import os
import base64
import logging
import smtplib
import ssl
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError

logger = logging.getLogger(__name__)

# Email configuration
SMTP_SERVER = os.getenv("SMTP_SERVER", "127.0.0.1")
SMTP_PORT = int(os.getenv("SMTP_PORT", "1025"))
# Prioritize EMAIL_ID and EMAIL_PASSWORD if available
SMTP_USERNAME = os.getenv("EMAIL_ID") or os.getenv("SMTP_USERNAME", "sender@domain.com")
SMTP_PASSWORD = os.getenv("EMAIL_PASSWORD") or os.getenv("SMTP_PASSWORD", "yourpassword")

# Auto-configure for Gmail if using defaults and gmail address
if SMTP_SERVER == "127.0.0.1" and "gmail.com" in SMTP_USERNAME:
    SMTP_SERVER = "smtp.gmail.com"
    SMTP_PORT = 465

SMTP_SENDER = os.getenv("SMTP_SENDER", SMTP_USERNAME)

class GmailService:
    SCOPES = ['https://www.googleapis.com/auth/gmail.send']

    def __init__(self):
        self.creds = None
        self.service = None
        # Server-side credentials for Gmail API
        self.client_id = os.getenv('SERVER_GOOGLE_CLIENT_ID') or os.getenv('GOOGLE_CLIENT_ID')
        self.client_secret = os.getenv('SERVER_GOOGLE_CLIENT_SECRET') or os.getenv('GOOGLE_CLIENT_SECRET')
        self.refresh_token = os.getenv('SERVER_GOOGLE_REFRESH_TOKEN') or os.getenv('GOOGLE_REFRESH_TOKEN')
        self.sender_email = os.getenv('SMTP_SENDER') or os.getenv('EMAIL_ID')

    def authenticate(self):
        """Authenticate using the refresh token."""
        if not all([self.client_id, self.client_secret, self.refresh_token]):
            # logger.error("Missing Google API credentials (CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN)")
            return False

        try:
            # Create credentials object from the refresh token
            self.creds = Credentials(
                None,  # No access token initially
                refresh_token=self.refresh_token,
                token_uri="https://oauth2.googleapis.com/token",
                client_id=self.client_id,
                client_secret=self.client_secret,
                scopes=self.SCOPES
            )
            
            # Refresh the token (get a new access token)
            if self.creds and self.creds.expired and self.creds.refresh_token:
                self.creds.refresh(Request())
                
            self.service = build('gmail', 'v1', credentials=self.creds)
            return True
        except Exception as e:
            logger.error(f"Failed to authenticate with Gmail API: {e}")
            return False

    def send_email(self, to_email: str, subject: str, body: str) -> bool:
        """Send an email using the Gmail API."""
        if not self.service:
            if not self.authenticate():
                return False

        try:
            message = MIMEMultipart()
            message['to'] = to_email
            # Format sender with display name
            sender_name = "AnimateImage"
            if self.sender_email and "<" not in self.sender_email:
                message['from'] = f"{sender_name} <{self.sender_email}>"
            else:
                message['from'] = self.sender_email or "unknown@example.com"
            message['subject'] = subject
            message.attach(MIMEText(body, 'plain'))

            raw_message = base64.urlsafe_b64encode(message.as_bytes()).decode('utf-8')
            body = {'raw': raw_message}

            message = (self.service.users().messages().send(userId="me", body=body).execute())
            logger.info(f"Email sent to {to_email} (Message Id: {message['id']})")
            return True

        except HttpError as error:
            logger.error(f"An error occurred sending email to {to_email}: {error}")
            return False
        except Exception as e:
            logger.error(f"Unexpected error sending email: {e}")
            return False

# Initialize global instance
gmail_service = GmailService()

def send_email(to_email: str, subject: str, body: str):
    """
    Send an email using Gmail API with SMTP fallback.
    This function is blocking and should be run in a background task.
    """
    # Try Gmail API first
    if gmail_service.authenticate():
        if gmail_service.send_email(to_email, subject, body):
            return True
    
    logger.warning("Gmail API credentials not found or invalid. Falling back to SMTP.")
    
    # Fallback to SMTP (Original Implementation)
    try:
        message = MIMEMultipart()
        message["From"] = SMTP_SENDER
        message["To"] = to_email
        message["Subject"] = subject
        
        message.attach(MIMEText(body, "plain"))
        
        # Create a secure SSL context
        context = ssl.create_default_context()
        context.check_hostname = False
        context.verify_mode = ssl.CERT_NONE

        with smtplib.SMTP_SSL(SMTP_SERVER, SMTP_PORT, context=context) as server:
            server.login(SMTP_USERNAME, SMTP_PASSWORD)
            server.sendmail(SMTP_SENDER, to_email, message.as_string())
            
        logger.info(f"Email sent successfully to {to_email} via SMTP")
        return True
    except Exception as e:
        logger.error(f"Failed to send email to {to_email}: {e}")
        return False