// A thermostat with one setpoint and the modes HEAT, COOL and OFF: Alexa.ThermostatController, and
// Alexa.TemperatureSensor for the temperature of the room. It works in Celsius and takes Fahrenheit and Kelvin.
//
//   ALEX2MQTT_USERNAME=... ALEX2MQTT_PASSWORD=... ALEX2MQTT_ROOT_TOPIC=... node examples/thermostat.js
//
// "alex2node" is the installed package; inside this checkout it resolves to the built dist/.
const { Alex2MQTT, AlexaErrors, ThermostatController, TemperatureSensor } = require("alex2node");

const missing = ["ALEX2MQTT_USERNAME", "ALEX2MQTT_PASSWORD", "ALEX2MQTT_ROOT_TOPIC"].filter((name) => !process.env[name]);
if (missing.length > 0) {
  console.error(`${missing.join(", ")} not set. Set the MQTT user name, the password and the root topic of your Alex2MQTT account.`);
  process.exit(1);
}
const { ALEX2MQTT_USERNAME, ALEX2MQTT_PASSWORD, ALEX2MQTT_ROOT_TOPIC } = process.env;

const bridge = new Alex2MQTT(ALEX2MQTT_USERNAME, ALEX2MQTT_PASSWORD, ALEX2MQTT_ROOT_TOPIC);
bridge.on("connect", () => console.log("connected, discover the devices in the Alexa app"));
bridge.on("error", (err) => console.error("bridge:", err.message));

const MODES = ["HEAT", "COOL", "OFF"];
const RANGE = { min: 5, max: 30 };
const thermostat = { mode: "HEAT", target: 21, room: 19.5 };

const celsius = (value) => ({ value, scale: "CELSIUS" });
// A difference has no offset: 9 degrees Fahrenheit more are 5 degrees Celsius more
const deltaInCelsius = ({ value, scale }) => (scale === "FAHRENHEIT" ? (value * 5) / 9 : value);
function inCelsius({ value, scale }) {
  if (scale === "FAHRENHEIT") return ((value - 32) * 5) / 9;
  return scale === "KELVIN" ? value - 273.15 : value;
}

const device = bridge.addDevice({
  endpointId: "hall-thermostat", name: "Hall Thermostat", categories: ["THERMOSTAT", "TEMPERATURE_SENSOR"],
});
const control = device.add(ThermostatController, { supportedModes: MODES, properties: ["targetSetpoint", "thermostatMode"] });
const sensor = device.add(TemperatureSensor);

device.state((s) => s
  .set(control, "targetSetpoint", celsius(thermostat.target))
  .set(control, "thermostatMode", thermostat.mode)
  .set(sensor, "temperature", celsius(thermostat.room))
  .health("OK"));

function setTarget(ctx, target) {
  if (thermostat.mode === "OFF") throw AlexaErrors.thermostatIsOff("The thermostat is off");
  const rounded = Math.round(target * 2) / 2;
  if (rounded < RANGE.min || rounded > RANGE.max) {
    throw AlexaErrors.temperatureOutOfRange(
      `The thermostat takes ${RANGE.min} to ${RANGE.max} degrees Celsius`,
      { minimumValue: celsius(RANGE.min), maximumValue: celsius(RANGE.max) }
    );
  }
  thermostat.target = rounded;
  return ctx.respond();
}

control.on("SetTargetTemperature", (ctx) => {
  const { targetSetpoint, lowerSetpoint, upperSetpoint } = ctx.payload;
  if (!targetSetpoint || lowerSetpoint || upperSetpoint) {
    throw AlexaErrors.dualSetpointsUnsupported("The thermostat has one setpoint");
  }
  return setTarget(ctx, inCelsius(targetSetpoint));
});
control.on("AdjustTargetTemperature", (ctx) => setTarget(ctx, thermostat.target + deltaInCelsius(ctx.payload.targetSetpointDelta)));
control.on("SetThermostatMode", (ctx) => {
  const mode = ctx.payload.thermostatMode.value;
  if (!MODES.includes(mode)) throw AlexaErrors.unsupportedThermostatMode(`The thermostat has no mode ${mode}`);
  thermostat.mode = mode;
  return ctx.respond();
});

bridge.connect();