function stripHtml(text) {
    return String(text || '')
        .replace(/<[^>]+>/g, '')
        .trim();
}

/** 去掉末尾 [doi] 等杂质，返回纯 DOI */
function cleanDoiString(raw) {
    let text = String(raw || '').trim();
    if (!text) {
        return null;
    }
    text = text.replace(/\[doi\]$/i, '').trim();
    text = text.replace(/[.,;)\]]+$/g, '').trim();
    return text || null;
}

/** 从文献行数据中解析 DOI */
export function resolveReferenceDoi(row) {
    const candidates = [row && row.doilink, row && row.refer_doi, row && row.doi].filter(Boolean);
    for (let i = 0; i < candidates.length; i += 1) {
        const text = String(candidates[i]).trim();
        if (!text) {
            continue;
        }
        const match = text.match(/10\.\d{4,9}\/[^\s\[]+/i);
        if (match) {
            return cleanDoiString(match[0]);
        }
        if (/^10\.\d/i.test(text)) {
            return cleanDoiString(text);
        }
    }
    return null;
}

/** 从 book 类型文献中解析 ISBN */
export function resolveReferenceIsbn(row) {
    const raw = String((row && row.isbn) || '').trim();
    if (!raw) {
        return null;
    }
    const isbn13 = raw.match(/97[89][-\s.]?(?:\d[-\s.]?){9}[\dXx]/i);
    if (isbn13) {
        return isbn13[0].replace(/\s+/g, '-');
    }
    const isbn10 = raw.match(/(?<!\d)(?:\d[-\s.]?){9}[\dXx](?!\d)/i);
    if (isbn10) {
        return isbn10[0].replace(/\s+/g, '-');
    }
    const compact = raw.replace(/[^\dXx]/gi, '');
    if (compact.length === 10 || compact.length === 13) {
        return raw.replace(/\s+/g, ' ').trim();
    }
    return null;
}

export function resolveReferenceTitle(row) {
    if (!row) {
        return '';
    }
    return stripHtml(row.title || row.refer_frag || '');
}

/**
 * 生成 journal/other 文献跳转链接
 * @param {string|null|undefined} doi - 文献 DOI
 * @param {string} title - 文献标题（无 DOI 时用于搜索）
 */
export function getReferenceLinks(doi, title) {
    const normalizedDoi = cleanDoiString(doi);
    const normalizedTitle = stripHtml(title);
    const encodedTitle = encodeURIComponent(normalizedTitle);

    const pubmedLink = normalizedDoi
        ? `https://pubmed.ncbi.nlm.nih.gov/?term=${encodeURIComponent(normalizedDoi)}`
        : null;

    const scholarLink = normalizedDoi
        ? `https://scholar.google.com/scholar?q=${encodeURIComponent(normalizedDoi)}`
        : `https://scholar.google.com/scholar?q=${encodedTitle}`;

    const doiLink = normalizedDoi ? `https://doi.org/${encodeURIComponent(normalizedDoi)}` : null;

    return {
        pubmedLink,
        scholarLink,
        doiLink,
        googleLink: null,
        isBook: false
    };
}

/** book 类型：用 ISBN 在 Google 检索 */
export function getBookReferenceLinks(row) {
    const isbn = resolveReferenceIsbn(row);
    const title = resolveReferenceTitle(row);
    const searchQuery = isbn || title;
    const encodedQuery = encodeURIComponent(searchQuery);

    return {
        pubmedLink: null,
        scholarLink: null,
        doiLink: null,
        googleLink: searchQuery ? `https://www.google.com/search?q=${encodedQuery}` : null,
        isBook: true,
        searchQuery
    };
}

export function getReferenceLinksFromRow(row) {
    if (row && row.refer_type === 'book') {
        return getBookReferenceLinks(row);
    }
    return getReferenceLinks(resolveReferenceDoi(row), resolveReferenceTitle(row));
}