/** Live, off-chain Wikipedia data. Text fields are plain strings, never HTML. */
export interface PageEnrichment {
  pageId: number;
  title: string;
  description: string | null;
  wikidataId: string | null;
  revisionId: number;
  pageBytes: number;
  /** Number of returned interlanguage links (a lower bound when truncated). */
  languageCount: number;
  languagesTruncated: boolean;
  categories: string[];
  categoriesTruncated: boolean;
  fetchedAt: string;
  pageviews: {
    status: 'available' | 'unavailable';
    /** Six completed UTC months, oldest first, identified as YYYY-MM. */
    months: { month: string; views: number }[];
    latestMonth: string;
    total: number | null;
    /** Latest completed month's views divided by its actual UTC day count. */
    dailyAverage: number | null;
    trendPercent: number | null;
  };
  stats: { attention: number | null; depth: number; reach: number };
}

/** Immutable numeric Wikipedia metrics committed to a minted block. */
export type MintStatsSnapshot = {
  capturedAt: string;
  revisionId: number;
  pageBytes: number;
  languageCount: number;
  languagesTruncated: boolean;
  pageviews: PageEnrichment['pageviews'];
  stats: PageEnrichment['stats'];
};

export function snapshotStats(data: PageEnrichment): MintStatsSnapshot {
  return {
    capturedAt: new Date().toISOString(),
    revisionId: data.revisionId,
    pageBytes: data.pageBytes,
    languageCount: data.languageCount,
    languagesTruncated: data.languagesTruncated,
    pageviews: { ...data.pageviews, months: data.pageviews.months.map(item => ({ ...item })) },
    stats: { ...data.stats },
  };
}

/** Attention uses the latest completed month's views, not the six-month total. */
export function deriveStats(pageBytes: number, languageCount: number, monthlyViews: number | null): PageEnrichment['stats'] {
  const score = (value: number, scale: number) => {
    if (!Number.isFinite(value) || value < 0) throw new RangeError('Invalid enrichment score input');
    return Math.min(100, Math.round(Math.log10(value + 1) / scale * 100));
  };
  return { attention: monthlyViews === null ? null : score(monthlyViews, 6),
    depth: score(pageBytes, 6), reach: score(languageCount, 3) };
}