from collections.abc import Sequence
from typing import Any, ClassVar, TypeAlias

from django.core import mail
from django.template import loader

import mdformat
from markdownify import markdownify

Context: TypeAlias = dict[str, Any]


class EmailBase:
    subject: ClassVar[str]
    from_email: ClassVar[str | None] = None
    reply_to: ClassVar[Sequence[str] | None] = None

    context: Context

    def __init__(self, context: Context) -> None:
        self.context = context

    def render_body(self) -> str:
        raise NotImplementedError

    @classmethod
    def render(
        cls,
        context: Context,
        to: list[str] | None = None,
        cc: list[str] | None = None,
        bcc: list[str] | None = None,
    ) -> mail.EmailMessage:
        self = cls(context)

        body = self.render_body()

        return mail.EmailMessage(
            self.subject,
            body,
            from_email=self.from_email,
            reply_to=self.reply_to,
            to=to,
            cc=cc,
            bcc=bcc,
        )


class TemplatedMultipartEmail(EmailBase):
    template: ClassVar[str]

    def render_html_body(self) -> str:
        template = loader.get_template(self.template)
        return template.render(self.context)

    def render_body(self, html_body: str) -> str:
        return mdformat.text(markdownify(html_body), extensions={"tables"})

    @classmethod
    def render(
        cls,
        context: Context,
        to: list[str] | None = None,
        cc: list[str] | None = None,
        bcc: list[str] | None = None,
    ) -> mail.EmailMessage:
        self = cls(context)

        html_body = self.render_html_body()
        plain_body = self.render_body(html_body)

        return mail.EmailMultiAlternatives(
            self.subject,
            plain_body,
            from_email=self.from_email,
            reply_to=self.reply_to,
            to=to,
            cc=cc,
            bcc=bcc,
            alternatives=[(html_body, "text/html")],
        )