#! /usr/bin/env python3

import smtplib, ssl
from email import utils
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
import pypandoc
import yaml
import argparse
from datetime import datetime
import certifi
import os

def get_yaml(f):
	'''Extracts the yamlHeader from a Markdown file'''
	pointer = f.tell()
	if f.readline() != '---\n':
		f.seek(pointer)
		return ''
	readline = iter(f.readline, '')
	readline = iter(readline.__next__, '---\n')
	return ''.join(readline)


def checkHeader(header):
	"""check the header for validity

	useful, if the title was forgotten

	Args:
		header (dict): yamlHeader of the mdNewsletter

	Returns:
		bool: true if header is alright, false if an error was detected
	"""
	retVal = True
	if not 'title' in header:
		print("Header has no 'title' attribute")
		retVal = False
	else:
		if header['title'] is False:
			print("Empty title!")
			retVal = False
	return retVal

argParser = argparse.ArgumentParser(
	description="Send an Markdown-File as eMail"
)
argParser.add_argument(
	"mdFilePath", 
	help="Path to MarkdownFile to send"
)
argParser.add_argument(
	"-E", "--EmailAddressFilePath", 
	default=None, 
	help="File with eMailAddresses, one per line, to wich to send the eMail TO"
)
argParser.add_argument(
	"-e", "--toEmailAddress", 
	default=None, 
	help="address, to wich to send the eMail TO"
)

# StandardValues
receiverEmails = [
	"cwsvjudo@arcor.de",
	"marko.bunzel@arcor.de",
	"cwsvjudo@gmail.com",
	"judo.cwsv@t-online.de",
]

config = None 
with open('./config.yaml', 'r') as file:
	config = yaml.safe_load(file)

if __name__=="__main__":
	argv = argParser.parse_args()

	# Loading the EmailAdresses from a file
	if argv.EmailAddressFilePath:
		receiverEmails = []
		with open(argv.EmailAddressFilePath) as inFile:
			for line in inFile:
				receiverEmails.append(line)
	
	if argv.toEmailAddress:
		receiverEmails = [argv.toEmailAddress]

	# read markdownfile as header and text
	mdHeader =[]
	mdText = []
	with open(argv.mdFilePath) as f:
		mdHeader = yaml.safe_load(get_yaml(f))
	
	if not checkHeader(mdHeader):
		print("Header not valid!")

	# Create the plain-text and HTML version of your message
	text = pypandoc.convert_file(argv.mdFilePath, "markdown", extra_args=["--self-contained", "--resource-path=../aufgaben"])
	html = pypandoc.convert_file(argv.mdFilePath, "html",  extra_args=["--self-contained", "--resource-path=../aufgaben"])
	
	# Turn these into plain/html MIMEText objects
	txtMimeText  = MIMEText(text, "plain")
	htmlMimeText = MIMEText(html, "html")

	# Create a secure SSL context
	context = ssl.create_default_context()
	# @todo This is a very bad hack, because the cert checking doesn't wor anymore
	context.check_hostname = False
	context.verify_mode = ssl.CERT_NONE
	with smtplib.SMTP_SSL(config['smtp']['serverAddress'], config['smtp']['serverPort'], context=context) as server:
		server.login(config['smtp']['login'], config['smtp']['password'])
		for receiverEmail in receiverEmails:
			# create the mail
			message = MIMEMultipart("alternative")
			# Setting header data
			message["Subject"] = mdHeader['title']
			message["From"] = config['senderEmailAddress']
			message["Reply-To"] = config['senderEmailAddress']
			message["Date"] = str(utils.formatdate(localtime=True))
			# only set the to-header one time: setting it multiple 
			# times results in a multiple to-entries in the header!
			# Meanig the mail has to be recreated for each to address.
			# @todo Find a way to reuse the created mail for every recipent
			message["To"] = receiverEmail
			
			# Add HTML/plain-text parts to MIMEMultipart message
			# The email client will try to render the last part first
			message.attach(htmlMimeText)
			message.attach(txtMimeText)
			
			server.sendmail(config['senderEmailAddress'], receiverEmail, message.as_string())