"""Validated saved volume choices for the existing stock audible alerts."""

from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path
from typing import Any

AUTO = 101
MAX_RAW_BYTES = 16

# The first two warnings retain an audible floor. The immediate warning still
# ramps to full volume in soundd, including the selfdrive timeout warning.
VOLUMES = (
  ("WarningImmediateVolume", "Immediate Warning", 25),
  ("WarningSoftVolume", "Soft Warning", 25),
  ("RefuseVolume", "Engagement Refused", 0),
  ("PromptDistractedVolume", "Distracted Driver", 0),
  ("EngageVolume", "Engagement Chime", 0),
  ("DisengageVolume", "Disengagement Alert", 0),
  ("PromptVolume", "General Prompt", 0),
)
SPECS = {key: (label, minimum) for key, label, minimum in VOLUMES}


@dataclass(frozen=True)
class SavedVolume:
  raw: bytes | None
  value: int | None
  readable: bool = True

  @property
  def valid(self) -> bool:
    return self.readable and self.value is not None


def parse_volume(key: str, raw: bytes | None) -> int | None:
  if key not in SPECS:
    raise KeyError(key)
  if raw is None:
    return AUTO
  if not raw or len(raw) > MAX_RAW_BYTES or not raw.isascii() or not raw.isdigit():
    return None
  value = int(raw)
  minimum = SPECS[key][1]
  return value if value == AUTO or minimum <= value <= 100 else None


def read_volume(params: Any, key: str) -> SavedVolume:
  if key not in SPECS:
    raise KeyError(key)
  try:
    with Path(params.get_param_path(key)).open("rb") as file:
      raw = file.read(MAX_RAW_BYTES + 1)
  except FileNotFoundError:
    raw = None
  except (OSError, ValueError):
    return SavedVolume(None, None, False)
  if raw is not None and len(raw) > MAX_RAW_BYTES:
    return SavedVolume(raw, None, False)
  return SavedVolume(raw, parse_volume(key, raw))


def effective_volume(key: str, saved: int | None, ambient: float, *, immediate_ramp: float | None = None) -> float:
  """Return gain without changing the stock Auto path or immediate-warning ramp."""
  if key not in SPECS:
    raise KeyError(key)
  if saved is None or saved == AUTO:
    return ambient
  selected = saved / 100.0
  return max(selected, immediate_ramp) if immediate_ramp is not None else selected