from django.conf import settings
from django.core.mail import EmailMultiAlternatives
from django.template import loader, TemplateDoesNotExist
from django.utils.timezone import now as timezone_now
from zerver.models import UserProfile, ScheduledJob, get_user_profile_by_email

import datetime
from email.utils import parseaddr
import ujson

from typing import Any, Dict, Iterable, List, Mapping, Optional, Text

def display_email(user):
    # type: (UserProfile) -> Text
    # Change to '%s <%s>' % (user.full_name, user.email) once
    # https://github.com/zulip/zulip/issues/4676 is resolved
    return user.email

def send_email(template_prefix, to_email, from_email=None, reply_to_email=None, context={}):
    # type: (str, Text, Optional[Text], Optional[Text], Dict[str, Any]) -> bool
    subject = loader.render_to_string(template_prefix + '.subject', context).strip()
    message = loader.render_to_string(template_prefix + '.txt', context)
    # Remove try/expect once https://github.com/zulip/zulip/issues/4691 is resolved.
    try:
        html_message = loader.render_to_string(template_prefix + '.html', context)
    except TemplateDoesNotExist:
        html_message = None
    if from_email is None:
        from_email = settings.NOREPLY_EMAIL_ADDRESS
    reply_to = None
    if reply_to_email is not None:
        reply_to = [reply_to_email]

    mail = EmailMultiAlternatives(subject, message, from_email, [to_email], reply_to=reply_to)
    if html_message is not None:
        mail.attach_alternative(html_message, 'text/html')
    return mail.send() > 0

def send_email_to_user(template_prefix, user, from_email=None, context={}):
    # type: (str, UserProfile, Optional[Text], Dict[str, Text]) -> bool
    return send_email(template_prefix, display_email(user), from_email=from_email, context=context)

# Returns None instead of bool so that the type signature matches the third
# argument of zerver.lib.queue.queue_json_publish
def send_email_from_dict(email_dict):
    # type: (Mapping[str, Any]) -> None
    send_email(**dict(email_dict))

def send_future_email(template_prefix, to_email, from_email=None, context={},
                      delay=datetime.timedelta(0)):
    # type: (str, Text, Optional[Text], Dict[str, Any], datetime.timedelta) -> None
    email_fields = {'template_prefix': template_prefix, 'to_email': to_email, 'from_email': from_email,
                    'context': context}
    ScheduledJob.objects.create(type=ScheduledJob.EMAIL, filter_string=parseaddr(to_email)[1],
                                data=ujson.dumps(email_fields),
                                scheduled_timestamp=timezone_now() + delay)