import logging
import smtplib
import time
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from string import Template

import pandas as pd

from vars import *


def get_contacts(filename):
    """
    Return the lists containing the infos
    read from a file specified by filename.
    """

    logging.debug(f'Loading contacts from {filename}...')

    return pd.read_csv(filename)


def read_template(filename):
    """
    Returns a Template object comprising the contents of the
    file specified by filename.
    """

    with open(filename, 'r', encoding='utf-8') as template_file:
        template_file_content = template_file.read()
    return Template(template_file_content)


def main():
    logging.basicConfig(level=LOGLEVEL, format='%(asctime)s - %(levelname)s - %(message)s')

    logging.info('Starting pymail')

    contacts = get_contacts('contacts.csv')
    message_template = read_template('message.html')

    # set up the SMTP server
    s = smtplib.SMTP(HOST, PORT)
    s.starttls()
    s.login(MY_ADDRESS, PASSWORD)
    logging.debug('Mail server is set up.')

    logging.info(f'Starting to send mails to {len(contacts.index)} recipients, this might take a while...')

    # For each contact, send the email:
    for i in contacts.index:
        logging.info(f"Sending email {i+1} of {len(contacts.index)}\n")
        msg = MIMEMultipart()       # create a message

        # add in the actual person name to the message template
        contact_dict = {col: contacts[col][i] for col in contacts.columns}
        message = message_template.substitute(contact_dict)

        # Prints out the message body for our sake
        logging.debug(f"{message}\n")

        # setup the parameters of the message
        msg['From'] = MY_ADDRESS
        msg['To'] = contacts[MAIL_COLUMN][i]
        msg['Subject'] = SUBJECT

        # add in the message body
        msg.attach(MIMEText(message, 'html'))

        if not DRY_RUN:
            # send the message via the server set up earlier.
            s.send_message(msg)
        del msg

        # Wait for DELAY_SEC seconds every WAIT_EVERY-th message
        if (i + 1) % WAIT_EVERY == 0:
            time.sleep(DELAY_SEC)

    # Terminate the SMTP session and close the connection
    s.quit()

    logging.info('Done!')


if __name__ == '__main__':
    main()