(() => {
    const normalizeUrl = (url) => {
        const next = new URL(url, window.location.origin);
        next.searchParams.set('partial', '1');
        return next.toString();
    };

    const renderError = (host, message) => {
        host.innerHTML = `
            <div class="window-app-shell um-shell">
                <div class="window-app-frame um-frame">
                    <main class="window-app-main um-main">
                        <div class="window-app-panel um-panel">
                            <section class="window-app-card um-card">
                                <p class="um-message is-error">${String(message || 'User Management konnte nicht geladen werden.')}</p>
                            </section>
                        </div>
                    </main>
                </div>
            </div>
        `;
    };

    const escapeHtml = (value) => String(value ?? '')
        .replaceAll('&', '&amp;')
        .replaceAll('<', '&lt;')
        .replaceAll('>', '&gt;')
        .replaceAll('"', '&quot;')
        .replaceAll("'", '&#39;');

    const bindUserPickers = (host) => {
        const dataNode = host.querySelector('#um-existing-users-data');
        if (!(dataNode instanceof HTMLScriptElement)) {
            return;
        }

        let users = [];
        try {
            const decoded = JSON.parse(dataNode.textContent || '[]');
            if (Array.isArray(decoded)) {
                users = decoded;
            }
        } catch (_error) {
            users = [];
        }

        const normalizedUsers = users.map((user) => ({
            username: String(user?.username || ''),
            display_name: String(user?.display_name || ''),
            email: String(user?.email || ''),
            group_dns: Array.isArray(user?.group_dns) ? user.group_dns.map((group) => String(group || '')) : [],
            search: [
                String(user?.username || ''),
                String(user?.display_name || ''),
                String(user?.email || ''),
            ].join(' ').toLowerCase(),
        })).filter((user) => user.username !== '');

        const closeAll = () => {
            host.querySelectorAll('[data-user-picker-list]').forEach((list) => {
                list.setAttribute('hidden', 'hidden');
                list.innerHTML = '';
            });
        };

        host.querySelectorAll('[data-user-picker]').forEach((picker) => {
            const input = picker.querySelector('[data-user-picker-input]');
            const list = picker.querySelector('[data-user-picker-list]');
            if (!(input instanceof HTMLInputElement) || !(list instanceof HTMLElement)) {
                return;
            }

            if (input.dataset.umPickerBound === '1') {
                return;
            }
            input.dataset.umPickerBound = '1';

            const syncGroupSelection = (username) => {
                const normalizedUsername = String(username || '').trim().toLowerCase();
                host.querySelectorAll('input[name="manual_group_dns[]"]').forEach((checkbox) => {
                    if (!(checkbox instanceof HTMLInputElement)) {
                        return;
                    }

                    checkbox.checked = false;
                });

                if (normalizedUsername === '') {
                    return;
                }

                const user = normalizedUsers.find((entry) => entry.username.toLowerCase() === normalizedUsername);
                if (!user) {
                    return;
                }

                const selectedGroups = new Set(user.group_dns);
                host.querySelectorAll('input[name="manual_group_dns[]"]').forEach((checkbox) => {
                    if (!(checkbox instanceof HTMLInputElement)) {
                        return;
                    }

                    checkbox.checked = selectedGroups.has(checkbox.value);
                });
            };

            const renderMatches = () => {
                const needle = input.value.trim().toLowerCase();
                const matches = normalizedUsers
                    .filter((user) => needle === '' || user.search.includes(needle))
                    .slice(0, needle === '' ? 80 : 25);

                list.innerHTML = '';
                if (matches.length === 0) {
                    list.innerHTML = '<div class="um-user-picker-empty">Keine passenden Benutzer gefunden.</div>';
                    list.hidden = false;
                    return;
                }

                list.innerHTML = matches.map((user) => `
                    <button class="um-user-picker-option" type="button" data-user-picker-value="${escapeHtml(user.username)}">
                        <strong>${escapeHtml(user.username)}</strong>
                        <span>${escapeHtml(user.display_name || 'Ohne Anzeigename')}</span>
                        <span>${escapeHtml(user.email || 'Keine E-Mail')}</span>
                    </button>
                `).join('');
                list.hidden = false;
            };

            input.addEventListener('focus', renderMatches);
            input.addEventListener('input', renderMatches);

            list.addEventListener('click', (event) => {
                const option = event.target.closest('[data-user-picker-value]');
                if (!(option instanceof HTMLElement)) {
                    return;
                }

                input.value = String(option.dataset.userPickerValue || '');
                list.hidden = true;
                list.innerHTML = '';
                syncGroupSelection(input.value);
                input.dispatchEvent(new Event('change', { bubbles: true }));
            });

            input.addEventListener('change', () => {
                syncGroupSelection(input.value);
            });

            if (input.value.trim() !== '') {
                syncGroupSelection(input.value);
            }
        });

        if (!host.dataset.umPickerOutsideBound) {
            host.dataset.umPickerOutsideBound = '1';
            document.addEventListener('click', (event) => {
                if (!(event.target instanceof Node) || !host.contains(event.target)) {
                    closeAll();
                    return;
                }

                const insidePicker = event.target instanceof Element && event.target.closest('[data-user-picker]');
                if (!insidePicker) {
                    closeAll();
                }
            });
        }
    };

    const bindInteractions = (host, loadRoute) => {
        host.querySelectorAll('a[href]').forEach((link) => {
            if (link.dataset.umBound === '1') {
                return;
            }

            const href = String(link.getAttribute('href') || '');
            if (!href.startsWith('/admin/users/')) {
                return;
            }

            link.dataset.umBound = '1';
            link.addEventListener('click', (event) => {
                event.preventDefault();
                loadRoute(href);
            });
        });

        host.querySelectorAll('form[action]').forEach((form) => {
            if (form.dataset.umBound === '1') {
                return;
            }

            const action = String(form.getAttribute('action') || '');
            if (!action.startsWith('/admin/users/')) {
                return;
            }

            form.dataset.umBound = '1';
            form.addEventListener('submit', async (event) => {
                event.preventDefault();

                try {
                    host.classList.add('is-loading');
                    const response = await fetch(normalizeUrl(action), {
                        method: 'POST',
                        credentials: 'same-origin',
                        body: new FormData(form),
                    });

                    const html = await response.text();
                    if (!response.ok) {
                        throw new Error(`HTTP ${response.status}`);
                    }

                    host.innerHTML = html;
                    bindInteractions(host, loadRoute);
                    bindUserPickers(host);
                } catch (error) {
                    renderError(host, error?.message || 'Formular konnte nicht verarbeitet werden.');
                } finally {
                    host.classList.remove('is-loading');
                }
            });
        });
    };

    window.initUserManagementApp = function initUserManagementApp(host, options = {}) {
        if (!(host instanceof Element)) {
            return;
        }

        if (host.dataset.umAppBound === '1') {
            return;
        }

        host.dataset.umAppBound = '1';

        const entryRoute = String(options.entryRoute || '/admin/users/');
        const loadRoute = async (route) => {
            try {
                host.classList.add('is-loading');
                const response = await fetch(normalizeUrl(route), {
                    credentials: 'same-origin',
                    headers: { Accept: 'text/html' },
                });
                const html = await response.text();
                if (!response.ok) {
                    throw new Error(`HTTP ${response.status}`);
                }

                host.innerHTML = html;
                bindInteractions(host, loadRoute);
                bindUserPickers(host);
            } catch (error) {
                renderError(host, error?.message || 'User Management konnte nicht geladen werden.');
            } finally {
                host.classList.remove('is-loading');
            }
        };

        if (options.standalone) {
            bindInteractions(host, loadRoute);
            bindUserPickers(host);
            return;
        }

        loadRoute(entryRoute);
    };
})();