let activeDialog = null;

function ensureDialogRoot() {
    let root = document.getElementById('project-dialog-root');
    if (!root) {
        root = document.createElement('div');
        root.id = 'project-dialog-root';
        document.body.appendChild(root);
    }
    return root;
}

export function showDialog({ title, message, confirmLabel = 'Подтвердить', cancelLabel = 'Отмена', danger = false, input = null }) {
    activeDialog?.close(false);
    const root = ensureDialogRoot();
    const previousFocus = document.activeElement;
    root.innerHTML = `
        <div class="project-dialog-backdrop">
            <section class="project-dialog" role="dialog" aria-modal="true" aria-labelledby="project-dialog-title" aria-describedby="project-dialog-message">
                <header>
                    <h2 id="project-dialog-title">${escapeText(title || 'Подтвердите действие')}</h2>
                    <button type="button" class="btn btn-icon-md btn-ghost" data-dialog-cancel aria-label="Закрыть">×</button>
                </header>
                <p id="project-dialog-message">${escapeText(message || '')}</p>
                ${input ? `<label class="project-dialog-field"><span>${escapeText(input.label || 'Комментарий')}</span><textarea data-dialog-input rows="4" maxlength="${Number(input.maxlength || 2000)}" placeholder="${escapeText(input.placeholder || '')}">${escapeText(input.value || '')}</textarea></label>` : ''}
                <div class="project-dialog-error" data-dialog-error role="alert"></div>
                <footer>
                    ${cancelLabel ? `<button type="button" class="btn btn-md btn-secondary" data-dialog-cancel>${escapeText(cancelLabel)}</button>` : ''}
                    <button type="button" class="btn btn-md ${danger ? 'btn-danger' : 'btn-primary'}" data-dialog-confirm>${escapeText(confirmLabel)}</button>
                </footer>
            </section>
        </div>
    `;
    const backdrop = root.firstElementChild;
    const dialog = backdrop.querySelector('.project-dialog');
    const inputElement = dialog.querySelector('[data-dialog-input]');

    return new Promise(resolve => {
        const close = result => {
            document.removeEventListener('keydown', handleKeydown);
            root.innerHTML = '';
            activeDialog = null;
            previousFocus?.focus?.();
            resolve(result);
        };
        activeDialog = { close };
        const cancel = () => close(input ? null : false);
        const confirm = () => {
            if (input?.required && !inputElement?.value.trim()) {
                dialog.querySelector('[data-dialog-error]').textContent = input.requiredMessage || 'Заполните поле';
                inputElement?.focus();
                return;
            }
            close(input ? inputElement.value.trim() : true);
        };
        const handleKeydown = event => {
            if (event.key === 'Escape') cancel();
            if (event.key === 'Tab') trapFocus(event, dialog);
        };
        document.addEventListener('keydown', handleKeydown);
        dialog.querySelectorAll('[data-dialog-cancel]').forEach(button => button.addEventListener('click', cancel));
        dialog.querySelector('[data-dialog-confirm]').addEventListener('click', confirm);
        backdrop.addEventListener('click', event => {
            if (event.target === backdrop) cancel();
        });
        window.setTimeout(() => (inputElement || dialog.querySelector('[data-dialog-confirm]')).focus(), 0);
    });
}

export function confirmAction(options) {
    return showDialog(options);
}

export function promptAction(options) {
    return showDialog({ ...options, input: options.input || { label: 'Комментарий' } });
}

export function alertAction(options) {
    return showDialog({ ...options, cancelLabel: null, confirmLabel: options.confirmLabel || 'Понятно' });
}

function trapFocus(event, root) {
    const focusable = [...root.querySelectorAll('button:not([disabled]), textarea:not([disabled]), input:not([disabled]), select:not([disabled]), [tabindex]:not([tabindex="-1"])')];
    if (!focusable.length) return;
    const first = focusable[0];
    const last = focusable.at(-1);
    if (event.shiftKey && document.activeElement === first) {
        event.preventDefault();
        last.focus();
    } else if (!event.shiftKey && document.activeElement === last) {
        event.preventDefault();
        first.focus();
    }
}

function escapeText(value) {
    return String(value ?? '')
        .replaceAll('&', '&amp;')
        .replaceAll('<', '&lt;')
        .replaceAll('>', '&gt;')
        .replaceAll('"', '&quot;')
        .replaceAll("'", '&#039;');
}