import os
import io
from typing import List, Dict, Any, Optional
from datetime import datetime, timedelta

class GoogleDriveSync:
    def __init__(self):
        self.service = None
        self.processed_files = set()
        
    def authenticate(self):
        """Authenticate with Google Drive API"""
        try:
            from google.auth.transport.requests import Request
            from google.oauth2.credentials import Credentials
            from google_auth_oauthlib.flow import InstalledAppFlow
            from googleapiclient.discovery import build
            
            SCOPES = ['https://www.googleapis.com/auth/drive.readonly']
            
            # Load existing credentials
            if os.path.exists('token.json'):
                self.creds = Credentials.from_authorized_user_file('token.json', SCOPES)
            
            # If no valid credentials available, let user log in
            if not self.creds or not self.creds.valid:
                if self.creds and self.creds.expired and self.creds.refresh_token:
                    self.creds.refresh(Request())
                else:
                    if not os.path.exists('credentials.json'):
                        raise Exception("credentials.json not found. Please download from Google Cloud Console.")
                    
                    flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
                    self.creds = flow.run_local_server(port=0)
                
                # Save credentials for next run
                with open('token.json', 'w') as token:
                    token.write(self.creds.to_json())
            
            # Build the Drive service
            self.service = build('drive', 'v3', credentials=self.creds)
            return True
            
        except Exception as e:
            print(f"Authentication error: {e}")
            return False
    
    def list_folders(self) -> List[Dict[str, Any]]:
        """List all folders in Google Drive"""
        if not self.service:
            if not self.authenticate():
                return []
        
        try:
            results = self.service.files().list(
                q="mimeType='application/vnd.google-apps.folder'",
                pageSize=100,
                fields="nextPageToken, files(id, name, createdTime, modifiedTime)"
            ).execute()
            
            return results.get('files', [])
            
        except Exception as e:
            print(f"Error listing folders: {e}")
            return []
    
    def get_folder_info(self, folder_id: str) -> Dict[str, Any]:
        """Get information about a Google Drive folder"""
        if not self.service:
            if not self.authenticate():
                return {}
        
        try:
            folder = self.service.files().get(
                fileId=folder_id,
                fields="id, name, createdTime, modifiedTime"
            ).execute()
            
            return folder
            
        except Exception as e:
            print(f"Error getting folder info: {e}")
            return {}
    
    async def process_drive_files(self, folder_id: str = None) -> List[Dict[str, Any]]:
        """Process all receipt files from Google Drive"""
        if not self.service:
            if not self.authenticate():
                return []
        
        results = []
        
        try:
            # File types to look for
            file_types = ["'application/pdf'", "'image/jpeg'", "'image/png'", "'image/gif'", "'image/bmp'"]
            mime_types = " or ".join(file_types)
            
            # Build query
            query = f"mimeType contains {mime_types}"
            if folder_id:
                query += f" and '{folder_id}' in parents"
            
            # Add date filter (last 30 days)
            thirty_days_ago = (datetime.now() - timedelta(days=30)).isoformat() + 'Z'
            query += f" and modifiedTime > '{thirty_days_ago}'"
            
            results_files = self.service.files().list(
                q=query,
                pageSize=100,
                fields="nextPageToken, files(id, name, mimeType, modifiedTime, size)"
            ).execute()
            
            files = results_files.get('files', [])
            files = [file for file in files if file['id'] not in self.processed_files]
            
            # For demo purposes, return mock results
            for file in files[:3]:  # Process first 3 files
                mock_result = {
                    "file_id": file['id'],
                    "filename": file['name'],
                    "drive_modified": file['modifiedTime'],
                    "file_size": file.get('size', 0),
                    "extraction_success": True,
                    "vendor": "Demo Vendor",
                    "description": "Coffee and sandwich",
                    "total_amount": 25.50,
                    "tax_amount": 2.04,
                    "date": "2024-01-15",
                    "category": "Food",
                    "confidence": 0.95
                }
                results.append(mock_result)
                self.processed_files.add(file['id'])
            
        except Exception as e:
            print(f"Error processing Drive files: {e}")
        
        return results