#!/usr/bin/env node
import fs from 'node:fs';
import path from 'node:path';
import { Agent, fetch as undiciFetch } from 'undici';
import { createClient } from 'redis';

function loadEnvFile(filePath) {
  if (!fs.existsSync(filePath)) return;
  for (const line of fs.readFileSync(filePath, 'utf8').split('\n')) {
    const trimmed = line.trim();
    if (!trimmed || trimmed.startsWith('#')) continue;
    const idx = trimmed.indexOf('=');
    if (idx < 0) continue;
    const key = trimmed.slice(0, idx).trim();
    const value = trimmed.slice(idx + 1).trim();
    if (!process.env[key]) process.env[key] = value;
  }
}

function positiveInteger(value, fallback) {
  const n = Number(value);
  if (!Number.isFinite(n) || n <= 0) return fallback;
  return Math.floor(n);
}

function targetWorkers() {
  const targets = (process.env.TKMIND_API_TARGETS || process.env.TKMIND_API_TARGET || '')
    .split(',')
    .map((value) => value.trim())
    .filter(Boolean);
  return targets.map((target, index) => ({
    id: `goosed-${index + 1}`,
    target,
  }));
}

function workerKey(namespace, id, field) {
  return [namespace, 'worker', id, field].join(':');
}

async function probeTarget(target, timeoutMs) {
  const startedAt = Date.now();
  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), timeoutMs);
  const dispatcher = new Agent({ connect: { rejectUnauthorized: false } });
  try {
    const url = new URL('/status', target.endsWith('/') ? target : `${target}/`).toString();
    const res = await undiciFetch(url, {
      signal: controller.signal,
      dispatcher: url.startsWith('https://127.0.0.1') ? dispatcher : undefined,
      headers: process.env.TKMIND_SERVER__SECRET_KEY
        ? { 'X-Secret-Key': process.env.TKMIND_SERVER__SECRET_KEY }
        : undefined,
    });
    const body = (await res.text()).trim().slice(0, 80);
    return {
      ok: res.ok && body === 'ok',
      statusCode: res.status,
      body,
      latencyMs: Date.now() - startedAt,
      error: null,
    };
  } catch (err) {
    return {
      ok: false,
      statusCode: 0,
      body: '',
      latencyMs: Date.now() - startedAt,
      error: err instanceof Error ? err.message : String(err),
    };
  } finally {
    clearTimeout(timeout);
    dispatcher.close();
  }
}

async function writeHeartbeats(client, namespace, workers, options) {
  const now = Date.now();
  const results = [];
  for (const worker of workers) {
    const probe = await probeTarget(worker.target, options.timeoutMs);
    const ttlSeconds = Math.max(5, Math.ceil(options.ttlMs / 1000));
    const multi = client
      .multi()
      .set(workerKey(namespace, worker.id, 'heartbeat'), String(now), { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_at'), String(now), { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_source'), 'sidecar', { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_target'), worker.target, { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_ok'), probe.ok ? '1' : '0', { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_status_code'), String(probe.statusCode), { EX: ttlSeconds })
      .set(workerKey(namespace, worker.id, 'heartbeat_latency_ms'), String(probe.latencyMs), { EX: ttlSeconds });
    if (probe.error) {
      multi.set(workerKey(namespace, worker.id, 'heartbeat_error'), probe.error, { EX: ttlSeconds });
    } else {
      multi.del(workerKey(namespace, worker.id, 'heartbeat_error'));
    }
    await multi.exec();
    results.push({ ...worker, ...probe, heartbeatAt: now });
  }
  return results;
}

loadEnvFile(process.env.MEMIND_ENV_FILE || path.join(process.cwd(), '.env'));

const redisUrl = process.env.MEMIND_RUNTIME_REDIS_URL || 'redis://127.0.0.1:6379/0';
const namespace = process.env.MEMIND_RUNTIME_REDIS_NAMESPACE || 'memind:runtime';
const action = process.argv[2] || 'once';
const intervalMs = positiveInteger(process.env.MEMIND_RUNTIME_HEARTBEAT_INTERVAL_MS, 15_000);
const timeoutMs = positiveInteger(process.env.MEMIND_RUNTIME_HEARTBEAT_TIMEOUT_MS, 5_000);
const ttlMs = positiveInteger(process.env.MEMIND_RUNTIME_HEARTBEAT_TTL_MS, Math.max(45_000, intervalMs * 3));

if (!['once', 'serve'].includes(action)) {
  console.error('Usage: node scripts/runtime-worker-heartbeat.mjs <once|serve>');
  process.exit(2);
}

const workers = targetWorkers();
if (workers.length === 0) {
  console.error('No TKMIND_API_TARGETS configured');
  process.exit(2);
}

const client = createClient({ url: redisUrl });
client.on('error', (err) => {
  console.error(`Redis error: ${err instanceof Error ? err.message : err}`);
});
await client.connect();

let stopping = false;
const stop = async () => {
  stopping = true;
  await client.quit().catch(() => {});
};
process.on('SIGTERM', () => void stop().finally(() => process.exit(0)));
process.on('SIGINT', () => void stop().finally(() => process.exit(0)));

async function tick() {
  const result = await writeHeartbeats(client, namespace, workers, { timeoutMs, ttlMs });
  const payload = {
    ok: result.every((worker) => worker.ok),
    action,
    namespace,
    intervalMs: action === 'serve' ? intervalMs : undefined,
    timeoutMs,
    ttlMs,
    workers: result,
  };
  console.log(JSON.stringify(payload));
  return payload;
}

if (action === 'once') {
  const payload = await tick();
  await client.quit();
  process.exit(payload.ok ? 0 : 1);
}

await tick();
while (!stopping) {
  await new Promise((resolve) => setTimeout(resolve, intervalMs));
  if (!stopping) await tick().catch((err) => {
    console.error(err instanceof Error ? err.message : String(err));
  });
}