from itertools import groupby

from django.core import mail
from django.core.mail.message import sanitize_address
from django.contrib.auth import get_user_model
from django.template import loader

from markdownify import markdownify
import mdformat


def make_multipart_email(subject, html_body, to):
    plain_body = mdformat.text(markdownify(html_body), extensions={"tables"})

    email = mail.EmailMultiAlternatives(
        subject,
        plain_body,
        "Claremont MakerSpace Member Certification System <Certifications@ClaremontMakerSpace.org>",
        to,
        reply_to=["Claremont MakerSpace <Info@ClaremontMakerSpace.org>"],
    )

    email.attach_alternative(html_body, "text/html")
    return email


def make_department_email(department, certifications):
    template = loader.get_template("paperwork/email/department_certifications.dj.html")
    shop_leads = department.shop_lead_flag.members.values_list(
        "first_name", "account_name", "email", named=True
    )

    html_body = template.render(
        {
            "shop_lead_names": [shop_lead.first_name for shop_lead in shop_leads],
            "department": department,
            "certifications": certifications,
        }
    )

    return make_multipart_email(
        f"{len(certifications)} new CMS Certifications issued for {department}",
        html_body,
        to=[
            sanitize_address((shop_lead.account_name, shop_lead.email), "ascii")
            for shop_lead in shop_leads
        ],
    )


def department_emails(ordered_queryset):
    certifications_by_department = groupby(
        ordered_queryset, lambda c: c.certification_version.definition.department
    )

    for department, certifications in certifications_by_department:
        if department.shop_lead_flag is not None:
            yield make_department_email(department, list(certifications))


def make_member_email(member, certifications):
    template = loader.get_template("paperwork/email/member_certifications.dj.html")

    html_body = template.render({"member": member, "certifications": certifications})

    return make_multipart_email(
        f"You have been issued {len(certifications)} new CMS Certifications",
        html_body,
        to=[sanitize_address((member.account_name, member.email), "ascii")],
    )


def member_emails(ordered_queryset):
    certifications_by_member = groupby(
        ordered_queryset.filter(member__isnull=False), lambda c: c.member
    )

    for member, certifications in certifications_by_member:
        yield make_member_email(member, list(certifications))


def admin_email(ordered_queryset):
    template = loader.get_template("paperwork/email/admin_certifications.dj.html")
    html_body = template.render({"certifications": ordered_queryset})

    return make_multipart_email(
        f"{len(ordered_queryset)} new CMS Certifications issued",
        html_body,
        to=(
            get_user_model()
            .objects.with_perm(
                "paperwork.receive_certification_emails",
                include_superusers=False,
                # TODO: backend should not be hardcoded
                # TODO: LDAPBackend does not support with_perm() directly
                backend="django.contrib.auth.backends.ModelBackend",
            )
            .values_list("email", flat=True)
        ),
    )


def all_certification_emails(queryset):
    ordered_queryset = queryset.select_related(
        "certification_version__definition"
    ).order_by("certification_version__definition__department")

    yield from department_emails(ordered_queryset)
    yield from member_emails(ordered_queryset)
    yield admin_email(ordered_queryset)