import select
import socket
import time
import datetime
from threading import Lock, RLock, Condition, Thread
from typing import Callable, Optional, IO, Container

from . import mqtt, util
from .util import timestamp

class DoorControlNfc(util.Loggable):
    """Validates tokens read from a socket and tells a DoorControl to toggle its target"""
    def __init__(self, config, control, mqtt_client = None):
        super().__init__("nfc")
        self._config = config
        self._nfc = self._open_nfc_fifo()
        self._control = control
        self._stop = True
        self._mutex = RLock()
        self._cond = Condition(self._mutex)
        self._fifo = None
        self._mqttc = mqtt_client
        self._read_valid_tokens()
        self.last_invalid_token = mqtt.Value(self._mqttc,
                                            "door/token/last_invalid", persistent=True)

    def _open_nfc_fifo(self) -> IO:
        """Opens config.nfc_fifo as the FIFO through which detected tokens are passed in."""
        self._logger().debug(f"Opening FIFO {self._config.nfc_fifo}")
        return open(self._config.nfc_fifo, "r")

    def _read_valid_tokens(self) -> Container:
        """Refreshes all tokens from config.valid_tokens"""
        with self._mutex:
            valid = {}
            try:
                self._logger().info("Loading tokens")
                lines =[ s.strip() for s in open(self._config.valid_tokens, "r").readlines() ]
                for i, line in enumerate(lines):
                    l = line.split('|')
                    if len(l) == 5:
                        if not l[0].strip().startswith('#'):
                            token, name, organization, email, valid_thru = l
                            try:
                                if len(valid_thru.strip()) > 0:
                                    valid_thru = datetime.date.fromisoformat(valid_thru)
                                else:
                                    valid_thru = None
                            except Exception:
                                self._logger().exception(f"Could not parse valid thru date {valid_thru} for token {token} in line {i+1}")
                                valid_thru = None
                            self._logger().debug(f"Got token {token} associated with {name} <{email}> of {organization}, valid thru {valid_thru}")
                            if token in valid:
                                self._logger().warning(f"Overwriting token {token}")
                            valid[token] = {
                                'name': name,
                                'organization': organization,
                                'email': email,
                                'valid_thru': valid_thru
                            }
                    else:
                        self._logger().warning(f"Skipping line {i} ({line}) since it does not contain exactly 5 data field")
            except Exception as e:
                valid = {}
                self._logger().error(f"Error reading token file. Exception: {e}")

            self._tokens = valid

    def _run(self):
        with self._cond:
            while not self._stop:
                if not self._fifo:
                    self._read_valid_tokens()
                    self._fifo = self._open_nfc_fifo()
                    if not self._fifo:
                        time.sleep(5)
                        continue

                self._cond.release()
                readable, _, _ = select.select(
                    [self._fifo],
                    [], [], 1)
                self._cond.acquire()
                
                if self._fifo in readable:
                    token = self._fifo.readline().strip()
                    if token == "":
                        self._fifo = None
                        continue
                    self._logger().debug(f"Token from nfc_fifo: {token}")
                    self.handle_token(token)

    def handle_token(self, token):
        with self._mutex:
            if token in self._tokens:
                data = self._tokens[token]

                if data['valid_thru'] is not None:
                    # if a valid thru date has been set we check if the token is still valid
                    authorized = datetime.date.today() <= data['valid_thru']
                else:
                    # otherwise we don't need to check
                    authorized = True

                if authorized:
                    self._logger().info(f"Valid token {token} of {data['name']}")
                    self._control.toggle()
                else:
                    self._logger().warning(f"Token {token} of {data['name']} expired on {data['valid_thru']}")
            else:
                self._logger().warning(f"Invalid token: {token}")
                self.last_invalid_token(f"{timestamp()};{token}")

    def start(self):
        with self._mutex:
            if self._stop:
                self._stop = False
                self._task = Thread(target=self._run, daemon=True)
                self._task.start()
                print("Done")
    
    def stop(self):
        with self._cond:
            if not self._stop:
                self._stop = True
                self._cond.notify()
        self._task.join()