from dataclasses import dataclass

from edge.detectors.fall import FallConfig
from edge.detectors.immobility import ImmobilityConfig
from edge.detectors.ghost import GhostConfig
from edge.detectors.zone import ZoneConfig
from edge.engine import EngineConfig


@dataclass
class Config:
    device_id: str
    camera_id: str
    cafe24_url: str
    secret: str
    fall: FallConfig
    immobility: ImmobilityConfig
    ghost: GhostConfig
    zone: ZoneConfig
    engine: EngineConfig


def _f(env: dict, key: str, default: float) -> float:
    return float(env[key]) if key in env else default


def frame_interval_from_env(env: dict) -> float:
    """Seconds per frame from TARGET_FPS, validated. TARGET_FPS=0 (ZeroDivisionError) or a
    non-numeric value (ValueError) would otherwise crash at every startup into an infinite
    systemd restart loop (Restart=always + StartLimitIntervalSec=0)."""
    raw = env.get("TARGET_FPS", "12")
    try:
        fps = float(raw)
    except (TypeError, ValueError):
        raise ValueError(f"TARGET_FPS={raw!r} is not a number")
    if fps <= 0:
        raise ValueError(f"TARGET_FPS={raw!r} must be > 0")
    return 1.0 / fps


def queue_db_path(env: dict) -> str:
    """Absolute sqlite path for the offline queue. A relative 'queue.db' resolves against the
    unit's read-only WorkingDirectory under ProtectSystem=strict and cannot be created ->
    crash loop. Default to the systemd StateDirectory, the one writable path."""
    return env.get("QUEUE_DB") or "/var/lib/move-detect/queue.db"


def require_upload_config(cfg: Config) -> None:
    """Fail LOUD at startup when the daemon cannot possibly deliver events.

    load_config defaults cafe24_url and secret to '' so unit tests can build a Config from a
    minimal env — but a real daemon with either blank runs perfectly green while every upload
    fails (a bad/empty URL makes requests raise, which PostClient catches and returns False),
    and the offline queue grows until the SD card is full. The operator sees a healthy unit
    and an empty dashboard. Refuse to start instead.
    """
    missing = [name for name, val in (("CAFE24_URL", cfg.cafe24_url),
                                      ("DEVICE_SECRET", cfg.secret)) if not val.strip()]
    if missing:
        raise ValueError(
            f"FATAL: {', '.join(missing)} not set in /etc/move-detect/edge.env — the daemon "
            f"would run but upload nothing. CAFE24_URL must include the app path, e.g. "
            f"https://<domain>/move_detect ; DEVICE_SECRET is the per-device secret from the "
            f"cloud."
        )


def load_config(env: dict) -> Config:
    camera_id = env.get("CAMERA_ID", "cam-01")
    fall = FallConfig(
        prone_confirm_s=_f(env, "FALL_PRONE_S", 3.0),
        no_motion_s=_f(env, "FALL_NO_MOTION_S", 10.0),
    )
    immobility = ImmobilityConfig(immobile_s=_f(env, "IMMOBILE_S", 120.0))
    ghost = GhostConfig(reappear_s=_f(env, "GHOST_REAPPEAR_S", 10.0))
    zone = ZoneConfig(debounce_s=_f(env, "ZONE_DEBOUNCE_S", 0.75))
    engine = EngineConfig(camera_id=camera_id, cooldown_s=_f(env, "COOLDOWN_S", 30.0))
    return Config(
        device_id=env.get("DEVICE_ID", "pi-unknown"),
        camera_id=camera_id,
        cafe24_url=env.get("CAFE24_URL", ""),
        secret=env.get("DEVICE_SECRET", ""),
        fall=fall, immobility=immobility, ghost=ghost, zone=zone, engine=engine,
    )