"""Загрузка и валидация конфигурации NVR из cameras.yaml."""
from __future__ import annotations

import os
from dataclasses import dataclass, field
from functools import lru_cache

import yaml


@dataclass(frozen=True)
class Camera:
    id: str
    name: str
    enabled: bool
    ip: str
    user: str
    password: str
    main_path: str
    sub_path: str | None = None

    def rtsp_url(self, path: str) -> str:
        return f"rtsp://{self.user}:{self.password}@{self.ip}:554{path}"

    @property
    def record_url(self) -> str:
        """Поток для записи (основной, H.265, копированием)."""
        return self.rtsp_url(self.main_path)


@dataclass(frozen=True)
class Storage:
    path: str = "/records"
    quota_gb: int = 50
    retention_days: int = 7
    segment_seconds: int = 600


@dataclass(frozen=True)
class Live:
    go2rtc_url: str = "http://localhost:1984"


@dataclass
class Config:
    storage: Storage
    live: Live
    cameras: list[Camera] = field(default_factory=list)

    def camera(self, cam_id: str) -> Camera | None:
        return next((c for c in self.cameras if c.id == cam_id), None)

    @property
    def enabled_cameras(self) -> list[Camera]:
        return [c for c in self.cameras if c.enabled]


def load_config(path: str | None = None) -> Config:
    path = path or os.environ.get("NVR_CONFIG", "cameras.yaml")
    with open(path, "r", encoding="utf-8") as fh:
        raw = yaml.safe_load(fh) or {}

    storage = Storage(**(raw.get("storage") or {}))
    live = Live(**(raw.get("live") or {}))
    cameras = [
        Camera(
            id=c["id"],
            name=c.get("name", c["id"]),
            enabled=c.get("enabled", True),
            ip=c["ip"],
            user=c["user"],
            password=c["password"],
            main_path=c["main_path"],
            sub_path=c.get("sub_path"),
        )
        for c in (raw.get("cameras") or [])
    ]
    return Config(storage=storage, live=live, cameras=cameras)


def camera_to_yaml(c: Camera) -> dict:
    return {
        "id": c.id,
        "name": c.name,
        "enabled": c.enabled,
        "ip": c.ip,
        "user": c.user,
        "password": c.password,
        "main_path": c.main_path,
        "sub_path": c.sub_path,
    }


def save_config(config: Config, path: str | None = None) -> None:
    """Сохраняет конфиг обратно в cameras.yaml (комментарии теряются)."""
    path = path or os.environ.get("NVR_CONFIG", "cameras.yaml")
    data = {
        "storage": {
            "path": config.storage.path,
            "quota_gb": config.storage.quota_gb,
            "retention_days": config.storage.retention_days,
            "segment_seconds": config.storage.segment_seconds,
        },
        "live": {"go2rtc_url": config.live.go2rtc_url},
        "cameras": [camera_to_yaml(c) for c in config.cameras],
    }
    # пишем на месте: cameras.yaml примонтирован как отдельный файл (bind mount),
    # переименование поверх точки монтирования даёт EBUSY.
    with open(path, "w", encoding="utf-8") as fh:
        yaml.safe_dump(data, fh, allow_unicode=True, sort_keys=False)


@lru_cache(maxsize=1)
def get_config() -> Config:
    return load_config()