#!/usr/bin/python3
import argparse
import secrets
from subprocess import PIPE, Popen
from email.mime.text import MIMEText

PASSWORD_ALLOWED_CHARS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

def runCommand(args, input=""):
    args_string = []
    for i in range(len(args)):
        if type(args[i]) == str:
            args_string.append(args[i])
        else:
            args_string.append(str(args[i]))
    process = Popen(args_string, stdin=PIPE, stdout=PIPE, stderr=PIPE)
    output = {"stdout": "", "stderr": "", "returncode": -1}
    output["stdout"], output["stderr"] = process.communicate(bytes(input, 'utf-8'))
    process.poll()
    if not process.returncode == 0:
        command = " ".join(args_string)
        print(f"System call failed with error code {process.returncode}")
        print("Command:")
        print(command)
        print("stdout:")
        print(output["stdout"])
        print("stderr:")
        print(output["stderr"])
        raise Exception(f"Command {command} failed to run")
    else:
        return str(output["stdout"], "UTF-8").strip()

def randomPassword(length):
    return "".join(secrets.choice(PASSWORD_ALLOWED_CHARS) for i in range(length))

def mailUser(email, username, password):
    hostname = runCommand(["/usr/bin/hostname", "--fqdn"])
    mailbody = f"""Hello {username},
    Your CWP password for {username} has been reset.
        
     Your username is: {username}
    Your password is: {password}"""

    msg = MIMEText(mailbody)
    msg['Subject'] = f"CWP Password Change on {hostname}"
    msg['From'] = f"root@{hostname}"
    msg['To'] = email

    p = Popen(["/usr/sbin/sendmail", "-t"], stdin=PIPE)

    p.communicate(msg.as_bytes())

def updateUserPW(username, email):
    newpw = randomPassword(16)
    runCommand(["/usr/bin/passwd",username,"--stdin"], newpw)
    mailUser(email,username,newpw)

parser = argparse.ArgumentParser(description="Reset User Password")
parser.add_argument("username", type=str,
                    help="Username")
parser.add_argument("email", type=str,
                    help="E-mail to send password to")
                    
args = parser.parse_args()

updateUserPW(args.username, args.email)