"""
Singleton AWS session class.
"""

from boto3.session import Session as BaseSession
from boto3.s3 import inject as boto3_s3_inject
from common.src.logger import new_logger

logger = new_logger(__name__)


class Session(BaseSession):
    """Singleton boto3 session with safe S3 injection."""

    _instance: BaseSession = None

    def __new__(cls, *args, **kwargs):
        """Create a new instance of the Session class."""
        if cls._instance is None:
            instance = super().__new__(cls)
            instance._initialize(*args, **kwargs)

            # Inject S3 methods once. This prevents issues with
            # S3 upload_file and download_file methods, specifically when
            # injecting them multiple times.
            s3_cls = instance.client("s3").__class__
            if not hasattr(s3_cls, "upload_file"):
                boto3_s3_inject.inject_s3_transfer_methods(s3_cls)

            cls._instance = instance
        return cls._instance

    def _initialize(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        logger.debug("AWS Singleton Session created.")