import difflib
from datetime import datetime
from io import BytesIO

from telegram.ext import Job, CallbackContext, Updater

from src.database import Database
from src.utils import wrap, render, sendRequest


class Scheduler:
    tasks: {str: {str: Job}} = {}
    cache: {str: {str: str}} = {}

    def __init__(self, database: Database, updater: Updater):
        self.database = database
        self.updater = updater

    def create(self, user: str, taskName: str, request):
        if user not in self.cache:
            self.cache[user] = {}

        def task(context: CallbackContext):
            # Send request
            text = wrap(sendRequest(request))

            # First time http request
            if taskName not in self.cache[user]:
                self.cache[user][taskName] = text

            # Compare diff
            else:
                # Generate diff
                diffRaw = difflib.unified_diff(self.cache[user][taskName].splitlines(1), text.splitlines(1),
                                               fromfile='before', tofile='after')
                diff = ''.join(diffRaw)
                self.cache[user][taskName] = text

                if diff != '':
                    # Render diff
                    doc = BytesIO(render(diff))
                    time = datetime.now().strftime('%b %d %Y %H-%M-%S')
                    fileName = 'diff %s %s.png' % (taskName, time)
                    caption = '*%s Changed!*' % taskName

                    # Send as file
                    context.bot.send_document(int(user), doc, fileName, caption, parse_mode='markdown')

        return task

    def start(self, user: str, name: str):
        if self.isStarted(user, name):
            return False

        request = self.database.reqs[user][name]
        if user not in self.tasks:
            self.tasks[user] = {}

        self.tasks[user][name] = self.updater.job_queue.run_repeating(self.create(user, name, request), interval=request.get('interval', 120), first=0)

        # Keep record
        if not request['enabled']:
            request['enabled'] = True
            self.database.save()

        return True

    def stop(self, user: str, name: str):
        if not self.isStarted(user, name):
            return False

        # Stop and remove task
        job = self.tasks[user][name]
        job.enabled = False
        job.schedule_removal()
        self.tasks[user].pop(name, None)
        self.database.reqs[user][name]['enabled'] = False
        self.database.save()

        return True

    def isStarted(self, user: str, name: str):
        return user in self.tasks and name in self.tasks[user]

    def updateInterval(self, user: str, name: str):
        if not self.isStarted(user, name):
            return False

        self.stop(user, name)
        self.start(user, name)
        return True