import streamlit as st

# Grade to points mapping
grade_points = {
    'A+': 4.0,
    'A': 4.0,
    'A-': 3.7,
    'B+': 3.3,
    'B': 3.0,
    'B-': 2.7,
    'C+': 2.3,
    'C': 2.0,
    'C-': 1.7,
    'D': 1.0,
    'F': 0.0
}

# Initialize session state
if 'courses' not in st.session_state:
    st.session_state.courses = []

st.title("🎓 GPA Calculator")
st.subheader("Calculate your Semester GPA")

# Course input form
with st.form("course_form"):
    col1, col2, col3 = st.columns([3, 1, 1])
    with col1:
        course_name = st.text_input("Course Name (optional)", key=f"name_{len(st.session_state.courses)}")
    with col2:
        credits = st.number_input("Credits", min_value=1, max_value=5, value=3, key=f"credits_{len(st.session_state.courses)}")
    with col3:
        grade = st.selectbox("Grade", list(grade_points.keys()), key=f"grade_{len(st.session_state.courses)}")
    
    submitted = st.form_submit_button("Add Course")
    if submitted:
        st.session_state.courses.append({
            'name': course_name,
            'credits': credits,
            'grade': grade
        })

# Display entered courses
if st.session_state.courses:
    st.write("### Entered Courses")
    for i, course in enumerate(st.session_state.courses, 1):
        with st.expander(f"Course {i}: {course['name'] or 'Unnamed Course'}"):
            col1, col2, col3 = st.columns([3, 1, 1])
            col1.write(f"Course Name: {course['name'] or 'N/A'}")
            col2.write(f"Credits: {course['credits']}")
            col3.write(f"Grade: {course['grade']}")

# Calculate GPA
if st.button("Calculate GPA"):
    total_points = 0
    total_credits = 0
    
    for course in st.session_state.courses:
        points = grade_points[course['grade']]
        total_points += points * course['credits']
        total_credits += course['credits']
    
    if total_credits == 0:
        st.error("Please add at least one course with credits")
    else:
        gpa = total_points / total_credits
        st.success(f"Your GPA is: **{gpa:.2f}**")
        
        # Display detailed breakdown
        st.write("### Breakdown")
        st.write(f"Total Quality Points: {total_points:.2f}")
        st.write(f"Total Credits: {total_credits}")
        st.write(f"GPA: {gpa:.2f}")

# Reset button
if st.button("Reset All Courses"):
    st.session_state.courses = []
    st.experimental_rerun()