# Source code for brian2.core.clocks

    """
    Clocks for the simulator.
    """

    __docformat__ = "restructuredtext en"

    import numpy as np

    from brian2.core.names import Nameable
    from brian2.core.variables import Variables
    from brian2.groups.group import VariableOwner
    from brian2.units.allunits import second
    from brian2.units.fundamentalunits import Quantity, check_units
    from brian2.utils.logger import get_logger

    __all__ = ["Clock", "defaultclock"]

    logger = get_logger(__name__)

    def check_dt(new_dt, old_dt, target_t):
        """
        Check that the target time can be represented equally well with the new
        dt.

        Parameters
        ----------
        new_dt : float
            The new dt value
        old_dt : float
            The old dt value
        target_t : float
            The target time

        Raises
        ------
        ValueError
            If using the new dt value would lead to a difference in the target
            time of more than `Clock.epsilon_dt` times ``new_dt`` (by default,
            0.01% of the new dt).

        Examples
        --------
        >>> from brian2 import *
        >>> check_dt(float(17*ms), float(0.1*ms), float(0*ms))  # For t=0s, every dt is fine
        >>> check_dt(float(0.05*ms), float(0.1*ms), float(10*ms))  # t=10*ms can be represented with the new dt
        >>> check_dt(float(0.2*ms), float(0.1*ms), float(10.1*ms))  # t=10.1ms cannot be represented with dt=0.2ms # doctest: +ELLIPSIS
        Traceback (most recent call last):
        ...
        ValueError: Cannot set dt from 100. us to 200. us, the time 10.1 ms is not a multiple of 200. us.
        """
        old_t = np.int64(np.round(target_t / old_dt)) * old_dt
        new_t = np.int64(np.round(target_t / new_dt)) * new_dt
        error_t = target_t
        if abs(new_t - old_t) / new_dt > Clock.epsilon_dt:
            old = str(old_dt * second)
            new = str(new_dt * second)
            t = str(error_t * second)
            raise ValueError(
                f"Cannot set dt from {old} to {new}, the "
                f"time {t} is not a multiple of {new}."
            )

    class Clock(VariableOwner):
        """
        An object that holds the simulation time and the time step.

        Parameters
        ----------
        dt : float
            The time step of the simulation as a float
        name : str, optional
            An explicit name, if not specified gives an automatically generated name

        Notes
        -----
        Clocks are run in the same `Network.run` iteration if `~Clock.t` is the
        same. The condition for two
        clocks to be considered as having the same time is
        ``abs(t1-t2)<epsilon*abs(t1)``, a standard test for equality of floating
        point values. The value of ``epsilon`` is ``1e-14``.
        """

        def __init__(self, dt, name="clock*"):
            # We need a name right away because some devices (e.g. cpp_standalone)
            # need a name for the object when creating the variables
            Nameable.__init__(self, name=name)
            self._old_dt = None
            self.variables = Variables(self)
            self.variables.add_array(
                "timestep", size=1, dtype=np.int64, read_only=True, scalar=True
            )
            self.variables.add_array(
                "t",
                dimensions=second.dim,
                size=1,
                dtype=np.float64,
                read_only=True,
                scalar=True,
            )
            self.variables.add_array(
                "dt",
                dimensions=second.dim,
                size=1,
                values=float(dt),
                dtype=np.float64,
                read_only=True,
                constant=True,
                scalar=True,
            )
            self.variables.add_constant("N", value=1)
            self._enable_group_attributes()
            self.dt = dt
            logger.diagnostic(f"Created clock {self.name} with dt={self.dt}")

        @check_units(t=second)
        def _set_t_update_dt(self, target_t=0 * second):
            new_dt = self.dt_
            old_dt = self._old_dt
            target_t = float(target_t)
            if old_dt is not None and new_dt != old_dt:
                self._old_dt = None
                # Only allow a new dt which allows to correctly set the new time step
                check_dt(new_dt, old_dt, target_t)

            new_timestep = self._calc_timestep(target_t)
            # Since these attributes are read-only for normal users, we have to
            # update them via the variables object directly
            self.variables["timestep"].set_value(new_timestep)
            self.variables["t"].set_value(new_timestep * new_dt)
            logger.diagnostic(f"Setting Clock {self.name} to t={self.t}, dt={self.dt}")

        def _calc_timestep(self, target_t):
            """
            Calculate the integer time step for the target time. If it cannot be
            exactly represented (up to 0.01% of dt), round up.

            Parameters
            ----------
            target_t : float
                The target time in seconds

            Returns
            -------
            timestep : int
                The target time in integers (based on dt)
            """
            new_i = np.int64(np.round(target_t / self.dt_))
            new_t = new_i * self.dt_
            if new_t == target_t or np.abs(new_t - target_t) / self.dt_ <= Clock.epsilon_dt:
                new_timestep = new_i
            else:
                new_timestep = np.int64(np.ceil(target_t / self.dt_))
            return new_timestep

        def __repr__(self):
            return f"Clock(dt={self.dt!r}, name={self.name!r})"

        def _get_dt_(self):
            return self.variables["dt"].get_value().item()

        @check_units(dt_=1)
        def _set_dt_(self, dt_):
            self._old_dt = self._get_dt_()
            self.variables["dt"].set_value(dt_)

        @check_units(dt=second)
        def _set_dt(self, dt):
            self._set_dt_(float(dt))

        dt = property(
            fget=lambda self: Quantity(self.dt_, dim=second.dim),
            fset=_set_dt,
            doc="""The time step of the simulation in seconds.""",
        )
        dt_ = property(
            fget=_get_dt_,
            fset=_set_dt_,
            doc="""The time step of the simulation as a float (in seconds)""",
        )

        @check_units(start=second, end=second)
        def set_interval(self, start, end):
            """
            set_interval(self, start, end)

            Set the start and end time of the simulation.

            Sets the start and end value of the clock precisely if
            possible (using epsilon) or rounding up if not. This assures that
            multiple calls to `Network.run` will not re-run the same time step.
            """
            self._set_t_update_dt(target_t=start)
            end = float(end)
            self._i_end = self._calc_timestep(end)
            if self._i_end > 2**40:
                logger.warn(
                    "The end time of the simulation has been set to "
                    f"{str(end*second)}, which based on the dt value of "
                    f"{str(self.dt)} means that {self._i_end} "
                    "time steps will be simulated. This can lead to "
                    "numerical problems, e.g. the times t will not "
                    "correspond to exact multiples of "
                    "dt.",
                    "many_timesteps",
                )

        #: The relative difference for times (in terms of dt) so that they are
        #: considered identical.
        epsilon_dt = 1e-4

    class DefaultClockProxy:
        """
        Method proxy to access the defaultclock of the currently active device
        """

        def __getattr__(self, name):
            if name == "_is_proxy":
                return True
            from brian2.devices.device import active_device

            return getattr(active_device.defaultclock, name)

        def __setattr__(self, key, value):
            from brian2.devices.device import active_device

            setattr(active_device.defaultclock, key, value)

    #: The standard clock, used for objects that do not specify any clock or dt
    defaultclock = DefaultClockProxy()