#!/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

MQTT_BROKER="hass.lan"
MQTT_PORT=1883
MQTT_USERNAME="pve"
MQTT_PASSWORD="TeLEARDHemAS"


NAME="Host $(hostname -s)"
ID="host_$(hostname -s)"
TOPIC="host/$(hostname -s)"

DEVICE_CLASS="power"
UNIT="W"
ICON="mdi:lightning-bolt"
MANUFACTURER="custom"
MODEL="custom"
EXPIRE_AFTER_S="90"

MQTT_CONFIG_TOPIC="homeassistant/sensor/${ID}/config"
MQTT_STATE_TOPIC="${TOPIC}/${DEVICE_CLASS}"

function send {
    TOPIC=$1
    PAYLOAD=$2
    echo "Sending payload to ${MQTT_BROKER}:${MQTT_PORT}/${TOPIC} ..."
    echo "$1"
    mosquitto_pub -h "${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\": \"${DEVICE_CLASS}\",\
\"unique_id\": \"${ID}_${DEVICE_CLASS}\",\
\"device_class\": \"${DEVICE_CLASS}\",\
\"unit_of_measurement\": \"${UNIT}\",\
\"state_topic\": \"${MQTT_STATE_TOPIC}\",\
\"expire_after\": \"${EXPIRE_AFTER_S}\",\
\"icon\": \"${ICON}\",\
\"device\": {\
\"name\": \"${NAME}\",\
\"identifiers\": \"${ID}\",\
\"manufacturer\": \"${MANUFACTURER}\",\
\"model\": \"${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