#!/bin/bash

# MQTT configuration attributes
# https://www.home-assistant.io/integrations/sensor.mqtt/
# https://www.home-assistant.io/integrations/switch.mqtt/

# Explanation
# https://www.youtube.com/watch?v=VHiCtZqllU8
# https://resinchemtech.blogspot.com/2023/12/mqtt-auto-discovery.html

# Prerequesite
#apt install mosquitto-clients

source ~/.mqtt-hass.conf

LC_NAME="${DEVICE_NAME,,}"

# Device attriutes
DEVICE_ID="${LC_NAME// /_}"
DEVICE_MANUFACTURER="custom"
DEVICE_MODEL="${DEVICE_NAME}" #"custom"

# Sensor attributes
SENSOR_ID="${DEVICE_ID}_${SENSOR_TYPE}"
SENSOR_EXPIRE_AFTER_S="600"

case ${SENSOR_TYPE} in
    "power")
        SENSOR_UNIT="W"
        SENSOR_ICON="mdi:lightning-bolt"
    ;;
    "voltage")
        SENSOR_UNIT="V"
        SENSOR_ICON="mdi:sine-wave"
    ;;
    "temperature")
        SENSOR_UNIT="°C"
        SENSOR_ICON="mdi:thermometer"
    ;;
    "humidity")
        SENSOR_UNIT="%"
        SENSOR_ICON="mdi:water-percent"
    ;;
    *)
        echo "Unknown sensor type: ${SENSOR_TYPE}" >&2
        exit 1
    ;;
esac

# MQTT attributes
MQTT_CONFIG_TOPIC="homeassistant/sensor/${SENSOR_ID}/config"
MQTT_STATE_TOPIC="${LC_NAME// //}/${SENSOR_TYPE}/state"

function send {
    TOPIC=$1
    PAYLOAD=$2
    echo "Sending payload to ${MQTT_BROKER}:${MQTT_PORT}/${TOPIC} ..."
    echo "TOPIC=$TOPIC"
    echo "PAYLOAD=$PAYLOAD"
    mosquitto_pub -h "${MQTT_BROKER}" -p "${MQTT_PORT}" -u "${MQTT_USERNAME}" -P "${MQTT_PASSWORD}" \
        -t "$TOPIC" \
        -m "$PAYLOAD"
}

function config {
    send "${MQTT_CONFIG_TOPIC}" "$1"
}

function state {
    send "${MQTT_STATE_TOPIC}" "$1"
}

function setupEntity {
    config "{\
\"name\": \"${SENSOR_NAME}\",\
\"unique_id\": \"${SENSOR_ID}\",\
\"device_class\": \"${SENSOR_TYPE}\",\
\"unit_of_measurement\": \"${SENSOR_UNIT}\",\
\"state_topic\": \"${MQTT_STATE_TOPIC}\",\
\"expire_after\": \"${SENSOR_EXPIRE_AFTER_S}\",\
\"icon\": \"${SENSOR_ICON}\",\
\"device\": {\
\"name\": \"${DEVICE_NAME}\",\
\"identifiers\": [\"${DEVICE_ID}\"],\
\"manufacturer\": \"${DEVICE_MANUFACTURER}\",\
\"model\": \"${DEVICE_MODEL}\"\
}}"

#\"firendly_name\": \"${NAME} power\",\
#    "hw_version":"1.02",
#     "sw_version":"2.45",
#     "configuration_url":"http://192.168.1.226"
}

function deleteEntity {
    config ""
}

if [ "$1" == "r" ]; then
    deleteEntity
    exit 0 
fi

if [ -n "$1" ]; then
    setupEntity
    state "$1"
    exit 0 
fi

if [ -z "$1" ]; then
    setupEntity
    exit 0
fi

exit 1