curo1305
bcb887e61d
- CloudConnectionError imported from google_drive_backend (shared exception type) - CHUNK_SIZE = 10 * 1024 * 1024 (10 MB — above Graph 4 MB limit, Pitfall 6) - All 7 StorageBackend methods implemented as async coroutines - Resumable upload sessions (createUploadSession) used for ALL uploads - _ensure_valid_token() checks expiry with 60s buffer, calls _refresh_token() if expired - _refresh_token() wraps msal.ConfidentialClientApplication in asyncio.to_thread() - invalid_grant → CloudConnectionError(reason='invalid_grant') per D-06 / B2 design - presigned_get_url and generate_presigned_put_url raise NotImplementedError (D-14) - delete_object silently ignores 404 (no-op per StorageBackend contract) - Backend is stateless — no DB writes (B2 design)
280 lines
11 KiB
Python
280 lines
11 KiB
Python
"""
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Microsoft Graph / OneDrive StorageBackend implementation for DocuVault.
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Design notes:
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- Resumable upload sessions (createUploadSession) are used for ALL uploads,
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regardless of file size (Pitfall 6 — Microsoft Graph's simple upload is
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limited to 4 MB; resumable sessions handle both small and large files).
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- CHUNK_SIZE = 10 MB (above Graph's 4 MB simple upload limit).
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- All sync MSAL calls are wrapped in asyncio.to_thread(); httpx calls are
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already async and awaited directly.
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- CloudConnectionError is imported from google_drive_backend (shared type).
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This keeps the exception hierarchy unified across all cloud backends.
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- B2 design: This backend is STATELESS. It raises CloudConnectionError but
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does NOT update the DB or CloudConnection objects. DB state transitions
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(e.g., REQUIRES_REAUTH) are handled by _call_cloud_op() in cloud.py.
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- _ensure_valid_token() checks expiry before each API call and calls
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_refresh_token() if the token is within 60 seconds of expiry. If the
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refresh returns None (invalid_grant), CloudConnectionError is raised.
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- Token key format stored in credentials dict:
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access_token — current OAuth bearer token
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refresh_token — long-lived refresh token
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expires_at — ISO 8601 datetime string (when the access_token expires)
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"""
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from __future__ import annotations
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import asyncio
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import datetime
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import io
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import uuid
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import httpx
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import msal
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from config import settings
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from storage.base import StorageBackend
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from storage.google_drive_backend import CloudConnectionError # reuse shared exception
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GRAPH_BASE = "https://graph.microsoft.com/v1.0"
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CHUNK_SIZE = 10 * 1024 * 1024 # 10 MB — above Graph's 4 MB simple upload limit (Pitfall 6)
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class OneDriveBackend(StorageBackend):
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"""Microsoft Graph / OneDrive implementation of StorageBackend.
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Uses MSAL for token management and httpx for async HTTP to Microsoft Graph.
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All sync MSAL calls are wrapped in asyncio.to_thread(). The backend is
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stateless — it raises CloudConnectionError but never writes to the DB.
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"""
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def __init__(self, credentials: dict) -> None:
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"""Initialise with a decrypted credentials dict.
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Expected keys:
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access_token str — current OAuth bearer token
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refresh_token str — long-lived refresh token
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expires_at str — ISO 8601 datetime string (when access_token expires)
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"""
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self._credentials = credentials
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# ── Internal helpers ──────────────────────────────────────────────────────
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def _auth_headers(self) -> dict:
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"""Return Authorization header with current access token."""
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return {"Authorization": f"Bearer {self._credentials['access_token']}"}
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async def _ensure_valid_token(self) -> None:
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"""Check if the access token is expired (within 60 s buffer) and refresh if so.
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Raises:
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CloudConnectionError(reason='invalid_grant') — if the refresh token has
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been revoked (MSAL returns result['error'] == 'invalid_grant').
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"""
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expires_at_str = self._credentials.get("expires_at", "")
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if expires_at_str:
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try:
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expires_at = datetime.datetime.fromisoformat(expires_at_str)
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# Make expires_at timezone-aware if needed for comparison
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if expires_at.tzinfo is None:
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expires_at = expires_at.replace(tzinfo=datetime.timezone.utc)
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now = datetime.datetime.now(tz=datetime.timezone.utc)
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if expires_at > now + datetime.timedelta(seconds=60):
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# Token is still valid — no refresh needed
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return
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except ValueError:
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# Unparseable expiry — attempt refresh to be safe
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pass
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# Token expired or expiry unparseable — attempt refresh
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new_creds = await self._refresh_token()
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if new_creds is None:
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raise CloudConnectionError(
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"OneDrive connection requires re-authentication (invalid_grant)",
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reason="invalid_grant",
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)
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self._credentials = new_creds
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async def _refresh_token(self) -> dict | None:
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"""Refresh the access token via MSAL.
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Wraps the sync MSAL call in asyncio.to_thread() to avoid blocking
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the event loop.
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Returns:
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Updated credentials dict on success.
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None if MSAL returns result['error'] == 'invalid_grant' (D-06).
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"""
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def _msal_refresh() -> dict | None:
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app = msal.ConfidentialClientApplication(
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client_id=settings.onedrive_client_id,
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client_credential=settings.onedrive_client_secret,
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authority=f"https://login.microsoftonline.com/{settings.onedrive_tenant_id}",
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)
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result = app.acquire_token_by_refresh_token(
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self._credentials["refresh_token"],
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scopes=["Files.ReadWrite", "offline_access"],
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)
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if result.get("error") == "invalid_grant":
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return None # Signal to _ensure_valid_token to raise CloudConnectionError
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if "access_token" not in result:
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# Unexpected MSAL error — treat as token_expired for retry logic
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return None
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# Build new credentials dict with refreshed tokens
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expires_in = result.get("expires_in", 3600)
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expires_at = (
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datetime.datetime.now(tz=datetime.timezone.utc)
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+ datetime.timedelta(seconds=expires_in)
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).isoformat()
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return {
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"access_token": result["access_token"],
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"refresh_token": result.get(
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"refresh_token", self._credentials["refresh_token"]
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),
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"expires_at": expires_at,
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}
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return await asyncio.to_thread(_msal_refresh)
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# ── StorageBackend interface ──────────────────────────────────────────────
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async def put_object(
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self,
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user_id: str,
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document_id: str,
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file_bytes: bytes,
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extension: str,
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content_type: str,
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) -> str:
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"""Upload bytes to OneDrive via a resumable upload session.
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Uses createUploadSession for ALL files (Pitfall 6 — avoids 4 MB limit
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of simple upload). Chunks file in CHUNK_SIZE (10 MB) slices.
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Returns the OneDrive item_id as object_key.
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"""
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await self._ensure_valid_token()
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# Path within the user's OneDrive: docuvault/{user_id}/{document_id}{extension}
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remote_path = f"docuvault/{user_id}/{document_id}{extension}"
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create_session_url = (
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f"{GRAPH_BASE}/me/drive/root:/{remote_path}:/createUploadSession"
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)
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async with httpx.AsyncClient() as client:
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# Step 1: Create a resumable upload session
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session_response = await client.post(
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create_session_url,
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headers={**self._auth_headers(), "Content-Type": "application/json"},
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json={"item": {"@microsoft.graph.conflictBehavior": "replace"}},
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)
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session_response.raise_for_status()
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upload_url = session_response.json()["uploadUrl"]
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# Step 2: Upload file in CHUNK_SIZE chunks
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total_size = len(file_bytes)
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item_id: str = ""
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offset = 0
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while offset < total_size:
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chunk = file_bytes[offset : offset + CHUNK_SIZE]
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chunk_size = len(chunk)
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end = offset + chunk_size - 1
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chunk_response = await client.put(
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upload_url,
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content=chunk,
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headers={
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"Content-Length": str(chunk_size),
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"Content-Range": f"bytes {offset}-{end}/{total_size}",
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"Content-Type": content_type,
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},
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)
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chunk_response.raise_for_status()
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# The final chunk response contains the item metadata with id
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if chunk_response.status_code in (200, 201):
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item_id = chunk_response.json().get("id", "")
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offset += chunk_size
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return item_id
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async def get_object(self, object_key: str) -> bytes:
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"""Download file bytes from OneDrive by item_id.
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Follows redirects — Microsoft Graph returns a redirect to the CDN URL.
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"""
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await self._ensure_valid_token()
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async with httpx.AsyncClient() as client:
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r = await client.get(
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f"{GRAPH_BASE}/me/drive/items/{object_key}/content",
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headers=self._auth_headers(),
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follow_redirects=True,
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)
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r.raise_for_status()
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return r.content
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async def delete_object(self, object_key: str) -> None:
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"""Delete a OneDrive item by item_id. Silent no-op on 404."""
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await self._ensure_valid_token()
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async with httpx.AsyncClient() as client:
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r = await client.delete(
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f"{GRAPH_BASE}/me/drive/items/{object_key}",
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headers=self._auth_headers(),
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)
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if r.status_code not in (204, 404):
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r.raise_for_status()
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async def presigned_get_url(self, object_key: str, expires_minutes: int = 60) -> str:
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"""Not supported by OneDrive — raises NotImplementedError (D-14).
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Use get_object() for direct streaming instead.
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"""
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raise NotImplementedError(
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"OneDrive backend does not support presigned URLs — "
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"use get_object() for streaming"
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)
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async def generate_presigned_put_url(
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self, object_key: str, expires_minutes: int = 15
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) -> str:
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"""Not supported by OneDrive — raises NotImplementedError (D-14).
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Use put_object() for direct upload via FastAPI intermediary.
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"""
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raise NotImplementedError(
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"OneDrive backend does not support presigned put URLs — "
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"use put_object() for direct upload"
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)
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async def stat_object(self, object_key: str) -> int:
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"""Return the file size in bytes from OneDrive item metadata."""
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await self._ensure_valid_token()
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async with httpx.AsyncClient() as client:
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r = await client.get(
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f"{GRAPH_BASE}/me/drive/items/{object_key}",
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params={"$select": "size"},
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headers=self._auth_headers(),
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)
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r.raise_for_status()
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return int(r.json().get("size", 0))
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async def health_check(self) -> bool:
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"""Return True if the OneDrive service is reachable and the token is valid.
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Makes a minimal GET /me/drive request selecting only the id field.
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Returns False on any error.
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"""
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try:
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await self._ensure_valid_token()
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async with httpx.AsyncClient() as client:
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r = await client.get(
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f"{GRAPH_BASE}/me/drive",
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params={"$select": "id"},
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headers=self._auth_headers(),
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)
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return r.is_success
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except Exception:
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return False
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