/**
 * Mock KSP telemetry publisher.
 *
 * Generates a universe snapshot at a configurable cadence (default 1Hz)
 * using the KERBOL_SYSTEM catalog and a starter fleet of vessels. The
 * vessel orbits are propagated forward in time using the
 * @kerbal-rt/orbital-math library — exactly the same math the live-map
 * uses to render the scene, so the publisher and renderer stay in sync.
 *
 * Each generated snapshot is POSTed to the API at /api/v1/ingest.
 * Connect the hub's /debug page (or any WS client) and you'll see the
 * state update in real time.
 */
import { meanMotion } from '@kerbal-rt/orbital-math';
import type {
  CelestialBody,
  KeplerianElements,
  UniverseSnapshot,
  Vessel,
} from '@kerbal-rt/shared-types';
import { KERBOL_SYSTEM, STARTER_FLEET } from './catalog.js';

const API_URL = process.env.MOCK_API_URL ?? 'http://localhost:4000';
const API_KEY = process.env.INGEST_API_KEY ?? '';
const INTERVAL_MS = Number(process.env.MOCK_INTERVAL_MS ?? 1000);
const START_UT = Number(process.env.MOCK_START_UT ?? 4_700_000);

interface MutableVessel {
  id: string;
  name: string;
  type: string | null;
  owner: string | null;
  situation: Vessel['situation'];
  status: Vessel['status'];
  referenceBodyId: string;
  /** Working keplerian elements at the last emitted time. */
  elements: KeplerianElements;
  createdAt: string;
  retiredAt: string | null;
}

const bodies: CelestialBody[] = KERBOL_SYSTEM;
const bodiesById = new Map(bodies.map((b) => [b.id, b]));

const vessels: MutableVessel[] = STARTER_FLEET.map((v) => ({
  id: v.id,
  name: v.name,
  type: v.type,
  owner: v.owner,
  situation: v.situation,
  status: v.status,
  referenceBodyId: v.referenceBodyId,
  elements: { ...v.initialOrbit, epoch: START_UT },
  createdAt: v.createdAt,
  retiredAt: null,
}));

let currentUt = START_UT;
let snapshotCount = 0;
let lastError: string | null = null;

async function publish(snap: UniverseSnapshot): Promise<void> {
  const headers: Record<string, string> = { 'content-type': 'application/json' };
  if (API_KEY) headers['x-api-key'] = API_KEY;

  try {
    const res = await fetch(`${API_URL}/api/v1/ingest`, {
      method: 'POST',
      headers,
      body: JSON.stringify(snap),
    });
    if (!res.ok) {
      lastError = `HTTP ${res.status}`;
    } else {
      lastError = null;
    }
  } catch (err) {
    lastError = String((err as Error).message ?? err);
  }
}

function buildSnapshot(ut: number): UniverseSnapshot {
  // Advance each vessel's mean anomaly by n·dt from its last known epoch.
  for (const v of vessels) {
    const ref = bodiesById.get(v.referenceBodyId);
    if (!ref) continue;
    const dt = ut - v.elements.epoch;
    if (dt !== 0) {
      const n = meanMotion(v.elements.semiMajorAxis, ref.gravitationalParameter);
      v.elements = {
        ...v.elements,
        meanAnomalyAtEpoch: v.elements.meanAnomalyAtEpoch + n * dt,
        epoch: ut,
      };
    }
  }

  const vesselsOut: Vessel[] = vessels.map((v) => ({
    id: v.id,
    name: v.name,
    type: v.type,
    owner: v.owner,
    situation: v.situation,
    status: v.status,
    orbit: v.elements,
    referenceBodyId: v.referenceBodyId,
    createdAt: v.createdAt,
    retiredAt: v.retiredAt,
  }));

  return {
    ut,
    capturedAt: new Date().toISOString(),
    activeVesselId: vessels[0]?.id ?? null,
    bodies,
    vessels: vesselsOut,
    groundStations: [
      {
        id: 'montana',
        name: 'Montana DSN',
        bodyId: 'kerbin',
        lat: 47.0,
        lon: -110.0,
        alt: 1200,
      },
    ],
  };
}

async function tick(): Promise<void> {
  currentUt += INTERVAL_MS / 1000; // 1s wall = 1s KSP UT (1x speed)
  const snap = buildSnapshot(currentUt);
  snapshotCount += 1;
  await publish(snap);
}

function printStatus(): void {
  const status = lastError ? `ERROR (${lastError})` : 'OK';
  // eslint-disable-next-line no-console
  console.log(
    `[mock-telemetry] ut=${currentUt.toFixed(0)}  snapshots=${snapshotCount}  → ${API_URL}  ${status}`,
  );
}

async function main(): Promise<void> {
  // eslint-disable-next-line no-console
  console.log(
    `[mock-telemetry] starting — API=${API_URL} interval=${INTERVAL_MS}ms key=${API_KEY ? 'set' : 'unset'} start_ut=${START_UT}`,
  );
  // eslint-disable-next-line no-console
  console.log(`[mock-telemetry] publishing ${bodies.length} bodies, ${vessels.length} vessels`);

  // Send the first snapshot immediately, then on the interval.
  await tick();
  printStatus();
  setInterval(async () => {
    await tick();
  }, INTERVAL_MS);
  setInterval(printStatus, 10_000);
}

main().catch((err) => {
  // eslint-disable-next-line no-console
  console.error('[mock-telemetry] fatal:', err);
  process.exit(1);
});