# SPDX-License-Identifier: GPL-3.0-or-later
"""
Email service for Golf game authentication.

Provides email sending via Resend for verification, password reset, and notifications.
"""

import logging
from typing import Optional

from config import config

logger = logging.getLogger(__name__)


class EmailService:
    """
    Email service using Resend API.

    Handles all transactional emails for authentication:
    - Email verification
    - Password reset
    - Password changed notification
    """

    def __init__(self, api_key: str, from_address: str, base_url: str):
        """
        Initialize email service.

        Args:
            api_key: Resend API key.
            from_address: Sender email address.
            base_url: Base URL for verification/reset links.
        """
        self.api_key = api_key
        self.from_address = from_address
        self.base_url = base_url.rstrip("/")
        self._client = None

    @classmethod
    def create(cls) -> "EmailService":
        """Create EmailService from config."""
        return cls(
            api_key=config.RESEND_API_KEY,
            from_address=config.EMAIL_FROM,
            base_url=config.BASE_URL,
        )

    @property
    def client(self):
        """Lazy-load Resend client."""
        if self._client is None:
            try:
                import resend
                resend.api_key = self.api_key
                self._client = resend
            except ImportError:
                logger.warning("resend package not installed, emails will be logged only")
                self._client = None
        return self._client

    def is_configured(self) -> bool:
        """Check if email service is properly configured."""
        return bool(self.api_key)

    async def send_verification_email(
        self,
        to: str,
        token: str,
        username: str,
    ) -> Optional[str]:
        """
        Send email verification email.

        Args:
            to: Recipient email address.
            token: Verification token.
            username: User's display name.

        Returns:
            Resend message ID if sent, None if not configured.
        """
        if not self.is_configured():
            logger.info(f"Email not configured. Would send verification to {to}")
            return None

        verify_url = f"{self.base_url}/verify-email?token={token}"

        subject = "Verify your Golf Game account"
        html = f"""
        <h2>Welcome to Golf Game, {username}!</h2>
        <p>Please verify your email address by clicking the link below:</p>
        <p><a href="{verify_url}">Verify Email Address</a></p>
        <p>Or copy and paste this URL into your browser:</p>
        <p>{verify_url}</p>
        <p>This link will expire in 24 hours.</p>
        <p>If you didn't create this account, you can safely ignore this email.</p>
        """

        return await self._send_email(to, subject, html)

    async def send_password_reset_email(
        self,
        to: str,
        token: str,
        username: str,
    ) -> Optional[str]:
        """
        Send password reset email.

        Args:
            to: Recipient email address.
            token: Reset token.
            username: User's display name.

        Returns:
            Resend message ID if sent, None if not configured.
        """
        if not self.is_configured():
            logger.info(f"Email not configured. Would send password reset to {to}")
            return None

        reset_url = f"{self.base_url}/reset-password?token={token}"

        subject = "Reset your Golf Game password"
        html = f"""
        <h2>Password Reset Request</h2>
        <p>Hi {username},</p>
        <p>We received a request to reset your password. Click the link below to set a new password:</p>
        <p><a href="{reset_url}">Reset Password</a></p>
        <p>Or copy and paste this URL into your browser:</p>
        <p>{reset_url}</p>
        <p>This link will expire in 1 hour.</p>
        <p>If you didn't request this, you can safely ignore this email. Your password will remain unchanged.</p>
        """

        return await self._send_email(to, subject, html)

    async def send_password_changed_notification(
        self,
        to: str,
        username: str,
    ) -> Optional[str]:
        """
        Send password changed notification email.

        Args:
            to: Recipient email address.
            username: User's display name.

        Returns:
            Resend message ID if sent, None if not configured.
        """
        if not self.is_configured():
            logger.info(f"Email not configured. Would send password change notification to {to}")
            return None

        subject = "Your Golf Game password was changed"
        html = f"""
        <h2>Password Changed</h2>
        <p>Hi {username},</p>
        <p>Your password was successfully changed.</p>
        <p>If you did not make this change, please contact support immediately.</p>
        """

        return await self._send_email(to, subject, html)

    async def _send_email(
        self,
        to: str,
        subject: str,
        html: str,
    ) -> Optional[str]:
        """
        Send an email via Resend.

        Args:
            to: Recipient email address.
            subject: Email subject.
            html: HTML email body.

        Returns:
            Resend message ID if sent, None on error.
        """
        if not self.client:
            logger.warning(f"Resend not available. Email to {to}: {subject}")
            return None

        try:
            params = {
                "from": self.from_address,
                "to": [to],
                "subject": subject,
                "html": html,
            }

            response = self.client.Emails.send(params)
            message_id = response.get("id") if isinstance(response, dict) else getattr(response, "id", None)
            logger.info(f"Email sent to {to}: {message_id}")
            return message_id

        except Exception as e:
            logger.error(f"Failed to send email to {to}: {e}")
            return None


# Global email service instance
_email_service: Optional[EmailService] = None


def get_email_service() -> EmailService:
    """Get or create the global email service instance."""
    global _email_service
    if _email_service is None:
        _email_service = EmailService.create()
    return _email_service