const DEFAULT_HEADER_SELECTOR = [...new Array(6)]
    .map((_, i) => `[vp-content] h${i + 1}`)
    .join(',');
export const resolveHeaders = (headers, levels = 2) => {
    if (levels === false) {
        return [];
    }
    const [high, low] = typeof levels === 'number'
        ? [levels, levels]
        : levels === 'deep'
            ? [2, 6]
            : levels;
    const allowedHeaders = headers.filter((header) => header.level >= high && header.level <= low);
    const result = [];
    // eslint-disable-next-line no-restricted-syntax
    outer: for (let i = 0; i < allowedHeaders.length; i++) {
        const current = allowedHeaders[i];
        if (i === 0) {
            result.push(current);
        }
        else {
            for (let j = i - 1; j >= 0; j--) {
                const prev = allowedHeaders[j];
                if (prev.level < current.level) {
                    prev.children.push(current);
                    continue outer;
                }
            }
            result.push(current);
        }
    }
    return result;
};
const serializeHeader = (h, ignore = []) => {
    let text;
    if (ignore.length) {
        const clone = h.cloneNode(true);
        clone.querySelectorAll(ignore.join(',')).forEach((el) => {
            el.remove();
        });
        text = clone.textContent || '';
    }
    else {
        text = h.textContent || '';
    }
    return text.trim();
};
export const getHeadersFromDom = (selector = DEFAULT_HEADER_SELECTOR, ignore = []) => Array.from(document.querySelectorAll(selector))
    .filter((el) => el.id && el.hasChildNodes())
    .map((el) => ({
    element: el,
    title: serializeHeader(el, ignore),
    link: `#${el.id}`,
    slug: el.id,
    level: Number(el.tagName[1]),
    children: [],
}));
/**
 * Get headers of current page.
 *
 * 获取当前页面的标题
 *
 * @param options - Options for getting headers / 获取标题的选项
 *
 * @returns Array of header items / 标题项数组
 */
export const getHeaders = ({ selector = DEFAULT_HEADER_SELECTOR, levels = 2, ignore = [], } = {}) => resolveHeaders(getHeadersFromDom(selector, ignore), levels);