from selfdrive.controls.lib.pid import PIController
from common.numpy_fast import interp
from cereal import car

_DT = 0.01    # 100Hz
_DT_MPC = 0.05  # 20Hz


def get_steer_max(CP, v_ego):
  return interp(v_ego, CP.steerMaxBP, CP.steerMaxV)


class LatControl(object):
  def __init__(self, CP):
    self.pid = PIController((CP.steerKpBP, CP.steerKpV),
                            (CP.steerKiBP, CP.steerKiV),
                            k_f=CP.steerKf, pos_limit=1.0)
    self.last_cloudlog_t = 0.0
    self.angle_steers_des = 0.

  def reset(self):
    self.pid.reset()

  def update(self, active, v_ego, angle_steers, steer_override, CP, VM, path_plan):
    if v_ego < 0.3 or not active:
      output_steer = 0.0
      self.pid.reset()
    else:
      # TODO: ideally we should interp, but for tuning reasons we keep the mpc solution
      # constant for 0.05s.
      #dt = min(cur_time - self.angle_steers_des_time, _DT_MPC + _DT) + _DT  # no greater than dt mpc + dt, to prevent too high extraps
      #self.angle_steers_des = self.angle_steers_des_prev + (dt / _DT_MPC) * (self.angle_steers_des_mpc - self.angle_steers_des_prev)
      self.angle_steers_des = path_plan.angleSteers  # get from MPC/PathPlanner

      steers_max = get_steer_max(CP, v_ego)
      self.pid.pos_limit = steers_max
      self.pid.neg_limit = -steers_max
      steer_feedforward = self.angle_steers_des   # feedforward desired angle
      if CP.steerControlType == car.CarParams.SteerControlType.torque:
        # TODO: feedforward something based on path_plan.rateSteers
        steer_feedforward -= path_plan.angleOffset   # subtract the offset, since it does not contribute to resistive torque
        steer_feedforward *= v_ego**2  # proportional to realigning tire momentum (~ lateral accel)
      deadzone = 0.0
      output_steer = self.pid.update(self.angle_steers_des, angle_steers, check_saturation=(v_ego > 10), override=steer_override,
                                     feedforward=steer_feedforward, speed=v_ego, deadzone=deadzone)

    self.sat_flag = self.pid.saturated
    return output_steer, float(self.angle_steers_des)