const express = require("express");
const mqtt = require("mqtt");
const path = require("path");

const PORT = process.env.PORT || 3000;

const BUTTON_KEYS = ["start1", "stop1", "start2", "stop2"];

const state = {
  brokerUrl: process.env.BROKER_URL || "mqtt://192.168.1.209:1883",
  connected: false,
  lastError: null,
  heartbeatEnabled: true,
  heartbeatIntervalMs: 3000,
  buttons: {
    start1: { mac: "AA:BB:CC:DD:EE:01", voltage: 3700 },
    stop1:  { mac: "AA:BB:CC:DD:EE:02", voltage: 3700 },
    start2: { mac: "AA:BB:CC:DD:EE:03", voltage: 3700 },
    stop2:  { mac: "AA:BB:CC:DD:EE:04", voltage: 3700 },
  },
  log: [],
};

let client = null;
let heartbeatTimer = null;
let bootTime = Date.now();

function logEvent(direction, text) {
  const entry = { t: Date.now(), direction, text };
  state.log.push(entry);
  if (state.log.length > 200) state.log.shift();
  const arrow = direction === "out" ? "→" : direction === "in" ? "←" : "·";
  console.log(`[${new Date(entry.t).toISOString()}] ${arrow} ${text}`);
}

function publish(topic, payload) {
  if (!client || !state.connected) {
    logEvent("err", `publish abgelehnt (nicht verbunden): ${topic}`);
    return false;
  }
  const body = typeof payload === "string" ? payload : JSON.stringify(payload);
  client.publish(topic, body, { qos: 0 }, (err) => {
    if (err) logEvent("err", `publish fehlgeschlagen ${topic}: ${err.message}`);
  });
  logEvent("out", `${topic}  ${body}`);
  return true;
}

function startHeartbeats() {
  stopHeartbeats();
  if (!state.heartbeatEnabled) return;
  heartbeatTimer = setInterval(() => {
    if (!state.connected) return;
    const now = Date.now();
    const uptime = now - bootTime;
    for (const key of BUTTON_KEYS) {
      const mac = state.buttons[key].mac;
      publish(`heartbeat/alive/${mac}`, { timestamp: now, uptime });
      publish(`aquacross/battery/${mac}`, {
        timestamp: now,
        voltage: state.buttons[key].voltage,
      });
    }
  }, state.heartbeatIntervalMs);
}

function stopHeartbeats() {
  if (heartbeatTimer) {
    clearInterval(heartbeatTimer);
    heartbeatTimer = null;
  }
}

function connectBroker(url) {
  disconnectBroker();
  state.brokerUrl = url;
  state.lastError = null;
  logEvent("sys", `Verbinde zu ${url} ...`);

  client = mqtt.connect(url, {
    clientId: `button-simulator-${Math.random().toString(16).slice(2, 10)}`,
    reconnectPeriod: 0,
    connectTimeout: 5000,
    clean: true,
  });

  client.on("connect", () => {
    state.connected = true;
    bootTime = Date.now();
    logEvent("sys", `Verbunden mit ${url}`);
    startHeartbeats();
  });

  client.on("error", (err) => {
    state.lastError = err.message;
    logEvent("err", `MQTT Fehler: ${err.message}`);
  });

  client.on("close", () => {
    if (state.connected) logEvent("sys", "Verbindung geschlossen");
    state.connected = false;
    stopHeartbeats();
  });

  client.on("offline", () => {
    state.connected = false;
    logEvent("sys", "offline");
  });
}

function disconnectBroker() {
  stopHeartbeats();
  if (client) {
    try { client.end(true); } catch (_) {}
    client = null;
  }
  state.connected = false;
}

const app = express();
app.use(express.json());
app.use(express.static(path.join(__dirname, "public")));

app.get("/api/status", (_req, res) => {
  res.json({
    brokerUrl: state.brokerUrl,
    connected: state.connected,
    lastError: state.lastError,
    heartbeatEnabled: state.heartbeatEnabled,
    heartbeatIntervalMs: state.heartbeatIntervalMs,
    buttons: state.buttons,
    log: state.log.slice(-80),
  });
});

app.post("/api/connect", (req, res) => {
  const url = (req.body && req.body.brokerUrl) || state.brokerUrl;
  connectBroker(url);
  res.json({ ok: true });
});

app.post("/api/disconnect", (_req, res) => {
  disconnectBroker();
  logEvent("sys", "Getrennt (manuell)");
  res.json({ ok: true });
});

app.post("/api/config", (req, res) => {
  const { button, mac, voltage } = req.body || {};
  if (!BUTTON_KEYS.includes(button)) {
    return res.status(400).json({ ok: false, error: "unbekannter Button" });
  }
  if (typeof mac === "string" && mac.length > 0) {
    state.buttons[button].mac = mac.toUpperCase();
  }
  if (typeof voltage === "number" && voltage >= 2500 && voltage <= 4500) {
    state.buttons[button].voltage = Math.round(voltage);
  }
  res.json({ ok: true, button: state.buttons[button] });
});

app.post("/api/heartbeat", (req, res) => {
  const { enabled, intervalMs } = req.body || {};
  if (typeof enabled === "boolean") state.heartbeatEnabled = enabled;
  if (typeof intervalMs === "number" && intervalMs >= 500 && intervalMs <= 60000) {
    state.heartbeatIntervalMs = Math.round(intervalMs);
  }
  if (state.connected) startHeartbeats();
  res.json({
    ok: true,
    heartbeatEnabled: state.heartbeatEnabled,
    heartbeatIntervalMs: state.heartbeatIntervalMs,
  });
});

app.post("/api/press", (req, res) => {
  const { button } = req.body || {};
  if (!BUTTON_KEYS.includes(button)) {
    return res.status(400).json({ ok: false, error: "unbekannter Button" });
  }
  // start* sendet type=2, stop* sendet type=1 (siehe communication.h)
  const type = button.startsWith("start") ? 2 : 1;
  const mac = state.buttons[button].mac;
  const payload = { type, timestamp: Date.now() };
  const ok = publish(`aquacross/button/${mac}`, payload);
  res.json({ ok, button, mac, payload });
});

app.post("/api/battery", (req, res) => {
  const { button, voltage } = req.body || {};
  if (!BUTTON_KEYS.includes(button)) {
    return res.status(400).json({ ok: false, error: "unbekannter Button" });
  }
  if (typeof voltage !== "number") {
    return res.status(400).json({ ok: false, error: "voltage fehlt" });
  }
  state.buttons[button].voltage = Math.round(voltage);
  const mac = state.buttons[button].mac;
  const ok = publish(`aquacross/battery/${mac}`, {
    timestamp: Date.now(),
    voltage: state.buttons[button].voltage,
  });
  res.json({ ok, button, mac, voltage: state.buttons[button].voltage });
});

app.listen(PORT, () => {
  console.log(`Button-Simulator läuft: http://localhost:${PORT}`);
  console.log(`Broker (Default): ${state.brokerUrl}`);
});