// Websocket debug tool
//
// Usage: ./websocket-linux-amd64 ws://<shelly-ip>/rpc
//
// This tools is intended to support development of the Websocket-based
// application programming interface (API) of the Shelly Internet of Things
// (IoT) devices.

package main

import (
	"log"
	"net/url"
	"os"
	"os/signal"
	"syscall"

	"github.com/gorilla/websocket"
)

func main() {
	log.SetFlags(0)

	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt)

	var u url.URL = getURL()
	log.Printf("connecting to %s", u.String())

	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()

	go func() {
		for {
			_, message, err := c.ReadMessage()
			if err != nil {
				log.Println("read:", err)
				return
			}
			log.Printf("recv: %s", message)
		}
	}()

	getConfig(c)

	Await(syscall.SIGTERM, syscall.SIGINT)
}

func getURL() url.URL {
	if len(os.Args) != 2 {
		log.Fatalf("Exactly one argument expected but got %d.", len(os.Args) - 1)
	}

	maybeURL, err := url.Parse(os.Args[1])
	if err != nil {
		log.Fatalf("Cannot parse given URL: %s", os.Args[1])
	}

	return *maybeURL
}

func Await(signals ...os.Signal) {
	listener := make(chan os.Signal, 1)
	signal.Notify(listener, signals...)
	defer signal.Stop(listener)

	sig := <-listener
	log.Printf("Received OS signal '%v'\n", sig)
}

func getConfig(c *websocket.Conn) {
	request := `
{
	"jsonrpc":"2.0",
	"id": 1,
	"src":"user_1",
	"method":"Sys.GetConfig",
	"params": {
		"id":2
	}
}
`
	err := c.WriteMessage(websocket.TextMessage, []byte(request))
	if err != nil {
		log.Fatal(err)
	}
}