import ctypes


class reb_dp7(ctypes.Structure):
    _fields_ = [("p0", ctypes.POINTER(ctypes.c_double)),
                ("p1", ctypes.POINTER(ctypes.c_double)),
                ("p2", ctypes.POINTER(ctypes.c_double)),
                ("p3", ctypes.POINTER(ctypes.c_double)),
                ("p4", ctypes.POINTER(ctypes.c_double)),
                ("p5", ctypes.POINTER(ctypes.c_double)),
                ("p6", ctypes.POINTER(ctypes.c_double))]

class IntegratorIAS15(ctypes.Structure):
    """
    This class is an abstraction of the C-struct reb_integrator_ias15.
    It controls the behaviour of the SEI integrator. See Rein & Spiegel (2015)
    for more information.

    Example usage:

    >>> sim = rebound.Simulation()
    >>> sim.integrator = "ias15"
    >>> sim.ri_ias15.epsilon = 0.

    :ivar float epsilon:          
        Controls the precision of the integrator. Set to 0 for fixed timesteps.
    
    :ivar float min_dt:          
        IAS15 is an adaptive method. This sets the minimum timestep.
    
    :ivar float adaptive_mode:
        Determines how the adaptive timestep is chosen. 
        This replaces the previous epsilon_global variable.
        The default is 2 which corresponds to the timestep criterion described in Pham, Rein, and Spiegel (2024).  This should be optimal in almost all cases.
        If set to 0, the fractional error is estimated via `max(acceleration_error/acceleration)` and the timestep criterion of Rein and Spiegel (2015) is used. 
        If set to 1, IAS15 estimates the fractional error via `max(acceleration_error)/max(acceleration)` where the maximum is taken over all particles. As before, the timestep criterion of Rein and Spiegel (2015) is used. This was the default until January 2024. 
        If set to 3, then the criterion of Aarseth (1985) is used.
    
    """
    def __repr__(self):
        return '<{0}.{1} object at {2}, epsilon={3}, min_dt={4}>'.format(self.__module__, type(self).__name__, hex(id(self)), self.epsilon, self.min_dt)
    
    _fields_ = [("epsilon", ctypes.c_double),
                ("min_dt", ctypes.c_double),
                ("adaptive_mode", ctypes.c_uint),
                ("_iterations_max_exceeded", ctypes.c_uint64),
                ("_N_allocated", ctypes.c_uint),
                ("_at", ctypes.POINTER(ctypes.c_double)),
                ("_x0", ctypes.POINTER(ctypes.c_double)),
                ("_v0", ctypes.POINTER(ctypes.c_double)),
                ("_a0", ctypes.POINTER(ctypes.c_double)),
                ("_csx", ctypes.POINTER(ctypes.c_double)),
                ("_csv", ctypes.POINTER(ctypes.c_double)),
                ("_csa0", ctypes.POINTER(ctypes.c_double)),
                ("_g", reb_dp7),
                ("_b", reb_dp7),
                ("_csb", reb_dp7),
                ("_e", reb_dp7),
                ("_br", reb_dp7),
                ("_er", reb_dp7),
                ("_map", ctypes.POINTER(ctypes.c_int)),
                ("_map_allocated_n", ctypes.c_uint),
                ]