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

  # allow new devices to join
  enablePairing = true;

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

  lights = {
    "light_1" = {
      id = "0x7cb03eaa0a0347b5";
      room = "floor_room_essential";
    };
    "light_2" = {
      id = "0x7cb03eaa0a0387b9";
      room = "floor_room";
    };
    "light_3" = {
      id = "0x7cb03eaa0a033a86";
      room = "living_room";
    };
    "light_4" = {
      id = "0x7cb03eaa0a04aabf";
      room = "bath_room_essential";
    };
    "light_5" = {
      id = "0x7cb03eaa0a0346e4";
      room = "living_room";
    };
    "light_6" = { id = "0x7cb03eaa0a034b46"; };
    "light_7" = { id = "0x7cb03eaa0a033b4f"; };
    "light_8" = {
      id = "0x7cb03eaa0a0384d3";
      room = "bed_room";
    };

  };
  sensors = {
    buttons = {
      "button_1" = {
        id = "0x00158d0002b04f65";
        # room = "living_room"; # is where it actually is placed (optional) (default "unknown")
        # presents = "living_room_present" # presents group to append (optional) (default "unknown")
        # states = { click = "input_boolean.living_room_button"; } # input state to hold (optional) (default "input_boolean.single_${name}")
        room = "living_room_present";
      };
      "button_2" = {
        id = "0x00158d0002b04f09";
        room = "bed_room_present";
        states.single = "input_boolean.bed_room_buttons";
      };
      "button_3" = {
        id = "0x00158d0002b00e04";
        room = "bed_room_present";
        states.single = "input_boolean.bed_room_buttons";
      };
    };
    temperature = {
      "temperature_sensor_1" = {
        id = "0x00158d0002d79220";
        room = "living_room_present";
      };
      "temperature_sensor_2" = {
        id = "0x00158d0002d7913d";
        room = "living_room_present";
      };
    };
    motion = {
      "motion_sensor_1" = {
        id = "0x00158d0002fbd451";
        room = "kitchen_room_present";
      };
      "motion_sensor_2" = {
        id = "0x00158d0002f9a6b8";
        room = "kitchen_room_present";
      };
      "motion_sensor_3" = {
        id = "0x00158d0002f04522";
        room = "living_room_present";
      };
      "motion_sensor_4" = {
        id = "0x00158d0002f9a558";
        room = "living_room_present";
      };
      "motion_sensor_5" = {
        id = "0x00158d0002f9a56f";
        room = "bath_room_essential_present";
      };
      "motion_sensor_6" = {
        id = "0x00158d0002f9a5cb";
        room = "floor_room_present";
      };
      "motion_sensor_7" = {
        id = "0x00158d0002f9a6aa";
        room = "bed_room_essential_present";
      };
      "motion_sensor_8" = {
        id = "0x00158d0002f04637";
        room = "bath_room_essential_present";
      };
    };
    door = {
      "door_sensor_1" = { id = "0x00158d000312dc52"; };
      "door_sensor_2" = {
        id = "0x00158d000316d5bf";
        room = "floor_room_present";
      };
      "door_sensor_3" = { id = "0x00158d0002f9516f"; };
      "door_sensor_4" = {
        id = "0x00158d00031383b9";
        room = "floor_room_present";
      };
      "door_sensor_5" = { id = "0x00158d0003120d3e"; };
    };
  };

  # todo : generate automatically
  allSensors = with sensors; buttons // temperature // motion // door;
  allLights = lights;

  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 // allLights);
  };

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

  services.homeAssistantConfig = {

    # define input_boolean
    # --------------------
    # which get toggled by the buttons
    input_boolean = let stripEmpty = lib.filter (a: a != { });
    in builtins.listToAttrs (stripEmpty (lib.flatten (lib.mapAttrsToList (name:
      { states ? { }, ... }: [
        (lib.optionalAttrs (!lib.hasAttr "single" states) {
          name = "single_${name}";
          value = { icon = "mdi:toggle-switch"; };
        })
        (lib.optionalAttrs (!lib.hasAttr "double" states) {
          name = "double_${name}";
          value = { icon = "mdi:toggle-switch"; };
        })
        (lib.optionalAttrs (!lib.hasAttr "hold" states) {
          name = "hold_${name}";
          value = { icon = "mdi:toggle-switch"; };
        })
      ]) sensors.buttons)));

    light = lib.mapAttrsToList (name:
      { ... }: {
        platform = "mqtt";
        name = name;
        #icon = "mdi:toggle-switch";
        state_topic = "zigbee2mqtt/${name}";
        availability_topic = "zigbee2mqtt/bridge/state";
        command_topic = "zigbee2mqtt/${name}/set";
        value_template = "{{ value_json.click }}";
        brightness = true;
        color_temp = true;
        schema = "json";
      }) allLights;

    # define sensors
    # --------------
    sensor = let

      # define button sensors
      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;

      # define temperature sensors
      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;

      # define meta information sensors
      informations = lib.mapAttrsToList (name:
        { ... }: [
          {
            name = "battery_${name}";
            platform = "mqtt";
            state_topic = "zigbee2mqtt/${name}";
            availability_topic = "zigbee2mqtt/bridge/state";
            unit_of_measurement = "%";
            icon = "mdi:battery-10";
            value_template = "{{ value_json.battery }}";
          }
          {
            name = "link_${name}";
            platform = "mqtt";
            state_topic = "zigbee2mqtt/${name}";
            availability_topic = "zigbee2mqtt/bridge/state";
            icon = "mdi:signal";
            unit_of_measurement = "lqi";
            value_template = "{{ value_json.linkquality }}";
          }
        ]) (allSensors // allLights);

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

    # define binary sensors
    # ---------------------
    binary_sensor = let

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

      # define door sensors
      # -------------------
      door = lib.mapAttrsToList (name:
        { ... }: {
          name = name;
          platform = "mqtt";
          device_class = "door";
          state_topic = "zigbee2mqtt/${name}";
          availability_topic = "zigbee2mqtt/bridge/state";
          payload_on = false;
          payload_off = true;
          value_template = "{{ value_json.contact}}";
        }) sensors.door;

    in lib.flatten (motion ++ door);

    # create groups
    # -------------
    # to have nice panels for every device
    group = let

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

      lightGroups = lib.mapAttrs' (name:
        { ... }: {
          name = name;
          value = {
            control = "hidden";
            entities = [ "light.${name}" ] ++ (information name);
          };
        }) allLights;

      sensorButtons = lib.mapAttrs' (name:
        { states ? { }, ... }:
        let
          entityIds = { single ? "input_boolean.single_${name}"
            , double ? "input_boolean.double_${name}"
            , hold ? "input_boolean.hold_${name}", ... }: [
              single
              double
              hold
            ];
        in {
          name = name;
          value = {
            control = "hidden";
            entities = [ "sensor.${name}" ] ++ (entityIds states)
              ++ (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);

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

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

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

      # sort sensors in room groups
      # ---------------------------
      allRoomsGroups = let
        createGroupEntities = { sensors, entityNameing }:
          let
            flatSensors =
              lib.mapAttrsToList (name: values: { name = name; } // values)
              sensors;
            allRooms' =
              lib.groupBy ({ room ? "unknown", ... }: room) flatSensors;
            allRooms =
              lib.mapAttrs (_: devices: map entityNameing devices) allRooms';
          in allRooms;
        groupEntries = {
          motionGroups = createGroupEntities {
            sensors = sensors.motion;
            entityNameing = ({ name, ... }: "binary_sensor.${name}");
          };
          buttonGroups = createGroupEntities {
            sensors = sensors.buttons;
            entityNameing = ({ name
              , states ? { single = "input_boolean.single_${name}"; }, ... }:
              states.single);
          };
          doorGroups = createGroupEntities {
            sensors = sensors.door;
            entityNameing = ({ name, ... }: "binary_sensor.${name}");
          };
          lightGroups = createGroupEntities {
            sensors = allLights;
            entityNameing = ({ name, ... }: "light.${name}");
          };
        };

        # merge all group entries
      in lib.mapAttrs (_: entities: { entities = lib.flatten entities; })
      (lib.zipAttrs (builtins.attrValues groupEntries));

    in lightGroups // views // allRoomsGroups // sensorButtons // sensorMotions
    // sensorTemperature // sensorDoors // {
      all_sensors.entities =
        (lib.mapAttrsToList (name: { ... }: "sensor.${name}")
          (sensors.buttons // sensors.temperature))
        ++ (lib.mapAttrsToList (name: { ... }: "binary_sensor.${name}")
          (sensors.motion // sensors.door));
      all_lights.entities =
        lib.mapAttrsToList (name: { ... }: "light.${name}") allLights;
    };

    # create automation
    # -----------------
    automation = let

      # single click
      toggle_single_button_input = lib.mapAttrsToList (name:
        { states ? { }, ... }:
        let
          entityId = if (lib.hasAttr "single" states) then
            states.single
          else
            "input_boolean.single_${name}";
        in {
          alias = "toggle single click ${name}";
          trigger = {
            platform = "mqtt";
            topic = "zigbee2mqtt/${name}";
          };
          condition = {
            condition = "template";
            value_template = ''{{ "single" == trigger.payload_json.click}}'';
          };
          action = {
            service = "input_boolean.toggle";
            data.entity_id = entityId;
          };
        }) sensors.buttons;

      # double click
      toggle_double_button_input = lib.mapAttrsToList (name:
        { states ? { }, ... }:
        let
          entityId = if (lib.hasAttr "double" states) then
            states.double
          else
            "input_boolean.double_${name}";
        in {
          alias = "toggle double click ${name}";
          trigger = {
            platform = "mqtt";
            topic = "zigbee2mqtt/${name}";
          };
          condition = {
            condition = "template";
            value_template = ''{{ "double" == trigger.payload_json.click}}'';
          };
          action = {
            service = "input_boolean.toggle";
            data.entity_id = entityId;
          };
        }) sensors.buttons;

      # hold
      toggle_hold_button_input = lib.mapAttrsToList (name:
        { states ? { }, ... }:
        let
          entityId = if (lib.hasAttr "hold" states) then
            states.hold
          else
            "input_boolean.hold_${name}";
        in {
          alias = "toggle hold ${name}";
          trigger = {
            platform = "mqtt";
            topic = "zigbee2mqtt/${name}";
          };
          condition = {
            condition = "template";
            value_template = ''{{ "hold" == trigger.payload_json.action}}'';
          };
          action = {
            service = "input_boolean.toggle";
            data.entity_id = entityId;
          };
        }) sensors.buttons;

    in lib.flatten (toggle_single_button_input ++ toggle_double_button_input
      ++ toggle_hold_button_input);

  };

  # manage zigbee2mqtt
  # ------------------

  # todo : einen eigenen container bauen mit dockerTool : https://nixos.wiki/wiki/Docker
  virtualisation.docker.enable = true;
  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
    '';
  };

}