app.py

import streamlit as st
import pandas as pd
from ortools.sat.python import cp_model

# Initialize session state if not already done
if "timetable" not in st.session_state:
    st.session_state.timetable = pd.DataFrame(columns=["Day", "Time", "Subject", "Teacher", "Room"])

if "subjects" not in st.session_state:
    st.session_state.subjects = {}

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

if "rooms" not in st.session_state:
    st.session_state.rooms = []

# App title
st.title("Subject Timetable Generator")

# Sidebar inputs to add data
st.sidebar.header("Add Data")

# Add subjects with weekly slots
subject = st.sidebar.text_input("Enter Subject Name")
weekly_slots = st.sidebar.number_input("Number of Weekly Slots", min_value=1, max_value=10, step=1)
if st.sidebar.button("Add Subject"):
    if subject and weekly_slots > 0:
        st.session_state.subjects[subject] = weekly_slots
        st.success(f"Added Subject: {subject} with {weekly_slots} slots per week")
    else:
        st.error("Please provide a valid subject and weekly slots.")

# Add teachers
teacher = st.sidebar.text_input("Enter Teacher Name")
if st.sidebar.button("Add Teacher"):
    if teacher:
        st.session_state.teachers.append(teacher)
        st.success(f"Added Teacher: {teacher}")
    else:
        st.error("Teacher name cannot be empty!")

# Add rooms
room = st.sidebar.text_input("Enter Room Name")
if st.sidebar.button("Add Room"):
    if room:
        st.session_state.rooms.append(room)
        st.success(f"Added Room: {room}")
    else:
        st.error("Room name cannot be empty!")

# Show current data
st.write("### Current Data")
st.write("**Subjects:**", st.session_state.subjects)
st.write("**Teachers:**", st.session_state.teachers)
st.write("**Rooms:**", st.session_state.rooms)

# Timetable generation logic with debugging
def generate_timetable(subjects, teachers, rooms, time_slots, days):
    model = cp_model.CpModel()
    schedule = {}

    # Create variables for each subject-teacher-room-time-slot combination
    for subject, slots in subjects.items():
        for teacher in teachers:
            for room in rooms:
                for day in days:
                    for time_slot in time_slots:
                        schedule[(subject, teacher, room, day, time_slot)] = model.NewBoolVar(
                            f"{subject}_{teacher}_{room}_{day}_{time_slot}"
                        )

    # Constraints: Each subject should have the required number of weekly slots
    for subject, slots in subjects.items():
        model.Add(
            sum(
                schedule[(subject, teacher, room, day, time_slot)]
                for teacher in teachers
                for room in rooms
                for day in days
                for time_slot in time_slots
            ) == slots
        )

    # Constraints: No teacher or room should be double-booked
    for teacher in teachers:
        for day in days:
            for time_slot in time_slots:
                model.Add(
                    sum(
                        schedule[(subject, teacher, room, day, time_slot)]
                        for subject in subjects
                        for room in rooms
                    ) <= 1  # A teacher can only be in one class at a time
                )

    for room in rooms:
        for day in days:
            for time_slot in time_slots:
                model.Add(
                    sum(
                        schedule[(subject, teacher, room, day, time_slot)]
                        for subject in subjects
                        for teacher in teachers
                    ) <= 1  # A room can only be used for one subject at a time
                )

    # Solve the model
    solver = cp_model.CpSolver()
    status = solver.Solve(model)

    # Debugging: Print the solver status and results
    if status != cp_model.OPTIMAL:
        st.error(f"Solver failed to find a solution. Solver status: {status}")
        return []

    result = []
    for key, var in schedule.items():
        if solver.Value(var) == 1:
            result.append(key)

    return result

# Time slots and days for timetable
time_slots = [f"{hour}:00 - {hour+1}:00" for hour in range(8, 18)]  # 8 AM to 6 PM
days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]

# Generate timetable button
if st.button("Generate Timetable"):
    timetable = generate_timetable(
        st.session_state.subjects, st.session_state.teachers, st.session_state.rooms, time_slots, days
    )
    if timetable:
        # Store the generated timetable
        for entry in timetable:
            subject, teacher, room, day, time_slot = entry
            st.session_state.timetable = pd.concat(
                [st.session_state.timetable, pd.DataFrame([[day, time_slot, subject, teacher, room]],
                                                          columns=["Day", "Time", "Subject", "Teacher", "Room"])],
                ignore_index=True
            )
        st.success("Timetable generated successfully!")
    else:
        st.error("Failed to generate timetable. Check constraints!")

# Display the generated timetable
st.write("### Generated Timetable")
if not st.session_state.timetable.empty:
    st.dataframe(st.session_state.timetable)
    st.download_button(
        "Download Timetable (CSV)",
        data=st.session_state.timetable.to_csv(index=False),
        file_name="timetable.csv",
        mime="text/csv"
    )
else:
    st.write("No timetable generated yet.")