# functions common among cars
import capnp
from collections import namedtuple

from cereal import car
from common.numpy_fast import clip, interp
from typing import Dict

# kg of standard extra cargo to count for drive, gas, etc...
STD_CARGO_KG = 136.

ButtonType = car.CarState.ButtonEvent.Type
EventName = car.CarEvent.EventName
AngleRateLimit = namedtuple('AngleRateLimit', ['speed_bp', 'angle_v'])


def apply_hysteresis(val: float, val_steady: float, hyst_gap: float) -> float:
  if val > val_steady + hyst_gap:
    val_steady = val - hyst_gap
  elif val < val_steady - hyst_gap:
    val_steady = val + hyst_gap
  return val_steady


def create_button_event(cur_but: int, prev_but: int, buttons_dict: Dict[int, capnp.lib.capnp._EnumModule],
                        unpressed: int = 0) -> capnp.lib.capnp._DynamicStructBuilder:
  if cur_but != unpressed:
    be = car.CarState.ButtonEvent(pressed=True)
    but = cur_but
  else:
    be = car.CarState.ButtonEvent(pressed=False)
    but = prev_but
  be.type = buttons_dict.get(but, ButtonType.unknown)
  return be


def gen_empty_fingerprint():
  return {i: {} for i in range(0, 8)}


# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
class CivicParams:
  MASS = 1326. + STD_CARGO_KG
  WHEELBASE = 2.70
  CENTER_TO_FRONT = WHEELBASE * 0.4
  CENTER_TO_REAR = WHEELBASE - CENTER_TO_FRONT
  ROTATIONAL_INERTIA = 2500
  TIRE_STIFFNESS_FRONT = 192150
  TIRE_STIFFNESS_REAR = 202500


# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
def scale_rot_inertia(mass, wheelbase):
  return CivicParams.ROTATIONAL_INERTIA * mass * wheelbase ** 2 / (CivicParams.MASS * CivicParams.WHEELBASE ** 2)


# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
def scale_tire_stiffness(mass, wheelbase, center_to_front, tire_stiffness_factor=1.0):
  center_to_rear = wheelbase - center_to_front
  tire_stiffness_front = (CivicParams.TIRE_STIFFNESS_FRONT * tire_stiffness_factor) * mass / CivicParams.MASS * \
                         (center_to_rear / wheelbase) / (CivicParams.CENTER_TO_REAR / CivicParams.WHEELBASE)

  tire_stiffness_rear = (CivicParams.TIRE_STIFFNESS_REAR * tire_stiffness_factor) * mass / CivicParams.MASS * \
                        (center_to_front / wheelbase) / (CivicParams.CENTER_TO_FRONT / CivicParams.WHEELBASE)

  return tire_stiffness_front, tire_stiffness_rear


def dbc_dict(pt_dbc, radar_dbc, chassis_dbc=None, body_dbc=None) -> Dict[str, str]:
  return {'pt': pt_dbc, 'radar': radar_dbc, 'chassis': chassis_dbc, 'body': body_dbc}


def apply_std_steer_torque_limits(apply_torque, apply_torque_last, driver_torque, LIMITS):

  # limits due to driver torque
  driver_max_torque = LIMITS.STEER_MAX + (LIMITS.STEER_DRIVER_ALLOWANCE + driver_torque * LIMITS.STEER_DRIVER_FACTOR) * LIMITS.STEER_DRIVER_MULTIPLIER
  driver_min_torque = -LIMITS.STEER_MAX + (-LIMITS.STEER_DRIVER_ALLOWANCE + driver_torque * LIMITS.STEER_DRIVER_FACTOR) * LIMITS.STEER_DRIVER_MULTIPLIER
  max_steer_allowed = max(min(LIMITS.STEER_MAX, driver_max_torque), 0)
  min_steer_allowed = min(max(-LIMITS.STEER_MAX, driver_min_torque), 0)
  apply_torque = clip(apply_torque, min_steer_allowed, max_steer_allowed)

  # slow rate if steer torque increases in magnitude
  if apply_torque_last > 0:
    apply_torque = clip(apply_torque, max(apply_torque_last - LIMITS.STEER_DELTA_DOWN, -LIMITS.STEER_DELTA_UP),
                        apply_torque_last + LIMITS.STEER_DELTA_UP)
  else:
    apply_torque = clip(apply_torque, apply_torque_last - LIMITS.STEER_DELTA_UP,
                        min(apply_torque_last + LIMITS.STEER_DELTA_DOWN, LIMITS.STEER_DELTA_UP))

  return int(round(float(apply_torque)))


def apply_toyota_steer_torque_limits(apply_torque, apply_torque_last, motor_torque, LIMITS):
  # limits due to comparison of commanded torque VS motor reported torque
  max_lim = min(max(motor_torque + LIMITS.STEER_ERROR_MAX, LIMITS.STEER_ERROR_MAX), LIMITS.STEER_MAX)
  min_lim = max(min(motor_torque - LIMITS.STEER_ERROR_MAX, -LIMITS.STEER_ERROR_MAX), -LIMITS.STEER_MAX)

  apply_torque = clip(apply_torque, min_lim, max_lim)

  # slow rate if steer torque increases in magnitude
  if apply_torque_last > 0:
    apply_torque = clip(apply_torque,
                        max(apply_torque_last - LIMITS.STEER_DELTA_DOWN, -LIMITS.STEER_DELTA_UP),
                        apply_torque_last + LIMITS.STEER_DELTA_UP)
  else:
    apply_torque = clip(apply_torque,
                        apply_torque_last - LIMITS.STEER_DELTA_UP,
                        min(apply_torque_last + LIMITS.STEER_DELTA_DOWN, LIMITS.STEER_DELTA_UP))

  return int(round(float(apply_torque)))


def apply_std_steer_angle_limits(apply_angle, apply_angle_last, v_ego, LIMITS):
  # pick angle rate limits based on wind up/down
  steer_up = apply_angle_last * apply_angle > 0. and abs(apply_angle) > abs(apply_angle_last)
  rate_limits = LIMITS.ANGLE_RATE_LIMIT_UP if steer_up else LIMITS.ANGLE_RATE_LIMIT_DOWN

  angle_rate_lim = interp(v_ego, rate_limits.speed_bp, rate_limits.angle_v)
  return clip(apply_angle, apply_angle_last - angle_rate_lim, apply_angle_last + angle_rate_lim)


def crc8_pedal(data):
  crc = 0xFF    # standard init value
  poly = 0xD5   # standard crc8: x8+x7+x6+x4+x2+1
  size = len(data)
  for i in range(size - 1, -1, -1):
    crc ^= data[i]
    for _ in range(8):
      if ((crc & 0x80) != 0):
        crc = ((crc << 1) ^ poly) & 0xFF
      else:
        crc <<= 1
  return crc


def create_gas_interceptor_command(packer, gas_amount, idx):
  # Common gas pedal msg generator
  enable = gas_amount > 0.001

  values = {
    "ENABLE": enable,
    "COUNTER_PEDAL": idx & 0xF,
  }

  if enable:
    values["GAS_COMMAND"] = gas_amount * 255.
    values["GAS_COMMAND2"] = gas_amount * 255.

  dat = packer.make_can_msg("GAS_COMMAND", 0, values)[2]

  checksum = crc8_pedal(dat[:-1])
  values["CHECKSUM_PEDAL"] = checksum

  return packer.make_can_msg("GAS_COMMAND", 0, values)


def make_can_msg(addr, dat, bus):
  return [addr, 0, dat, bus]


def get_safety_config(safety_model, safety_param = None):
  ret = car.CarParams.SafetyConfig.new_message()
  ret.safetyModel = safety_model
  if safety_param is not None:
    ret.safetyParam = safety_param
  return ret