/**
 * The control plane's health check, run by celilo rather than by a hook.
 *
 * ## Why this is not a hook
 *
 * It was `modules/celilo-mgmt/scripts/health-check.ts` until celilo#1225, and
 * it failed under the hook jail in the way that is worst: **it reported a
 * healthy fleet's database missing.** The hook asked `existsSync(db_path)`,
 * the jail does not bind celilo's data directory (deliberately — that is where
 * `master.key` and `celilo.db` live), so the answer was `false` and the deploy
 * failed on a file that was sitting right there. Its other two checks shelled
 * out to the CLI, which a jailed hook cannot reach at all.
 *
 * Every one of those was celilo inspecting itself. Deleting `on_install` for
 * that reason and leaving this behind would have fixed one hook and left the
 * deploy failing on the next.
 *
 * ## What replaced it is stronger, not merely relocated
 *
 * The hook asked two questions: does a file exist, and is this hostname in
 * `celilo machine list`. `runFleetChecks` is what celilo already runs for
 * `celilo system doctor`, and it asks eight, including the four-part dispatcher
 * probe whose whole point is that "a process is up" reports green on a
 * dispatcher that is unsupervised, on stale code, and delivering nothing.
 *
 * So the module gets a better check by having none of its own. That is the
 * outcome to keep in mind before anyone adds a hook back: a health_check hook
 * here can only re-ask, worse, questions celilo can answer directly.
 */

import type { DbClient } from '../db/client';
import { withCeliloBusAsync } from './control-plane-bootstrap';
import { type FleetFinding, runFleetChecks } from './fleet-checks';
import type { HealthCheckItem } from './health-runner';

/** `FleetFinding`'s three statuses in `HealthCheckItem`'s vocabulary. */
const STATUS: Record<FleetFinding['status'], HealthCheckItem['status']> = {
  ok: 'pass',
  warn: 'warn',
  fail: 'fail',
};

/**
 * One finding as a health item.
 *
 * `detail` and `remediation` are folded into `details` rather than dropped:
 * the health path is what runs unattended every fifteen minutes, so the line
 * telling an operator what to DO has to survive the mapping.
 */
export function findingAsHealthCheck(finding: FleetFinding): HealthCheckItem {
  const details = [
    ...finding.detail,
    ...(finding.remediation ? [`Fix: ${finding.remediation}`] : []),
  ];
  return {
    name: finding.id,
    status: STATUS[finding.status],
    message: finding.summary,
    ...(details.length > 0 ? { details: details.join('\n') } : {}),
  };
}

/** Run celilo's own fleet checks and report them as the control plane's health. */
export async function controlPlaneHealthChecks(db: DbClient): Promise<HealthCheckItem[]> {
  const findings = await withCeliloBusAsync((bus) => runFleetChecks(bus, db));
  return findings.map(findingAsHealthCheck);
}