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"""This module contains Google Cloud Storage to SFTP operator."""
import os
from tempfile import NamedTemporaryFile
from typing import Optional, Sequence, Union

from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.providers.google.cloud.hooks.gcs import GCSHook
from airflow.providers.sftp.hooks.sftp import SFTPHook
from airflow.utils.decorators import apply_defaults

WILDCARD = "*"


class GCSToSFTPOperator(BaseOperator):
    """
    Transfer files from a Google Cloud Storage bucket to SFTP server.

    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:GCSToSFTPOperator`

    :param source_bucket: The source Google Cloud Storage bucket where the
         object is. (templated)
    :type source_bucket: str
    :param source_object: The source name of the object to copy in the Google cloud
        storage bucket. (templated)
        You can use only one wildcard for objects (filenames) within your
        bucket. The wildcard can appear inside the object name or at the
        end of the object name. Appending a wildcard to the bucket name is
        unsupported.
    :type source_object: str
    :param destination_path: The sftp remote path. This is the specified directory path for
        uploading to the SFTP server.
    :type destination_path: str
    :param move_object: When move object is True, the object is moved instead
        of copied to the new location. This is the equivalent of a mv command
        as opposed to a cp command.
    :type move_object: bool
    :param gcp_conn_id: (Optional) The connection ID used to connect to Google Cloud.
    :type gcp_conn_id: str
    :param sftp_conn_id: The sftp connection id. The name or identifier for
        establishing a connection to the SFTP server.
    :type sftp_conn_id: str
    :param delegate_to: The account to impersonate using domain-wide delegation of authority,
        if any. For this to work, the service account making the request must have
        domain-wide delegation enabled.
    :type delegate_to: str
    :param impersonation_chain: Optional service account to impersonate using short-term
        credentials, or chained list of accounts required to get the access_token
        of the last account in the list, which will be impersonated in the request.
        If set as a string, the account must grant the originating account
        the Service Account Token Creator IAM role.
        If set as a sequence, the identities from the list must grant
        Service Account Token Creator IAM role to the directly preceding identity, with first
        account from the list granting this role to the originating account (templated).
    :type impersonation_chain: Union[str, Sequence[str]]
    """

    template_fields = (
        "source_bucket",
        "source_object",
        "destination_path",
        "impersonation_chain",
    )
    ui_color = "#f0eee4"

    # pylint: disable=too-many-arguments
    @apply_defaults
    def __init__(
        self,
        *,
        source_bucket: str,
        source_object: str,
        destination_path: str,
        move_object: bool = False,
        gcp_conn_id: str = "google_cloud_default",
        sftp_conn_id: str = "ssh_default",
        delegate_to: Optional[str] = None,
        impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
        **kwargs,
    ) -> None:
        super().__init__(**kwargs)

        self.source_bucket = source_bucket
        self.source_object = source_object
        self.destination_path = destination_path
        self.move_object = move_object
        self.gcp_conn_id = gcp_conn_id
        self.sftp_conn_id = sftp_conn_id
        self.delegate_to = delegate_to
        self.impersonation_chain = impersonation_chain
        self.sftp_dirs = None

    def execute(self, context):
        gcs_hook = GCSHook(
            gcp_conn_id=self.gcp_conn_id,
            delegate_to=self.delegate_to,
            impersonation_chain=self.impersonation_chain,
        )

        sftp_hook = SFTPHook(self.sftp_conn_id)

        if WILDCARD in self.source_object:
            total_wildcards = self.source_object.count(WILDCARD)
            if total_wildcards > 1:
                raise AirflowException(
                    "Only one wildcard '*' is allowed in source_object parameter. "
                    "Found {} in {}.".format(total_wildcards, self.source_object)
                )

            prefix, delimiter = self.source_object.split(WILDCARD, 1)
            objects = gcs_hook.list(self.source_bucket, prefix=prefix, delimiter=delimiter)

            for source_object in objects:
                destination_path = os.path.join(self.destination_path, source_object)
                self._copy_single_object(gcs_hook, sftp_hook, source_object, destination_path)

            self.log.info("Done. Uploaded '%d' files to %s", len(objects), self.destination_path)
        else:
            destination_path = os.path.join(self.destination_path, self.source_object)
            self._copy_single_object(gcs_hook, sftp_hook, self.source_object, destination_path)
            self.log.info("Done. Uploaded '%s' file to %s", self.source_object, destination_path)

    def _copy_single_object(
        self,
        gcs_hook: GCSHook,
        sftp_hook: SFTPHook,
        source_object: str,
        destination_path: str,
    ) -> None:
        """Helper function to copy single object."""
        self.log.info(
            "Executing copy of gs://%s/%s to %s",
            self.source_bucket,
            source_object,
            destination_path,
        )

        dir_path = os.path.dirname(destination_path)
        sftp_hook.create_directory(dir_path)

        with NamedTemporaryFile("w") as tmp:
            gcs_hook.download(
                bucket_name=self.source_bucket,
                object_name=source_object,
                filename=tmp.name,
            )
            sftp_hook.store_file(destination_path, tmp.name)

        if self.move_object:
            self.log.info("Executing delete of gs://%s/%s", self.source_bucket, source_object)
            gcs_hook.delete(self.source_bucket, source_object)
