document.addEventListener('DOMContentLoaded', () => {
    const downloadCodeInput = document.getElementById('download_code_input');
    const downloadButton = document.getElementById('download_button');
    const downloadForm = document.getElementById('download_form');
    downloadCodeInput.addEventListener('beforeinput', (e) => {
        if (/^[a-zA-Z0-9-]+$/.test(e.data)) { return; }
        e.preventDefault();
        if (e.data === ' ') {
            downloadCodeInput.value += '-';
        }
    });
    const disableEnableDownload = () => { downloadButton.disabled = (downloadCodeInput.value === ''); };
    disableEnableDownload();
    downloadCodeInput.addEventListener('input', disableEnableDownload);
    downloadForm.addEventListener('submit', (e) => {
        if (downloadCodeInput.value === '') {
            e.preventDefault();
        } else {
            setTimeout(() => {
                downloadCodeInput.value = '';
                downloadButton.disabled = true;
            }, 0);
        }
    });
    downloadCodeInput.focus();
});