function validateForm() {
    var departure = document.getElementById('departure').value;
    var destination = document.getElementById('destination').value;
    var warning = document.getElementById('destination-warning');
    if (departure === destination) {
        warning.textContent = '出发地和目的地不能相同';
        return false;
    } else {
        warning.textContent = '';
    }
    return true;
}

function increment() {
    var passengers = document.getElementById("passengers");
    var value = parseInt(passengers.value, 10);
    if (value < 50) {
        passengers.value = value + 1;
    }
}

function decrement() {
    var passengers = document.getElementById("passengers");
    var value = parseInt(passengers.value, 10);
    if (value > 1) {
        passengers.value = value - 1;
    }
}

document.addEventListener('DOMContentLoaded', function() {
    // Set default date to tomorrow
    var departureDate = document.getElementById('departure-date');
    if (!departureDate.value) {
        var today = new Date();
        var tomorrow = new Date(today);
        tomorrow.setDate(tomorrow.getDate() + 1);
        var month = ('0' + (tomorrow.getMonth() + 1)).slice(-2);
        var day = ('0' + tomorrow.getDate()).slice(-2);
        var year = tomorrow.getFullYear();
        departureDate.value = `${year}-${month}-${day}`;
    }
});