export interface CoverageEntry {
  instrument: string;
  market?: string;
  asset_type?: string;
  requested_start?: string | null;
  requested_end?: string | null;
  actual_start?: string | null;
  actual_end?: string | null;
  row_count?: number;
  warnings?: string[];
}

export interface CoverageSummary {
  common: { start: string | null; end: string | null };
  warnings: string[];
}

export function summarizeCoverage(entries: CoverageEntry[]): CoverageSummary {
  const warnings: string[] = [];
  const withData = entries.filter((e) => (e.row_count ?? 0) > 0 && e.actual_start && e.actual_end);
  for (const e of entries) {
    if ((e.row_count ?? 0) === 0) {
      warnings.push(`${e.instrument} 没有返回任何数据行`);
    } else if (!e.actual_start || !e.actual_end) {
      warnings.push(`${e.instrument} 数据区间不完整`);
    }
  }
  let common: { start: string | null; end: string | null } = { start: null, end: null };
  if (withData.length > 0) {
    const starts = withData.map((e) => e.actual_start as string).sort();
    const startsAsc = [...starts];
    const earliest = startsAsc[0];
    const lateStart = starts[starts.length - 1];
    if (lateStart > earliest) {
      const owner = withData.find((e) => e.actual_start === lateStart);
      if (owner) {
        warnings.push(`${owner.instrument} 起始数据较其他标的更晚（${lateStart}）`);
      }
    }
    const ends = withData.map((e) => e.actual_end as string);
    const commonEnd = ends.sort()[0];
    const earlyOwners = withData.filter((e) => e.actual_end === commonEnd);
    const otherEnds = withData.filter((e) => (e.actual_end as string) > commonEnd);
    if (otherEnds.length > 0) {
      for (const e of earlyOwners) {
        warnings.push(`${e.instrument} 较早结束（${commonEnd}），造成共有区间缺失`);
      }
    }
    common = { start: lateStart, end: commonEnd };
  }
  return { common, warnings };
}