#!/usr/bin/env python

import os
import fileinput

from pathlib import Path
from typing import Annotated
from argon2 import PasswordHasher
from argon2.exceptions import VerifyMismatchError
import configparser

from fastapi import FastAPI, Depends, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

from mw40v import Mw40V

app = FastAPI()

security = HTTPBasic()

USB_DHCPD_FILENAME = '/etc/dhcpcd-backup.conf'
#USB_DHCPD_FILENAME = './dhcpcd-backup.conf'
AIR_INTERFACE_NAME = 'usb0'
METRIC_ON = 50
METRIC_OFF = 300


class Config:
    config = None

    @classmethod
    def get(cls):
        if cls.config is None:
            cls.config = configparser.ConfigParser()
            cls.config.read('./config.ini')

        return cls.config


class AirModem:
    airModem = None

    @classmethod
    def get(cls):
        if cls.airModem is None:
            config = Config.get()

            cls.airModem = Mw40V(
                config['MW40V']['username'],
                config['MW40V']['password'],
                config['MW40V']['encrypt_key'],
                config['MW40V']['verification_key'],
            )

        return cls.airModem


def get_username(credentials: Annotated[HTTPBasicCredentials, Depends(security)]):
    config = Config.get()

    if credentials.username != config['credentials']['username']:
        raise_unauthorized()

    try:
        PasswordHasher().verify(config['credentials']['password_hash'], credentials.password)
    except VerifyMismatchError:
        raise_unauthorized()

    return credentials.username


def raise_unauthorized():
    raise HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Incorrect username or password",
        headers={"WWW-Authenticate": "Basic"},
    )


@app.get('/status')
async def get_status(username: Annotated[str, Depends(get_username)]):
    return {"status": "usb" if is_usb_on() else "eth"}


@app.post('/status/{status}')
async def set_status(username: Annotated[str, Depends(get_username)], status):
    if status == 'usb' and not is_usb_on():
        switch_status(True)
    elif status == 'eth' and is_usb_on():
        switch_status(False)

    return {'status': 'usb' if is_usb_on() else 'eth'}


def is_usb_on():
    with open(USB_DHCPD_FILENAME, 'r') as dhcpd_file:
        right_interface = False
        for line in dhcpd_file:
            if line.startswith('interface'):
                right_interface = line.strip().split(' ')[-1] == AIR_INTERFACE_NAME

            if right_interface and 'metric' in line:
                return line.strip().split(' ')[-1] == str(METRIC_ON)


def switch_status(turn_on):
    if turn_on:
        update_usb_modem(turn_on)
        update_dhcp_conf(turn_on)
    else:
        update_dhcp_conf(turn_on)
        update_usb_modem(turn_on)


def update_dhcp_conf(turn_on):
    right_interface = False
    for line in fileinput.input(USB_DHCPD_FILENAME, inplace=True):
        if line.startswith('interface'):
            right_interface = line.strip().split(' ')[-1] == AIR_INTERFACE_NAME

        if right_interface and 'metric' in line:
            print("\tmetric {}\n".format(METRIC_ON if turn_on else METRIC_OFF), end='')
        else:
            print(line, end='')


def update_usb_modem(turn_on):
    if turn_on:
        AirModem.get().connect()
    else:
        AirModem.get().disconnect()


def initialize_app():
    script_dir = Path(__file__).parent.absolute()
    credentials_file_path = str(script_dir) + '/config.ini'
    if not os.path.isfile(credentials_file_path):

        config = configparser.ConfigParser()

        username = input("Enter a username for the API")
        password = input("Enter a password for the API")
        config['credentials'] = {
            'username': username,
            'password_hash': PasswordHasher().hash(password)
        }

        username_mw40v = input("Enter the username for MW40V")
        password_mw40v = input("Enter the password for MW40V")
        encrypt_key = input("Enter the encrypt_key for MW40V")
        verification_key = input("Enter the verification_key for MW40V")
        config['MW40V'] = {
            'username': username_mw40v,
            'password': password_mw40v,
            'encrypt_key': encrypt_key,
            'verification_key': verification_key
        }

        with open(credentials_file_path, 'w') as configfile:
            config.write(configfile)


if __name__ == "__main__":
    initialize_app()

    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)