/**
 * `celilo dns` — operator views over celilo's DNS bookkeeping.
 *
 * `registrations` lists the dns_registrations ledger: every (provider,
 * fqdn) the framework has registered via dns_registrar.registerHost,
 * with every module that depends on it and when it was last re-asserted
 * by the provider's refresh_registrations hook. Read-only; names only
 * (module ids), never UUIDs. See
 * designs/DISPATCHER_DAEMON_AND_TIMER_EVENTS.md (B2b).
 */

import { getDb } from '../../db/client';
import { listDnsRegistrations } from '../../services/dns-registrations';
import type { CommandResult } from '../types';

function formatAge(from: Date | null, now: Date): string {
  if (!from) return 'never';
  const mins = Math.floor((now.getTime() - from.getTime()) / 60_000);
  if (mins < 1) return 'just now';
  if (mins < 60) return `${mins}m ago`;
  const hours = Math.floor(mins / 60);
  if (hours < 48) return `${hours}h ago`;
  return `${Math.floor(hours / 24)}d ago`;
}

export async function handleDnsRegistrations(
  _args: string[],
  flags: Record<string, string | boolean>,
): Promise<CommandResult> {
  const db = getDb();
  const provider = typeof flags.provider === 'string' ? flags.provider : undefined;
  const rows = listDnsRegistrations(db, { providerModuleId: provider });

  if (rows.length === 0) {
    const scope = provider ? ` for provider '${provider}'` : '';
    return {
      success: true,
      message: `No DNS registrations recorded${scope}\n\nRegistrations are recorded when a module registers a hostname via the dns_registrar capability (e.g. during deploy).`,
    };
  }

  const now = new Date();
  // No address column: the ledger stores none. What a name actually resolves
  // to publicly is what `celilo system audit`'s public_dns check reports, from
  // off-fleet — reading it back out of celilo's own table is what made a
  // nine-day outage invisible (design.md D1).
  const header = ['FQDN', 'KIND', 'PROVIDER', 'CONSUMERS', 'REGISTERED', 'REFRESHED'];
  const table = rows.map((r) => [
    r.fqdn,
    r.companion ? 'companion' : 'declared',
    r.providerModuleId,
    r.consumerModuleIds.join(', ') || '—',
    formatAge(r.registeredAt, now),
    formatAge(r.refreshedAt, now),
  ]);
  const widths = header.map((h, i) => Math.max(h.length, ...table.map((row) => row[i].length)));
  const render = (row: string[]) => row.map((cell, i) => cell.padEnd(widths[i])).join('  ');

  const lines = [render(header), ...table.map(render)];
  return { success: true, message: lines.join('\n'), data: rows };
}