f.py

import streamlit as st
import pandas as pd
from datetime import datetime, timedelta

# Load schedule data from CSV
@st.cache_data
def load_schedule():
    try:
        schedule_data = pd.read_csv('schedule.csv')
    except FileNotFoundError:
        schedule_data = pd.DataFrame(columns=['Class', 'Day', 'Start Time', 'Username', 'System'])
    return schedule_data

# Save schedule data to CSV
def save_schedule(schedule_data):
    schedule_data.to_csv('schedule.csv', index=False)

# Load user details from CSV
@st.cache_data
def load_user_details():
    try:
        user_details = pd.read_csv('details.csv')
    except FileNotFoundError:
        user_details = pd.DataFrame(columns=['username', 'password'])
    return user_details

# Check for system availability
def has_system_availability(schedule_data, class_selected, day_selected, start_time_selected, system_selected):
    bookings = schedule_data[
        (schedule_data['Class'] == class_selected) & 
        (schedule_data['Day'] == day_selected) & 
        (schedule_data['Start Time'] == start_time_selected)
    ]
    if len(bookings) >= 6:
        return False
    elif system_selected in bookings['System'].values:
        return False
    else:
        return True

# Convert string day and time to datetime
def get_class_datetime(day_selected, start_time_selected):
    days_of_week = ["Sunday", "Monday", "Tuesday", "Wednesday"]
    today = datetime.now()
    current_day_index = today.weekday()

    # Find the date of the next occurrence of the given day
    target_day_index = days_of_week.index(day_selected)
    delta_days = (target_day_index - current_day_index) % 7

    # If the class day is today but time has passed, move to the next week
    if delta_days == 0 and datetime.strptime(start_time_selected, "%I:%M %p").time() < today.time():
        delta_days = 7

    class_date = today + timedelta(days=delta_days)
    class_time = datetime.strptime(start_time_selected, "%I:%M %p").time()
    class_datetime = datetime.combine(class_date.date(), class_time)

    return class_datetime

# Initialize session state variables
if 'username' not in st.session_state:
    st.session_state.username = ""
if 'password' not in st.session_state:
    st.session_state.password = ""
if 'schedule_data' not in st.session_state:
    st.session_state.schedule_data = load_schedule()
if 'authenticated' not in st.session_state:
    st.session_state.authenticated = False
if 'is_admin' not in st.session_state:
    st.session_state.is_admin = False

# Login Page
def login_page():
    st.title("Login")
    st.session_state.username = st.text_input("Username")
    st.session_state.password = st.text_input("Password", type='password')

    user_details = load_user_details()

    if st.button("Login"):
        if (
            (st.session_state.username in user_details['username'].values) and 
            (st.session_state.password in user_details[user_details['username'] == st.session_state.username]['password'].values)
        ) or (st.session_state.username == "armin" and st.session_state.password == "12345679"):
            st.session_state.authenticated = True
            st.session_state.is_admin = (st.session_state.username == "armin")
            st.experimental_rerun()
        else:
            st.error("Invalid username or password. Please try again.")

# Class Schedule Page
def schedule_page():
    st.title("Class Schedule")

    classes = ["mobile", "Math", "Chemistry", "Programming"]
    days = ["Sunday", "Monday", "Tuesday", "Wednesday"]
    start_times = ["8:00 AM", "10:00 AM", "12:00 PM", "2:00 PM"]
    systems = ["System 1", "System 2", "System 3", "System 4", "System 5", "System 6"]

    st.header("Manage Classes")

    col1, col2 = st.columns(2)
    
    with col1:
        st.subheader("Add a Class")
        class_selected = st.selectbox("Class", classes, key='add_class_select')
        day_selected = st.selectbox("Day", days, key='add_day_select')
        start_time_selected = st.selectbox("Start Time", start_times, key='add_time_select')
        system_selected = st.selectbox("System", systems, key='add_system_select')
        
        if st.button("Add Class"):
            class_datetime = get_class_datetime(day_selected, start_time_selected)
            if class_datetime - datetime.now() < timedelta(hours=30):
                st.error("Classes can only be booked at least 30 hours in advance.")
            elif not has_system_availability(st.session_state.schedule_data, class_selected, day_selected, start_time_selected, system_selected):
                st.error(f"System '{system_selected}' is not available for '{class_selected}' at {start_time_selected} on {day_selected}.")
            else:
                new_row = pd.DataFrame([[class_selected, day_selected, start_time_selected, st.session_state.username, system_selected]], columns=['Class', 'Day', 'Start Time', 'Username', 'System'])
                st.session_state.schedule_data = pd.concat([st.session_state.schedule_data, new_row], ignore_index=True)
                save_schedule(st.session_state.schedule_data)
                st.success(f"Class {class_selected} added successfully with {system_selected}.")
    
    with col2:
        st.subheader("Remove a Class")
        class_to_remove = st.selectbox("Class", st.session_state.schedule_data['Class'].unique(), key='remove_class_select')
        user_booking = st.session_state.schedule_data[
            (st.session_state.schedule_data['Class'] == class_to_remove) & 
            (st.session_state.schedule_data['Username'] == st.session_state.username)
        ]

        if st.button("Remove Class"):
            if st.session_state.is_admin or not user_booking.empty:
                st.session_state.schedule_data = st.session_state.schedule_data[~(
                    (st.session_state.schedule_data['Class'] == class_to_remove) &
                    ((st.session_state.is_admin) or (st.session_state.schedule_data['Username'] == st.session_state.username))
                )]
                save_schedule(st.session_state.schedule_data)
                st.success(f"Class {class_to_remove} removed successfully.")
            else:
                st.error("You can only remove your own classes.")
    
    st.header("Your Schedule")
    st.table(st.session_state.schedule_data)

    if st.button("Log Out"):
        st.session_state['authenticated'] = False
        st.session_state['username'] = ""
        st.session_state['password'] = ""
        st.session_state['is_admin'] = False
        st.experimental_rerun()

# Authentication check
if not st.session_state['authenticated']:
    login_page()
else:
    schedule_page()