package main

import (
	"fmt"
	"log"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"
	"xengineering.eu/homematic-go/homematic"
)

const (
	OPENCCU                    = `http://127.0.0.1:8080`
	BROKER                     = `tcp://127.0.0.1:1883`
	CLIENT_ID                  = `sia-server`
	TOPIC_PREFIX               = `sia`
	QOS                        = byte(0)
	RETAINED                   = false
	MQTT_CONNECT_TIMEOUT       = time.Second * 5
	MQTT_DISCONNECT_TIMEOUT_US = 500
)

func main() {
	log.Println("+++ Started Sia server +++")
	defer log.Println("--- Stopped Sia server ---")

	req := homematic.NewRequester(OPENCCU)
	log.Printf("Created Homematic requester (%s).", OPENCCU)

	inventory, err := req.ListDevices()
	if err != nil {
		log.Fatalf("Failed to retrieve device list: %v", err)
	}
	log.Printf("Retrieved Homematic inventory with %d devices.", len(inventory))

	client, err := ConnectMQTT(BROKER, CLIENT_ID)
	if err != nil {
		log.Fatalf("Could not connect to MQTT broker: %v", err)
	}
	defer func () {
		client.Disconnect(MQTT_DISCONNECT_TIMEOUT_US)
		log.Println("Disconnected from MQTT broker.")
	}()
	log.Printf("Connected to MQTT broker (%s).", BROKER)

	for _, device := range inventory {
		if device.Type == `SHUTTER_CONTACT` {
			state, err := req.GetValue(device.Address)
			if err != nil {
				log.Fatalf("Failed to get value: %v", err)
			}

			topic := fmt.Sprintf("%s/contact/%s/state", TOPIC_PREFIX, device.Address)
			payload := []byte(fmt.Sprintf("%t", state))
			client.Publish(topic, QOS, RETAINED, payload)
		}
	}
}

func ConnectMQTT(broker string, id string) (mqtt.Client, error) {
	opts := mqtt.NewClientOptions()
	opts.AddBroker(broker)
	opts.SetClientID(id)
	opts.SetCleanSession(true)

	client := mqtt.NewClient(opts)

	token := client.Connect()

	success := token.WaitTimeout(MQTT_CONNECT_TIMEOUT)
	if !success {
		return client, fmt.Errorf("Timed out after %v.", MQTT_CONNECT_TIMEOUT)
	}

	err := token.Error()
	if err != nil {
		return client, err
	}

	return client, nil
}