#! /usr/bin/env python

import paramiko #Used for SSH
import time
import re
import getpass #Used for masking passwords

def disable_paging(_conn):
    '''Disable paging on a Cisco router'''

    remote_conn.send("terminal length 0\n")
    time.sleep(1)

    # Clear the buffer on the screen
    output = remote_conn.recv(9000)

    return output

def stp_changes(ip, username, password):
    # Create instance of SSHClient object
    remote_conn_pre = paramiko.SSHClient()

    # Automatically add untrusted hosts
    remote_conn_pre.set_missing_host_key_policy(paramiko.AutoAddPolicy())

    # Initiate SSH connection
    remote_conn_pre.connect(ip, username=username, password=password)

    # Use invoke_shell to establish an 'interactive session'
    remote_conn = remote_conn_pre.invoke_shell()

    # Strip the initial router prompt
    output = remote_conn.recv(9000)

    # Turn off paging
    disable_paging(remote_conn)

    # send a command
    remote_conn.send("\n")
    remote_conn.send("show spanning-tree detail | i ieee|from|last\n")

    # Wait for the command to complete
    time.sleep(2)

    #Gat output from previous command
    stp_changes = remote_conn.recv(9000)

    #Change from bytes to readable code
    stp_changes = stp_changes.decode("utf-8")
    print(stp_changes)
    print('\n')
    remote_conn.close()



if __name__ == '__main__':
    #Prompt user for credentials to be used for authentication
    filename = 'switches.txt'
    username = input("Username:")
    #Get password with masking
    password = getpass.getpass()
    #Open file
    with open(filename, 'r') as f:
        for ip in f:
            stp_changes(ip.rstrip('\n'), username, password)