"""摄像头管理模块：加载设备列表、切换当前设备并解析播放地址。"""

from __future__ import annotations

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

from app.capacity_api import CapacityApiClient


@dataclass(frozen=True)
class Device:
    name: str
    device_num: str


class DeviceManager:
    def __init__(self, path: str, api_client: CapacityApiClient, fallback_url: str = ""):
        self.devices = self._load_devices(path)
        self.api_client = api_client
        self.fallback_url = fallback_url
        self.lock = threading.Lock()
        self.current_device_num = self.devices[0].device_num if self.devices else ""
        self.current_url = fallback_url
        self.timings: dict[str, float] = {}
        self.updated_at = 0.0
        self.version = 0

    def set_current_device(self, device_num: str) -> int:
        if device_num not in {device.device_num for device in self.devices}:
            raise ValueError("设备不在 devicelist.env 中")
        with self.lock:
            old_device_num = self.current_device_num
            self.current_device_num = device_num
            self.current_url = ""
            self.timings = {}
            self.updated_at = time.time()
            self.version += 1
            print(
                f"[device-switch] manager set old={old_device_num} new={device_num} version={self.version}",
                flush=True,
            )
            return self.version

    def resolve_stream_url(self) -> str:
        with self.lock:
            device_num = self.current_device_num
            version = self.version
        if not device_num:
            if self.fallback_url:
                return self.fallback_url
            raise RuntimeError("devicelist.env 中没有可用设备号")

        print(f"[device-switch] resolve start device={device_num} version={version}", flush=True)
        try:
            result = self.api_client.get_stream_url_details(device_num)
        except Exception as exc:
            print(
                f"[device-switch] resolve failed device={device_num} version={version} error={exc}",
                flush=True,
            )
            raise
        with self.lock:
            # 避免旧摄像头的慢接口响应覆盖用户刚切换的新选择。
            if version != self.version or device_num != self.current_device_num:
                print(
                    f"[device-switch] resolve stale device={device_num} version={version} current={self.current_device_num} current_version={self.version}",
                    flush=True,
                )
                return self.current_url
            self.current_url = result.url
            self.timings = dict(result.timings)
            self.updated_at = time.time()
        print(f"[device-switch] resolve success device={device_num} version={version}", flush=True)
        return result.url

    def resolve_stream_url_for(self, device_num: str) -> str:
        if device_num not in {device.device_num for device in self.devices}:
            raise ValueError("设备不在 devicelist.env 中")
        result = self.api_client.get_stream_url_details(device_num)
        return result.url

    def get_video_grid_devices(self, limit: int = 4) -> list[Device]:
        return self.devices[:limit]

    def get_snapshot(self) -> dict[str, Any]:
        with self.lock:
            return {
                "devices": [device.__dict__ for device in self.devices],
                "current_device_num": self.current_device_num,
                "current_url": self.current_url,
                "source_timings": dict(self.timings),
                "source_updated_at": self.updated_at,
            }

    @staticmethod
    def _load_devices(path: str) -> list[Device]:
        devices: list[Device] = []
        file_path = Path(path)
        if not file_path.exists():
            return devices

        for line in file_path.read_text(encoding="utf-8").splitlines():
            stripped = line.strip()
            if not stripped or stripped.startswith("#"):
                continue
            if "=" in stripped:
                name, value = stripped.split("=", 1)
                values = [item.strip() for item in value.split(",") if item.strip()]
                display_name = name.strip()
            else:
                values = [stripped]
                display_name = "摄像头"
            for device_num in values:
                name = display_name if len(values) == 1 else f"摄像头 {len(devices) + 1}"
                devices.append(Device(name, device_num))
        return devices