# This file is part of naxalnet.
# Copyright (C) 2021 The naxalnet Authors

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
scripts.py
----------

The functions in this file is used for reading configs, args
and doing the things this program is supposed to do.
This file is named scripts.py because the original developer
of this program could not think of a better name that suits this file.
If you want to hack naxalnet, this is the right place to start.
When run from the commandline, the function main() is called.
"""

import sys
from pathlib import Path
from shutil import copy
from dasbus.error import DBusError
from systemd.daemon import notify
from naxalnet import __version__
from naxalnet.default import REPORT_BUG_INFO
from naxalnet.log import logger
from naxalnet.iwd import Adapter, Device, IWD
from naxalnet.config import args
from naxalnet.daemon import Daemon


def copy_files():
    """
    Copy networkd configs to volatile dir.
    The D-Bus API does not support creating new interfaces
    or linking to bridges. So we use config files.
    See man:systemd.network(5)
    """
    try:
        notify("STATUS=Configuring the network...")
        logger.info("Copying network config files")
        dest = Path(args.networkd_runtime_dir)
        src = Path(args.networkd_config_dir)

        # Create the volatile directory if it doesn't exist
        dest.mkdir(parents=True, exist_ok=True)

        # Copy all files in src to dest
        for i in src.iterdir():
            copy(i, dest)
    except PermissionError:
        logger.exception("A PermissionError occured while copying files")
        logger.error(REPORT_BUG_INFO)
        sys.exit(3)
    except:
        logger.exception("An unknown error occured while copying files")
        logger.error(REPORT_BUG_INFO)
        sys.exit(3)


def setup_devices():
    """
    Setup wifi interfaces using iwd
    This function should be called every time an interface
    is connected or removed.
    """
    try:
        notify("STATUS=Setting up mesh...")
        iwd = IWD()
        devices = iwd.get_devices()
        adhoc_devices = []
        ap_devices = []

        # Find devices supporting ad-hoc and ap
        for i in devices:
            # For each device, check if its adapter supports
            # ad-hoc or ap. Many adapters will support both,
            # so we will prioritise ad-hoc over ap.
            device = Device(i)
            logger.debug("Found device %s", device.name)
            adapter = Adapter(device.adapter)
            if adapter.supports_mode("ad-hoc"):
                logger.debug("The device %s can be used for ad-hoc", device.name)
                adhoc_devices.append(i)
            if adapter.supports_mode("ap"):
                logger.debug("The device %s can be used for ap", device.name)
                ap_devices.append(i)

        if len(adhoc_devices) != 0:
            # Start ad-hoc on first device supporting ad-hoc
            adhoc_device = Device(adhoc_devices.pop())
            # The same device is likely to have ap support too.
            # But we can't start ad-hoc and ap on the same interface.
            # So we will remove adhoc_device from ap_devices if it exists there
            if adhoc_device.name in ap_devices:
                ap_devices.remove(adhoc_device.name)

            # Turn on adapter if it is off
            # See issue #9
            adhoc_adapter = Adapter(adhoc_device.adapter)
            if not adhoc_adapter.is_powered_on():
                logger.debug("Adapter %s is off. Turning on", adhoc_adapter.name)
                adhoc_adapter.power_on()
            logger.info("Starting mesh on %s", adhoc_device.name)
            adhoc_device.start_adhoc_open(args.adhoc_name)
            # Start Access point if ap_device is not empty,
            # ie, we have more devices
            if len(ap_devices) != 0:
                ap_device = Device(ap_devices.pop())
                logger.info("Starting WiFi Access Point on %s", ap_device.name)
                logger.info("Use naxalnet --print-wifi to get password")
                # Turn on adapter if it is off
                # See issue #9
                ap_adapter = Adapter(ap_device.adapter)
                if not ap_adapter.is_powered_on():
                    logger.debug("Adapter %s is off. Turning on", ap_adapter.name)
                    ap_adapter.power_on()
                ap_device.start_ap(args.ap_ssid, args.ap_passwd)
            else:
                logger.warning("Not setting up WiFi AP.")
        else:
            logger.warning(
                "No device found to setup mesh. Make sure a WiFi adapter is connected"
            )

    except DBusError:
        logger.exception("Error while communicating with iwd")
        logger.error(REPORT_BUG_INFO)
        sys.exit(4)
    except:
        logger.exception("An unknown error occured while setting up the mesh")
        logger.error(REPORT_BUG_INFO)
        sys.exit(4)


def print_wifi():
    """
    Prints the name and password of the adhoc, and ap
    from the arguments
    """
    print("Mesh name:", args.adhoc_name)
    print("SSID:", args.ap_ssid)
    print("Password:", args.ap_passwd)


def print_version():
    """Just does what the name suggests"""
    print(__version__)


def main():
    """
    This is where the magic happens!
    This function is run every time you
    execute naxalnet from the commandline
    """

    if args.print_wifi:
        print_wifi()
        sys.exit(0)
    elif args.version:
        print_version()
        sys.exit(0)
    copy_files()

    setup_devices()
    # Notify systemd that naxalnet is ready.
    # see man:sd_notify(3)
    notify("READY=1")

    # Start the daemon so that setup_devices() is called every
    # time a device is connected or removed.
    daemon = Daemon()
    daemon.add_callback(setup_devices)

    notify("STATUS=Waiting for changes")
    daemon.start()

    # naxalnet prints Bye while exiting.
    logger.info("Bye")