# functions common among cars
import numpy as np
from dataclasses import dataclass, field
from enum import IntFlag, ReprEnum, StrEnum, EnumType, auto
from dataclasses import replace

from opendbc.car import structs, uds
from opendbc.car.can_definitions import CanData
from opendbc.car.docs_definitions import CarDocs, ExtraCarDocs

DT_CTRL = 0.01  # car state and control loop timestep (s)

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

ACCELERATION_DUE_TO_GRAVITY = 9.81  # m/s^2

ButtonType = structs.CarState.ButtonEvent.Type


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_events(cur_btn: int, prev_btn: int, buttons_dict: dict[int, structs.CarState.ButtonEvent.Type],
                         unpressed_btn: int = 0) -> list[structs.CarState.ButtonEvent]:
  events: list[structs.CarState.ButtonEvent] = []

  if cur_btn == prev_btn:
    return events

  # Add events for button presses, multiple when a button switches without going to unpressed
  for pressed, btn in ((False, prev_btn), (True, cur_btn)):
    if btn != unpressed_btn:
      events.append(structs.CarState.ButtonEvent(pressed=pressed,
                                                 type=buttons_dict.get(btn, ButtonType.unknown)))
  return events


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


# these params were derived for the Civic and used to calculate params for other cars
class VehicleDynamicsParams:
  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 VehicleDynamicsParams.ROTATIONAL_INERTIA * mass * wheelbase ** 2 / (VehicleDynamicsParams.MASS * VehicleDynamicsParams.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):
  center_to_rear = wheelbase - center_to_front
  tire_stiffness_front = (VehicleDynamicsParams.TIRE_STIFFNESS_FRONT * tire_stiffness_factor) * mass / VehicleDynamicsParams.MASS * \
                         (center_to_rear / wheelbase) / (VehicleDynamicsParams.CENTER_TO_REAR / VehicleDynamicsParams.WHEELBASE)

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

  return tire_stiffness_front, tire_stiffness_rear


DbcDict = dict[StrEnum, str]


class Bus(StrEnum):
  pt = auto()
  cam = auto()
  radar = auto()
  adas = auto()
  alt = auto()
  body = auto()
  chassis = auto()
  loopback = auto()
  main = auto()
  party = auto()
  ap_party = auto()


def rate_limit(new_value, last_value, dw_step, up_step):
  return float(np.clip(new_value, last_value + dw_step, last_value + up_step))


def make_tester_present_msg(addr, bus, subaddr=None, suppress_response=False):
  dat = [0x02, uds.SERVICE_TYPE.TESTER_PRESENT]
  if subaddr is not None:
    dat.insert(0, subaddr)
  dat.append(0x80 if suppress_response else 0x0)  # sub-function

  dat.extend([0x0] * (8 - len(dat)))
  return CanData(addr, bytes(dat), bus)


def get_safety_config(safety_model: structs.CarParams.SafetyModel, safety_param: int = None) -> structs.CarParams.SafetyConfig:
  ret = structs.CarParams.SafetyConfig()
  ret.safetyModel = safety_model
  if safety_param is not None:
    ret.safetyParam = safety_param
  return ret


class CanBusBase:
  offset: int

  def __init__(self, CP, fingerprint: dict[int, dict[int, int]] | None) -> None:
    if CP is None:
      assert fingerprint is not None
      num = max([k for k, v in fingerprint.items() if len(v)], default=0) // 4 + 1
    else:
      num = len(CP.safetyConfigs)
    self.offset = 4 * (num - 1)


class CanSignalRateCalculator:
  """
  Calculates the instantaneous rate of a CAN signal by using the counter
  variable and the known frequency of the CAN message that contains it.
  """
  def __init__(self, frequency):
    self.frequency = frequency
    self.previous_counter = 0
    self.previous_value = 0
    self.rate = 0

  def update(self, current_value, current_counter):
    if current_counter != self.previous_counter:
      self.rate = (current_value - self.previous_value) * self.frequency

    self.previous_counter = current_counter
    self.previous_value = current_value

    return self.rate


@dataclass(frozen=True, kw_only=True)
class CarSpecs:
  mass: float  # kg, curb weight
  wheelbase: float  # meters
  steerRatio: float
  centerToFrontRatio: float = 0.5
  minSteerSpeed: float = 0.0  # m/s
  minEnableSpeed: float = -1.0  # m/s
  tireStiffnessFactor: float = 1.0

  def override(self, **kwargs):
    return replace(self, **kwargs)


class Freezable:
  _frozen: bool = False

  def freeze(self):
    if not self._frozen:
      self._frozen = True

  def __setattr__(self, *args, **kwargs):
    if self._frozen:
      raise Exception("cannot modify frozen object")
    super().__setattr__(*args, **kwargs)


@dataclass(order=True)
class PlatformConfigBase(Freezable):
  car_docs: list[CarDocs] | list[ExtraCarDocs]
  specs: CarSpecs

  dbc_dict: DbcDict

  flags: int = 0

  platform_str: str | None = None

  def __hash__(self) -> int:
    return hash(self.platform_str)

  def override(self, **kwargs):
    return replace(self, **kwargs)

  def init(self):
    pass

  def __post_init__(self):
    self.init()


@dataclass(order=True)
class PlatformConfig(PlatformConfigBase):
  car_docs: list[CarDocs]
  specs: CarSpecs
  dbc_dict: DbcDict


@dataclass(order=True)
class ExtraPlatformConfig(PlatformConfigBase):
  car_docs: list[ExtraCarDocs]
  specs: CarSpecs = CarSpecs(mass=0., wheelbase=0., steerRatio=0.)
  dbc_dict: DbcDict = field(default_factory=lambda: dict())


class PlatformsType(EnumType):
  def __new__(metacls, cls, bases, classdict, *, boundary=None, _simple=False, **kwds):
    for key in classdict._member_names.keys():
      cfg: PlatformConfig = classdict[key]
      cfg.platform_str = key
      cfg.freeze()
    return super().__new__(metacls, cls, bases, classdict, boundary=boundary, _simple=_simple, **kwds)


class Platforms(str, ReprEnum, metaclass=PlatformsType):
  config: PlatformConfigBase

  def __new__(cls, platform_config: PlatformConfig):
    member = str.__new__(cls, platform_config.platform_str)
    member.config = platform_config
    member._value_ = platform_config.platform_str
    return member

  def __repr__(self):
    return f"<{self.__class__.__name__}.{self.name}>"

  @classmethod
  def create_dbc_map(cls) -> dict[str, DbcDict]:
    return {p: p.config.dbc_dict for p in cls}

  @classmethod
  def with_flags(cls, flags: IntFlag) -> set['Platforms']:
    return {p for p in cls if p.config.flags & flags}
