package main

import (
	"encoding/binary"
	"fmt"
	"math"
	"os"
	"os/signal"
	"time"

	"github.com/karalabe/hid"
)

const (
	vendorID     = 0x1446
	productID    = 0x6A73
	refreshRate  = 500 * time.Millisecond
	calibration  = 0.952 // scale correction factor: 2.1 reported = 2.0 actual
)

func main() {
	devices := hid.Enumerate(vendorID, productID)
	if len(devices) == 0 {
		fmt.Println("❌ Scale not found.")
		os.Exit(1)
	}

	device, err := devices[0].Open()
	if err != nil {
		fmt.Println("❌ Failed to open scale:", err)
		os.Exit(1)
	}
	defer device.Close()
	fmt.Println("✅ Scale connected. Reading... (Ctrl+C to quit)")

	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	go func() {
		<-c
		fmt.Print("\n👋 Exiting.\n")
		device.Close()
		os.Exit(0)
	}()

	for {
		buf := make([]byte, 8)
		n, err := device.Read(buf)
		if err != nil || n < 6 {
			fmt.Print("\r⚠️  No data              ")
			time.Sleep(refreshRate)
			continue
		}

		raw := binary.LittleEndian.Uint16(buf[4:6])
		oz := float64(raw) / 10.0 * calibration
		rounded := math.Round(oz*10) / 10

		fmt.Printf("\r📦 Weight: %.1f oz       ", rounded)
		time.Sleep(refreshRate)
	}
}