#!/usr/bin/env python3
#-*- coding: utf-8 -*-

import logging
from os import makedirs, urandom
from os.path import abspath, dirname, isfile, join
from shutil import move
from sys import version_info

from flask import Flask, render_template, request
from waitress.server import create_server
from werkzeug.middleware.dispatcher import DispatcherMiddleware

from backend.db import DBConnection, ThreadedTaskDispatcher, close_db, setup_db
from frontend.api import api, api_prefix, reminder_handler
from frontend.ui import ui

HOST = '0.0.0.0'
PORT = '8080'
URL_PREFIX = '' # Must either be empty or start with '/' e.g. '/mind' 
LOGGING_LEVEL = logging.INFO
THREADS = 10
DB_FILENAME = 'db', 'MIND.db'

logging.basicConfig(
	level=LOGGING_LEVEL,
	format='[%(asctime)s][%(threadName)s][%(levelname)s] %(message)s',
	datefmt='%Y-%m-%d %H:%M:%S'
)

def _folder_path(*folders) -> str:
	"""Turn filepaths relative to the project folder into absolute paths
	Returns:
		str: The absolute filepath
	"""
	return join(dirname(abspath(__file__)), *folders)

def _create_app() -> Flask:
	"""Create a Flask app instance
	Returns:
		Flask: The created app instance
	"""	
	app = Flask(
		__name__,
		template_folder=_folder_path('frontend','templates'),
		static_folder=_folder_path('frontend','static'),
		static_url_path='/static'
	)
	app.config['SECRET_KEY'] = urandom(32)
	app.config['JSONIFY_PRETTYPRINT_REGULAR'] = True
	app.config['JSON_SORT_KEYS'] = False
	app.config['APPLICATION_ROOT'] = URL_PREFIX
	app.wsgi_app = DispatcherMiddleware(Flask(__name__), {URL_PREFIX: app.wsgi_app})

	# Add error handlers
	@app.errorhandler(400)
	def bad_request(e):
		return {'error': 'Bad request', 'result': {}}, 400

	@app.errorhandler(405)
	def method_not_allowed(e):
		return {'error': 'Method not allowed', 'result': {}}, 405

	@app.errorhandler(500)
	def internal_error(e):
		return {'error': 'Internal error', 'result': {}}, 500
	
	@app.errorhandler(404)
	def not_found(e):
		if request.path.startswith('/api'):
			return {'error': 'Not Found', 'result': {}}, 404
		return render_template('page_not_found.html', url_prefix=logging.URL_PREFIX)

	app.register_blueprint(ui)
	app.register_blueprint(api, url_prefix=api_prefix)

	# Setup closing database
	app.teardown_appcontext(close_db)
	
	return app

def MIND() -> None:
	"""The main function of MIND
	Returns:
		None
	"""
	# Check python version
	if (version_info.major < 3) or (version_info.major == 3 and version_info.minor < 7):
		logging.error('Error: the minimum python version required is python3.7 (currently ' + version_info.major + '.' + version_info.minor + '.' + version_info.micro + ')')
		exit(1)

	# Register web server
	# We need to get the value to ui.py but MIND.py imports from ui.py so we get an import loop.
	# To go around this, we abuse the fact that the logging module is a singleton.
	# We add an attribute to the logging module and in ui.py get the value this way.
	logging.URL_PREFIX = URL_PREFIX
	app = _create_app()
	with app.app_context():
		if isfile(_folder_path('db', 'Noted.db')):
			move(_folder_path('db', 'Noted.db'), _folder_path(*DB_FILENAME))

		db_location = _folder_path(*DB_FILENAME)
		logging.debug(f'Database location: {db_location}')
		makedirs(dirname(db_location), exist_ok=True)

		DBConnection.file = db_location
		setup_db()
		reminder_handler.find_next_reminder()

	# Create waitress server and run
	dispatcher = ThreadedTaskDispatcher()
	dispatcher.set_thread_count(THREADS)
	server = create_server(app, _dispatcher=dispatcher, host=HOST, port=PORT, threads=THREADS)
	logging.info(f'MIND running on http://{HOST}:{PORT}{URL_PREFIX}')
	server.run()
	
	# Stopping thread
	reminder_handler.stop_handling()

	return

if __name__ == "__main__":
	MIND()