text: import datetime
  import hashlib
  import logging
  import os
  from email.headerregistry import Address
  from email.parser import Parser
  from email.policy import default
  from email.utils import formataddr, parseaddr
  from typing import Any, Dict, List, Mapping, Optional, Tuple
  
  import orjson
  from django.conf import settings
  from django.core.mail import EmailMultiAlternatives
  from django.core.mail.message import sanitize_address
  from django.core.management import CommandError
  from django.db import transaction
  from django.template import loader
  from django.template.exceptions import TemplateDoesNotExist
  from django.utils.timezone import now as timezone_now
  from django.utils.translation import override as override_language
  from django.utils.translation import ugettext as _
  
  from confirmation.models import generate_key
  from scripts.setup.inline_email_css import inline_template
  from zerver.lib.logging_util import log_to_file
  from zerver.models import EMAIL_TYPES, Realm, ScheduledEmail, UserProfile, get_user_profile_by_id
  
  ## Logging setup ##
  
  logger = logging.getLogger("zulip.send_email")
  log_to_file(logger, settings.EMAIL_LOG_PATH)
  
  
  class FromAddress:
      SUPPORT = parseaddr(settings.ZULIP_ADMINISTRATOR)[1]
      NOREPLY = parseaddr(settings.NOREPLY_EMAIL_ADDRESS)[1]
  
      support_placeholder = "SUPPORT"
      no_reply_placeholder = "NO_REPLY"
      tokenized_no_reply_placeholder = "TOKENIZED_NO_REPLY"
  
      # Generates an unpredictable noreply address.
      @staticmethod
      def tokenized_no_reply_address() -> str:
          if settings.ADD_TOKENS_TO_NOREPLY_ADDRESS:
              return parseaddr(settings.TOKENIZED_NOREPLY_EMAIL_ADDRESS)[1].format(
                  token=generate_key()
              )
          return FromAddress.NOREPLY
  
      @staticmethod
      def security_email_from_name(
          language: Optional[str] = None, user_profile: Optional[UserProfile] = None
      ) -> str:
          if language is None:
              assert user_profile is not None
              language = user_profile.default_language
  
          with override_language(language):
              return _("Zulip Account Security")
  
  
  def build_email(
      template_prefix: str,
      to_user_ids: Optional[List[int]] = None,
      to_emails: Optional[List[str]] = None,
      from_name: Optional[str] = None,
      from_address: Optional[str] = None,
      reply_to_email: Optional[str] = None,
      language: Optional[str] = None,
      context: Mapping[str, Any] = {},
      realm: Optional[Realm] = None,
  ) -> EmailMultiAlternatives:
      # Callers should pass exactly one of to_user_id and to_email.
      assert (to_user_ids is None) ^ (to_emails is None)
      if to_user_ids is not None:
          to_users = [get_user_profile_by_id(to_user_id) for to_user_id in to_user_ids]
          if realm is None:
              assert len({to_user.realm_id for to_user in to_users}) == 1
              realm = to_users[0].realm
          to_emails = [
              str(Address(display_name=to_user.full_name, addr_spec=to_user.delivery_email))
              for to_user in to_users
          ]
  
      extra_headers = {}
      if realm is not None:
          # formaddr is meant for formatting (display_name, email_address) pair for headers like "To",
          # but we can use its utility for formatting the List-Id header, as it follows the same format,
          # except having just a domain instead of an email address.
          extra_headers["List-Id"] = formataddr((realm.name, realm.host))
  
      context = {
          **context,
          "support_email": FromAddress.SUPPORT,
          "email_images_base_uri": settings.ROOT_DOMAIN_URI + "/static/images/emails",
          "physical_address": settings.PHYSICAL_ADDRESS,
      }
  
      def render_templates() -> Tuple[str, str, str]:
          email_subject = (
              loader.render_to_string(
                  template_prefix + ".subject.txt", context=context, using="Jinja2_plaintext"
              )
              .strip()
              .replace("\n", "")
          )
          message = loader.render_to_string(
              template_prefix + ".txt", context=context, using="Jinja2_plaintext"
          )
  
          try:
              html_message = loader.render_to_string(template_prefix + ".html", context)
          except TemplateDoesNotExist:
              emails_dir = os.path.dirname(template_prefix)
              template = os.path.basename(template_prefix)
              compiled_template_prefix = os.path.join(emails_dir, "compiled", template)
              html_message = loader.render_to_string(compiled_template_prefix + ".html", context)
          return (html_message, message, email_subject)
  
      # The i18n story for emails is a bit complicated.  For emails
      # going to a single user, we want to use the language that user
      # has configured for their Zulip account.  For emails going to
      # multiple users or to email addresses without a known Zulip
      # account (E.g. invitations), we want to use the default language
      # configured for the Zulip organization.
      #
      # See our i18n documentation for some high-level details:
      # https://zulip.readthedocs.io/en/latest/translating/internationalization.html
  
      if not language and to_user_ids is not None:
          language = to_users[0].default_language
      if language:
          with override_language(language):
              # Make sure that we render the email using the target's native language
              (html_message, message, email_subject) = render_templates()
      else:
          (html_message, message, email_subject) = render_templates()
          logger.warning("Missing language for email template '%s'", template_prefix)
  
      if from_name is None:
          from_name = "Zulip"
      if from_address is None:
          from_address = FromAddress.NOREPLY
      if from_address == FromAddress.tokenized_no_reply_placeholder:
          from_address = FromAddress.tokenized_no_reply_address()
      if from_address == FromAddress.no_reply_placeholder:
          from_address = FromAddress.NOREPLY
      if from_address == FromAddress.support_placeholder:
          from_address = FromAddress.SUPPORT
  
      # Set the "From" that is displayed separately from the envelope-from.
      extra_headers["From"] = str(Address(display_name=from_name, addr_spec=from_address))
      # Check ASCII encoding length.  Amazon SES rejects emails with
      # From names longer than 320 characters (which appears to be a
      # misinterpretation of the RFC); in that case we drop the name
      # from the From line, under the theory that it's better to send
      # the email with a simplified From field than not.
      if len(sanitize_address(extra_headers["From"], "utf-8")) > 320:
          extra_headers["From"] = str(Address(addr_spec=from_address))
  
      reply_to = None
      if reply_to_email is not None:
          reply_to = [reply_to_email]
      # Remove the from_name in the reply-to for noreply emails, so that users
      # see "noreply@..." rather than "Zulip" or whatever the from_name is
      # when they reply in their email client.
      elif from_address == FromAddress.NOREPLY:
          reply_to = [FromAddress.NOREPLY]
  
      envelope_from = FromAddress.NOREPLY
      mail = EmailMultiAlternatives(
          email_subject, message, envelope_from, to_emails, reply_to=reply_to, headers=extra_headers
      )
      if html_message is not None:
          mail.attach_alternative(html_message, "text/html")
      return mail
  
  
  class EmailNotDeliveredException(Exception):
      pass
  
  
  class DoubledEmailArgumentException(CommandError):
      def __init__(self, argument_name: str) -> None:
          msg = (
              f"Argument '{argument_name}' is ambiguously present in both options and email template."
          )
          super().__init__(msg)
  
  
  class NoEmailArgumentException(CommandError):
      def __init__(self, argument_name: str) -> None:
          msg = f"Argument '{argument_name}' is required in either options or email template."
          super().__init__(msg)
  
  
  # When changing the arguments to this function, you may need to write a
  # migration to change or remove any emails in ScheduledEmail.
  def send_email(
      template_prefix: str,
      to_user_ids: Optional[List[int]] = None,
      to_emails: Optional[List[str]] = None,
      from_name: Optional[str] = None,
      from_address: Optional[str] = None,
      reply_to_email: Optional[str] = None,
      language: Optional[str] = None,
      context: Dict[str, Any] = {},
      realm: Optional[Realm] = None,
  ) -> None:
      mail = build_email(
          template_prefix,
          to_user_ids=to_user_ids,
          to_emails=to_emails,
          from_name=from_name,
          from_address=from_address,
          reply_to_email=reply_to_email,
          language=language,
          context=context,
          realm=realm,
      )
      template = template_prefix.split("/")[-1]
      logger.info("Sending %s email to %s", template, mail.to)
  
      if mail.send() == 0:
          logger.error("Error sending %s email to %s", template, mail.to)
          raise EmailNotDeliveredException
  
  
  def send_email_from_dict(email_dict: Mapping[str, Any]) -> None:
      send_email(**dict(email_dict))
  
  
  def send_future_email(
      template_prefix: str,
      realm: Realm,
      to_user_ids: Optional[List[int]] = None,
      to_emails: Optional[List[str]] = None,
      from_name: Optional[str] = None,
      from_address: Optional[str] = None,
      language: Optional[str] = None,
      context: Dict[str, Any] = {},
      delay: datetime.timedelta = datetime.timedelta(0),
  ) -> None:
      template_name = template_prefix.split("/")[-1]
      email_fields = {
          "template_prefix": template_prefix,
          "from_name": from_name,
          "from_address": from_address,
          "language": language,
          "context": context,
      }
  
      if settings.DEVELOPMENT_LOG_EMAILS:
          send_email(
              template_prefix,
              to_user_ids=to_user_ids,
              to_emails=to_emails,
              from_name=from_name,
              from_address=from_address,
              language=language,
              context=context,
          )
          # For logging the email
  
      assert (to_user_ids is None) ^ (to_emails is None)
      email = ScheduledEmail.objects.create(
          type=EMAIL_TYPES[template_name],
          scheduled_timestamp=timezone_now() + delay,
          realm=realm,
          data=orjson.dumps(email_fields).decode(),
      )
  
      # We store the recipients in the ScheduledEmail object itself,
      # rather than the JSON data object, so that we can find and clear
      # them using clear_scheduled_emails.
      try:
          if to_user_ids is not None:
              email.users.add(*to_user_ids)
          else:
              assert to_emails is not None
              assert len(to_emails) == 1
              email.address = parseaddr(to_emails[0])[1]
          email.save()
      except Exception as e:
          email.delete()
          raise e
  
  
  def send_email_to_admins(
      template_prefix: str,
      realm: Realm,
      from_name: Optional[str] = None,
      from_address: Optional[str] = None,
      language: Optional[str] = None,
      context: Dict[str, Any] = {},
  ) -> None:
      admins = realm.get_human_admin_users()
      admin_user_ids = [admin.id for admin in admins]
      send_email(
          template_prefix,
          to_user_ids=admin_user_ids,
          from_name=from_name,
          from_address=from_address,
          language=language,
          context=context,
      )
  
  
  def clear_scheduled_invitation_emails(email: str) -> None:
      """Unlike most scheduled emails, invitation emails don't have an
      existing user object to key off of, so we filter by address here."""
      items = ScheduledEmail.objects.filter(
          address__iexact=email, type=ScheduledEmail.INVITATION_REMINDER
      )
      items.delete()
  
  
  @transaction.atomic(savepoint=False)
  def clear_scheduled_emails(user_ids: List[int], email_type: Optional[int] = None) -> None:
      # We need to obtain a FOR UPDATE lock on the selected rows to keep a concurrent
      # execution of this function (or something else) from deleting them before we access
      # the .users attribute.
      items = ScheduledEmail.objects.filter(users__in=user_ids).select_for_update()
      if email_type is not None:
          items = items.filter(type=email_type)
  
      deduplicated_items = {}
      for item in items:
          deduplicated_items[item.id] = item
      for item in deduplicated_items.values():
          # Now we want a FOR UPDATE lock on the item.users rows
          # to prevent a concurrent transaction from mutating them
          # simultaneously.
          item.users.all().select_for_update()
          item.users.remove(*user_ids)
          if item.users.all().count() == 0:
              # Due to our transaction holding the row lock we have a guarantee
              # that the obtained COUNT is accurate, thus we can reliably use it
              # to decide whether to delete the ScheduledEmail row.
              item.delete()
  
  
  def handle_send_email_format_changes(job: Dict[str, Any]) -> None:
      # Reformat any jobs that used the old to_email
      # and to_user_ids argument formats.
      if "to_email" in job:
          if job["to_email"] is not None:
              job["to_emails"] = [job["to_email"]]
          del job["to_email"]
      if "to_user_id" in job:
          if job["to_user_id"] is not None:
              job["to_user_ids"] = [job["to_user_id"]]
          del job["to_user_id"]
  
  
  def deliver_email(email: ScheduledEmail) -> None:
      data = orjson.loads(email.data)
      user_ids = list(email.users.values_list("id", flat=True))
      if not user_ids and not email.address:
          # This state doesn't make sense, so something must be mutating,
          # or in the process of deleting, the object. We assume it will bring
          # things to a correct state, and we just do nothing except logging this event.
          logger.warning("ScheduledEmail id %s has empty users and address attributes.", email.id)
          return
  
      if user_ids:
          data["to_user_ids"] = user_ids
      if email.address is not None:
          data["to_emails"] = [email.address]
      handle_send_email_format_changes(data)
      send_email(**data)
      email.delete()
  
  
  def get_header(option: Optional[str], header: Optional[str], name: str) -> str:
      if option and header:
          raise DoubledEmailArgumentException(name)
      if not option and not header:
          raise NoEmailArgumentException(name)
      return str(option or header)
  
  
  def send_custom_email(users: List[UserProfile], options: Dict[str, Any]) -> None:
      """
      Can be used directly with from a management shell with
      send_custom_email(user_profile_list, dict(
          markdown_template_path="/path/to/markdown/file.md",
          subject="Email Subject",
          from_name="Sender Name")
      )
      """
  
      with open(options["markdown_template_path"]) as f:
          text = f.read()
          parsed_email_template = Parser(policy=default).parsestr(text)
          email_template_hash = hashlib.sha256(text.encode("utf-8")).hexdigest()[0:32]
  
      email_filename = f"custom/custom_email_{email_template_hash}.source.html"
      email_id = f"zerver/emails/custom/custom_email_{email_template_hash}"
      markdown_email_base_template_path = "templates/zerver/emails/custom_email_base.pre.html"
      html_source_template_path = f"templates/{email_id}.source.html"
      plain_text_template_path = f"templates/{email_id}.txt"
      subject_path = f"templates/{email_id}.subject.txt"
      os.makedirs(os.path.dirname(html_source_template_path), exist_ok=True)
  
      # First, we render the Markdown input file just like our
      # user-facing docs with render_markdown_path.
      with open(plain_text_template_path, "w") as f:
          f.write(parsed_email_template.get_payload())
  
      from zerver.templatetags.app_filters import render_markdown_path
  
      rendered_input = render_markdown_path(plain_text_template_path.replace("templates/", ""))
  
      # And then extend it with our standard email headers.
      with open(html_source_template_path, "w") as f:
          with open(markdown_email_base_template_path) as base_template:
              # Note that we're doing a hacky non-Jinja2 substitution here;
              # we do this because the normal render_markdown_path ordering
              # doesn't commute properly with inline_email_css.
              f.write(base_template.read().replace("{{ rendered_input }}", rendered_input))
  
      with open(subject_path, "w") as f:
          f.write(get_header(options.get("subject"), parsed_email_template.get("subject"), "subject"))
  
      inline_template(email_filename)
  
      # Finally, we send the actual emails.
      for user_profile in users:
          if options.get("admins_only") and not user_profile.is_realm_admin:
              continue
          context = {
              "realm_uri": user_profile.realm.uri,
              "realm_name": user_profile.realm.name,
          }
          send_email(
              email_id,
              to_user_ids=[user_profile.id],
              from_address=FromAddress.SUPPORT,
              reply_to_email=options.get("reply_to"),
              from_name=get_header(
                  options.get("from_name"), parsed_email_template.get("from"), "from_name"
              ),
              context=context,
          )
  