first commit

app/device_manager.py

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+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:
+            self.current_device_num = device_num
+            self.current_url = ""
+            self.timings = {}
+            self.updated_at = time.time()
+            self.version += 1
+            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")
+
+        result = self.api_client.get_stream_url_details(device_num)
+        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:
+                return self.current_url
+            self.current_url = result.url
+            self.timings = dict(result.timings)
+            self.updated_at = time.time()
+        return result.url
+
+    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