import imaplib
import ssl
import logging
from typing import List, Dict, Optional, Tuple
from email.header import decode_header
from app.models import db, Folder, User
from app import create_app

class IMAPService:
    def __init__(self, user: User):
        self.user = user
        self.config = user.imap_config or {}
        self.connection = None
    
    def test_connection(self) -> Tuple[bool, str]:
        """Test IMAP connection with current configuration."""
        try:
            if not self.config:
                return False, "No IMAP configuration found"
            
            # Create SSL context
            context = ssl.create_default_context()
            
            # Connect to IMAP server
            self.connection = imaplib.IMAP4_SSL(
                self.config.get('server', 'imap.gmail.com'),
                self.config.get('port', 993)
            )
            
            # Login
            self.connection.login(
                self.config.get('username', ''),
                self.config.get('password', '')
            )
            
            # Select inbox to verify connection
            self.connection.select('INBOX')
            
            # Close connection
            self.connection.close()
            self.connection.logout()
            
            return True, "Connection successful"
            
        except imaplib.IMAP4.error as e:
            return False, f"IMAP connection error: {str(e)}"
        except Exception as e:
            return False, f"Connection error: {str(e)}"
        finally:
            if self.connection:
                try:
                    self.connection.logout()
                except:
                    pass
    
    def get_folders(self) -> List[Dict[str, str]]:
        """Get list of folders from IMAP server."""
        try:
            if not self.config:
                return []
            
            # Create SSL context
            context = ssl.create_default_context()
            
            # Connect to IMAP server
            self.connection = imaplib.IMAP4_SSL(
                self.config.get('server', 'imap.gmail.com'),
                self.config.get('port', 993)
            )
            
            # Login
            self.connection.login(
                self.config.get('username', ''),
                self.config.get('password', '')
            )
            
            # List folders
            status, folder_data = self.connection.list()
            
            if status != 'OK':
                return []
            
            folders = []
            for folder_item in folder_data:
                if isinstance(folder_item, bytes):
                    folder_item = folder_item.decode('utf-8')
                
                # Parse folder name (handle different IMAP server formats)
                parts = folder_item.split('"')
                if len(parts) >= 3:
                    folder_name = parts[-1] if parts[-1] else parts[-2]
                else:
                    folder_name = folder_item.split()[-1]
                
                # Handle nested folders (convert to slash notation)
                if folder_name.startswith('"') and folder_name.endswith('"'):
                    folder_name = folder_name[1:-1]
                
                folders.append({
                    'name': folder_name,
                    'full_path': folder_name
                })
            
            # Close connection
            self.connection.close()
            self.connection.logout()
            
            return folders
            
        except Exception as e:
            logging.error(f"Error fetching IMAP folders: {str(e)}")
            return []
        finally:
            if self.connection:
                try:
                    self.connection.logout()
                except:
                    pass
    
    def sync_folders(self) -> Tuple[bool, str]:
        """Sync IMAP folders with local database."""
        try:
            if not self.config:
                return False, "No IMAP configuration found"
            
            # Get folders from IMAP server
            imap_folders = self.get_folders()
            
            if not imap_folders:
                return False, "No folders found on IMAP server"
            
            # Process each folder
            synced_count = 0
            for imap_folder in imap_folders:
                folder_name = imap_folder['name']
                
                # Skip special folders that might not be needed
                if folder_name.lower() in ['inbox', 'sent', 'drafts', 'spam', 'trash']:
                    continue
                
                # Handle nested folder names (convert slashes to underscores or keep as-is)
                # According to requirements, nested folders should be created with slashes in the name
                display_name = folder_name
                
                # Check if folder already exists
                existing_folder = Folder.query.filter_by(
                    user_id=self.user.id,
                    name=display_name
                ).first()
                
                if not existing_folder:
                    # Create new folder
                    new_folder = Folder(
                        user_id=self.user.id,
                        name=display_name,
                        rule_text=f"Auto-synced from IMAP folder: {folder_name}",
                        priority=0  # Default priority
                    )
                    db.session.add(new_folder)
                    synced_count += 1
            
            db.session.commit()
            return True, f"Successfully synced {synced_count} folders"
            
        except Exception as e:
            db.session.rollback()
            return False, f"Sync error: {str(e)}"