import logging

from django.conf import settings
from django.core.mail import EmailMessage, get_connection

from infrasynth.shared.enums import ChannelType
from infrasynth.shared.results import Result
from infrasynth.shared.settings_utils import get_setting

from .base import BaseChannel

logger = logging.getLogger(__name__)


class SMTPChannel(BaseChannel):
    """Email channel that sends via a configurable SMTP backend.

    Configuration keys (read from ``ChannelConfig.config``):
    - ``host``, ``port``, ``username``, ``password``
    - ``use_tls``, ``use_ssl``, ``timeout``
    - ``backend`` (dotted path, defaults to Django's SMTP backend)
    - ``from_email`` (falls back to DEFAULT_FROM_EMAIL / INFRASYNTH_NOTIFICATIONS)
    """

    channel_type = ChannelType.EMAIL

    def __init__(
        self,
        host=None,
        port=None,
        username=None,
        password=None,
        use_tls=True,
        use_ssl=False,
        timeout=30,
        backend=None,
        from_email=None,
    ):
        self.host = host
        self.port = port or 587
        self.username = username
        self.password = password
        self.use_tls = use_tls
        self.use_ssl = use_ssl
        self.timeout = timeout
        self.backend = backend or "django.core.mail.backends.smtp.EmailBackend"
        self.from_email = (
            from_email
            or getattr(settings, "DEFAULT_FROM_EMAIL", None)
            or get_setting("INFRASYNTH_NOTIFICATIONS", "DEFAULT_FROM_EMAIL", "noreply@example.com")
        )

    @classmethod
    def from_config(cls, config: dict) -> "SMTPChannel":
        config = {str(key).lower(): value for key, value in (config or {}).items()}
        return cls(**config)

    def send(
        self,
        recipient: str,
        subject: str,
        body: str,
        is_html: bool = True,
        attachments=None,
    ) -> Result[bool, str]:
        if not self.host:
            return Result.err("SMTP host not configured")
        try:
            message = EmailMessage(
                subject=subject,
                body=body,
                from_email=self.from_email,
                to=[recipient],
                connection=self._get_connection(),
            )
            if is_html:
                message.content_subtype = "html"
            for attachment in attachments or []:
                message.attach(attachment.filename, attachment.content, attachment.mime_type)
            message.send()
        except Exception as exc:  # noqa: BLE001
            logger.exception("SMTP send failed for %s", recipient)
            return Result.err(str(exc))
        return Result.ok(True)

    def health_check(self) -> bool:
        return bool(self.host)

    def _get_connection(self):
        return get_connection(
            backend=self.backend,
            host=self.host or None,
            port=self.port,
            username=self.username or "",
            password=self.password or "",
            use_tls=self.use_tls,
            use_ssl=self.use_ssl,
            timeout=self.timeout,
        )