function calculate() {
    // Get values
    const dTax = parseFloat(document.getElementById('dTax').value) || 0;
    const dPrice = parseFloat(document.getElementById('dPrice').value) || 0;
    const dCons = parseFloat(document.getElementById('dCons').value) || 0;
    
    const pTax = parseFloat(document.getElementById('pTax').value) || 0;
    const pPrice = parseFloat(document.getElementById('pPrice').value) || 0;
    const pCons = parseFloat(document.getElementById('pCons').value) || 0;
    
    const annualKm = parseFloat(document.getElementById('annualKm').value) || 0;

    // 1. Calculate Break-Even Petrol Consumption
    // Formula: P_Cons = (100 * (dTax - pTax) / (annualKm * pPrice)) + (dCons * dPrice / pPrice)
    const taxDiff = dTax - pTax;
    const breakEven = (100 * taxDiff / (annualKm * pPrice)) + (dCons * dPrice / pPrice);
    
    document.getElementById('displayKm').innerText = annualKm.toLocaleString();
    document.getElementById('breakEvenCons').innerText = isFinite(breakEven) ? breakEven.toFixed(2) : "0.00";

    // 2. Calculate Minimum Diesel Price where user's pCons equals break-even consumption
    // We want to solve for dPrice such that: pCons = (100 * taxDiff / (annualKm * pPrice)) + (dCons * dPrice / pPrice)
    // Rearranging for dPrice:
    // pCons - (100 * taxDiff / (annualKm * pPrice)) = (dCons * dPrice / pPrice)
    // dPrice = (pCons - (100 * taxDiff / (annualKm * pPrice))) * pPrice / dCons
    
    let minDieselPrice = 0;
    if (dCons > 0 && annualKm > 0 && pPrice > 0) {
        const firstTerm = 100 * taxDiff / (annualKm * pPrice);
        const secondTerm = pCons - firstTerm;
        minDieselPrice = secondTerm * pPrice / dCons;
    }
    
    document.getElementById('minDieselPrice').innerText = isFinite(minDieselPrice) ? minDieselPrice.toFixed(2) : "0.00";

    // 3. Generate Table
    const distances = [5000, 10000, 15000, 20000, 25000, 30000];
    const tbody = document.querySelector('#comparisonTable tbody');
    tbody.innerHTML = '';

    distances.forEach(km => {
        const dTotal = dTax + (km * dCons / 100 * dPrice);
        const pTotal = pTax + (km * pCons / 100 * pPrice);
        const diff = pTotal - dTotal;
        
        const row = document.createElement('tr');
        const diffClass = diff >= 0 ? 'saving' : 'loss';
        const diffText = diff >= 0 ? `Saving €${diff.toFixed(2)}` : `Loss €${Math.abs(diff).toFixed(2)}`;

        row.innerHTML = `
            <td>${km.toLocaleString()} km</td>
            <td>€${dTotal.toFixed(2)}</td>
            <td>€${pTotal.toFixed(2)}</td>
            <td class="${diffClass}">${diffText}</td>
        `;
        tbody.appendChild(row);
    });
}

// Initial run
calculate();

function toggleTheme() {
    const body = document.body;
    body.classList.toggle('dark-mode');
    
    // Save preference to localStorage
    if (body.classList.contains('dark-mode')) {
        localStorage.setItem('theme', 'dark');
    } else {
        localStorage.setItem('theme', 'light');
    }
}

// Check for saved theme preference and set dark mode by default
document.addEventListener('DOMContentLoaded', function() {
    const savedTheme = localStorage.getItem('theme');
    if (savedTheme === 'dark' || !savedTheme) { // Default to dark mode
        document.body.classList.add('dark-mode');
    }
});