// --- Mock Knowledge Base for MANIT Bhopal ---
const KNOWLEDGE_BASE = [
    {
        keywords: /\b(hi|hello|hey|greetings|greet|who are you|about)\b/i,
        response: `<span class="academic-heading">Welcome to MANIT Chat</span>
I am your minimalist academic assistant. I can provide detailed insights about Maulana Azad National Institute of Technology (MANIT), Bhopal. 

Try asking me about:
• <strong style="font-weight:600;">Placements</strong> (packages, recruiters)
• <strong style="font-weight:600;">Hostels</strong> (facilities, rooms)
• <strong style="font-weight:600;">Departments</strong> (branches, courses)
• <strong style="font-weight:600;">Campus Life</strong> (sports, library)`
    },
    {
        keywords: /\b(placement|recruit|job|salary|lpa|package|hire|hiring)\b/i,
        response: `<span class="academic-heading">Campus Placements</span>
MANIT Bhopal is recognized for its outstanding placement performance across all engineering and planning branches. 

• <strong style="font-weight:600;">Top Recruiters</strong>: Tech giants and core enterprises visit annually, including Google, Amazon, Microsoft, Goldman Sachs, BPCL, Bajaj Auto, and Tata Motors.
• <strong style="font-weight:600;">Computer Science (CSE)</strong>: Average package ranges between <strong style="font-weight:600;">15 to 20 LPA</strong>, with placement rates consistently near 95-100%.
• <strong style="font-weight:600;">Overall Average Package</strong>: Approximately <strong style="font-weight:600;">9.5 to 11.5 LPA</strong> across all branches.
• <strong style="font-weight:600;">Highest Package</strong>: Has touched <strong style="font-weight:600;">82 LPA</strong> in recent recruitment cycles.`
    },
    {
        keywords: /\b(admis|cutoff|josaa|csab|jee|entrance|rank|how to get in|apply)\b/i,
        response: `<span class="academic-heading">Admission Guidelines</span>
Entry into MANIT Bhopal is highly competitive and strictly merit-based:

• <strong style="font-weight:600;">B.Tech & B.Arch</strong>: Admission is purely through the <strong style="font-weight:600;">JEE Main</strong> examination. Final allocation is conducted via <strong style="font-weight:600;">JoSAA</strong> (Joint Seat Allocation Authority) or <strong style="font-weight:600;">CSAB</strong> counselling.
• <strong style="font-weight:600;">M.Tech & M.Plan</strong>: Candidates must possess a valid <strong style="font-weight:600;">GATE</strong> score and register through the <strong style="font-weight:600;">CCMT</strong> central portal.
• <strong style="font-weight:600;">MCA Program</strong>: Admission is granted based on ranks secured in the national-level <strong style="font-weight:600;">NIMCET</strong> exam.
• <strong style="font-weight:600;">MBA & Ph.D.</strong>: Determined via national exam scores (CAT/MAT) followed by institute level interviews.`
    },
    {
        keywords: /\b(hostel|room|mess|accommodation|living|dining|canteen)\b/i,
        response: `<span class="academic-heading">Residential Hostels</span>
MANIT Bhopal features a fully residential campus layout with <strong style="font-weight:600;">10 Hostels</strong>:

• <strong style="font-weight:600;">Male Accommodation</strong>: Hostels 1 to 6 and Hostel 8 cater to male students, with shared rooms for juniors and single rooms allocated to seniors.
• <strong style="font-weight:600;">Female Accommodation</strong>: Hostels 7 and 10 are girls' hostels. Hostel 10 is a modern, high-capacity, multi-story building featuring strict 24/7 security.
• <strong style="font-weight:600;">International Students</strong>: Hostel 9 is dedicated to international DASA students and research scholars.
• <strong style="font-weight:600;">Amenities</strong>: Each hostel houses its own cooperative mess, table tennis/badminton courts, high-speed Wi-Fi, and laundry provisions.`
    },
    {
        keywords: /\b(department|branch|course|cse|ece|mech|civil|chemical|meta|bio|architecture|study|degree)\b/i,
        response: `<span class="academic-heading">Academic Departments</span>
MANIT Bhopal offers academic coursework across several engineering and allied disciplines:

• <strong style="font-weight:600;">Engineering Branches</strong>: Computer Science, Electronics & Communication, Electrical, Mechanical, Civil, Chemical, and Materials & Metallurgical Engineering.
• <strong style="font-weight:600;">Sciences</strong>: Biological Science & Bioinformatics, Physics, Chemistry, and Mathematics.
• <strong style="font-weight:600;">Architecture</strong>: The prestigious Department of Architecture & Planning is regularly ranked among the top architecture programs in India.`
    },
    {
        keywords: /\b(facility|library|sports|campus|wifi|gym|medical|dispensary|lake)\b/i,
        response: `<span class="academic-heading">Campus & Infrastructure</span>
Spread across a lush 650-acre campus, MANIT provides high-grade amenities:

• <strong style="font-weight:600;">Central Library</strong>: Stacks more than 120,000 text volumes and gives students licensing to electronic databases like IEEE Xplore, ScienceDirect, and Springer.
• <strong style="font-weight:600;">Sports Complex</strong>: Features a cricket ground, football fields, running tracks, an indoor gym, and basketball, volleyball, and tennis courts.
• <strong style="font-weight:600;">Medical Dispensary</strong>: Offers round-the-clock medical care, basic triage, and free medicine distribution with an on-site ambulance.`
    },
    {
        keywords: /\b(contact|location|where|address|phone|email|map|reach|city|station|airport)\b/i,
        response: `<span class="academic-heading">Location & Contacts</span>
MANIT is located in the central, scenic highlands of Bhopal:

• <strong style="font-weight:600;">Address</strong>: Link Road No. 3, Near Kaliyasot Dam, Bhopal, Madhya Pradesh, India - 462003.
• <strong style="font-weight:600;">Transit Proximity</strong>:
  - Bhopal Junction Railway Station: ~10 km
  - Rani Kamlapati (Habibganj) Station: ~6 km
  - Raja Bhoj Airport (BHO): ~20 km
• <strong style="font-weight:600;">General Email</strong>: pro@manit.ac.in
• <strong style="font-weight:600;">Web Portal</strong>: www.manit.ac.in`
    }
];

// --- Fallback Response ---
const DEFAULT_RESPONSE = `<span class="academic-heading">Search Query Processed</span>
I couldn't locate details matching those specific terms. However, you can find exhaustive resources on the official <strong style="font-weight:600;">MANIT Bhopal Portal</strong> (www.manit.ac.in).

Alternatively, try asking about:
• Placement statistics or top recruiters
• Hostels, mess facilities, or campus size
• Academic departments (CSE, ECE, Architecture)`;

// --- DOM Elements ---
const chatForm = document.getElementById('chat-form');
const chatInput = document.getElementById('chat-input');
const sendButton = document.getElementById('send-button');
const chatArea = document.getElementById('chat-area');
const chatWrapper = document.getElementById('chat-wrapper');

// --- Input Visual States ---
chatInput.addEventListener('input', () => {
    if (chatInput.value.trim().length > 0) {
        sendButton.classList.add('active');
    } else {
        sendButton.classList.remove('active');
    }
});

// --- Chat Core Controls ---
chatForm.addEventListener('submit', (e) => {
    e.preventDefault();
    const queryText = chatInput.value.trim();
    if (!queryText) return;

    // Reset Input
    chatInput.value = '';
    sendButton.classList.remove('active');

    // Add User Message
    addUserMessage(queryText);

    // Disable input while bot processing
    toggleInputState(true);

    // Show Custom Loading State
    showLoadingState(async (loadingBubble, clearLoadingTimer) => {
        // Formulate Response
        const backendData = await getBotResponse(queryText);
        // 2. Kill the loading animation the exact millisecond the server responds
        clearLoadingTimer();
        loadingBubble.remove();

        const message= backendData.reply? backendData.reply: backendData
        const parsedHTML = marked.parse(message, { breaks: true });
        addBotMessage(parsedHTML);
    });
});

// --- UI Helpers ---

function scrollToBottom() {
    chatArea.scrollTop = chatArea.scrollHeight;
}

function toggleInputState(disabled) {
    chatInput.disabled = disabled;
    sendButton.disabled = disabled;
    if (disabled) {
        chatInput.blur();
    } else {
        chatInput.focus();
    }
}

function addUserMessage(text) {
    const msgDiv = document.createElement('div');
    msgDiv.className = 'message user-message';
    msgDiv.innerHTML = `<div class="message-content"></div>`;
    msgDiv.querySelector('.message-content').textContent = text;
    chatWrapper.appendChild(msgDiv);
    scrollToBottom();
}

/**
 * Creates and cycles loading text phrases
 */
function showLoadingState(callback) {
    const loadingDiv = document.createElement('div');
    loadingDiv.className = 'loading-bubble';
    loadingDiv.innerHTML = `
        <div class="loading-dots">
            <span class="loading-dot"></span>
            <span class="loading-dot"></span>
            <span class="loading-dot"></span>
        </div>
        <span class="loading-text-span" id="loading-text-span">Thinking...</span>
    `;
    chatWrapper.appendChild(loadingDiv);
    scrollToBottom();

    const loadingTextSpan = loadingDiv.querySelector('#loading-text-span');
    const phrases = ["Thinking...", "Searching MANIT Database...", "Processing Query..."];
    let phraseIndex = 0;

    // Cycle text phrase with visual fade
    const cycleInterval = setInterval(() => {
        loadingTextSpan.classList.add('fade-out');
        
        // Wait for CSS transition to fade out (300ms) before updating text and fading back in
        setTimeout(() => {
            phraseIndex = (phraseIndex + 1) % phrases.length;
            loadingTextSpan.textContent = phrases[phraseIndex];
            loadingTextSpan.classList.remove('fade-out');
        }, 300);

    }, 1200);

    // Provide the DOM node and a cleanup callback
    const clearLoadingTimer = () => {
        clearInterval(cycleInterval);
    };

    callback(loadingDiv, clearLoadingTimer);
}

/**
 * Maps input queries to responses in the database
 */
async function getBotResponse(user_query) {
    try{
        // Connect to port 8000 if opened as a local file or viewed on Live Preview (port 3000)
        const isDevEnv = window.location.protocol === 'file:' || window.location.port === '3000';
        const apiBaseUrl = isDevEnv ? 'http://127.0.0.1:8000' : '';
        const response= await fetch(`${apiBaseUrl}/chat`,{
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({query:user_query})
        })
        // 1. THE FIX: Catch server errors BEFORE parsing JSON
        if (!response.ok) {
            // Read the raw text (which will be your 401 Unauthorized message)
            const errorText = await response.text(); 
            console.error(`Backend Error (${response.status}):`, errorText);
            
            // Return a safe fallback dictionary so your UI doesn't crash
            return { reply: `Connection error: Server returned ${response.status}. Please check backend logs.` };
        }

        const data= await response.json()
        return data
    }

    catch(err){
        console.log("error in recieving output from server: ",err)
        return { reply: DEFAULT_RESPONSE };
    }
}

/**
 * Adds bot response directly and instantly to the chat area.
 */
function addBotMessage(htmlContent) {
    // Create container bubble
    const msgDiv = document.createElement('div');
    msgDiv.className = 'message bot-message';
    
    const contentDiv = document.createElement('div');
    contentDiv.className = 'message-content';
    contentDiv.innerHTML = htmlContent;
    msgDiv.appendChild(contentDiv);
    
    chatWrapper.appendChild(msgDiv);
    scrollToBottom();

    // Instantly restore user input state
    toggleInputState(false);
}