import imaplib
import email
from email.header import decode_header
import re
import logging
from config import settings
from services.qwen_service import qwen_service
import json

logger = logging.getLogger(__name__)

class GmailSyncService:
    def __init__(self):
        pass

    async def fetch_latest_meezan_transaction(self, credentials: dict = None):
        try:
            # Use dynamic credentials if provided, else fallback to settings
            gmail_user = credentials.get("gmail") if credentials else settings.SMTP_USER
            gmail_pass = credentials.get("app_password") if credentials else settings.SMTP_PASS

            if not gmail_user or not gmail_pass:
                logger.error("Missing Gmail credentials for sync.")
                return None

            # Connect to Gmail IMAP with 3-second timeout
            mail = imaplib.IMAP4_SSL("imap.gmail.com", timeout=3)
            mail.login(gmail_user, gmail_pass)
            mail.select("INBOX", readonly=True)

            logger.info(f"Successfully logged into {gmail_user} for sync.")

            # Sniper Search: Specifically look for the Meezan subject line
            search_query = '(OR SUBJECT "Credit Transaction Alert" SUBJECT "Debit Transaction Alert")'
            status, messages = mail.search(None, search_query)
            
            logger.info(f"Sniper Search Status: {status}, IDs Found: {messages}")

            if status != "OK" or not messages[0] or messages[0] == b'':
                logger.info("Specific subject search failed. Trying generic Meezan search...")
                status, messages = mail.search(None, 'FROM "meezanbank.com"')
            
            if status != "OK" or not messages[0] or messages[0] == b'':
                logger.info("No Meezan transaction alerts found.")
                return None

            # Get the IDs and take the newest one
            email_ids = messages[0].split()
            latest_id = email_ids[-1] 

            status, data = mail.fetch(latest_id, "(RFC822)")
            raw_email = data[0][1]
            msg = email.message_from_bytes(raw_email)
            
            logger.info(f">>> FETCHED TARGET EMAIL: Subject='{msg.get('Subject')}'")

            # Extract body
            target_body = None
            if msg.is_multipart():
                for part in msg.walk():
                    if part.get_content_type() == "text/plain":
                        target_body = part.get_payload(decode=True).decode()
                        break
            else:
                target_body = msg.get_payload(decode=True).decode()

            mail.logout()
            
            if not target_body:
                return None

            # Use Qwen to parse the email and check for fraud
            return await self.analyze_with_ai(target_body)

        except Exception as e:
            logger.error(f"Gmail Sync Error: {str(e)}")
            return None

    async def analyze_with_ai(self, email_body: str):
        prompt = f"""
        You are a NadraGuard Fraud Detection Agent. 
        Analyze the following bank transaction email body and extract the details in JSON format.
        Also, provide a 'fraud_verdict' (SAFE or SUSPICIOUS) and a short 'reason'.
        
        EMAIL BODY:
        {email_body}
        
        JSON STRUCTURE:
        {{
            "title": "Short title like 'Transfer to X'",
            "amount": float (negative if debit),
            "bank": "Meezan Bank",
            "date": "Extracted date",
            "fraud_verdict": "SAFE/SUSPICIOUS",
            "reason": "Why it is safe or suspicious"
        }}
        """
        
        res = await qwen_service.generate_response(prompt, temperature=0.3)
        if not res["success"]:
            logger.error(f"AI response failed: {res.get('error')}")
            return None
            
        try:
            content = res.get("content", "")
            json_text = content.replace('```json', '').replace('```', '').strip()
            data = json.loads(json_text)
            return data
        except Exception as e:
            logger.error(f"Failed to parse AI response: {e}")
            return None

gmail_sync_service = GmailSyncService()