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app/clients/ga_client.py

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+"""Google Analytics client.
+
+Thin proxy over the GA4 Data API and Admin API. Request/response bodies are
+forwarded as-is so callers keep the full flexibility of Google's API; this
+module only handles authentication (Bearer token), the base URL, and error
+mapping.
+
+Authentication (per chosen model, token wins over service account):
+  * If ``X-GA-Access-Token`` was supplied, it is used directly.
+  * Otherwise a short-lived access token is minted from the service-account
+    JSON via google-auth and cached in-memory (keyed by key id + scope) until
+    shortly before it expires. The key material is never written to disk or log.
+"""
+from __future__ import annotations
+
+import hashlib
+import threading
+import time
+from typing import Any
+
+import httpx
+from fastapi.concurrency import run_in_threadpool
+
+from .. import config
+from ..credentials import GaCredentials
+from ..errors import MissingCredentialsError, UpstreamError
+from ..logging_config import get_logger
+
+logger = get_logger(__name__)
+
+# In-memory access-token cache: { cache_key: (token, expiry_epoch_seconds) }.
+# Memory only - mirrors the stateless design (no secret ever persisted).
+_token_cache: dict[str, tuple[str, float]] = {}
+_token_lock = threading.Lock()
+
+# Refresh a minted token this many seconds before its real expiry.
+_EXPIRY_SKEW = 60.0
+
+
+def _mint_token_sync(info: dict, scope: str) -> tuple[str, float]:
+    """Mint an OAuth2 access token from a service-account key (blocking)."""
+    # Imported lazily so the module imports even if google-auth is missing,
+    # and so the dependency is only needed when service-account auth is used.
+    from google.auth.transport.requests import Request
+    from google.oauth2 import service_account
+
+    try:
+        creds = service_account.Credentials.from_service_account_info(
+            info, scopes=[scope]
+        )
+    except (ValueError, KeyError) as exc:
+        raise MissingCredentialsError(
+            f"X-GA-Credentials is not a usable service-account key: {exc}"
+        ) from exc
+
+    try:
+        creds.refresh(Request())
+    except Exception as exc:  # google.auth.exceptions.RefreshError and friends
+        # Surface as upstream auth failure - do NOT log the key material.
+        raise UpstreamError(
+            f"Failed to obtain Google access token from service account: {exc}",
+            status=401,
+        ) from exc
+
+    expiry = creds.expiry.timestamp() if creds.expiry else (time.time() + 3600)
+    return creds.token, expiry
+
+
+def _cache_key(info: dict, scope: str) -> str:
+    # Identify a key by its private_key_id + client_email + scope. Hashed so the
+    # raw identifiers never sit in a dict key we might later log.
+    raw = f"{info.get('private_key_id', '')}|{info.get('client_email', '')}|{scope}"
+    return hashlib.sha256(raw.encode("utf-8")).hexdigest()
+
+
+async def _bearer_token(creds: GaCredentials) -> str:
+    if creds.access_token:
+        return creds.access_token
+
+    if creds.service_account_info is None:
+        # get_ga_credentials guarantees one of the two, but be defensive.
+        raise MissingCredentialsError(
+            "No GA access token and no service-account credentials available."
+        )
+
+    scope = config.GA_SCOPE
+    key = _cache_key(creds.service_account_info, scope)
+    now = time.time()
+
+    with _token_lock:
+        cached = _token_cache.get(key)
+        if cached and cached[1] - _EXPIRY_SKEW > now:
+            return cached[0]
+
+    # Mint outside the lock (network call); google-auth is blocking, so offload
+    # it to a thread to avoid stalling the event loop.
+    token, expiry = await run_in_threadpool(
+        _mint_token_sync, creds.service_account_info, scope
+    )
+    with _token_lock:
+        _token_cache[key] = (token, expiry)
+    return token
+
+
+class GoogleAnalyticsClient:
+    """Authenticated HTTP client for the GA4 Data and Admin APIs."""
+
+    def __init__(self, creds: GaCredentials) -> None:
+        self._creds = creds
+
+    async def _request(
+        self,
+        method: str,
+        base_url: str,
+        path: str,
+        *,
+        params: dict | None = None,
+        json_body: Any | None = None,
+    ) -> Any:
+        token = await _bearer_token(self._creds)
+        headers = {"Authorization": f"Bearer {token}"}
+        if self._creds.quota_project:
+            headers["x-goog-user-project"] = self._creds.quota_project
+
+        url = f"{base_url}{path}"
+        try:
+            async with httpx.AsyncClient(
+                timeout=config.HTTP_TIMEOUT_SECONDS
+            ) as client:
+                resp = await client.request(
+                    method, url, params=params, json=json_body, headers=headers
+                )
+        except httpx.TimeoutException as exc:
+            raise UpstreamError(
+                "Google Analytics request timed out.", status=504
+            ) from exc
+        except httpx.HTTPError as exc:
+            raise UpstreamError(
+                f"Google Analytics is unreachable: {exc}", status=502
+            ) from exc
+
+        return _parse_google_response(resp)
+
+    # --- Data API -------------------------------------------------------------
+    async def data_post(self, path: str, body: Any) -> Any:
+        return await self._request(
+            "POST", config.GA_DATA_BASE_URL, path, json_body=body
+        )
+
+    async def data_get(self, path: str, params: dict | None = None) -> Any:
+        return await self._request(
+            "GET", config.GA_DATA_BASE_URL, path, params=params
+        )
+
+    # --- Admin API ------------------------------------------------------------
+    async def admin_get(self, path: str, params: dict | None = None) -> Any:
+        return await self._request(
+            "GET", config.GA_ADMIN_BASE_URL, path, params=params
+        )
+
+
+def _parse_google_response(resp: httpx.Response) -> Any:
+    try:
+        payload = resp.json()
+    except ValueError:
+        payload = {"raw": resp.text}
+
+    if resp.is_success:
+        return payload
+
+    # Google returns {"error": {"code", "message", "status", ...}}.
+    message = "Google Analytics API error"
+    if isinstance(payload, dict) and isinstance(payload.get("error"), dict):
+        message = payload["error"].get("message", message)
+    raise UpstreamError(
+        message,
+        status=502 if resp.status_code >= 500 else resp.status_code,
+        upstream_status=resp.status_code,
+        body=payload,
+    )