// ... existing variables ...
const BUY_RATE = 88;
const SELL_RATE = 87; // Sell rate thoda kam rakhte hain profit ke liye
let mode = 'BUY'; // Default

function setMode(m) {
    mode = m;
    // UI Toggle Logic...
    if(m == 'BUY') {
        document.getElementById('mainBtn').innerText = "Proceed to Buy";
        document.querySelector('.label-addr').innerText = "Your Wallet Address (TRC20)";
        document.getElementById('addr').placeholder = "Paste your USDT Address";
        document.querySelector('.rate-tag').innerText = "1 USDT = ₹" + BUY_RATE;
    } else {
        document.getElementById('mainBtn').innerText = "Proceed to Withdraw";
        document.querySelector('.label-addr').innerText = "Your UPI ID (For Payment)";
        document.getElementById('addr').placeholder = "e.g. user@ybl";
        document.querySelector('.rate-tag').innerText = "1 USDT = ₹" + SELL_RATE;
    }
    document.getElementById('inr').value = '';
    document.getElementById('usdt').value = '';
}

function calc() {
    let v = document.getElementById('inr').value;
    let rate = mode == 'BUY' ? BUY_RATE : SELL_RATE;
    
    if(v > 0) {
        document.getElementById('usdt').value = (v / rate).toFixed(2);
        let addr = document.getElementById('addr').value;
        if(v >= 500 && addr.length > 3) document.getElementById('mainBtn').disabled = false;
        else document.getElementById('mainBtn').disabled = true;
    }
}

function submitOrder() {
    // ... UI Hiding Logic ...

    let fd = new FormData();
    fd.append('action', 'create');
    fd.append('type', mode); // Sends BUY or SELL
    fd.append('inr', document.getElementById('inr').value);
    fd.append('usdt', document.getElementById('usdt').value);
    
    // IMPORTANT: Yeh line check karo. 'addr' field ab multipurpose hai.
    // Buy me ye Wallet Address hai, Sell me ye UPI ID hai.
    fd.append('details', document.getElementById('addr').value); 
    
    fd.append('proof', document.getElementById('file').files[0]);

    // Send to PHP
    fetch('api.php', {method:'POST', body:fd})
    .then(r=>r.json())
    .then(d=>{
        if(d.status=='success'){
            orderId = d.id;
            // ... Start Polling ...
        }
    });
}