#!/usr/bin/env python3
import click
import sys
import email.parser
import smtplib
import json
from pathlib import Path


DEFAULT_CONFIG_FILE_PATH = Path.home() / ".pmmlrc"


def read_config_file(config_file_path):
    with open(config_file_path) as f:
        config = json.load(f)
    return config


def setup_smtp_session(smtp_server, smtp_port, smtp_user, smtp_pass):
    smtp_client = smtplib.SMTP(host=smtp_server, port=smtp_port)
    smtp_client.ehlo()
    smtp_client.starttls()
    smtp_client.login(smtp_user, smtp_pass)
    return smtp_client


@click.command()
@click.option("-f", "--config-file", default=DEFAULT_CONFIG_FILE_PATH)
@click.argument("mailing-list-address")
def cli(config_file, mailing_list_address):
    ignore_subjects = ("Undelivered Mail Returned to Sender",)
    input = sys.stdin
    config = read_config_file(config_file)[mailing_list_address]
    msg = email.parser.Parser().parse(input)

    if msg["Subject"] in ignore_subjects:
        print(f"Skipping processing because of subject: {msg['Subject']}")
    else:
        smtp_client = setup_smtp_session(
            config["smtp_server"],
            config["smtp_port"],
            config["smtp_user"],
            config["smtp_pass"],
        )
        smtp_client.sendmail(
            mailing_list_address, config["recipients"], msg.as_string().encode('utf-8')
        )
        smtp_client.quit()


if __name__ == "__main__":
    cli()