tasks.py

from celery import Celery
from datetime import datetime, timedelta
from models import db, Book, Request, Section, User,Feedback
import csv
import os
from flask import Flask
from smtplib import SMTP
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from celeryconfig import timezone
from celery.schedules import crontab
from flask import render_template
from jinja2 import Template

# Create a Celery instance
celery = Celery(__name__, broker='redis://localhost:6379/0')

def create_app():
    app = Flask(__name__)
    app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///library.db'
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
    db.init_app(app)
    return app
app = create_app()


@celery.task(bind=True)
def export_books_csv(self, librarian_id):
    app = create_app()

    with app.app_context():
        books = db.session.query(
            Book.name.label('book_name'),
            Book.content.label('content'),
            Book.author.label('author'),
            Request.date_requested.label('date_issued'),
            Request.date_returned.label('return_date'),
            Section.name.label('section_name')
        ).join(Request, Request.book_id == Book.id).join(Section, Book.section_id == Section.id).filter(
            Request.status.in_(['approved', 'returned', 'revoked'])
        ).all()

        if not books:
            return 'No books found to export.'

        file_path = os.path.join(app.root_path, 'exports', f'books_export_{librarian_id}_{datetime.now().strftime("%Y%m%d%H%M%S")}.csv')
        os.makedirs(os.path.dirname(file_path), exist_ok=True)

        with open(file_path, mode='w', newline='', encoding='utf-8') as csv_file:
            writer = csv.writer(csv_file)
            writer.writerow(['Book Name', 'Content', 'Author', 'Date Issued', 'Return Date', 'Section Name'])
            for book in books:
                writer.writerow([book.book_name, book.content, book.author, book.date_issued, book.return_date, book.section_name])

        return file_path

# SMTP configuration
SMTP_HOST = "localhost"
SMTP_PORT = 1025
SENDER_EMAIL = '21f1003387@ds.study.iitm.ac.in'
SENDER_PASSWORD = ''

def send_message(to, subject, content_body):
    msg = MIMEMultipart()
    msg["To"] = to
    msg["Subject"] = subject
    msg["From"] = SENDER_EMAIL
    msg.attach(MIMEText(content_body, 'html'))
    
    with SMTP(host=SMTP_HOST, port=SMTP_PORT) as client:
        client.send_message(msg)

@celery.task
def send_daily_reminders():
    app = create_app()

    with app.app_context():
        now = datetime.now()
        reminder_time = now.replace(hour=12, minute=0, second=0, microsecond=0)
        if now > reminder_time:
            reminder_time += timedelta(days=1)
        
        users = db.session.query(User).all()
        for user in users:
            if user.last_login is None or (now - user.last_login).days > 1:
                subject = 'Reminder to Visit Library'
                body = f'Hello {user.username},<br><br>Please visit the library to return or borrow books.<br><br>Best regards,<br>Library Management System'
                send_message(user.email, subject, body)
            
            books_due_soon = db.session.query(Request).join(Book).filter(
                Request.user_id == user.id,
                Request.status == 'approved',
                Book.return_date <= reminder_time
            ).all()
            
            if books_due_soon:
                subject = 'Reminder: Book Return Due Soon'
                body = f'Hello {user.username},<br><br>You have books that need to be returned soon. Please return them by the due date.<br><br>Best regards,<br>Library Management System'
                send_message(user.email, subject, body)



@celery.on_after_configure.connect
def setup_periodic_tasks(sender, **kwargs):
    sender.add_periodic_task(
        crontab(hour=12, minute=0, second=0, microsecond=0),  
        send_daily_reminders.s(),
        name='daily'
    )

@celery.task
def generate_monthly_report():
    app = create_app()
    
    with app.app_context():
        now = datetime.now()
        start_date = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
        end_date = (now + timedelta(days=31)).replace(day=1, hour=0, minute=0, second=0, microsecond=0)
        
        # Fetch sections
        sections = db.session.query(Section).all()
        
        # Fetch issued books with their sections
        issued_books = db.session.query(
            Book.name.label('book_name'),
            Book.content.label('content'),
            Book.author.label('author'),
            Request.date_requested.label('date_issued'),
            Request.date_returned.label('return_date'),
            Section.name.label('section_name')
        ).join(Request, Request.book_id == Book.id).join(Section, Book.section_id == Section.id).filter(
            Request.date_requested.between(start_date, end_date)
        ).all()
        
        # Fetch ratings
        ratings = db.session.query(
            Book.name.label('book_name'),
            Feedback.rating.label('rating'),
            Feedback.comment.label('comment'),
            Feedback.date_created.label('date_created')
        ).join(Book, Feedback.book_id == Book.id).filter(
            Feedback.date_created.between(start_date, end_date)
        ).all()
        
        # Count users who logged in this month
        user_logins = db.session.query(User).filter(
            User.last_login.between(start_date, end_date)
        ).count()

        # Generate HTML report
        html_content = render_template('monthly_report.html', 
                                       sections=sections, 
                                       issued_books=issued_books, 
                                       ratings=ratings, 
                                       user_logins=user_logins-1)
        
        subject = 'Monthly Activity Report'
        # Define the recipient, e.g., librarian's email
        recipient_email = '21f1003387@ds.study.iitm.ac.in'
        send_message(recipient_email, subject, html_content)

        return 'Monthly report sent successfully'

@celery.on_after_configure.connect
def setup_periodic_tasks(sender, **kwargs):
    sender.add_periodic_task(
        crontab(day_of_month='1', hour=0, minute=0),
        generate_monthly_report.s(),
        name='monthly_report'
    )