package main

import (
	"context"
	"encoding/json"
	"flag"
	"log"
	"os"
	"strconv"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"
	influxdb2 "github.com/influxdata/influxdb-client-go/v2"
	"github.com/influxdata/influxdb-client-go/v2/api"
)

type config struct {
	InfluxdbHost  string `json:"influxdb_host"`
	InfluxdbPort  int    `json:"influxdb_port"`
	InfluxdbToken string `json:"influxdb_token"`
	MqttBroker    string `json:"mqtt_broker"`
	MqttPort      int    `json:"mqtt_port"`
}

type data struct {
	Data struct {
		Dry   bool `json:"dry"`
		Debug struct {
			Value float64 `json:"value"`
			Unit  string  `json:"unit"`
		} `json:"debug"`
	} `json:"data"`
}

var (
	logger       log.Logger = *log.Default()
	config_path  string
	write_api    api.WriteAPIBlocking
	ctx          context.Context
	config_cache config
)

var message_pub_handler mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
	logger.Printf("Received message: %s from topic: %s\n", msg.Payload(), msg.Topic())
}

var soil_handler mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
	logger.Printf("Received message: %s from topic: %s\n", msg.Payload(), msg.Topic())
	var dry_data data
	err := json.Unmarshal(msg.Payload(), &dry_data)
	if err != nil {
		logger.Print(err)
		return
	}
	point := influxdb2.NewPointWithMeasurement("garden")
	point.AddTag("soil", "moisture")
	point.AddField("value", dry_data.Data.Debug.Value)
	point.AddField("unit", dry_data.Data.Debug.Unit)
	point.SetTime(time.Now())
	err = write_api.WritePoint(ctx, point)
	if err != nil {
		logger.Print(err.Error())
	}
}

var connect_handler mqtt.OnConnectHandler = func(client mqtt.Client) {
	logger.Println("Connected")
	subscribe(client)
}

var connect_lost_handler mqtt.ConnectionLostHandler = func(client mqtt.Client, err error) {
	logger.Printf("Connect lost: %v", err)
}

func init() {
	logger.SetPrefix("soil2db: ")
}

func read_config() {
	data, err := os.ReadFile(config_path)
	if err != nil {
		logger.Printf("Unable to read %s", config_path)
		return
	}
	err = json.Unmarshal(data, &config_cache)
	if err != nil {
		logger.Print("Unable to evaluate config data")
		return
	}
}

func connect() mqtt.Client {
	// MQTT connection
	opts := mqtt.NewClientOptions()
	broker := "tcp://" + config_cache.MqttBroker + ":" + strconv.Itoa(config_cache.MqttPort)
	opts.AddBroker(broker)
	opts.SetClientID("soil2db")
	opts.SetDefaultPublishHandler(message_pub_handler)
	opts.OnConnect = connect_handler
	opts.OnConnectionLost = connect_lost_handler
	client := mqtt.NewClient(opts)
	if token := client.Connect(); token.Wait() && token.Error() != nil {
		logger.Panic(token.Error())
	}
	return client
}

func subscribe(client mqtt.Client) {
	// MQTT subscribtion
	topic := "garden/soil/moisture"
	token := client.Subscribe(topic, 1, soil_handler)
	token.Wait()
	logger.Printf("Subscribed to topic %s", topic)
}

func main() {
	flag.StringVar(&config_path, "c", "./config/config.json", "Specify path to find the config file. Default is ./config/config.json")
	flag.Parse()
	read_config()

	mqtt_client := connect()
	subscribe(mqtt_client)

	influxdb_url := "http://" + config_cache.InfluxdbHost + ":" + strconv.Itoa(config_cache.InfluxdbPort)
	client := influxdb2.NewClient(influxdb_url, config_cache.InfluxdbToken)
	// always close client at the end
	defer client.Close()

	write_api = client.WriteAPIBlocking("tkl", "home")
	ctx = context.Background()

	for {
		time.Sleep(time.Second)
	}
}