and use make_table.py on it.", file=sys.stderr)

if live:
	print("Now watching for live posts.", file=sys.stderr)
	handle_live()

else:
	print("Use --live to keep watching new posts.", file=sys.stderr)


# Logout
if not TOKEN:
	mm.revoke_user_session()