# email_watcher.py
import os
import pickle
import base64
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
from config import Config

SCOPES = ['https://www.googleapis.com/auth/gmail.readonly']

def get_gmail_service():
    creds = None
    if os.path.exists(Config.GMAIL_TOKEN_FILE):
        with open(Config.GMAIL_TOKEN_FILE, 'rb') as token:
            creds = pickle.load(token)
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file(
                Config.GMAIL_CREDENTIALS_FILE, SCOPES)
            creds = flow.run_local_server(port=0)
        with open(Config.GMAIL_TOKEN_FILE, 'wb') as token:
            pickle.dump(creds, token)
    return build('gmail', 'v1', credentials=creds)

def check_for_new_fos_email(last_checked_time=None):
    """
    Returns a list of new emails from the FOS since last_checked_time.
    last_checked_time should be a datetime object.
    """
    service = get_gmail_service()
    query = f'from:{Config.FOS_EMAIL}'
    if last_checked_time:
        # Gmail uses after:timestamp in seconds
        timestamp = int(last_checked_time.timestamp())
        query += f' after:{timestamp}'
    
    result = service.users().messages().list(userId='me', q=query).execute()
    messages = result.get('messages', [])
    
    new_emails = []
    for msg in messages:
        msg_data = service.users().messages().get(userId='me', id=msg['id']).execute()
        payload = msg_data.get('payload', {})
        parts = payload.get('parts', [])
        if not parts:
            # simple email
            body = payload.get('body', {}).get('data', '')
        else:
            # multipart
            body = ''
            for part in parts:
                if part.get('mimeType') == 'text/plain':
                    body = part.get('body', {}).get('data', '')
                    break
        if body:
            body = base64.urlsafe_b64decode(body).decode('utf-8')
        headers = {h['name']: h['value'] for h in msg_data['payload']['headers']}
        new_emails.append({
            'id': msg['id'],
            'from': headers.get('From', ''),
            'subject': headers.get('Subject', ''),
            'date': headers.get('Date', ''),
            'body': body
        })
    return new_emails