import telegram_notifier  # Send notifications
import requests  # Check HTTP status code
import os  # Unix socket file handling
import subprocess  # Ping check if host online
import socket  # Hostname, unix socket
import yaml  # Config file
import logging  # Log messages
import signal  # Notify before exiting


class ColorFormatter(logging.Formatter):
    grey = "\x1b[90;20m"
    cyan = "\x1b[96;20m"
    yellow = "\x1b[33;20m"
    red = "\x1b[31;20m"
    bold_red = "\x1b[31;1m"
    reset = "\x1b[0m"
    format = "%(name)s %(asctime)s,%(msecs)03d %(levelname)-8s [%(filename)s:%(lineno)d] %(message)s"

    FORMATS = {
        logging.DEBUG: grey + format + reset,
        logging.INFO: cyan + format + reset,
        logging.WARNING: yellow + format + reset,
        logging.ERROR: red + format + reset,
        logging.CRITICAL: bold_red + format + reset
    }

    def format(self, record):
        log_fmt = self.FORMATS.get(record.levelno)
        formatter = logging.Formatter(log_fmt)
        return formatter.format(record)


logger = logging.getLogger(__name__)  # Instantiate a logger to be used in this module

# Display every message Change this to INFO to see INFO and above (filter out DEBUG)
# See: https://docs.python.org/3/howto/logging.html#logging-levels
logger.root.setLevel(logging.DEBUG)

stream_handler = logging.StreamHandler()  # This catches and handles log messages on the root handler
stream_handler.setFormatter(ColorFormatter())
logger.root.addHandler(stream_handler)

# Disable logging for sub libraries
logging.getLogger("urllib3").setLevel(logging.WARNING)
logging.getLogger("httpx").setLevel(logging.WARNING)
logging.getLogger("httpcore").setLevel(logging.WARNING)
logging.getLogger("asyncio").setLevel(logging.WARNING)
logging.getLogger("telegram").setLevel(logging.WARNING)

with open("config.yml", "r") as file:
    config = yaml.safe_load(file)

notifier = telegram_notifier.TelegramNotifier(config['telegram']['token'], config['telegram']['chat_id'])

# Set the path for the Unix socket
# without reinitialising entire script
# Used for SystemD timer to invoke status check, 
socket_path = "/tmp/server_status.sock"
hostname = socket.gethostname()
# Used to only notify on state change
# Initialise data structure based on targets in config file
state = {}
for host, host_config in config["hosts"].items():
    state[host] = {"online": None, "open_ports": []}
    if 'urls' in host_config:
        state[host]["http_status"] = {}
        for url in host_config['urls']:
            state[host]['http_status'][url] = None


def ping(host: str) -> bool:
    response = subprocess.run(["ping", "-c", "1", host])
    return response.returncode == 0


def check_target(host: str, host_config: dict) -> bool:
    """
    :param host: Hostname or IP
    :param host_config: Config from config file, specifying what to test and desired state
    :return: Host is desired state
    """
    # Ping
    online = ping(host)
    # Default to desire host online, if not specified in config file
    desired_online = host_config['desired_online'] if 'desired_online' in host_config else True
    host_is_desired_state = desired_online == online
    first_test = state[host]['online'] == None
    changed_state = not first_test and state[host]['online'] != online
    logger.debug(f'''
    host_is_desired_state: {host_is_desired_state}
    first_test:            {first_test}
    changed_state:         {changed_state}
    ''')
    # notify if the host online state changed, or on fresh boot, if it isn't the desired online state
    if changed_state or (first_test and not host_is_desired_state):
        message = f"❌ `{host}` is {'online' if online else 'offline'}"
        logger.warning(message)
        notifier.send_message(message)
    state[host]['online'] = online  # Save current state

    if online:
        messages = []
        for url in host_config['urls']:
            http_state = None
            # HTTP Code
            try:
                # print(f'''
                # ---=== Getting: {url} ===---
                # ''')
                r = requests.get(url)
                if r.status_code != 200:
                    http_state = r.status_code
            except requests.exceptions.SSLError as exception:
                try:
                    reason = exception.args[0].reason.args[0].verify_message
                except Exception as exception:
                    logger.warning("Unable to get reason")
                    raise
                http_state = "SSL error"
            except Exception as exception:
                raise
            if http_state:
                if state[host]['http_status'][url] is None or state[host]['http_status'][url] != http_state:
                    messages.append(f'[{url}]({url}) {http_state}')
                    state[host]['http_status'][url] = http_state

        if len(messages) > 0:
            notifier.send_message('❌ ' + '\n'.join(messages))

    return host_is_desired_state


def check_status() -> bool:
    """
    :return: All hosts are in desired state
    """
    try:
        logger.info("Checking status")
        all_hosts_are_in_desired_state = True
        for host, host_config in config["hosts"].items():
            host_is_desired_state = check_target(host, host_config)
            if host_is_desired_state == False:
                all_hosts_are_in_desired_state = False
        return all_hosts_are_in_desired_state
    except Exception as ex:
        notifier.send_message("Error getting status")
        raise ex


def listen():
    # remove the socket file if it already exists
    try:
        os.unlink(socket_path)
    except OSError:
        if os.path.exists(socket_path):
            raise

    try:
        # Create the Unix socket server
        server = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)

        # Bind the socket to the path
        server.bind(socket_path)

        # Listen for incoming connections
        server.listen(1)

        while True:
            try:
                # accept connections
                logger.info("Server is listening for incoming connections...")
                connection, client_address = server.accept()

                logger.debug("Connection from", str(connection).split(", ")[0][-4:])

                # receive data from the client
                while True:
                    data = connection.recv(1024)
                    if not data:
                        break
                    logger.debug("Received data:", data.decode())

                    # Send a response back to the client
                    response = "OK\n"
                    connection.sendall(response.encode())

                    check_status()
            finally:
                # Always close the connection if it"s been initialised
                if "connection" in locals():
                    connection.close()
    finally:
        # remove the socket file
        os.unlink(socket_path)


def main():
    notifier.send_message(f"✅ Server status checker on `{hostname}` *online*")
    alles_gut = check_status()
    if alles_gut == True:
        # First test, notify of outcome
        # If a non-desired state was caught in first check a notification would have been triggered.
        notifier.send_message("✅ All hosts are in desired state,\nand no discrepancies found")  # Vægter
    listen()


def service_exiting(signum, frame):
    # Ship going down
    notifier.send_message(f"❌ Server status checker on `{hostname}` *going down*")
    exit(0)


# Intercept SIGTERM (15) and notify before exiting
signal.signal(signal.SIGTERM, service_exiting)

if __name__ == "__main__":
    main()