{ pkgs, lib, config, ... }:
let

  # allow new devices to join
  enablePairing = true;

  device = "/dev/ttyACM0";
  dataFolder = "/srv/zigbee/data";

  sensors = {
    buttons = {
      "button_1".id = "0x00158d0002b04f65";
      "button_2".id = "0x00158d0002b04f09";
      "button_3".id = "0x00158d0002b00e04";
    };
    temperature = {
      "temperature_sensor_1".id = "0x00158d0002d79220";
      "temperature_sensor_2".id = "0x00158d0002d7913d";
    };
    motion = { "motion_sensor_1".id = "0x00158d0002fbd451"; };
  };

  # todo : rename with allSensors
  allSensors = with sensors; buttons // temperature // motion;

  zigBee2MqttConfig = {

    # Home Assistant integration (MQTT discovery)
    homeassistant = false;
    # homeassistant = true;

    # allow new devices to join
    permit_join = enablePairing;

    # MQTT settings
    mqtt = {
      # MQTT base topic for zigbee2mqtt MQTT messages
      base_topic = "zigbee2mqtt";
      # MQTT server URL
      server = "mqtt://127.0.0.1:1883";
      # MQTT server authentication, uncomment if required:
      user = "zigbee";
      password = lib.fileContents <secrets/zigbee/password>;
    };

    # Serial settings
    serial = {
      port = "/dev/ttyACM0";
      # Optional: disable LED of CC2531 USB sniffer
      disable_led = true;
    };

    devices = lib.mapAttrs' (name:
      { id, ... }: {
        name = id;
        value = {
          retain = false;
          friendly_name = name;
        };
      }) allSensors;
  };

  configurationYaml =
    pkgs.writeText "configuration.yml" (builtins.toJSON zigBee2MqttConfig);
in {
  imports = [ ./mqtt.nix ];

  services.homeAssistantConfig = {

    # group.unknown.entities = [ "sensor.button_1" ];

    sensor = let
      buttons = with lib;
        mapAttrsToList (name:
          { ... }: {
            platform = "mqtt";
            name = name;
            icon = "mdi:toggle-switch";
            state_topic = "zigbee2mqtt/${name}";
            availability_topic = "zigbee2mqtt/bridge/state";
            value_template = "{{ value_json.click }}";
          }) sensors.buttons;

      temperature = with lib;
        mapAttrsToList (name:
          { ... }: [
            {
              platform = "mqtt";
              name = name;
              state_topic = "zigbee2mqtt/${name}";
              availability_topic = "zigbee2mqtt/bridge/state";
              unit_of_measurement = "°C";
              device_class = "temperature";
              value_template = "{{ value_json.temperature }}";
            }
            {
              platform = "mqtt";
              name = "humidity_${name}";
              state_topic = "zigbee2mqtt/${name}";
              availability_topic = "zigbee2mqtt/bridge/state";
              unit_of_measurement = "%";
              device_class = "humidity";
              value_template = "{{ value_json.humidity }}";
            }
            {
              platform = "mqtt";
              name = "pressure_${name}";
              state_topic = "zigbee2mqtt/${name}";
              availability_topic = "zigbee2mqtt/bridge/state";
              unit_of_measurement = "hPa";
              device_class = "pressure";
              value_template = "{{ value_json.pressure }}";
            }
          ]) sensors.temperature;

      informations = lib.mapAttrsToList (name:
        { ... }: [
          {
            platform = "mqtt";
            name = "battery_${name}";
            state_topic = "zigbee2mqtt/${name}";
            availability_topic = "zigbee2mqtt/bridge/state";
            unit_of_measurement = "%";
            device_class = "battery";
            value_template = "{{ value_json.battery }}";
          }
          {
            name = "link_${name}";
            platform = "mqtt";
            state_topic = "zigbee2mqtt/${name}";
            availability_topic = "zigbee2mqtt/bridge/state";
            unit_of_measurement = "-";
            value_template = "{{ value_json.linkquality }}";
          }
        ]) allSensors;

    in lib.flatten (buttons ++ temperature ++ informations);

    binary_sensor = let

      motion = lib.mapAttrsToList (name:
        { ... }: {
          name = name;
          platform = "mqtt";
          device_class = "motion";
          #icon = "mdi:motion-sensor";
          state_topic = "zigbee2mqtt/${name}";
          availability_topic = "zigbee2mqtt/bridge/state";
          payload_on = true;
          payload_off = false;
          value_template = "{{ value_json.occupancy }}";
        }) sensors.motion;
    in lib.flatten (motion);

    group = let

      information = name: [ "sensor.battery_${name}" "sensor.link_${name}" ];

      sensor = lib.mapAttrs' (name:
        { ... }: {
          name = name;
          value = {
            control = "hidden";
            entities = [ "sensor.${name}" ] ++ (information name);
          };
        }) (sensors.buttons);

      sensorTemperature = lib.mapAttrs' (name:
        { ... }: {
          name = name;
          value = {
            control = "hidden";
            entities = [
              "sensor.${name}"
              "sensor.humidity_${name}"
              "sensor.pressure_${name}"
            ] ++ (information name);
          };
        }) (sensors.temperature);

      binarySensor = lib.mapAttrs' (name:
        { ... }: {
          name = name;
          value = {
            control = "hidden";
            entities = [ "binary_sensor.${name}" ] ++ (information name);
          };
        }) (sensors.motion);

      views = {
        view_sensors = {
          name = "Sensoren";
          control = "hidden";
          view = true;
          entities =
            lib.mapAttrsToList (name: { ... }: "group.${name}") allSensors;
        };
      };

    in views // sensor // binarySensor // sensorTemperature;

    automation = let
      lights = map (button: {
        alias = "Toggle all lights, on click";
        trigger = {
          platform = "mqtt";
          topic = "zigbee2mqtt/${button}";
        };
        condition = {
          condition = "template";
          value_template = ''{{ "single" == trigger.payload_json.click }}'';
        };
        action = {
          service = "switch.toggle";
          entity_id = "group.all_lights";
        };
      }) [ "button_1" "button_2" "button_3" ];
      mpd = map (button: {
        alias = "Toggle mpd, on double click";
        trigger = {
          platform = "mqtt";
          topic = "zigbee2mqtt/${button}";
        };
        condition = {
          condition = "template";
          value_template = ''{{ "double" == trigger.payload_json.click }}'';
        };
        action = {
          service = "media_player.toggle";
          # todo use a group here
          entity_id = "media_player.mpd";
        };
      }) [ "button_1" "button_2" "button_3" ];
    in lights ++ mpd;

    # click = double => music an aus

    # click = hold => film an aus

  };

  virtualisation.docker.enable = true;

  # todo : einen eigenen container bauen mit dockerTool : https://nixos.wiki/wiki/Docker

  systemd.services."zigbee2mqtt" = {
    enable = true;
    description =
      "Allows you to use your Zigbee devices without the vendors bridge/gateway.";
    after = [ "docker.service" ];
    requires = [ "docker.service" ];
    # todo : udev rule erstellen, die diesen service erst startet, dieses wanted by ist labil
    wantedBy = [ "home-assistant.service" ];

    preStart = ''
      if [ -f ${dataFolder}/configuration.yaml ]
      then
          rm ${dataFolder}/configuration.yaml
      fi
      mkdir -p ${dataFolder}
      cat ${configurationYaml} | ${pkgs.yq}/bin/yq --yaml-output '.' > ${dataFolder}/configuration.yaml
    '';

    restartTriggers = [ configurationYaml ];

    script = ''
      # delete old instance to ensure update
      ${pkgs.docker}/bin/docker stop zigbee2mqtt || true && ${pkgs.docker}/bin/docker rm -f zigbee2mqtt || true
      # start instance
      ${pkgs.docker}/bin/docker run \
                     --network="host" \
                     --name zigbee2mqtt \
                     -v ${dataFolder}:/app/data \
                     --device=${device} \
                     koenkk/zigbee2mqtt
    '';
  };

}