#!/usr/bin/env python3

"""
Doorlockd -- Binary Kitchen's smart door opener

Copyright (c) Binary Kitchen e.V., 2018

Author:
  Ralf Ramsauer <ralf@binary-kitchen.de>

This work is licensed under the terms of the GNU GPL, version 2.  See
the LICENSE file in the top-level directory.

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.
"""

import hashlib
import ldap
import logging
import sys

from enum import Enum
from os.path import join
from random import sample
from serial import Serial
from subprocess import Popen
from threading import Thread
from time import sleep

from flask import abort, Flask, jsonify, render_template, request
from flask_socketio import SocketIO
from flask_wtf import FlaskForm
from wtforms import PasswordField, StringField, SubmitField
from wtforms.validators import DataRequired, Length

SYSCONFDIR = '.'
PREFIX = '.'

root_prefix = join(PREFIX, 'share', 'doorlockd')
sounds_prefix = join(root_prefix, 'sounds')
static_folder = join(root_prefix, 'static')
template_folder = join(root_prefix, 'templates')
scripts_prefix = join(root_prefix, 'scripts')

flask_config = join(SYSCONFDIR, 'doorlockd.cfg')

__author__ = 'Ralf Ramsauer'
__copyright = 'Copyright (c) Ralf Ramsauer, 2018'
__license__ = 'GPLv2'
__email__ = 'ralf@binary-kitchen.de'
__status__ = 'Development'
__maintainer__ = 'Ralf Ramsauer'
__version__ = '0.01a'

log_level = logging.DEBUG
date_fmt = '%Y-%m-%d %H:%M:%S'
log_fmt = '%(asctime)-15s %(levelname)-8s %(message)s'
log = logging.getLogger()

default_ldap_uri = 'ldaps://ldap1.binary.kitchen/ ' \
                   'ldaps://ldap2.binary.kitchen/ ' \
                   'ldaps://ldapm.binary.kitchen/'
default_binddn = 'cn=%s,ou=people,dc=binary-kitchen,dc=de'

webapp = Flask(__name__,
               template_folder=template_folder,
               static_folder=static_folder)
webapp.config.from_pyfile(flask_config)
socketio = SocketIO(webapp, async_mode='threading')
serial_port = webapp.config.get('SERIAL_PORT')
simulate_ldap = webapp.config.get('SIMULATE_LDAP')
simulate_serial = webapp.config.get('SIMULATE_SERIAL')
run_hooks = webapp.config.get('RUN_HOOKS')
room = webapp.config.get('ROOM')
title = webapp.config.get('TITLE')
welcome = webapp.config.get('WELCOME')
file_local_db = webapp.config.get('LOCAL_USER_DB')

html_title = '%s (%s - v%s)' % (title, __status__, __version__)

ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_DEMAND)
ldap.set_option(ldap.OPT_REFERRALS, 0)
if 'LDAP_CA' in webapp.config.keys():
    ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, webapp.config.get('LDAP_CA'))

ldap_uri = webapp.config.get('LDAP_URI')
ldap_binddn = webapp.config.get('LDAP_BINDDN')

wave_emergency = 'emergency_unlock.wav'
wave_lock = 'lock.wav'
wave_lock_button = 'lock_button.wav'
wave_unlock = 'unlock.wav'
wave_unlock_button = 'unlock_button.wav'
wave_zonk = 'zonk.wav'

sounds = webapp.config.get('SOUNDS')

host = 'localhost'
if webapp.config.get('DEBUG'):
    host = '0.0.0.0'

# copied from sudo
eperm_insults = {
        'Wrong!  You cheating scum!',
        'And you call yourself a Rocket Scientist!',
        'No soap, honkie-lips.',
        'Where did you learn to type?',
        'Are you on drugs?',
        'My pet ferret can type better than you!',
        'You type like i drive.',
        'Do you think like you type?',
        'Your mind just hasn\'t been the same since the electro-shock, has it?',
        'Maybe if you used more than just two fingers...',
        'BOB says:  You seem to have forgotten your passwd, enter another!',
        'stty: unknown mode: doofus',
        'I can\'t hear you -- I\'m using the scrambler.',
        'The more you drive -- the dumber you get.',
        'Listen, broccoli brains, I don\'t have time to listen to this trash.',
        'I\'ve seen penguins that can type better than that.',
        'Have you considered trying to match wits with a rutabaga?',
        'You speak an infinite deal of nothing',
}


def choose_insult():
    return(sample(eperm_insults, 1)[0])


def playsound(filename):
    if not sounds:
        return
    Popen(['nohup', 'aplay', join(sounds_prefix, filename)])


def start_hook(script):
    if not run_hooks:
        log.info('Hooks disabled: not starting %s' % script)
        return
    log.info('Starting hook %s' % script)
    Popen(['nohup', join(scripts_prefix, script)])


class AuthMethod(Enum):
    LDAP_USER_PW = 1
    LOCAL_USER_DB = 2


class DoorState(Enum):
    # These numbers are used by the App since version 3.0, do NOT change them
    Open = 0
    Present = 1
    Closed = 2

    def from_string(string):
        if string == 'lock':
            return DoorState.Closed
        elif string == 'unlock':
            return DoorState.Open
        elif string == 'present':
            return DoorState.Present

        return None

    def is_open(self):
        if self != DoorState.Closed:
            return True
        return False

    def to_img(self):
        led = 'red'
        if self == DoorState.Present:
            led = 'yellow'
        elif self == DoorState.Open:
            led = 'green'
        return 'static/led-%s.png' % led

    def to_html(self):
        if self == DoorState.Open:
            return 'Offen'
        elif self == DoorState.Present:
            return 'Jemand da'
        return 'Geschlossen'


class LogicResponse(Enum):
    Success = 0
    Perm = 1
    AlreadyActive = 2
    # don't break old apps, value 3 is reserved now
    RESERVED = 3
    Inval = 4
    LDAP = 5

    EmergencyUnlock = 10,
    ButtonLock = 11,
    ButtonUnlock = 12,
    ButtonPresent = 13,

    def to_html(self):
        if self == LogicResponse.Success:
            return 'Yo, passt.'
        elif self == LogicResponse.Perm:
            return choose_insult()
        elif self == LogicResponse.AlreadyActive:
            return 'Zustand bereits aktiv'
        elif self == LogicResponse.Inval:
            return 'Das was du willst geht nicht.'
        elif self == LogicResponse.LDAP:
            return 'Moep! Geh LDAP fixen!'
        elif self == LogicResponse.EmergencyUnlock:
            return '!!! Emergency Unlock !!!'
        elif self == LogicResponse.ButtonLock:
            return 'Closed by button'
        elif self == LogicResponse.ButtonUnlock:
            return 'Opened by button'
        elif self == LogicResponse.ButtonPresent:
            return 'Present by button'

        return 'Bitte spezifizieren Sie.'


class DoorHandler:
    state = DoorState.Closed
    do_close = False

    CMD_PRESENT = b'y'
    CMD_OPEN = b'g'
    CMD_CLOSE = b'r'

    BUTTON_PRESENT = b'Y'
    BUTTON_OPEN = b'G'
    BUTTON_CLOSE = b'R'

    CMD_EMERGENCY_SWITCH = b'E'
    # TBD DOOR NOT CLOSED

    def __init__(self, device):
        if simulate_serial:
            return

        self.serial = Serial(device, baudrate=9600, bytesize=8, parity='N',
                             stopbits=1, timeout=0)
        self.thread = Thread(target=self.thread_worker)
        log.debug('Spawning RS232 Thread')
        self.thread.start()

    def thread_worker(self):
        while True:
            sleep(0.4)
            while True:
                rx = self.serial.read(1)
                if len(rx) == 0:
                    break
                if rx == DoorHandler.BUTTON_CLOSE:
                    self.close()
                    log.info('Closed due to Button press')
                    logic.emit_status(LogicResponse.ButtonLock)
                elif rx == DoorHandler.BUTTON_OPEN:
                    self.open()
                    log.info('Opened due to Button press')
                    logic.emit_status(LogicResponse.ButtonUnlock)
                elif rx == DoorHandler.BUTTON_PRESENT:
                    self.present()
                    log.info('Present due to Button press')
                    logic.emit_status(LogicResponse.ButtonPresent)
                elif rx == DoorHandler.CMD_EMERGENCY_SWITCH:
                    log.warning('Emergency unlock')
                    logic.emit_status(LogicResponse.EmergencyUnlock)
                else:
                    log.error('Received unknown message "%s" from AVR' % rx)

            if self.do_close:
                tx = DoorHandler.CMD_CLOSE
                self.do_close = False
            elif self.state == DoorState.Present:
                tx = DoorHandler.CMD_PRESENT
            elif self.state == DoorState.Open:
                tx = DoorHandler.CMD_OPEN
            else:
                continue

            self.serial.write(tx)
            self.serial.flush()

    def open(self):
        if self.state == DoorState.Open:
            return LogicResponse.AlreadyActive

        self.state = DoorState.Open
        start_hook('post_unlock')
        return LogicResponse.Success

    def present(self):
        if self.state == DoorState.Present:
            return LogicResponse.AlreadyActive

        self.state = DoorState.Present
        start_hook('post_present')
        return LogicResponse.Success

    def close(self):
        if self.state == DoorState.Closed:
            return LogicResponse.AlreadyActive

        self.do_close = True
        self.state = DoorState.Closed
        start_hook('post_lock')
        return LogicResponse.Success

    def request(self, state):
        if state == DoorState.Closed:
            return self.close()
        elif state == DoorState.Present:
            return self.present()
        elif state == DoorState.Open:
            return self.open()


class Logic:
    def __init__(self):
        self.door_handler = DoorHandler(serial_port)
        self.local_db = dict()

        if not file_local_db:
            return

        with open(file_local_db, 'r') as f:
            for line in f:
                line = line.split()
                user = line[0]
                pwd = line[1].split(':')
                self.local_db[user] = pwd

    def _try_auth_local(self, user, password):
        if user not in self.local_db:
            return LogicResponse.Perm

        stored_pw = self.local_db[user][0]
        stored_salt = self.local_db[user][1]
        if stored_pw == hashlib.sha256(stored_salt.encode() + password.encode()).hexdigest():
            return LogicResponse.Success

        return LogicResponse.Perm

    def _try_auth_ldap(self, user, password):
        if simulate_ldap:
            log.info('SIMULATION MODE! ACCEPTING ANYTHING!')
            return LogicResponse.Success

        log.info('  Trying to LDAP auth (user, password) as user %s', user)
        ldap_username = ldap_binddn % user
        try:
            l = ldap.initialize(ldap_uri)
            l.simple_bind_s(ldap_username, password)
            l.unbind_s()
        except ldap.INVALID_CREDENTIALS:
            log.info('  Invalid credentials')
            return LogicResponse.Perm
        except ldap.LDAPError as e:
            log.info('  LDAP Error: %s' % e)
            return LogicResponse.LDAP
        return LogicResponse.Success

    def try_auth(self, credentials):
        method = credentials[0]
        if method == AuthMethod.LDAP_USER_PW:
            return self._try_auth_ldap(credentials[1], credentials[2])
        elif method == AuthMethod.LOCAL_USER_DB:
            return self._try_auth_local(credentials[1], credentials[2])

        return LogicResponse.Inval

    def _request(self, state, credentials):
        err = self.try_auth(credentials)
        if err != LogicResponse.Success:
            return err
        return self.door_handler.request(state)

    def request(self, state, credentials):
        err = self._request(state, credentials)
        if err == LogicResponse.Success:
            if self.door_handler.state == DoorState.Open:
                playsound(wave_unlock)
            if self.door_handler.state == DoorState.Closed:
                playsound(wave_lock)
        elif err == LogicResponse.AlreadyActive:
            playsound(wave_zonk)
        self.emit_status(err)
        return err

    def emit_status(self, message=None):
        led = self.state.to_img()
        if message is None:
            message = self.state.to_html()
        else:
            message = message.to_html()

        socketio.emit('status', {'led': led, 'message': message})

    @property
    def state(self):
        return self.door_handler.state


class AuthenticationForm(FlaskForm):
    username = StringField('Username', [Length(min=3, max=25)])
    password = PasswordField('Password', [DataRequired()])
    open = SubmitField('Open')
    present = SubmitField('Present')
    close = SubmitField('Close')

    def __init__(self, *args, **kwargs):
        FlaskForm.__init__(self, *args, **kwargs)
        self.desired_state = DoorState.Closed

    def validate(self):
        if not FlaskForm.validate(self):
            return False

        if self.open.data:
            self.desired_state = DoorState.Open
        elif self.present.data:
            self.desired_state = DoorState.Present

        return True


@socketio.on('request_status')
@socketio.on('connect')
def on_connect():
	logic.emit_status()


@webapp.route('/display')
def display():
    return render_template('display.html',
                           room=room,
                           title=title,
                           welcome=welcome)


@webapp.route('/api', methods=['POST'])
def api():
    def json_response(response, msg=None):
        json = dict()
        json['err'] = response.value
        json['msg'] = response.to_html() if msg is None else msg
        if response == LogicResponse.Success or \
           response == LogicResponse.AlreadyActive:
            # TBD: Remove 'open'. No more users. Still used in App Version 2.1.1!
            json['open'] = logic.state.is_open()
            json['status'] = logic.state.value
        return jsonify(json)

    method = request.form.get('method')
    user = request.form.get('user')
    password = request.form.get('pass')
    command = request.form.get('command')

    if method == 'local':
        method = AuthMethod.LOCAL_USER_DB
    else: # 'ldap' or default
        method = AuthMethod.LDAP_USER_PW

    if any(v is None for v in [user, password, command]):
        log.warning('Incomplete API request')
        abort(400)

    if not user or not password:
        log.warning('Invalid username or password format')
        return json_response(LogicResponse.Inval,
                             'Invalid username or password format')

    credentials = method, user, password

    if command == 'status':
        return json_response(logic.try_auth(credentials))

    desired_state = DoorState.from_string(command)
    if not desired_state:
        return json_response(LogicResponse.Inval, "Invalid command requested")

    log.info('Incoming API request from %s' % user.encode('utf-8'))
    log.info('  desired state: %s' % desired_state)
    log.info('  current state: %s' % logic.state)

    response = logic.request(desired_state, credentials)

    return json_response(response)


@webapp.route('/', methods=['GET', 'POST'])
def home():
    authentication_form = AuthenticationForm()
    response = None

    if request.method == 'POST' and authentication_form.validate():
        user = authentication_form.username.data
        password = authentication_form.password.data
        credentials = AuthMethod.LDAP_USER_PW, user, password

        log.info('Incoming request from %s' % user.encode('utf-8'))
        desired_state = authentication_form.desired_state
        log.info('  desired state: %s' % desired_state)
        log.info('  current state: %s' % logic.state)
        response = logic.request(desired_state, credentials)
        log.info('  response: %s' % response)

    # Don't trust python, zero credentials
    user = password = credentials = None

    return render_template('index.html',
                           authentication_form=authentication_form,
                           response=response,
                           state_text=logic.state.to_html(),
                           led=logic.state.to_img(),
                           banner='%s - %s' % (title, room))


if __name__ == '__main__':
    logging.basicConfig(level=log_level, stream=sys.stdout,
                        format=log_fmt, datefmt=date_fmt)
    log.info('Starting doorlockd')
    log.info('Using serial port: %s' % webapp.config.get('SERIAL_PORT'))

    logic = Logic()

    socketio.run(webapp, host=host, port=8080, use_reloader=False)

    sys.exit(0)