#!/usr/bin/env python3
# Tests sending and receiving mail by sending a test message to yourself.

import sys
import imaplib
import smtplib
import uuid
import time
import socket
import dns.reversename
import dns.resolver

if len(sys.argv) < 3:
    print("Usage: tests/mail.py hostname emailaddress password")
    sys.exit(1)

host, emailaddress, pw = sys.argv[1:4]

# Attempt to login with IMAP. Our setup uses email addresses
# as IMAP/SMTP usernames.
try:
    M = imaplib.IMAP4_SSL(host)
    M.login(emailaddress, pw)
except OSError as e:
    print("Connection error:", e)
    sys.exit(1)
except imaplib.IMAP4.error as e:
    # any sort of login error
    e = ", ".join(a.decode("utf8") for a in e.args)
    print("IMAP error:", e)
    sys.exit(1)

M.select()
print("IMAP login is OK.")

# Attempt to send a mail to ourself.
mailsubject = "Mail-in-a-Box Automated Test Message " + uuid.uuid4().hex
emailto = emailaddress
msg = """From: {emailaddress}
To: {emailto}
Subject: {subject}

This is a test message. It should be automatically deleted by the test script.""".format(
    emailaddress=emailaddress,
    emailto=emailto,
    subject=mailsubject,
    )

# Connect to the server on the SMTP submission TLS port.
server = smtplib.SMTP(host, 587)
#server.set_debuglevel(1)
server.starttls()

# Verify that the EHLO name matches the server's reverse DNS.
ipaddr = socket.gethostbyname(host)  # IPv4 only!
reverse_ip = dns.reversename.from_address(ipaddr)  # e.g. "1.0.0.127.in-addr.arpa."

try:
    reverse_dns = dns.resolver.query(reverse_ip, 'PTR')[0].target.to_text(omit_final_dot=True)  # => hostname
except dns.resolver.NXDOMAIN:
    print("Reverse DNS lookup failed for %s. SMTP EHLO name check skipped." % ipaddr)
    reverse_dns = None
if reverse_dns is not None:
    server.ehlo_or_helo_if_needed()  # must send EHLO before getting the server's EHLO name
    helo_name = server.ehlo_resp.decode("utf8").split("\n")[0]  # first line is the EHLO name
    if helo_name != reverse_dns:
        print("The server's EHLO name does not match its reverse hostname. Check DNS settings.")
    else:
        print("SMTP EHLO name (%s) is OK." % helo_name)

# Login and send a test email.
server.login(emailaddress, pw)
server.sendmail(emailaddress, [emailto], msg)
server.quit()
print("SMTP submission is OK.")

while True:
    # Wait so the message can propagate to the inbox.
    time.sleep(10)

    # Read the subject lines of all of the emails in the inbox
    # to find our test message, and then delete it.
    found = False
    typ, data = M.search(None, 'ALL')
    for num in data[0].split():
        typ, data = M.fetch(num, '(BODY[HEADER.FIELDS (SUBJECT)])')
        imapsubjectline = data[0][1].strip().decode("utf8")
        if imapsubjectline == "Subject: " + mailsubject:
            # We found our test message.
            found = True

            # To test DKIM, download the whole mssage body. Unfortunately,
            # pydkim doesn't actually work.
            # You must 'sudo apt-get install python3-dkim python3-dnspython' first.
            #typ, msgdata = M.fetch(num, '(RFC822)')
            #msg = msgdata[0][1]
            #if dkim.verify(msg):
            #    print("DKIM signature on the test message is OK (verified).")
            #else:
            #    print("DKIM signature on the test message failed verification.")

            # Delete the test message.
            M.store(num, '+FLAGS', '\\Deleted')
            M.expunge()

            break

    if found:
        break

    print("Test message not present in the inbox yet...")

M.close()
M.logout()

print("Test message sent & received successfully.")