import logging


class Timer:
    """
    Generic timer (ignores mcu and energy status)
    """

    _vmstate = None

    def __init__(self, name, interrupt_signal, period=0, periodic=False):
        """
        Initializes a timer
        :param name: name of the timer
        :param interrupt_signal: interrupt signal to trigger when timer expires
        :param period: period of the timer in seconds
        :param periodic: whether the timer is periodic
        """
        self._name = name
        self._interrupt_signal = interrupt_signal
        self._period = period
        self._periodic = periodic
        self._timer_stopped = True
        self._timer_start_period = 0

    def start(self):
        """
        Starts the timer if the period is positive
        """
        if self._period > 0:
            logging.debug(f"Starting timer {self._name} ({self._period}s)")
            self._timer_stopped = False
            self._timer_start_period = self._get_current_time()

    def stop(self):
        """
        Stops the timer
        """
        self._timer_stopped = True

    def restart(self):
        """
        Restart the timer
        """
        self._timer_start_period = self._get_current_time()

    def set_period(self, period):
        """
        Updates the timer period
        :param period: period of the timer in seconds
        """
        self._period = period

    def check(self):
        """
        Checks if the timer has expired, triggers the associated interrupt, and restarts the timer if necessary
        """
        if self._timer_stopped:
            return

        if (self._get_current_time() - self._timer_start_period) >= self._period:
            logging.debug(f"Timer {self._name} elapsed... triggering {self._interrupt_signal}")
            self._vmstate.interrupts_manager.trigger_interrupt(self._interrupt_signal)

            if self._periodic:
                self.restart()
            else:
                self.stop()

    def _get_current_time(self):
        """
        Returns current time in seconds
        """
        return self._vmstate.config.analysis.energy.system_model.get_simulation_time()