#!/bin/python3

#importing the required modules

import json
import subprocess


#file which will hold the online/offline status of servers

file = "status.json"


#creating dictionary containing current server hostnames/ips from json

try:
    with open("/root/servers.json") as f:
        servers = json.load(f)
except FileNotFoundError:
    raise RuntimeError("servers json file not found")




#function for pinging servers to check if they are offline
#logic: create empty dictionary called status
#loop over pre-defined servers dictionary, key is server, value is ip
#ping each server's ip
#if the return code for the ping is 0, the server's online status is true
#else its false/offline/unreachable

def online_check():
    status = {}

    for server, ip in servers.items():
        result = subprocess.run(
            ["ping", "-c", "2", "-W", "1", ip],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL
        )

        if result.returncode == 0:
            status[server] = True
        else:
            status[server] = False

    return status



#function for sending an email notification
#logic: we are defining this subprocess as notify
#any argument given to it becomes "email"
#we later pass offline_message/online_message to it as the email to send

def notify(email):
    subprocess.run(
        ["msmtp", "cool@dude.wow"],
        input=email,
        text=True
    )






#check to see if we can ping apache-intranet
#(primary server for porygon monitoring)


result = subprocess.run(
    ["ping", "-c", "5", "-W", "2", "200.201.202.203"],
    stdout=subprocess.DEVNULL,
    stderr=subprocess.DEVNULL
)

#if apache-intranet is currently offline
#and we have a current status.json
#build previous status dictionary from it
try:
    with open(file) as f:
        previous_status = json.load(f)
except FileNotFoundError:
        pass


if result.returncode == 0:
    print("apache-intranet is online")
#apache-intranet is online
#delete status.json
#only need to keep track during outages
#this server is the backup
    subprocess.run(["rm", "-f", file])
else:
#apache-intranet is not offline
#check if status.json exists
#if it does we are currently in the midst of an outage
    check = subprocess.run(["test", "-f", file])
    if check.returncode == 0:
        status = online_check()
        for server, ip in servers.items():

            if status[server] == True:
                if previous_status.get(server) == False:

                    online_message = f"""To: this@again.com
Subject: {server} is back online

{server} at {ip} looks to be back online and is now respon>
"""
                    notify(online_message)

            if status[server] == False:
                if previous_status.get(server) == True:
                    offline_message = f"""To: lmao@haha.lol
Subject: {server} is offline

{server} at {ip} looks to be offline and is no longer responding to pings.
"""
                    notify(offline_message)
        with open(file, "w") as f:
            json.dump(status, f, indent=4)


#if status.json does not exist
#but apache-intranet is not reachable
#then this is the moment porygon has become aware of the outage
#we have no reference to track back online/healing alerts
#only offline ones
    else:
        subprocess.run(["touch", file])

        status = online_check()

        for server, ip in servers.items():

            offline_message = f"""To: oh.no@all.offline
Subject: {server} is offline

{server} at {ip} looks to be offline and is no longer responding to pings.
"""

            if status[server] == True:
                print(f"{server} is online")
                status[server] = True
            else:
                print(f"{server} is offline")
                notify(offline_message)

        with open(file, "w") as f:
            json.dump(status, f, indent=4)