Rebuild company overview analysis page

lib/server/sec-description.ts

@@ -0,0 +1,134 @@
+import type { Filing } from '@/lib/types';
+import { fetchPrimaryFilingText } from '@/lib/server/sec';
+
+type CacheEntry<T> = {
+  expiresAt: number;
+  value: T;
+};
+
+const DESCRIPTION_CACHE_TTL_MS = 1000 * 60 * 60 * 6;
+const DESCRIPTION_MAX_CHARS = 1_600;
+
+const descriptionCache = new Map<string, CacheEntry<string | null>>();
+
+function normalizeWhitespace(value: string) {
+  return value
+    .replace(/[ \t]+/g, ' ')
+    .replace(/\n{3,}/g, '\n\n')
+    .trim();
+}
+
+function clipAtSentenceBoundary(value: string, maxChars = DESCRIPTION_MAX_CHARS) {
+  if (value.length <= maxChars) {
+    return value;
+  }
+
+  const slice = value.slice(0, maxChars);
+  const sentenceBoundary = Math.max(
+    slice.lastIndexOf('. '),
+    slice.lastIndexOf('! '),
+    slice.lastIndexOf('? ')
+  );
+
+  if (sentenceBoundary > maxChars * 0.6) {
+    return slice.slice(0, sentenceBoundary + 1).trim();
+  }
+
+  const wordBoundary = slice.lastIndexOf(' ');
+  return (wordBoundary > maxChars * 0.7 ? slice.slice(0, wordBoundary) : slice).trim();
+}
+
+function cleanupExtractedSection(value: string) {
+  return clipAtSentenceBoundary(
+    normalizeWhitespace(
+      value
+        .replace(/\btable of contents\b/gi, ' ')
+        .replace(/\bitem\s+1\.?\s+business\b/gi, ' ')
+        .replace(/\bpart\s+i\b/gi, ' ')
+    )
+  );
+}
+
+function fallbackDescription(text: string) {
+  const paragraphs = text
+    .split(/\n{2,}/)
+    .map((paragraph) => normalizeWhitespace(paragraph))
+    .filter((paragraph) => paragraph.length >= 80)
+    .filter((paragraph) => !/^item\s+\d+[a-z]?\.?/i.test(paragraph))
+    .slice(0, 3);
+
+  if (paragraphs.length === 0) {
+    return null;
+  }
+
+  return clipAtSentenceBoundary(paragraphs.join(' '));
+}
+
+export function extractBusinessDescription(text: string) {
+  const normalized = normalizeWhitespace(text);
+  if (!normalized) {
+    return null;
+  }
+
+  const startMatch = /\bitem\s+1\.?\s+business\b/i.exec(normalized);
+  if (!startMatch || startMatch.index < 0) {
+    return fallbackDescription(normalized);
+  }
+
+  const afterStart = normalized.slice(startMatch.index + startMatch[0].length);
+  const endMatch = /\bitem\s+1a\.?\s+risk factors\b|\bitem\s+2\.?\s+properties\b|\bitem\s+2\.?\b/i.exec(afterStart);
+  const section = endMatch
+    ? afterStart.slice(0, endMatch.index)
+    : afterStart;
+  const extracted = cleanupExtractedSection(section);
+
+  if (extracted.length >= 120) {
+    return extracted;
+  }
+
+  return fallbackDescription(normalized);
+}
+
+export async function getCompanyDescription(
+  filing: Pick<Filing, 'accession_number' | 'cik' | 'filing_url' | 'primary_document'> | null
+) {
+  if (!filing) {
+    return null;
+  }
+
+  const cached = descriptionCache.get(filing.accession_number);
+  if (cached && cached.expiresAt > Date.now()) {
+    return cached.value;
+  }
+
+  try {
+    const document = await fetchPrimaryFilingText({
+      filingUrl: filing.filing_url,
+      cik: filing.cik,
+      accessionNumber: filing.accession_number,
+      primaryDocument: filing.primary_document ?? null
+    }, {
+      maxChars: 40_000
+    });
+    const description = document ? extractBusinessDescription(document.text) : null;
+
+    descriptionCache.set(filing.accession_number, {
+      value: description,
+      expiresAt: Date.now() + DESCRIPTION_CACHE_TTL_MS
+    });
+
+    return description;
+  } catch {
+    descriptionCache.set(filing.accession_number, {
+      value: null,
+      expiresAt: Date.now() + DESCRIPTION_CACHE_TTL_MS
+    });
+    return null;
+  }
+}
+
+export const __secDescriptionInternals = {
+  cleanupExtractedSection,
+  clipAtSentenceBoundary,
+  fallbackDescription
+};