let lastSelectedIndex = null;

function toggleSelection(element) {
    const elements = Array.from(document.getElementsByClassName('icon-text'));
    const index = elements.indexOf(element);

    if (document.body.classList.contains('shift-pressed') && lastSelectedIndex !== null) {
        const [start, end] = [lastSelectedIndex, index].sort((a, b) => a - b);
        let allSelected = true;
        for (let i = start; i <= end; i++) {
            if (!elements[i].classList.contains('selected')) {
                allSelected = false;
                break;
            }
        }
        for (let i = start; i <= end; i++) {
            if (allSelected) {
                elements[i].classList.remove('selected');
                elements[i].classList.add('unselected');
            } else {
                elements[i].classList.add('selected');
                elements[i].classList.remove('unselected');
            }
        }
        lastSelectedIndex = null;

        const elements2 = Array.from(document.getElementsByClassName('icon-text'));
        for (let i = 0; i < elements2.length; i++) {
            elements2[i].classList.remove('shiftselected');
        }
    } else if (document.body.classList.contains('shift-pressed') && lastSelectedIndex === null) {
        lastSelectedIndex = index;
        element.classList.toggle('shiftselected');
    } else {
        element.classList.toggle('selected');
        element.classList.toggle('unselected');
    }
    toggleSendButton();
}

function getSelectedModelsIDs() {
    var selectedModelsIDs = [];
    var selectedModels = document.getElementsByClassName('selected');
    for (var i = 0; i < selectedModels.length; i++) {
        selectedModelsIDs.push(selectedModels[i].getAttribute('data-id'));
    }
    return selectedModelsIDs.length > 0 ? JSON.stringify(selectedModelsIDs) : '[]';
}

function toggleSendButton() {
    var selectedModels = document.getElementsByClassName('selected');
    var sendButton = document.querySelector('button[disabled]');
    sendButton.disabled = selectedModels.length === 0;
}