'''
This script creates randoms pairs from a list of participants in a secret santa
game and sends them an email to notify them who the person is that they should 
buy presents for.
'''

# -*- encoding: utf-8 -*-
from argparse import ArgumentParser
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
import json
import random
import smtplib

parser = ArgumentParser()
parser.add_argument('-p', '--participants',
                    dest='pFileLocation',
                    default='participants.json',
                    help='read list of participants from FILE',
                    metavar='PARTICIPANTFILE')
parser.add_argument('-c', '--config',
                    dest='cFileLocation',
                    default='config.json',
                    help='read the configuration from FILE',
                    metavar='CONFIGFILE')

args = parser.parse_args()

# load and prepare a list containing all participants
with open(args.pFileLocation, 'r') as pFile:
  participants = json.load(pFile)

# create a copy of the list to make choosing a partner easier
copy = list(enumerate(participants[:]))

# choose a partner for each participant
for i in range(len(participants)):

  # if the last participant has only themselves left to choose, make them
  # switch partners with another random participant
  if len(copy) == 1 and participants[i] == copy[0][1]:

    current = participants[i]
    participants.remove(current)
    partner = random.choice(participants)

    current['partner'] = partner['partner']
    partner['partner'] = current['name'] + ' (' + current['mail']+')'
    participants.append(current)
    break

  # otherwise choose a random partner for each participant
  else:
    partner = random.choice(copy)
    while partner[0] == i:
      partner = random.choice(copy)

    participants[i]['partner'] = partner[1]['name']+' ('+partner[1]['mail']+')'
    copy.remove(partner)

# load mail server configuration and open smtp server connection
with open(args.cFileLocation, 'r') as cFile:
  config = json.load(cFile)
  
server = smtplib.SMTP(config['server'], config['port'])
server.ehlo()
server.starttls()
server.ehlo()
server.login(config['user'], config['pass'])

# create emails for all participants and send them
# change the text for the mail here if you want to
for r in participants:
  
  msg = MIMEMultipart('alternative')
  msg['From'] = config['sender']
  msg['To'] = r['mail']
  msg['Subject'] = 'Wichteln 🎄'
  
  body = 'Lieb'+r['gender']+' '+r['name']+'!'
  body += '\n\nDu bist heuer Wichtel für '+r['partner']
  body += '. \n Das Geschenk sollte nicht mehr als 50€ kosten.'
  body += '\nFrohe Weihnachten!\n\nDein Christkind 👼'
  
  msg.attach(MIMEText(body, 'plain', 'utf-8'))
  server.sendmail(config['sender'], r['mail'], msg.as_string())