/**
 * Output formatting helpers.
 *
 * Two modes:
 *  - JSON mode (--json flag): print raw JSON, nothing else.
 *  - Human mode (default): pretty-print tables / key-values.
 */
export interface OutputOptions {
  json: boolean;
}

/** Print as JSON (compact). Safe for agent parsing. */
export function printJson(value: unknown): void {
  process.stdout.write(JSON.stringify(value) + '\n');
}

/** Print a human-readable table. columns: [{key, header, width?}]; rows: object[]. */
export function printTable(
  columns: Array<{ key: string; header: string }>,
  rows: Array<Record<string, unknown>>
): void {
  const headers = columns.map((c) => c.header);
  const widths = columns.map((c) => Math.max(c.header.length, ...rows.map((r) => String(r[c.key] ?? '').length)));
  const sep = widths.map((w) => '-'.repeat(w)).join('  ');
  const fmtRow = (r: Record<string, unknown>) =>
    columns.map((c, i) => String(r[c.key] ?? '').padEnd(widths[i])).join('  ');
  process.stdout.write(headers.map((h, i) => h.padEnd(widths[i])).join('  ') + '\n');
  process.stdout.write(sep + '\n');
  rows.forEach((r) => process.stdout.write(fmtRow(r) + '\n'));
}

/** Print key: value pairs vertically. */
export function printKv(pairs: Array<[string, unknown]>): void {
  const width = Math.max(...pairs.map(([k]) => k.length));
  pairs.forEach(([k, v]) => {
    const val = typeof v === 'object' && v !== null ? JSON.stringify(v) : String(v ?? '');
    process.stdout.write(`${k.padEnd(width)}  ${val}\n`);
  });
}

/** Truncate a long string to width, appending ellipsis. */
export function truncate(s: unknown, width = 40): string {
  const str = String(s ?? '');
  return str.length > width ? str.slice(0, width - 1) + '…' : str;
}