import { ble, peripheral } from "mikro/ble";
import { sleep } from "mikro/sleep";

// Set a friendly name. If omitted, the runtime uses "mikrojs-<MAC suffix>".
ble.name = "mikrojs-hello";

// Peripheral lifecycle listeners. These fire on the JS loop thread as
// centrals connect, renegotiate MTU, or disconnect. Register before
// advertise so no event is missed.
peripheral.onConnect.subscribe((info) => {
  console.log("connected: %s mtu: %d", info.address, info.mtu);
});

peripheral.onDisconnect.subscribe(async (info) => {
  console.log("disconnected: %s mtu: %d", info.address, info.mtu);
  // NimBLE stops advertising on connect. Re-advertise so the device stays
  // discoverable once the peer goes away.
  const r = await peripheral.advertise({
    name: "mikrojs-hello",
    connectable: true,
    interval: { min: 100, max: 150 },
    includeTxPower: true,
    services: currentServices,
  });
  if (!r.ok) console.error("re-advertise failed:", r.error);
});

peripheral.onMtu.subscribe((info) => {
  console.log("mtu renegotiated on %d new mtu: %d", info.id, info.mtu);
});

// Characteristic declarations. The command characteristic has an onWrite
// handler that runs asynchronously after a central writes to it. The
// write is already acknowledged at the GATT layer by the time this runs.
const currentServices = [
  {
    uuid: "180f", // Battery Service
    characteristics: [
      {
        uuid: "2a19", // Battery Level
        properties: ["read", "notify"] as const,
        value: new Uint8Array([87]),
      },
    ],
  },
  {
    // Custom vendor service. Replace the UUID for real projects.
    uuid: "7f3a1b00-4a2f-4e5b-9a3c-1e2d3f4a5b6c",
    characteristics: [
      {
        // Read-only info string.
        uuid: "7f3a1b01-4a2f-4e5b-9a3c-1e2d3f4a5b6c",
        properties: ["read"] as const,
        value: new TextEncoder().encode("mikrojs v0: hello from BLE"),
      },
      {
        // Writable command characteristic. The onWrite handler logs the
        // received bytes whenever a central writes to it.
        uuid: "7f3a1b02-4a2f-4e5b-9a3c-1e2d3f4a5b6c",
        properties: ["read", "write", "writeWithoutResponse"] as const,
        value: new Uint8Array([0]),
        onWrite: (bytes: Uint8Array) => {
          const hex = Array.from(bytes, (b) => b.toString(16).padStart(2, "0")).join(" ");
          console.log("command write: %d bytes: %s", bytes.length, hex);
        },
      },
    ],
  },
];

const result = await peripheral.advertise({
  name: "mikrojs-hello",
  connectable: true,
  interval: { min: 100, max: 150 },
  includeTxPower: true,
  services: currentServices,
});

if (!result.ok) {
  console.error("ble.advertise failed:", result.error);
} else {
  console.log("BLE GATT peripheral advertising as %s", ble.name);
  console.log("address: %s", ble.address);
  console.log("open nRF Connect (or LightBlue) and connect to discover the services.");

  // Fake a battery draining from 87% down to 0% and wrapping back to 100%.
  // handle.notify both updates the cached value AND pushes the new bytes
  // to every subscriber that enabled notifications via the CCCD. If no
  // one is subscribed, it is a silent no-op. The value still updates, so
  // connecting later and reading Battery Level returns the current level.
  let level = 87;
  while (true) {
    await sleep(2000);
    level = level > 0 ? level - 1 : 100;
    const update = result.value.notify("180f", "2a19", new Uint8Array([level]));
    if (!update.ok) {
      console.error("notify failed:", update.error);
      break;
    }
  }
}