import sys
from urllib.parse import urlparse

from django.core.mail import EmailMultiAlternatives
from django.template.loader import render_to_string
from django.template import Context


def send_email_template(template, context, to, email_from=None, html=None, attachments=[]):
    """
    Renders an email template with this format:
        {% if subject %}Subject{% endif %}
        {% if message %}Email body{% endif %}
    
    context can be a dictionary or a template.Context instance
    """
    
    if isinstance(context, dict):
        context = Context(context)
    if isinstance(to, str):
        to = [to]
    
    if not 'site' in context:
        from orchestra import settings
        url = urlparse(settings.ORCHESTRA_SITE_URL)
        context['site'] = {
            'name': settings.ORCHESTRA_SITE_NAME,
            'scheme': url.scheme,
            'domain': url.netloc,
        }
    
    #subject cannot have new lines
    subject = render_to_string(template, {'subject': True}, context).strip()
    message = render_to_string(template, {'message': True}, context)
    msg = EmailMultiAlternatives(subject, message, email_from, to, attachments=attachments)
    if html:
        html_message = render_to_string(html, {'message': True}, context)
        msg.attach_alternative(html_message, "text/html")
    msg.send()


def running_syncdb():
    return 'migrate' in sys.argv or 'syncdb' in sys.argv or 'makemigrations' in sys.argv


def database_ready():
    return (not running_syncdb() and
            'setuppostgres' not in sys.argv and
            'test' not in sys.argv and
            # Celerybeat has yet to stablish a connection at AppConf.ready()
            'celerybeat' not in sys.argv and
            # Allow to run python manage.py without a database
            sys.argv != ['manage.py'] and '--help' not in sys.argv)


def dict_setting_to_choices(choices):
    return sorted(
        [ (name, opt.get('verbose_name', 'name')) for name, opt in choices.items() ],
        key=lambda e: e[0]
    )


def tuple_setting_to_choices(choices):
    return sorted(
        tuple((name, opt[0]) for name, opt in choices.items()),
        key=lambda e: e[0]
    )