(function () {
    'use strict';

    const COLLAPSED_KEY = 'sidebar-collapsed';
    const sidebar = document.getElementById('app-sidebar');
    const contentWrapper = document.getElementById('content-wrapper');
    const toggleBtn = document.getElementById('sidebarToggle');

    if (!sidebar) return;

    function applyCollapsed(collapsed) {
        sidebar.classList.toggle('collapsed', collapsed);
        contentWrapper.classList.toggle('sidebar-collapsed', collapsed);
    }

    // Restore saved state instantly — suppress transitions so there's no
    // collapse animation flash on every page navigation.
    sidebar.style.transition = 'none';
    contentWrapper.style.transition = 'none';
    if (toggleBtn) toggleBtn.style.transition = 'none';
    applyCollapsed(localStorage.getItem(COLLAPSED_KEY) === '1');
    // Re-enable transitions after one frame so the toggle button still animates.
    requestAnimationFrame(function () {
        requestAnimationFrame(function () {
            sidebar.style.transition = '';
            contentWrapper.style.transition = '';
            if (toggleBtn) toggleBtn.style.transition = '';
        });
    });

    if (toggleBtn) {
        toggleBtn.addEventListener('click', function () {
            const nowCollapsed = !sidebar.classList.contains('collapsed');
            applyCollapsed(nowCollapsed);
            localStorage.setItem(COLLAPSED_KEY, nowCollapsed ? '1' : '0');
        });
    }
})();