from django.conf import settings
from django.core.mail import EmailMultiAlternatives, EmailMessage
from django.template.loader import render_to_string
import six
from django.utils import translation

# Define exception classes
# --------------------------------
class MailerInvalidBodyError(Exception):
    def __init__(self, value):
        self.value = value
    def __str__(self):
        return repr(self.value)

class MailerMissingSubjectError(Exception):
    def __init__(self, value=None):
        self.value = value
    def __str__(self):
        return repr(self.value if value else '')

def send_email_default(*args, **kwargs):
    send_email(args[3],args[0],args[1], from_email=args[2], category='django core email')

def send_email(recipients, subject, text_content=None, html_content=None, from_email=None, use_base_template=True, category=None, fail_silently=False, language=None, cc=None, bcc=None, attachments=None, headers=None, bypass_queue=False, bypass_hijacking=False, attach_files=None):
    """
    Will send a multi-format email to recipients. Email may be queued through celery
    """
    from django.conf import settings
    if not bypass_queue and hasattr(settings, 'MAILING_USE_CELERY') and settings.MAILING_USE_CELERY:
        from celery.execute import send_task
        return send_task('mailing.queue_send_email',[recipients, subject, text_content, html_content, from_email, use_base_template, category, fail_silently, language if language else translation.get_language(), cc, bcc, attachments, headers, bypass_hijacking, attach_files])
    else:

        header_category_value = '%s%s' % (settings.MAILING_HEADER_CATEGORY_PREFIX if hasattr(settings, 'MAILING_HEADER_CATEGORY_PREFIX') else '', category)
        # Check for sendgrid support and add category header
        # --------------------------------
        if hasattr(settings, 'MAILING_USE_SENDGRID'):
            send_grid_support = settings.MAILING_USE_SENDGRID
        else:
            send_grid_support = False

        if not headers:
            headers = dict()        
        if send_grid_support and category:
            headers['X-SMTPAPI'] = '{"category": "%s"}' % header_category_value

        # Check for Mailgun support and add label header
        # --------------------------------
        if hasattr(settings, 'MAILING_USE_MAILGUN'):
            mailgun_support = settings.MAILING_USE_MAILGUN
        else:
            mailgun_support = False

        if not headers:
            headers = dict()        
        if mailgun_support and category:
            headers['X-Mailgun-Tag'] = header_category_value


        # Ensure recipients are in a list
        # --------------------------------
        if isinstance(recipients, six.string_types):
            recipients_list = [recipients]
        else:
            recipients_list = recipients

        # Check if we need to hijack the email
        # --------------------------------
        if hasattr(settings, 'MAILING_MAILTO_HIJACK') and not bypass_hijacking:
            headers['X-MAILER-ORIGINAL-MAILTO'] = ','.join(recipients_list)
            recipients_list = [settings.MAILING_MAILTO_HIJACK]

        if not subject:
            raise MailerMissingSubjectError('Subject not supplied')

        # Send ascii, html or multi-part email
        # --------------------------------
        if text_content or html_content:
            if use_base_template:
                prev_language = translation.get_language()
                language and translation.activate(language)
                text_content = render_to_string('mailing/base.txt', {'mailing_text_body': text_content, 'mailing_subject': subject, 'settings': settings}) if text_content else None
                html_content = render_to_string('mailing/base.html', {'mailing_html_body': html_content, 'mailing_subject': subject, 'settings': settings}) if html_content else None
                translation.activate(prev_language)
            msg = EmailMultiAlternatives(subject, text_content if text_content else html_content, from_email if from_email else settings.DEFAULT_FROM_EMAIL, recipients_list, cc=cc, bcc=bcc, attachments=attachments, headers = headers)
            if html_content and text_content:
                msg.attach_alternative(html_content, "text/html")
            elif html_content: # Only HTML
                msg.content_subtype = "html"

            # Attach files through attach_files helper
            # --------------------------------
            if attach_files:
                for att in attach_files:  # attachments are tuples of (filepath, mimetype, filename)
                    with open(att[0], 'rb') as f:
                        content = f.read()
                    msg.attach(att[2], content, att[1])

            # Send email
            # --------------------------------

            msg.send(fail_silently=fail_silently)
        else:
            raise MailerInvalidBodyError('No text or html body supplied.')
