"""
Norda Biznes - Email Service
=============================

Sends emails via Microsoft Graph API using Application permissions.
Based on mtbtracker implementation.

Author: Norda Biznes Development Team
Created: 2025-12-25
"""

import os
import logging
from typing import Optional, List
from dotenv import load_dotenv

# Load .env file for environment variables
load_dotenv()

logger = logging.getLogger(__name__)

# Check if msal is available
try:
    import msal
    import requests
    MSAL_AVAILABLE = True
except ImportError:
    MSAL_AVAILABLE = False
    logger.warning("msal package not installed. Email service will be disabled.")


class EmailService:
    """Service for sending emails via Microsoft Graph API"""

    def __init__(self, tenant_id: str, client_id: str, client_secret: str, mail_from: str):
        """
        Initialize Email Service

        Args:
            tenant_id: Azure AD Tenant ID
            client_id: Application (client) ID
            client_secret: Client secret value
            mail_from: Default sender email address (e.g., noreply@inpi.pl)
        """
        self.tenant_id = tenant_id
        self.client_id = client_id
        self.client_secret = client_secret
        self.mail_from = mail_from
        self.authority = f"https://login.microsoftonline.com/{tenant_id}"
        self.scope = ["https://graph.microsoft.com/.default"]
        self.graph_endpoint = "https://graph.microsoft.com/v1.0"

    def _get_access_token(self) -> Optional[str]:
        """
        Acquire access token using client credentials flow

        Returns:
            Access token string or None if failed
        """
        if not MSAL_AVAILABLE:
            logger.error("msal package not available")
            return None

        try:
            app = msal.ConfidentialClientApplication(
                self.client_id,
                authority=self.authority,
                client_credential=self.client_secret,
            )

            result = app.acquire_token_silent(self.scope, account=None)

            if not result:
                logger.info("No token in cache, acquiring new token")
                result = app.acquire_token_for_client(scopes=self.scope)

            if "access_token" in result:
                return result["access_token"]
            else:
                logger.error(f"Failed to acquire token: {result.get('error')}: {result.get('error_description')}")
                return None

        except Exception as e:
            logger.error(f"Exception during token acquisition: {e}", exc_info=True)
            return None

    def send_mail(
        self,
        to: List[str],
        subject: str,
        body_text: str,
        body_html: Optional[str] = None,
        from_address: Optional[str] = None
    ) -> bool:
        """
        Send email via Microsoft Graph API

        Args:
            to: List of recipient email addresses
            subject: Email subject
            body_text: Plain text email body
            body_html: HTML email body (optional)
            from_address: Sender email (optional, defaults to configured mail_from)

        Returns:
            True if sent successfully, False otherwise
        """
        if not MSAL_AVAILABLE:
            logger.error("msal package not available - cannot send email")
            return False

        try:
            # Get access token
            token = self._get_access_token()
            if not token:
                logger.error("Failed to acquire access token")
                return False

            # Use default sender if not specified
            sender = from_address or self.mail_from

            # Prepare recipients
            recipients = [{"emailAddress": {"address": email}} for email in to]

            # Prepare message body
            if body_html:
                content_type = "HTML"
                content = body_html
            else:
                content_type = "Text"
                content = body_text

            # Build email message
            # Display name for sender - shown in email clients
            sender_display_name = "Norda Biznes Partner"

            email_msg = {
                "message": {
                    "subject": subject,
                    "body": {
                        "contentType": content_type,
                        "content": content
                    },
                    "toRecipients": recipients,
                    "from": {
                        "emailAddress": {
                            "address": sender,
                            "name": sender_display_name
                        }
                    }
                },
                "saveToSentItems": "false"
            }

            # Send email via Graph API
            url = f"{self.graph_endpoint}/users/{sender}/sendMail"
            headers = {
                "Authorization": f"Bearer {token}",
                "Content-Type": "application/json"
            }

            response = requests.post(url, headers=headers, json=email_msg, timeout=30)

            if response.status_code == 202:
                logger.info(f"Email sent successfully to {to}")
                return True
            else:
                logger.error(f"Failed to send email. Status: {response.status_code}, Response: {response.text}")
                return False

        except Exception as e:
            logger.error(f"Exception during email sending: {e}", exc_info=True)
            return False


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


def init_email_service():
    """
    Initialize the global Email Service instance from environment variables

    Required env vars:
        AZURE_TENANT_ID: Azure AD Tenant ID
        AZURE_CLIENT_ID: Application (client) ID
        AZURE_CLIENT_SECRET: Client secret value
        MAIL_FROM: Default sender email address
    """
    global _email_service

    tenant_id = os.getenv('AZURE_TENANT_ID')
    client_id = os.getenv('AZURE_CLIENT_ID')
    client_secret = os.getenv('AZURE_CLIENT_SECRET')
    mail_from = os.getenv('MAIL_FROM', 'noreply@inpi.pl')

    if tenant_id and client_id and client_secret:
        _email_service = EmailService(tenant_id, client_id, client_secret, mail_from)
        logger.info(f"Email Service initialized with sender: {mail_from}")
        return True
    else:
        logger.warning("Email Service not configured - missing Azure credentials")
        return False


def send_email(
    to: List[str],
    subject: str,
    body_text: str,
    body_html: Optional[str] = None,
    from_address: Optional[str] = None,
    email_type: str = 'notification',
    user_id: Optional[int] = None,
    recipient_name: Optional[str] = None
) -> bool:
    """
    Send email using the global Email Service instance

    Args:
        to: List of recipient email addresses (can be single email as list)
        subject: Email subject
        body_text: Plain text email body
        body_html: HTML email body (optional)
        from_address: Sender email (optional)
        email_type: Type of email for logging (welcome, password_reset, notification)
        user_id: User ID for logging (optional)
        recipient_name: Recipient name for logging (optional)

    Returns:
        True if sent successfully, False otherwise
    """
    if not _email_service:
        logger.error("Email Service not initialized. Call init_email_service() first.")
        return False

    # Convert single email to list if needed
    if isinstance(to, str):
        to = [to]

    result = _email_service.send_mail(to, subject, body_text, body_html, from_address)

    # Log email to database
    _log_email(
        email_type=email_type,
        recipient_emails=to,
        recipient_name=recipient_name,
        subject=subject,
        user_id=user_id,
        sender_email=from_address or _email_service.mail_from if _email_service else None,
        success=result
    )

    return result


def _log_email(
    email_type: str,
    recipient_emails: List[str],
    subject: str,
    success: bool,
    recipient_name: Optional[str] = None,
    user_id: Optional[int] = None,
    sender_email: Optional[str] = None,
    error_message: Optional[str] = None
) -> None:
    """
    Log email to database for monitoring.

    Args:
        email_type: Type of email (welcome, password_reset, notification)
        recipient_emails: List of recipient email addresses
        subject: Email subject
        success: Whether email was sent successfully
        recipient_name: Recipient name (optional)
        user_id: User ID (optional)
        sender_email: Sender email address (optional)
        error_message: Error message if failed (optional)
    """
    try:
        from database import SessionLocal, EmailLog
        from datetime import datetime

        db = SessionLocal()
        try:
            for email in recipient_emails:
                log_entry = EmailLog(
                    email_type=email_type,
                    recipient_email=email,
                    recipient_name=recipient_name,
                    subject=subject,
                    user_id=user_id,
                    sender_email=sender_email,
                    status='sent' if success else 'failed',
                    sent_at=datetime.utcnow() if success else None,
                    error_message=error_message if not success else None
                )
                db.add(log_entry)
            db.commit()
            logger.info(f"Email logged: {email_type} -> {recipient_emails} (status: {'sent' if success else 'failed'})")
        except Exception as e:
            db.rollback()
            logger.error(f"Failed to log email to database: {e}")
        finally:
            db.close()
    except ImportError:
        # Database not available (e.g., during testing)
        logger.warning("Could not log email - database module not available")


def is_configured() -> bool:
    """
    Check if Email Service is configured and ready

    Returns:
        True if service is initialized, False otherwise
    """
    return _email_service is not None


# Auto-initialize on module load
init_email_service()


# ============================================================
# EMAIL TEMPLATES
# ============================================================

def send_password_reset_email(email: str, reset_url: str) -> bool:
    """
    Send password reset email

    Args:
        email: Recipient email address
        reset_url: Password reset URL with token

    Returns:
        True if sent successfully, False otherwise
    """
    subject = "Reset hasła - Norda Biznes Partner"

    body_text = f"""Otrzymałeś ten email, ponieważ zażądano resetowania hasła dla Twojego konta Norda Biznes Partner.

Aby zresetować hasło, kliknij w poniższy link:
{reset_url}

Link będzie ważny przez 1 godzinę.

Jeśli nie zażądałeś resetowania hasła, zignoruj ten email.

---
Norda Biznes Partner - Platforma Networkingu Regionalnej Izby Przedsiębiorców
https://nordabiznes.pl
"""

    body_html = f"""
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <style>
        body {{ font-family: 'Inter', Arial, sans-serif; line-height: 1.6; color: #1e293b; }}
        .container {{ max-width: 600px; margin: 0 auto; padding: 20px; background: #f8fafc; }}
        .header {{ background-color: #1e3a8a; background: linear-gradient(135deg, #1e40af, #1e3a8a); color: white; padding: 30px; text-align: center; border-radius: 8px 8px 0 0; }}
        .header h1 {{ margin: 0; font-size: 28px; font-weight: 700; text-shadow: 0 2px 4px rgba(0,0,0,0.3); }}
        .content {{ background: white; padding: 30px; border-radius: 0 0 8px 8px; }}
        .button {{ display: inline-block; padding: 14px 32px; background: #2563eb; color: white; text-decoration: none; border-radius: 8px; margin: 20px 0; font-weight: 600; }}
        .button:hover {{ background: #1e40af; }}
        .footer {{ text-align: center; padding: 20px; color: #64748b; font-size: 0.9em; }}
        .warning {{ background: #fef3c7; border-left: 4px solid #f59e0b; padding: 15px; margin: 20px 0; border-radius: 0 8px 8px 0; color: #92400e; }}
    </style>
</head>
<body>
    <div class="container">
        <div class="header">
            <h1>Reset hasła</h1>
        </div>
        <div class="content">
            <p>Otrzymałeś ten email, ponieważ zażądano resetowania hasła dla Twojego konta Norda Biznes Partner.</p>

            <p>Aby zresetować hasło, kliknij w poniższy przycisk:</p>

            <center>
                <a href="{reset_url}" class="button">Zresetuj hasło</a>
            </center>

            <div class="warning">
                <strong>Ważność linku:</strong> 1 godzina
            </div>

            <p>Jeśli przycisk nie działa, skopiuj i wklej poniższy link do przeglądarki:</p>
            <p style="word-break: break-all; color: #2563eb;">{reset_url}</p>

            <p style="margin-top: 30px; color: #64748b; font-size: 0.9em;">
                <strong>Nie zażądałeś resetowania hasła?</strong><br>
                Zignoruj ten email. Twoje hasło pozostanie bez zmian.
            </p>
        </div>
        <div class="footer">
            <p><strong>Norda Biznes Partner</strong> - Platforma Networkingu Regionalnej Izby Przedsiębiorców</p>
            <p><a href="https://nordabiznes.pl">nordabiznes.pl</a></p>
        </div>
    </div>
</body>
</html>
"""

    return send_email(
        to=[email],
        subject=subject,
        body_text=body_text,
        body_html=body_html,
        email_type='password_reset'
    )


def send_welcome_email(email: str, name: str, verification_url: str) -> bool:
    """
    Send welcome/verification email after registration

    Args:
        email: Recipient email address
        name: User's name
        verification_url: Email verification URL with token

    Returns:
        True if sent successfully, False otherwise
    """
    subject = "Witamy w Norda Biznes Partner - Potwierdź email"

    body_text = f"""Witaj {name}!

Dziękujemy za rejestrację w Norda Biznes Partner - platformie networkingu Regionalnej Izby Przedsiębiorców Norda Biznes.

Aby aktywować swoje konto, potwierdź adres email klikając w poniższy link:
{verification_url}

Link będzie ważny przez 24 godziny.

Po potwierdzeniu email będziesz mógł:
- Przeglądać profile firm członkowskich Izby
- Korzystać z asystenta AI do wyszukiwania usług
- Nawiązywać kontakty biznesowe

Pozdrawiamy,
Zespół Norda Biznes Partner

---
Norda Biznes Partner - Platforma Networkingu Regionalnej Izby Przedsiębiorców
https://nordabiznes.pl
"""

    body_html = f"""
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <style>
        body {{ font-family: 'Inter', Arial, sans-serif; line-height: 1.6; color: #1e293b; }}
        .container {{ max-width: 600px; margin: 0 auto; padding: 20px; background: #f8fafc; }}
        .header {{ background-color: #1e3a8a; background: linear-gradient(135deg, #1e40af, #1e3a8a); color: white; padding: 30px; text-align: center; border-radius: 8px 8px 0 0; }}
        .header h1 {{ margin: 0; font-size: 28px; font-weight: 700; text-shadow: 0 2px 4px rgba(0,0,0,0.3); }}
        .content {{ background: white; padding: 30px; border-radius: 0 0 8px 8px; }}
        .button {{ display: inline-block; padding: 14px 32px; background: #10b981; color: white; text-decoration: none; border-radius: 8px; margin: 20px 0; font-weight: 600; }}
        .footer {{ text-align: center; padding: 20px; color: #64748b; font-size: 0.9em; }}
        .features {{ background: #f0fdf4; padding: 20px; border-radius: 8px; margin: 20px 0; color: #166534; }}
        .features ul {{ margin: 10px 0; padding-left: 20px; }}
    </style>
</head>
<body>
    <div class="container">
        <div class="header">
            <h1>Witamy w Norda Biznes Partner!</h1>
        </div>
        <div class="content">
            <p>Witaj <strong>{name}</strong>!</p>

            <p>Dziękujemy za rejestrację w Norda Biznes Partner - platformie networkingu Regionalnej Izby Przedsiębiorców Norda Biznes.</p>

            <p>Aby aktywować swoje konto, potwierdź adres email:</p>

            <center>
                <a href="{verification_url}" class="button">Potwierdź email</a>
            </center>

            <div class="features">
                <strong>Po potwierdzeniu email będziesz mógł:</strong>
                <ul>
                    <li>Przeglądać profile firm członkowskich Izby</li>
                    <li>Korzystać z asystenta AI do wyszukiwania usług</li>
                    <li>Nawiązywać kontakty biznesowe</li>
                </ul>
            </div>

            <p style="color: #64748b; font-size: 0.9em;">
                Link będzie ważny przez 24 godziny.
            </p>
        </div>
        <div class="footer">
            <p><strong>Norda Biznes Partner</strong> - Platforma Networkingu Regionalnej Izby Przedsiębiorców</p>
            <p><a href="https://nordabiznes.pl">nordabiznes.pl</a></p>
        </div>
    </div>
</body>
</html>
"""

    return send_email(
        to=[email],
        subject=subject,
        body_text=body_text,
        body_html=body_html,
        email_type='welcome',
        recipient_name=name
    )