import re
import smtplib
import sys
import socket
import os
from time import gmtime, strftime
import dns.resolver

#settings
mode = 'vuw'

if mode == 'vuw':
    #use ecs vuw mail server
    sender = 'andersbenj1@ecs.vuw.ac.nz'
    server = 'mail.ecs.vuw.ac.nz'
    server_port = 25
    server_requires_authentication = False
elif mode == 'home':
    #use acidic.co.nz mail server
    #tutors / markers - use this if you want, but please don't hammer my mail server
    sender = 'nwen@acidic.co.nz'
    server = 'mail.acidic.co.nz'
    server_port = 587
    server_requires_authentication = True
    server_username = 'nwen+acidic.co.nz'
    server_password = 'nwen123'


def checkHostname(host):
    try:
        dns.resolver.query(host, "MX")
        return True
    except Exception:
        return False

if len(sys.argv) > 1:
    to = sys.argv[1]
else:
    to = input("Enter the email address to send to: ")

# check the email as a whole is roughly valid
if not re.match(r"[^@]+@[^@]+\.[^@]+", to):
    print("The email address you entered isn't valid")
    sys.exit(1)

# check the domain is valid
domain = to.split("@")[1]
if not checkHostname(domain):
    print("The domain server you entered isn't valid")
    sys.exit(1)

# get a list of files
if len(sys.argv) > 2:
    files = sys.argv[2:]
else:
    filelist = input("Enter the names of the files to be sent, deliminated by spaces:\n\t")
    if len(filelist) < 1:
        print("You need to specify the files to be sent")
        sys.exit(1)

    files = filelist.split(" ")

for f in files:
    if not os.path.isfile(f):
        files.remove(f)
        print("Cannot access '" + f + "'. Please ensure the file exists and try again")
        sys.exit(1)

# check the files are all ascii
for f in files:
    handle = open(f)
    test = handle.readlines()

    for line in test:
        try:
            line.encode("ascii")
        except UnicodeEncodeError:
            print("Cannot read " + f + " because the file is not ASCII text")
            sys.exit(1)

    handle.close()

#construct the message
date = strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime())
message = "From: File Postie <{0}>\r\nDate: {1}\r\nTo: {2} <{2}>\r\nSubject: File Delivery\r\n\r\nThese files have been sent to you via Ben Anderson (300237777)'s \"sendfile.py\" script!\r\n".format(sender, date, to)

# append the files to the message
for f in files:
    message += ("""
    ## """ + f + """ ##########################
    """)

    handle = open(f)
    for line in handle.readlines():
        message = message + line + "\r\n"

    message = message + "    ##########################\r\n\r\n"
    handle.close()

message = message + "Bye!"

# interaction is always a good thing. DNS name resolution may have taken a while, so showing the user something is a good idea
print("Sending, please wait..")

# create the recievers array - this could be used to do multiple recipents later
receivers = [to]

# create a smtp object based on the settings
smtpObj = smtplib.SMTP(server, server_port)
if server_requires_authentication:
    smtpObj.login(server_username, server_password)

try:
    smtpObj.sendmail(sender, receivers, message)
    smtpObj.quit()
    print("Sent!")
except Exception:
    print("Unable to send email")
    sys.exit(1)