text: #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  """
  This module provides everything to be able to search in mails for a specific attachment
  and also to download it.
  It uses the imaplib library that is already integrated in python 3.
  """
  import email
  import imaplib
  import os
  import re
  from typing import Any, Iterable, List, Optional, Tuple, Type, Union
  
  from airflow.exceptions import AirflowException
  from airflow.hooks.base import BaseHook
  from airflow.models.connection import Connection
  from airflow.utils.log.logging_mixin import LoggingMixin
  
  
  class ImapHook(BaseHook):
      """
      This hook connects to a mail server by using the imap protocol.
  
      .. note:: Please call this Hook as context manager via `with`
          to automatically open and close the connection to the mail server.
  
      :param imap_conn_id: The :ref:`imap connection id <howto/connection:imap>`
          that contains the information used to authenticate the client.
      :type imap_conn_id: str
      """
  
      conn_name_attr = 'imap_conn_id'
      default_conn_name = 'imap_default'
      conn_type = 'imap'
      hook_name = 'IMAP'
  
      def __init__(self, imap_conn_id: str = default_conn_name) -> None:
          super().__init__()
          self.imap_conn_id = imap_conn_id
          self.mail_client: Optional[Union[imaplib.IMAP4_SSL, imaplib.IMAP4]] = None
  
      def __enter__(self) -> 'ImapHook':
          return self.get_conn()
  
      def __exit__(self, exc_type, exc_val, exc_tb):
          self.mail_client.logout()
  
      def get_conn(self) -> 'ImapHook':
          """
          Login to the mail server.
  
          .. note:: Please call this Hook as context manager via `with`
              to automatically open and close the connection to the mail server.
  
          :return: an authorized ImapHook object.
          :rtype: ImapHook
          """
          if not self.mail_client:
              conn = self.get_connection(self.imap_conn_id)
              self.mail_client = self._build_client(conn)
              self.mail_client.login(conn.login, conn.password)
  
          return self
  
      def _build_client(self, conn: Connection) -> Union[imaplib.IMAP4_SSL, imaplib.IMAP4]:
          IMAP: Union[Type[imaplib.IMAP4_SSL], Type[imaplib.IMAP4]]
          if conn.extra_dejson.get('use_ssl', True):
              IMAP = imaplib.IMAP4_SSL
          else:
              IMAP = imaplib.IMAP4
  
          if conn.port:
              mail_client = IMAP(conn.host, conn.port)
          else:
              mail_client = IMAP(conn.host)
  
          return mail_client
  
      def has_mail_attachment(
          self, name: str, *, check_regex: bool = False, mail_folder: str = 'INBOX', mail_filter: str = 'All'
      ) -> bool:
          """
          Checks the mail folder for mails containing attachments with the given name.
  
          :param name: The name of the attachment that will be searched for.
          :type name: str
          :param check_regex: Checks the name for a regular expression.
          :type check_regex: bool
          :param mail_folder: The mail folder where to look at.
          :type mail_folder: str
          :param mail_filter: If set other than 'All' only specific mails will be checked.
              See :py:meth:`imaplib.IMAP4.search` for details.
          :type mail_filter: str
          :returns: True if there is an attachment with the given name and False if not.
          :rtype: bool
          """
          mail_attachments = self._retrieve_mails_attachments_by_name(
              name, check_regex, True, mail_folder, mail_filter
          )
          return len(mail_attachments) > 0
  
      def retrieve_mail_attachments(
          self,
          name: str,
          *,
          check_regex: bool = False,
          latest_only: bool = False,
          mail_folder: str = 'INBOX',
          mail_filter: str = 'All',
          not_found_mode: str = 'raise',
      ) -> List[Tuple]:
          """
          Retrieves mail's attachments in the mail folder by its name.
  
          :param name: The name of the attachment that will be downloaded.
          :type name: str
          :param check_regex: Checks the name for a regular expression.
          :type check_regex: bool
          :param latest_only: If set to True it will only retrieve the first matched attachment.
          :type latest_only: bool
          :param mail_folder: The mail folder where to look at.
          :type mail_folder: str
          :param mail_filter: If set other than 'All' only specific mails will be checked.
              See :py:meth:`imaplib.IMAP4.search` for details.
          :type mail_filter: str
          :param not_found_mode: Specify what should happen if no attachment has been found.
              Supported values are 'raise', 'warn' and 'ignore'.
              If it is set to 'raise' it will raise an exception,
              if set to 'warn' it will only print a warning and
              if set to 'ignore' it won't notify you at all.
          :type not_found_mode: str
          :returns: a list of tuple each containing the attachment filename and its payload.
          :rtype: a list of tuple
          """
          mail_attachments = self._retrieve_mails_attachments_by_name(
              name, check_regex, latest_only, mail_folder, mail_filter
          )
  
          if not mail_attachments:
              self._handle_not_found_mode(not_found_mode)
  
          return mail_attachments
  
      def download_mail_attachments(
          self,
          name: str,
          local_output_directory: str,
          *,
          check_regex: bool = False,
          latest_only: bool = False,
          mail_folder: str = 'INBOX',
          mail_filter: str = 'All',
          not_found_mode: str = 'raise',
      ) -> None:
          """
          Downloads mail's attachments in the mail folder by its name to the local directory.
  
          :param name: The name of the attachment that will be downloaded.
          :type name: str
          :param local_output_directory: The output directory on the local machine
              where the files will be downloaded to.
          :type local_output_directory: str
          :param check_regex: Checks the name for a regular expression.
          :type check_regex: bool
          :param latest_only: If set to True it will only download the first matched attachment.
          :type latest_only: bool
          :param mail_folder: The mail folder where to look at.
          :type mail_folder: str
          :param mail_filter: If set other than 'All' only specific mails will be checked.
              See :py:meth:`imaplib.IMAP4.search` for details.
          :type mail_filter: str
          :param not_found_mode: Specify what should happen if no attachment has been found.
              Supported values are 'raise', 'warn' and 'ignore'.
              If it is set to 'raise' it will raise an exception,
              if set to 'warn' it will only print a warning and
              if set to 'ignore' it won't notify you at all.
          :type not_found_mode: str
          """
          mail_attachments = self._retrieve_mails_attachments_by_name(
              name, check_regex, latest_only, mail_folder, mail_filter
          )
  
          if not mail_attachments:
              self._handle_not_found_mode(not_found_mode)
  
          self._create_files(mail_attachments, local_output_directory)
  
      def _handle_not_found_mode(self, not_found_mode: str) -> None:
          if not_found_mode == 'raise':
              raise AirflowException('No mail attachments found!')
          if not_found_mode == 'warn':
              self.log.warning('No mail attachments found!')
          elif not_found_mode == 'ignore':
              pass  # Do not notify if the attachment has not been found.
          else:
              self.log.error('Invalid "not_found_mode" %s', not_found_mode)
  
      def _retrieve_mails_attachments_by_name(
          self, name: str, check_regex: bool, latest_only: bool, mail_folder: str, mail_filter: str
      ) -> List:
          if not self.mail_client:
              raise Exception("The 'mail_client' should be initialized before!")
  
          all_matching_attachments = []
  
          self.mail_client.select(mail_folder)
  
          for mail_id in self._list_mail_ids_desc(mail_filter):
              response_mail_body = self._fetch_mail_body(mail_id)
              matching_attachments = self._check_mail_body(response_mail_body, name, check_regex, latest_only)
  
              if matching_attachments:
                  all_matching_attachments.extend(matching_attachments)
                  if latest_only:
                      break
  
          self.mail_client.close()
  
          return all_matching_attachments
  
      def _list_mail_ids_desc(self, mail_filter: str) -> Iterable[str]:
          if not self.mail_client:
              raise Exception("The 'mail_client' should be initialized before!")
          _, data = self.mail_client.search(None, mail_filter)
          mail_ids = data[0].split()
          return reversed(mail_ids)
  
      def _fetch_mail_body(self, mail_id: str) -> str:
          if not self.mail_client:
              raise Exception("The 'mail_client' should be initialized before!")
          _, data = self.mail_client.fetch(mail_id, '(RFC822)')
          mail_body = data[0][1]  # type: ignore # The mail body is always in this specific location
          mail_body_str = mail_body.decode('utf-8')  # type: ignore
          return mail_body_str
  
      def _check_mail_body(
          self, response_mail_body: str, name: str, check_regex: bool, latest_only: bool
      ) -> List[Tuple[Any, Any]]:
          mail = Mail(response_mail_body)
          if mail.has_attachments():
              return mail.get_attachments_by_name(name, check_regex, find_first=latest_only)
          return []
  
      def _create_files(self, mail_attachments: List, local_output_directory: str) -> None:
          for name, payload in mail_attachments:
              if self._is_symlink(name):
                  self.log.error('Can not create file because it is a symlink!')
              elif self._is_escaping_current_directory(name):
                  self.log.error('Can not create file because it is escaping the current directory!')
              else:
                  self._create_file(name, payload, local_output_directory)
  
      def _is_symlink(self, name: str) -> bool:
          # IMPORTANT NOTE: os.path.islink is not working for windows symlinks
          # See: https://stackoverflow.com/a/11068434
          return os.path.islink(name)
  
      def _is_escaping_current_directory(self, name: str) -> bool:
          return '../' in name
  
      def _correct_path(self, name: str, local_output_directory: str) -> str:
          return (
              local_output_directory + name
              if local_output_directory.endswith('/')
              else local_output_directory + '/' + name
          )
  
      def _create_file(self, name: str, payload: Any, local_output_directory: str) -> None:
          file_path = self._correct_path(name, local_output_directory)
  
          with open(file_path, 'wb') as file:
              file.write(payload)
  
  
  class Mail(LoggingMixin):
      """
      This class simplifies working with mails returned by the imaplib client.
  
      :param mail_body: The mail body of a mail received from imaplib client.
      :type mail_body: str
      """
  
      def __init__(self, mail_body: str) -> None:
          super().__init__()
          self.mail = email.message_from_string(mail_body)
  
      def has_attachments(self) -> bool:
          """
          Checks the mail for a attachments.
  
          :returns: True if it has attachments and False if not.
          :rtype: bool
          """
          return self.mail.get_content_maintype() == 'multipart'
  
      def get_attachments_by_name(
          self, name: str, check_regex: bool, find_first: bool = False
      ) -> List[Tuple[Any, Any]]:
          """
          Gets all attachments by name for the mail.
  
          :param name: The name of the attachment to look for.
          :type name: str
          :param check_regex: Checks the name for a regular expression.
          :type check_regex: bool
          :param find_first: If set to True it will only find the first match and then quit.
          :type find_first: bool
          :returns: a list of tuples each containing name and payload
              where the attachments name matches the given name.
          :rtype: list(tuple)
          """
          attachments = []
  
          for attachment in self._iterate_attachments():
              found_attachment = (
                  attachment.has_matching_name(name) if check_regex else attachment.has_equal_name(name)
              )
              if found_attachment:
                  file_name, file_payload = attachment.get_file()
                  self.log.info('Found attachment: %s', file_name)
                  attachments.append((file_name, file_payload))
                  if find_first:
                      break
  
          return attachments
  
      def _iterate_attachments(self) -> Iterable['MailPart']:
          for part in self.mail.walk():
              mail_part = MailPart(part)
              if mail_part.is_attachment():
                  yield mail_part
  
  
  class MailPart:
      """
      This class is a wrapper for a Mail object's part and gives it more features.
  
      :param part: The mail part in a Mail object.
      :type part: any
      """
  
      def __init__(self, part: Any) -> None:
          self.part = part
  
      def is_attachment(self) -> bool:
          """
          Checks if the part is a valid mail attachment.
  
          :returns: True if it is an attachment and False if not.
          :rtype: bool
          """
          return self.part.get_content_maintype() != 'multipart' and self.part.get('Content-Disposition')
  
      def has_matching_name(self, name: str) -> Optional[Tuple[Any, Any]]:
          """
          Checks if the given name matches the part's name.
  
          :param name: The name to look for.
          :type name: str
          :returns: True if it matches the name (including regular expression).
          :rtype: tuple
          """
          return re.match(name, self.part.get_filename())  # type: ignore
  
      def has_equal_name(self, name: str) -> bool:
          """
          Checks if the given name is equal to the part's name.
  
          :param name: The name to look for.
          :type name: str
          :returns: True if it is equal to the given name.
          :rtype: bool
          """
          return self.part.get_filename() == name
  
      def get_file(self) -> Tuple:
          """
          Gets the file including name and payload.
  
          :returns: the part's name and payload.
          :rtype: tuple
          """
          return self.part.get_filename(), self.part.get_payload(decode=True)
  