feat(backend): add FastAPI backend — procurement, inventory domain, Casdoor auth, PM arrival endpoints

backend/app/services/storage.py

@@ -0,0 +1,68 @@
+"""MinIO client — S3-compatible object storage for invoice / proforma attachments.
+
+The `minio` SDK is synchronous; every call is wrapped with
+``asyncio.to_thread`` so the event loop is never blocked.
+"""
+import asyncio
+import io
+import logging
+from functools import lru_cache
+
+from minio import Minio
+
+from app.config import settings
+
+logger = logging.getLogger(__name__)
+
+
+@lru_cache(maxsize=1)
+def get_client() -> Minio:
+    """Lazily built Minio client from the PROCUREMENT_MINIO_* settings."""
+    return Minio(
+        settings.MINIO_ENDPOINT,
+        access_key=settings.MINIO_ACCESS_KEY,
+        secret_key=settings.MINIO_SECRET_KEY,
+        secure=settings.MINIO_SECURE,
+    )
+
+
+async def ensure_bucket() -> None:
+    """Create the attachments bucket if it does not exist (idempotent)."""
+    client = get_client()
+    try:
+        exists = await asyncio.to_thread(client.bucket_exists, settings.MINIO_BUCKET)
+        if not exists:
+            await asyncio.to_thread(client.make_bucket, settings.MINIO_BUCKET)
+            logger.info("Created MinIO bucket %r", settings.MINIO_BUCKET)
+    except Exception:
+        logger.exception("MinIO bucket check failed — is the minio service reachable?")
+
+
+async def put_object(key: str, content: bytes, mime_type: str) -> None:
+    """Upload a byte payload to the bucket (overwrites any existing object)."""
+    await asyncio.to_thread(
+        get_client().put_object,
+        settings.MINIO_BUCKET,
+        key,
+        io.BytesIO(content),
+        length=len(content),
+        content_type=mime_type,
+    )
+
+
+async def get_object_bytes(key: str) -> bytes:
+    """Download an object's bytes from the bucket."""
+    response = await asyncio.to_thread(get_client().get_object, settings.MINIO_BUCKET, key)
+    try:
+        return response.read()
+    finally:
+        response.close()
+        response.release_conn()
+
+
+async def remove_object(key: str) -> None:
+    """Delete an object; missing objects are ignored (best-effort)."""
+    try:
+        await asyncio.to_thread(get_client().remove_object, settings.MINIO_BUCKET, key)
+    except Exception:
+        logger.warning("Could not remove MinIO object %r — ignoring", key)