first commit

app/capacity_api.py

@@ -0,0 +1,123 @@
+from __future__ import annotations
+
+import hashlib
+import json
+import time
+import urllib.parse
+import urllib.request
+from dataclasses import dataclass
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+
+@dataclass
+class Token:
+    access_token: str
+    expires_at: float
+
+
+@dataclass
+class StreamUrlResult:
+    url: str
+    timings: dict[str, float]
+
+
+class CapacityApiClient:
+    def __init__(
+        self,
+        base_url: str,
+        app_id: str,
+        app_secret: str,
+        account: str,
+        method: str,
+        timeout: int = 20,
+    ):
+        self.base_url = base_url.rstrip("/")
+        self.app_id = app_id
+        self.app_secret = app_secret
+        self.account = account
+        self.method = method
+        self.timeout = timeout
+        self.token: Token | None = None
+
+    def get_stream_url(self, device_num: str) -> str:
+        return self.get_stream_url_details(device_num).url
+
+    def get_stream_url_details(self, device_num: str) -> StreamUrlResult:
+        timings: dict[str, float] = {}
+        started = time.monotonic()
+        access_token = self._get_access_token(timings)
+        timings["token_ms"] = round((time.monotonic() - started) * 1000, 2)
+        started = time.monotonic()
+        business_params = {
+            "account": self.account,
+            "deviceNum": device_num,
+            "isSubStream": 0,
+            "networkType": 1,
+            "urlType": 1,
+        }
+        # 接口文档要求业务参数整体放进 params JSON 字符串后再参与签名。
+        params = {
+            "accessToken": access_token,
+            "appId": self.app_id,
+            "method": self.method,
+            "params": json.dumps(business_params, ensure_ascii=False, separators=(",", ":")),
+            "timestamp": self._timestamp(),
+            "v": "1.0.0",
+        }
+        params["sign"] = self._sign(params)
+        timings["sign_ms"] = round((time.monotonic() - started) * 1000, 2)
+        started = time.monotonic()
+        data = self._get_json(f"{self.base_url}/rest", params)
+        timings["stream_url_ms"] = round((time.monotonic() - started) * 1000, 2)
+        if data.get("errorCode") != "0":
+            raise RuntimeError(data.get("errorMsg") or f"播放地址接口返回错误 {data.get('errorCode')}")
+
+        payload = data.get("data") or {}
+        stream_url = payload.get("rtspUrl") or payload.get("rtspUri")
+        if not stream_url:
+            raise RuntimeError("播放地址接口未返回 RTSP 地址")
+        return StreamUrlResult(stream_url, timings)
+
+    def _get_access_token(self, timings: dict[str, float] | None = None) -> str:
+        if self.token and time.time() < self.token.expires_at - 300:
+            if timings is not None:
+                timings["token_cache"] = 1
+            return self.token.access_token
+
+        data = self._get_json(
+            f"{self.base_url}/oauth/token",
+            {
+                "grantType": "client_credential",
+                "appId": self.app_id,
+                "appSecret": self.app_secret,
+            },
+        )
+        if data.get("errorCode") != "0":
+            raise RuntimeError(data.get("errorMsg") or f"获取 accessToken 失败 {data.get('errorCode')}")
+
+        payload = data.get("data") or {}
+        access_token = payload.get("accessToken")
+        if not access_token:
+            raise RuntimeError("token 接口未返回 accessToken")
+
+        self.token = Token(
+            access_token=access_token,
+            expires_at=time.time() + int(payload.get("expiresIn") or 604800),
+        )
+        return access_token
+
+    def _get_json(self, url: str, params: dict[str, Any]) -> dict[str, Any]:
+        query = urllib.parse.urlencode(params)
+        with urllib.request.urlopen(f"{url}?{query}", timeout=self.timeout) as response:
+            body = response.read().decode("utf-8")
+        return json.loads(body)
+
+    def _sign(self, params: dict[str, Any]) -> str:
+        # 签名规则：appSecret + 按 ASCII key 排序后的 key/value + appSecret。
+        raw = self.app_secret + "".join(f"{key}{params[key]}" for key in sorted(params)) + self.app_secret
+        return hashlib.md5(raw.encode("utf-8")).hexdigest().upper()
+
+    @staticmethod
+    def _timestamp() -> str:
+        return datetime.now(timezone(timedelta(hours=8))).strftime("%Y-%m-%d %H:%M:%S")