function asArray(value) {
  return Array.isArray(value) ? value : [];
}

function hasSourceUrl(item) {
  return Boolean(item && (item.sourceUrl || item.webUrl || item.url));
}

function hasImage(item) {
  return Boolean(
    item &&
    (item.localCoverPath ||
      item.coverUrl ||
      (Array.isArray(item.imageUrls) && item.imageUrls.length))
  );
}

function hasText(item) {
  return Boolean(
    item &&
    String(item.contentExcerpt || item.rawExcerpt || item.content || item.desc || item.title || '').trim()
  );
}

function assessEvidenceQuality({ items, comments, itemLabel = '样本', collectionMode = 'sample' }) {
  const rows = asArray(items);
  const commentRows = asArray(comments);
  const sourceUrlCount = rows.filter(hasSourceUrl).length;
  const imageCount = rows.filter(hasImage).length;
  const textCount = rows.filter(hasText).length;
  const highLikeCommentCount = commentRows.filter(comment => Number(comment.likeCount || 0) > 0).length;

  let score = 0;
  if (rows.length >= 8) score += 2;
  else if (rows.length >= 3) score += 1;
  if (commentRows.length >= 50) score += 2;
  else if (commentRows.length >= 10) score += 1;
  if (sourceUrlCount >= Math.min(rows.length, 3)) score += 1;
  if (imageCount >= Math.min(rows.length, 3)) score += 1;
  if (highLikeCommentCount >= 3) score += 1;
  if (textCount >= Math.min(rows.length, 3)) score += 1;

  const grade = score >= 7 ? 'A' : score >= 4 ? 'B' : 'C';
  const canMakeBusinessDecision = grade === 'A' || (grade === 'B' && collectionMode === 'live');
  const recommendation = canMakeBusinessDecision
    ? '可以作为第一轮经营判断依据，但仍建议结合门店/销售/私域反馈校准。'
    : '只适合作为初步机会假设，不建议直接当最终经营结论。';

  return {
    grade,
    itemLabel,
    itemCount: rows.length,
    commentCount: commentRows.length,
    sourceUrlCount,
    imageCount,
    textCount,
    highLikeCommentCount,
    canMakeBusinessDecision,
    recommendation
  };
}

function buildEvidenceQualitySection(quality) {
  return [
    '## 证据质量门槛',
    '',
    `- 本轮证据质量：${quality.grade}`,
    `- ${quality.itemLabel}数量：${quality.itemCount}`,
    `- 评论数量：${quality.commentCount}`,
    `- 含原文/原视频链接：${quality.sourceUrlCount}`,
    `- 含图片/封面：${quality.imageCount}`,
    `- 含文本摘录：${quality.textCount}`,
    `- 含点赞评论：${quality.highLikeCommentCount}`,
    `- 是否适合直接做经营判断：${quality.canMakeBusinessDecision ? '适合第一轮判断' : '仅适合初步假设'}`,
    `- 使用建议：${quality.recommendation}`
  ];
}

function buildNoSampleFallbackMessage({ platformLabel, profile, examples = [] }) {
  const keywords = asArray(profile && profile.keywords).slice(0, 5).join('、') || '当前关键词';
  const exampleLines = examples.length ? examples.map(item => `- ${item}`) : [
    '- 换成更具体的品类词、场景词或城市词',
    '- 从产品词扩展到用户真实说法',
    '- 先用 sample 模式演示完整流程，但明确标注非真实采集'
  ];

  return [
    `本次 live 模式没有采到可用于分析的${platformLabel}样本。`,
    '',
    '这不代表行业没有机会，更可能是关键词过窄、平台内容表达不一样，或本轮上游没有返回可用内容。',
    '',
    '建议按这三步继续：',
    `1. 先保留当前方向：${keywords}`,
    '2. 自动换一组更贴近用户说法的关键词再试一次',
    '3. 如果仍然没有样本，降级到相关大词做第一轮机会假设，并明确标注“非真实采集/待验证”',
    '',
    '可尝试的关键词方向：',
    ...exampleLines
  ].join('\n');
}

module.exports = {
  assessEvidenceQuality,
  buildEvidenceQualitySection,
  buildNoSampleFallbackMessage
};