import streamlit as st
import pandas as pd

# Initialize session state for subjects, teachers, classrooms, and timetable
if 'subjects' not in st.session_state:
    st.session_state['subjects'] = []

if 'teachers' not in st.session_state:
    st.session_state['teachers'] = []

if 'classrooms' not in st.session_state:
    st.session_state['classrooms'] = []

if 'timetable' not in st.session_state:
    st.session_state['timetable'] = pd.DataFrame(columns=['Day', 'Time', 'Room', 'Subject', 'Teacher'])

# Define days and time slots
DAYS = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
TIMES = ["09:00-10:00", "10:00-11:00", "11:00-12:00", "12:00-01:00", "01:00-02:00", "02:00-03:00"]

# Title of the application
st.title("Smart Semester Subjects Timetable Management System")

# Sidebar navigation
menu = st.sidebar.radio("Menu", ["Add Subject", "Add Teacher", "Add Classroom", "Add Subject Lectures", "View Timetable"])

# Add Subject Page
if menu == "Add Subject":
    st.header("Add Subjects")
    subject = st.text_input("Enter Subject Name")

    if st.button("Add Subject"):
        if subject:
            st.session_state['subjects'].append(subject)
            st.success(f"Added subject: {subject}")
        else:
            st.error("Please enter a subject name.")

    st.subheader("Current Subjects")
    if st.session_state['subjects']:
        st.write(st.session_state['subjects'])
    else:
        st.write("No subjects added yet.")

# Add Teacher Page
elif menu == "Add Teacher":
    st.header("Add Teachers")
    teacher = st.text_input("Enter Teacher Name")

    if st.button("Add Teacher"):
        if teacher:
            st.session_state['teachers'].append(teacher)
            st.success(f"Added teacher: {teacher}")
        else:
            st.error("Please enter a teacher name.")

    st.subheader("Current Teachers")
    if st.session_state['teachers']:
        st.write(st.session_state['teachers'])
    else:
        st.write("No teachers added yet.")

# Add Classroom Page
elif menu == "Add Classroom":
    st.header("Add Classrooms")
    room = st.text_input("Enter Classroom Name")

    if st.button("Add Classroom"):
        if room:
            st.session_state['classrooms'].append(room)
            st.success(f"Added classroom: {room}")
        else:
            st.error("Please enter a classroom name.")

    st.subheader("Current Classrooms")
    if st.session_state['classrooms']:
        st.write(st.session_state['classrooms'])
    else:
        st.write("No classrooms added yet.")

# Add Subject Lectures Page
elif menu == "Add Subject Lectures":
    st.header("Add Subject Lectures")
    if not st.session_state['subjects'] or not st.session_state['teachers'] or not st.session_state['classrooms']:
        st.warning("Please ensure subjects, teachers, and classrooms are added first.")
    else:
        subject = st.selectbox("Select Subject", st.session_state['subjects'])
        teacher = st.selectbox("Select Teacher", st.session_state['teachers'])
        room = st.selectbox("Select Classroom", st.session_state['classrooms'])
        day = st.selectbox("Select Day", DAYS)
        time = st.selectbox("Select Time Slot", TIMES)

        if st.button("Add Lecture"):
            # Check if the slot is already taken
            if not st.session_state['timetable'][(st.session_state['timetable']['Day'] == day) &
                                                (st.session_state['timetable']['Time'] == time) &
                                                (st.session_state['timetable']['Room'] == room)].empty:
                st.error(f"Slot on {day} at {time} in {room} is already taken.")
            else:
                new_entry = pd.DataFrame({"Day": [day], "Time": [time], "Room": [room], "Subject": [subject], "Teacher": [teacher]})
                st.session_state['timetable'] = pd.concat([st.session_state['timetable'], new_entry], ignore_index=True)
                st.success("Lecture added successfully.")

# View Timetable Page
elif menu == "View Timetable":
    st.header("Weekly Timetable")
    if not st.session_state['timetable'].empty:
        # Create a pivot table for better visualization
        pivot_table = st.session_state['timetable'].pivot_table(
            index='Day',
            columns='Time',
            values=['Subject', 'Teacher'],
            aggfunc=lambda x: ' | '.join(x)
        )

        # Combine Subject and Teacher in each cell
        styled_table = pivot_table.apply(lambda x: x.dropna().apply(lambda y: y.split(' | ')[0] + "\n" + y.split(' | ')[1] if ' | ' in y else y), axis=1)

        st.write(styled_table.fillna("-"))

        if st.button("Clear Timetable"):
            st.session_state['timetable'] = pd.DataFrame(columns=['Day', 'Time', 'Room', 'Subject', 'Teacher'])
            st.success("Timetable cleared.")
    else:
        st.write("No timetable entries yet.")