import streamlit as st
import pandas as pd
import os

# Configure the page
st.set_page_config(
    page_title="NVIDIA GENL Mock Test",
    page_icon="🧠",
    layout="wide",
    initial_sidebar_state="expanded"
)

# Initialize session state
if 'current_sheet' not in st.session_state:
    st.session_state.current_sheet = None
if 'current_question' not in st.session_state:
    st.session_state.current_question = 0
if 'user_answers' not in st.session_state:
    st.session_state.user_answers = {}
if 'show_answers' not in st.session_state:
    st.session_state.show_answers = {}
if 'sheets_data' not in st.session_state:
    st.session_state.sheets_data = {}
if 'show_results' not in st.session_state:
    st.session_state.show_results = False

def load_excel_file(file_path):
    """Load the Excel file from the specified path"""
    try:
        excel_file = pd.read_excel(file_path, sheet_name=None)
        return excel_file
    except Exception as e:
        st.error(f"Error loading Excel file: {e}")
        return None

def clean_data(value):
    """Clean and format data values"""
    if pd.isna(value) or value == '':
        return None
    return str(value).strip()

def display_question(question_data, question_num, total_questions):
    """Display a single question and options with instant feedback"""
    
    # Create columns for better layout
    col1, col2 = st.columns([3, 1])
    
    with col1:
        st.markdown(f"### Question {question_num + 1} of {total_questions}")
    
    with col2:
        progress = (question_num + 1) / total_questions
        st.progress(progress)
        st.caption(f"Progress: {question_num + 1}/{total_questions}")
    
    # Display the question
    st.markdown(
        f"""
        <div style='
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            padding: 2rem;
            border-radius: 15px;
            margin-bottom: 2rem;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        '>
            <h3 style='margin:0; color: white; font-weight: 500;'>{question_data['Question']}</h3>
        </div>
        """, 
        unsafe_allow_html=True
    )
    
    # Get available choices
    choices = []
    for i in range(1, 7):
        choice_col = f'Choice{i}'
        if choice_col in question_data.index:
            choice_val = clean_data(question_data[choice_col])
            if choice_val:
                choices.append(choice_val)
    
    question_key = f"q_{question_num}"
    
    # Get current answer (None if not answered yet)
    current_answer = st.session_state.user_answers.get(question_key, None)
    
    # Display options
    if choices:
        # Radio button with no default selection
        selected_option = st.radio(
            "**Select your answer:**",
            options=[""] + choices,  # Add empty option at start
            format_func=lambda x: "-- Select an option --" if x == "" else x,
            key=f"radio_{question_key}",
            index=0 if current_answer is None else (choices.index(current_answer) + 1 if current_answer in choices else 0)
        )
        
        # Only store if a real choice is selected
        if selected_option != "":
            st.session_state.user_answers[question_key] = selected_option
            
            # Get correct answer
            correct_answer = clean_data(question_data['Answer'])
            
            # Show instant feedback
            st.markdown("<br>", unsafe_allow_html=True)
            if selected_option == correct_answer:
                st.markdown(
                    """
                    <div style='
                        background: #d4edda;
                        border-left: 5px solid #28a745;
                        padding: 1rem;
                        border-radius: 8px;
                        margin-top: 1rem;
                    '>
                        <span style='color: #155724; font-size: 1.1rem; font-weight: 600;'>
                            ✅ Correct! Well done.
                        </span>
                    </div>
                    """,
                    unsafe_allow_html=True
                )
            else:
                st.markdown(
                    """
                    <div style='
                        background: #f8d7da;
                        border-left: 5px solid #dc3545;
                        padding: 1rem;
                        border-radius: 8px;
                        margin-top: 1rem;
                    '>
                        <span style='color: #721c24; font-size: 1.1rem; font-weight: 600;'>
                            ❌ Incorrect
                        </span>
                    </div>
                    """,
                    unsafe_allow_html=True
                )
                
                # Show correct answer button
                if st.session_state.show_answers.get(question_key, False):
                    st.markdown(
                        f"""
                        <div style='
                            background: #d1ecf1;
                            border-left: 5px solid #0c5460;
                            padding: 1rem;
                            border-radius: 8px;
                            margin-top: 0.5rem;
                        '>
                            <span style='color: #0c5460; font-weight: 600;'>
                                💡 Correct answer: {correct_answer}
                            </span>
                        </div>
                        """,
                        unsafe_allow_html=True
                    )
                else:
                    if st.button("🔍 Show Correct Answer", key=f"show_{question_num}"):
                        st.session_state.show_answers[question_key] = True
                        st.rerun()
        else:
            # Remove answer if user deselects
            if question_key in st.session_state.user_answers:
                del st.session_state.user_answers[question_key]
    else:
        st.warning("⚠️ No choices found for this question.")

def calculate_score(sheet_data):
    """Calculate the score for the test"""
    total_score = 0
    max_score = 0
    results = []
    
    for i in range(len(sheet_data)):
        question_data = sheet_data.iloc[i]
        question_key = f"q_{i}"
        user_answer = st.session_state.user_answers.get(question_key, "")
        correct_answer = clean_data(question_data['Answer'])
        
        is_correct = user_answer == correct_answer if correct_answer else False
        
        try:
            marks = float(question_data.get('Marks', 1.0))
        except:
            marks = 1.0
        
        if is_correct:
            total_score += marks
        
        max_score += marks
        
        results.append({
            'question': i + 1,
            'question_text': question_data['Question'],
            'user_answer': user_answer,
            'correct_answer': correct_answer,
            'is_correct': is_correct,
            'marks': marks
        })
    
    return total_score, max_score, results

def main():
    # Enhanced CSS
    st.markdown("""
        <style>
        /* Import Google Fonts */
        @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');
        
        /* Global Styles */
        * {
            font-family: 'Inter', sans-serif;
        }
        
        .main-header {
            font-size: 3rem;
            font-weight: 700;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            text-align: center;
            margin-bottom: 2rem;
            animation: fadeIn 1s ease-in;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(-20px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        /* Sidebar Styling */
        [data-testid="stSidebar"] {
            background: linear-gradient(180deg, #f8f9fa 0%, #e9ecef 100%);
        }
        
        /* Metric Cards */
        .metric-card {
            background: white;
            padding: 1.5rem;
            border-radius: 15px;
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
            text-align: center;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        
        .metric-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.12);
        }
        
        /* Button Styling */
        .stButton>button {
            border-radius: 10px;
            font-weight: 600;
            transition: all 0.3s ease;
            border: none;
        }
        
        .stButton>button:hover {
            transform: scale(1.02);
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
        }
        
        /* Radio Button Styling */
        .stRadio > div {
            background: white;
            padding: 1.5rem;
            border-radius: 12px;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
        }
        
        /* Progress Bar */
        .stProgress > div > div > div {
            background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
        }
        
        /* Expander Styling */
        .streamlit-expanderHeader {
            background: white;
            border-radius: 10px;
            font-weight: 600;
        }
        
        /* Custom Scrollbar */
        ::-webkit-scrollbar {
            width: 10px;
        }
        
        ::-webkit-scrollbar-track {
            background: #f1f1f1;
        }
        
        ::-webkit-scrollbar-thumb {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border-radius: 5px;
        }
        
        ::-webkit-scrollbar-thumb:hover {
            background: #764ba2;
        }
        </style>
    """, unsafe_allow_html=True)
    
    # Header
    st.markdown('<h1 class="main-header">🧠 NVIDIA GENL Mock Test</h1>', unsafe_allow_html=True)
    
    # File path
    excel_file_path = "src/Nvidia GENL 1.xlsx"
    
    # Load data
    if not st.session_state.sheets_data:
        with st.spinner("📚 Loading test data..."):
            sheets_data = load_excel_file(excel_file_path)
            if sheets_data:
                st.session_state.sheets_data = sheets_data
                st.success("✅ Test data loaded successfully!")
            else:
                st.error(f"❌ Could not load Excel file from: {excel_file_path}")
                st.info("💡 Please make sure the file exists at the specified path.")
                return
    
    sheets_data = st.session_state.sheets_data
    
    # Sidebar
    with st.sidebar:
        st.markdown("## 🧭 Navigation")
        
        available_sheets = list(sheets_data.keys())
        selected_sheet = st.selectbox(
            "**Select Test Sheet:**",
            options=available_sheets,
            index=0
        )
        
        if selected_sheet != st.session_state.current_sheet:
            st.session_state.current_sheet = selected_sheet
            st.session_state.current_question = 0
            st.session_state.user_answers = {}
            st.session_state.show_answers = {}
            st.session_state.show_results = False
            st.rerun()
        
        st.markdown("---")
        
        current_data = sheets_data[selected_sheet]
        
        if 'Type' in current_data.columns:
            objective_questions = current_data[current_data['Type'] == 'Objective']
        else:
            objective_questions = current_data
        
        total_questions = len(objective_questions)
        
        # Info cards
        st.markdown(f"**📄 Sheet:** {selected_sheet}")
        st.markdown(f"**📝 Total Questions:** {total_questions}")
        
        answered_count = len([k for k in st.session_state.user_answers if st.session_state.user_answers[k]])
        st.markdown(f"**✅ Answered:** {answered_count}/{total_questions}")
        
        st.markdown("---")
        st.markdown("### 🎯 Quick Navigation")
        
        col1, col2 = st.columns(2)
        with col1:
            if st.button("◀ Prev", use_container_width=True, 
                        disabled=st.session_state.current_question == 0):
                st.session_state.current_question -= 1
                st.rerun()
        
        with col2:
            if st.button("Next ▶", use_container_width=True,
                        disabled=st.session_state.current_question >= total_questions - 1):
                st.session_state.current_question += 1
                st.rerun()
        
        selected_q = st.selectbox(
            "**Go to question:**",
            options=list(range(1, total_questions + 1)),
            index=st.session_state.current_question
        )
        
        if selected_q - 1 != st.session_state.current_question:
            st.session_state.current_question = selected_q - 1
            st.rerun()
        
        st.markdown("---")
        
        if st.button("🔄 Reset Test", use_container_width=True, type="secondary"):
            st.session_state.user_answers = {}
            st.session_state.current_question = 0
            st.session_state.show_answers = {}
            st.session_state.show_results = False
            st.rerun()
        
        if st.button("📊 View Results", use_container_width=True, type="primary"):
            if answered_count > 0:
                st.session_state.show_results = True
                st.rerun()
            else:
                st.warning("⚠️ Please answer some questions first!")
    
    # Main content
    if total_questions == 0:
        st.warning("⚠️ No questions found in this sheet.")
        return
    
    # Display question or results
    if st.session_state.show_results:
        st.markdown("---")
        st.markdown("## 📊 Test Results")
        
        total_score, max_score, results = calculate_score(objective_questions)
        
        col1, col2, col3, col4 = st.columns(4)
        
        with col1:
            st.markdown('<div class="metric-card">', unsafe_allow_html=True)
            st.metric("Total Score", f"{total_score:.1f}/{max_score:.1f}")
            st.markdown('</div>', unsafe_allow_html=True)
        
        with col2:
            st.markdown('<div class="metric-card">', unsafe_allow_html=True)
            percentage = (total_score / max_score) * 100 if max_score > 0 else 0
            st.metric("Percentage", f"{percentage:.1f}%")
            st.markdown('</div>', unsafe_allow_html=True)
        
        with col3:
            st.markdown('<div class="metric-card">', unsafe_allow_html=True)
            correct_count = sum(1 for r in results if r['is_correct'])
            st.metric("Correct", f"{correct_count}/{total_questions}")
            st.markdown('</div>', unsafe_allow_html=True)
        
        with col4:
            st.markdown('<div class="metric-card">', unsafe_allow_html=True)
            incorrect_count = total_questions - correct_count
            st.metric("Incorrect", f"{incorrect_count}")
            st.markdown('</div>', unsafe_allow_html=True)
        
        st.markdown("---")
        st.subheader("📋 Question-wise Results")
        
        for result in results:
            icon = "✅" if result['is_correct'] else "❌"
            
            with st.expander(f"{icon} Question {result['question']} ({result['marks']} mark{'s' if result['marks'] > 1 else ''})", expanded=False):
                st.write(f"**Question:** {result['question_text']}")
                
                col_a, col_b = st.columns(2)
                
                with col_a:
                    st.write("**Your Answer:**")
                    if result['user_answer']:
                        if result['is_correct']:
                            st.success(result['user_answer'])
                        else:
                            st.error(result['user_answer'])
                    else:
                        st.warning("Not answered")
                
                with col_b:
                    st.write("**Correct Answer:**")
                    st.success(result['correct_answer'])
        
        if st.button("← Back to Test", use_container_width=True, type="primary"):
            st.session_state.show_results = False
            st.rerun()
    else:
        current_q_data = objective_questions.iloc[st.session_state.current_question]
        display_question(current_q_data, st.session_state.current_question, total_questions)
        
        st.markdown("---")
        col1, col2, col3 = st.columns([1, 2, 1])
        
        with col1:
            if st.button("◀ Previous Question", use_container_width=True,
                        disabled=st.session_state.current_question == 0):
                st.session_state.current_question -= 1
                st.rerun()
        
        with col3:
            if st.button("Next Question ▶", use_container_width=True,
                        disabled=st.session_state.current_question >= total_questions - 1):
                st.session_state.current_question += 1
                st.rerun()

if __name__ == "__main__":
    main()