EVCC Battery Status via MQTT

# @name    EVCC Battery
# @desc    SOC and charge/discharge power directly from evcc via MQTT
# @author  Daniel
# @version 1.0

import string

class EVCCBattery
  var soc
  var power
  var label
  var color

  def init()
    self.soc = nil
    self.power = nil
    self.label = nil
    self.color = 0xAAAAAA
  end

  def setup()
    mqtt.subscribe("evcc/site/battery/soc", / t, p -> self.on_msg(t, p))
    mqtt.subscribe("evcc/site/battery/power", / t, p -> self.on_msg(t, p))
  end

  def on_msg(topic, payload)
    var value = num(payload)
    if value == nil
      return
    end

    if topic == "evcc/site/battery/soc"
      self.soc = value
    elif topic == "evcc/site/battery/power"
      self.power = value
    end

    self.rebuild()
  end

  def rebuild()
    if self.soc == nil || self.power == nil
      return
    end

    var direction = "Idle"
    var watts = self.power
    self.color = 0xAAAAAA

    if self.power > 50
      direction = "Discharging"
      self.color = 0xFFAA00
    elif self.power < -50
      direction = "Charging"
      self.color = 0x00FF66
      watts = -watts
    elif watts < 0
      watts = -watts
    end

    var kw = watts / 1000.0
    self.label = "Battery " + str(int(round(self.soc))) + "% | " +
                 direction + " " + string.format("%.2f", kw) + " kW"
  end

  def should_show()
    return self.label != nil
  end

  def draw()
    clear()
    if self.label == nil
      text(1, 6, "...", 0x666666)
      return
    end
    scroll_text(0, 6, width(), self.label, self.color)
  end
end

return EVCCBattery()