#!/usr/bin/python3
import datetime
from email.mime.text import MIMEText
from smtplib import SMTP_SSL
import socket
import subprocess
import sys

RELAY_EMAIL = 'dsorber.phalanx@gmail.com'
RELAY_PASSWD = "You'reNotMySupervisor"
TO_EMAIL = 'baranovich@gmail.com'

RAID_DEVS = ['md0']
BLOCK_DEVS = ['sda', 'sdb', 'sdc', 'sdd', 'sde', 'sdf']

SEP = '-' * 80

def send_email(subject, msg_text): 
    msg = MIMEText(msg_text, 'plain')
    msg['Subject'] = subject
    msg['To'] = TO_EMAIL
    try:
        conn = SMTP_SSL('smtp.gmail.com')
        conn.set_debuglevel(True)
        conn.login(RELAY_EMAIL, RELAY_PASSWD)
        try:
            conn.sendmail(RELAY_EMAIL, TO_EMAIL, msg.as_string())
        finally:
            conn.close()

    except Exception as exc:
        print('ERROR')
        print(exec)
        sys.exit("Mail failed: {}".format(exc))


def check_smart(devices):
    """ Check the SMART status of the passed list of block devices
    """
    if type(devices) is not list:
        devices = [devices]
    
    errors = []
    output = []
    
    for device in devices:
        # Get information about this device and SMART health check; prune the 
        # smartmontools banner from the output
        cmd = '/usr/sbin/smartctl -iH /dev/{:s}'.format(device)
        cmd_out = subprocess.check_output(cmd, shell=True)
        raw_out = cmd_out.decode('utf-8').strip().split('\n')[4:]
        
        # Parse out the SMART "overall-health" line and status
        smart_output = raw_out[len(raw_out) - 1]
        smart_status = smart_output[50:]
        
        # Now check smart status
        if smart_status != 'PASSED':
            errors.append('/dev/{:s} SMART check failed'.format(device))
        
        raw_out.insert(0, '/dev/{:s}'.format(device))
        raw_out.append('{:s}\n'.format(SEP))
        output.extend(raw_out)
        
        #~ print('\n'.join(raw_out))
    
    return (errors, output)

def check_raid(devices):
    """ Check the status of the passed list of software RAID devices
    """
    if type(devices) is not list:
        devices = [devices]
    
    errors = []
    output = []
    
    for device in devices:
        # Get information about this device
        cmd = '/sbin/mdadm --detail /dev/{:s}'.format(device)
        cmd_out = subprocess.check_output(cmd, shell=True)
        raw_out = cmd_out.decode('utf-8').strip().split('\n')
        
        # Parse out the 'state' line
        raid_state = raw_out[11][18:].strip()
        if raid_state != 'clean':
            errors.append('/dev/{:s} not in "clean" state'.format(device))
        
        output.extend(raw_out)
    
    return (errors, output)


def main():
    
    # Grab timestamp
    timestamp = datetime.datetime.now()
    ts_str = timestamp.strftime('%Y%m%d_%H%M')
    
    hostname = socket.gethostname()
    
    print('Checker for {:s} - {:s}\n\n'.format(hostname, ts_str))
    
    errors = []
    output = []
    output.append('Report for {:s} - {:s}\n'.format(hostname, ts_str))
    output.append('\n')
    
    # Report uptime
    output.append('Uptime:')
    cmd_out = subprocess.check_output('uptime', shell=True)
    output.append(cmd_out.decode('utf-8').strip())
    output.append('{:s}\n'.format(SEP))
    
    # Check software RAID devices
    raid_errors, raid_output = check_raid(RAID_DEVS)
    errors.extend(raid_errors)
    output.extend(raid_output)
    
    # Report df -h (disk utilization)
    cmd_out = subprocess.check_output('df -h', shell=True)
    output.append(cmd_out.decode('utf-8').strip())
    output.append('{:s}\n'.format(SEP))
    
    # Check block devices
    smart_errors, smart_output = check_smart(BLOCK_DEVS)
    errors.extend(smart_errors)
    output.extend(smart_output)

    # If no errors prepend "all okay" message
    should_send = False
    if not errors:
        output.insert(2, 'All OKAY.\n')
        
        # Send an email every Thursday at 3 AM even if status is okay
        if timestamp.weekday() == 3 and timestamp.hour == 3:
            should_send = True
    else:
        # Send email if there were any errors
        output.insert(2, '\n'.join(errors))
        should_send = True

    # Send email
    if should_send:
        send_email('Report: {:s} - {:s}\n'.format(hostname, ts_str), 
                   '\n'.join(output))

if __name__ == '__main__':
    sys.exit(main())