services/uploader/azure_blob_service.py

import os
import dotenv
from config.env_constant import EnvFilepath
dotenv.load_dotenv(EnvFilepath.ENVPATH)

from config.constant import AzureBlobConstants
from externals.storages.azure_blob import get_container_client
from fastapi import UploadFile
from utils.logger import get_logger


logger = get_logger("azure blob")


class AzureBlobStorageService:
    """
    A dedicated service class for interacting with Azure Blob Storage.
    Uses asynchronous clients for non-blocking I/O operations.
    """
    def __init__(self):
        # Initialize the BlobServiceClient for the entire application lifetime
        # self.blob_service_client = get_blob_service_client()
        # self.container_client = get_container_client()
        self.prefix = AzureBlobConstants.BLOB_PREFIX
        
        # if not self.container_client:
        #     raise ValueError("azure container client is not set.")


    async def upload_pdf(self, file: UploadFile) -> str:
        """
        Uploads a file stream directly to Azure Blob Storage.

        Args:
            file: The FastAPI UploadFile object.

        Returns:
            The URL of the uploaded blob.
        """
        # 1. Create a unique blob name (use the original filename for simplicity, 
        #    but consider using a UUID for production to avoid collisions)
        blob_name = file.filename 

        # 2. Get the blob client
        container_client = await get_container_client()
        blob_client = container_client.get_blob_client(blob_name)

        # 3. Read the file content asynchronously
        #    The file is read in chunks to avoid loading the entire file into memory 
        #    if it's very large.
        content = await file.read()

        # 4. Upload the content
        #    Setting content_settings is crucial for the browser to handle the file correctly
        await blob_client.upload_blob(
            content, 
            blob_type="BlockBlob", 
            overwrite=True,
            content_settings={"content_type": "application/pdf"}
        )

        # 5. Return the URL
        #    Note: This is the URL to the blob. If it needs to be publicly accessible, 
        #    ensure your container's access policy is configured correctly.
        return blob_client.url

    # --- Cleanup for Graceful Shutdown (Optional but Recommended) ---
    async def close(self):
        """Closes the Blob Service Client connection."""
        await self.blob_service_client.close()

# Initialize the service globally
blob_storage_service = AzureBlobStorageService()