"""Email notification functionality."""

import logging
import smtplib

from . import datetime_str
from email.mime.text import MIMEText
from email.utils import formatdate
from jinja2 import Environment, BaseLoader


def load_template(path):
    """
    Load template from file.

    Args:
        path: Path to template.
    Returns:
        Template if path was not None, None otherwise.
    """
    if path is None:
        return

    with open(path) as fh:
        data = fh.read()

    return Environment(
        loader=BaseLoader(),
        trim_blocks=True
    ).from_string(data)


class EmailService:
    """Email service for sending notifications."""

    def __init__(self, config):
        """
        Initialize email service.

        Args:
            config: Application configuration dictionary.
        """
        self.config = config.get("email", {})
        self.enabled = self.config.get("enabled", False)

        self.change_template = load_template(self.config.get("change_notification_template", None))
        self.expiry_template = load_template(self.config.get("expiry_notification_template", None))

        if not self.change_template and not self.expiry_template and self.enabled:
            logging.warning("No templates configured, disabling Email")
            self.enabled = False

    def send(self, to, subject, body):
        """
        Send email using configured SMTP server.

        Args:
            to: Recipient email address.
            subject: Email subject.
            body: Email body text.

        Returns:
            True if sent successfully, False otherwise.
        """
        if not self.enabled:
            logging.debug("Email disabled, skipping")
            return False

        try:
            msg = MIMEText(body)
            msg["Subject"] = subject
            msg["From"] = self.config["from_address"]
            msg["To"] = to
            msg["Date"] = formatdate(localtime=True)

            smtp_host = self.config["smtp_host"]
            smtp_port = self.config["smtp_port"]

            with smtplib.SMTP(smtp_host, smtp_port) as server:
                if self.config.get("smtp_starttls", False):
                    server.starttls()

                if self.config.get("smtp_user"):
                    server.login(
                        self.config["smtp_user"],
                        self.config["smtp_password"]
                    )
                server.sendmail(msg["From"], [to], msg.as_string())
                logging.info(f"Email sent: to={to} subject={subject}")
                return True

        except Exception as e:
            logging.error(f"Email send failed: to={to} error={e}")
            return False

    def send_change_notification(
        self,
        email,
        hostname,
        ipv4_changed,
        ipv6_changed
    ):
        """
        Send hostname changed notification email.

        Args:
            email: Recipient email.
            hostname: Changed hostname.
            ipv4_changed: Wheter IPv4 address changed.
            ipv6_changed: Wheter IPv6 address changed.

        Returns:
            True if sent successfully.
        """
        if not self.enabled:
            logging.debug("Email disabled, skipping")
            return False

        if not self.change_template:
            logging.debug("No change notification template configured, skipping")
            return False

        fqdn = f"{hostname.hostname}.{hostname.zone}"
        template_variables = {
            "hostname": hostname.hostname,
            "zone": hostname.zone,
            "fqdn": fqdn,
            "ipv4_changed": ipv4_changed,
            "ipv4": hostname.last_ipv4,
            "last_ipv4_update": datetime_str(hostname.last_ipv4_update),
            "ipv6_changed": ipv6_changed,
            "ipv6": hostname.last_ipv6,
            "last_ipv6_update": datetime_str(hostname.last_ipv6_update),
            "expiry_ttl": hostname.expiry_ttl,
        }

        subject = f"DDNS hostname changed: {fqdn}"
        body = self.change_template.render(**template_variables)

        return self.send(email, subject, body)

    def send_expiry_notification(
        self,
        email,
        hostname,
        ipv4_expired,
        ipv6_expired
    ):
        """
        Send hostname expiry notification email.

        Args:
            email: Recipient email.
            hostname: Expired hostname.
            ipv4_expired: Wheter IPv4 address expired.
            ipv6_expired: Wheter IPv6 address expired.

        Returns:
            True if sent successfully.
        """
        if not self.enabled:
            logging.debug("Email disabled, skipping")
            return False

        if not self.expiry_template:
            logging.debug("No expiry notification template configured, skipping")
            return False

        fqdn = f"{hostname.hostname}.{hostname.zone}"
        template_variables = {
            "hostname": hostname.hostname,
            "zone": hostname.zone,
            "fqdn": fqdn,
            "ipv4_expired": ipv4_expired,
            "last_ipv4": hostname.last_ipv4,
            "last_ipv4_update": datetime_str(hostname.last_ipv4_update),
            "ipv6_expired": ipv6_expired,
            "last_ipv6": hostname.last_ipv6,
            "last_ipv6_update": datetime_str(hostname.last_ipv6_update),
            "expiry_ttl": hostname.expiry_ttl,
        }

        subject = f"DDNS hostname expired: {fqdn}"
        body = self.expiry_template.render(**template_variables)

        return self.send(email, subject, body)