# This skeleton is valid for both Python 2.7 and Python 3.
# You should be aware of your additional code for compatibility of the Python version of your choice.

from socket import *
import argparse as ap
import getpass as gp

#Get sender_email and recipient_email as arguments to the program
parser = ap.ArgumentParser(description='A test SMTP client without authentication')
parser.add_argument('-f', '--from', dest='fromMail', required=True, metavar='<sender_email>')
parser.add_argument('-t', '--to', dest='toMail', required=True, metavar='<recipient_email>')
#If using the authentication of the SMTP server, also get a valid username (optional exercise)
#parser.add_argument('-u', '--username', dest='username', required=True, metavar='<username>')

args = parser.parse_args()
fromMail = args.fromMail #Sender's email address
toMail = args.toMail #Recipient's email address
#username = args.username #SMTP username in case you are implementing the optional exercise

#If using the authentication of the SMTP server, ask for a valid password (optional exercise)
#password = gp.getpass(prompt='Password: ')

# Message to send
msg = "\r\n I love computer networks!"
endmsg = "\r\n.\r\n"

# Our mail server is smtp.stud.ntnu.no but it allows only authenticated communications. (optional exercise)
#mailserver = 'smtp.stud.ntnu.no'
# You can run a local simple SMTP server such as "Fake SMTP Server" and communicate with it without authentication.

# Create socket called clientSocket and establish a TCP connection
# (use the appropriate port) with mailserver
#Fill in start
mailserver = ('', 8000)
clientSocket = socket(AF_INET, SOCK_STREAM)
clientSocket.connect(mailserver)

#Fill in end

recv = clientSocket.recv(1024)
print(recv.decode())
if recv[:3] != '220'.encode():
    print('220 reply not received from server.')

# Send HELO command and print server response.
# Can use EHLO instead since HELO is obsolete, but the latter can still be used
heloCommand = 'EHLO Alice\r\n'
clientSocket.send(heloCommand.encode()) #Python 3
#clientSocket.send(heloCommand) #Python 2.7
recv1 = clientSocket.recv(1024)
print(recv1.decode())
if recv1[:3] != '250'.encode():
    print('250 reply not received from server.')

# Send MAIL FROM command and print server response.
# Fill in start
clientSocket.send(('MAIL FROM:' + '<' + fromMail + '>' + '\r\n').encode())
recv2 = clientSocket.recv(1024)
print('After MAIL FROM command: ', recv2.decode())
# Fill in end

# Send RCPT TO command and print server response.
# Fill in start
clientSocket.send(('RCPT TO:' + '<' + toMail + '>' + '\r\n').encode())
recv3 = clientSocket.recv(1024)
print('After RCPT TO command: ', recv3.decode())
# Fill in end

# Send DATA command and print server response.
# Fill in start
clientSocket.send('DATA\r\n'.encode())
recv4 = clientSocket.recv(1024)
print('After DATA command: ', recv4.decode())
# Fill in end

# Send message data.
# Fill in start
clientSocket.send(msg.encode())
clientSocket.send(endmsg.encode())
# Fill in end

# Message ends with a single period.
# Fill in start
clientSocket.send('.'.encode())
recv5 = clientSocket.recv(1024)
print(recv5.decode())
# Fill in end

# Send QUIT command and get server response.
# Fill in start
quitCommand = 'QUIT\r\n'
clientSocket.send(quitCommand.encode())
recv6 = clientSocket.recv(1024)
print(recv6.decode())
clientSocket.close()
# Fill in end

#Note that there are more communications if you implement the optional exercise.