package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"time"

	"go.bug.st/serial"
	"google.golang.org/protobuf/proto"

	"powerpod/gotool/pb"
	uartframe "powerpod/gotool/uart"
)

const (
	defaultBaud  = 921600
	versionCmdID = byte(pb.MessageType_VERSION)
	readTimeout  = 3 * time.Second
)

func main() {
	portName := flag.String("port", "", "serial port (e.g. /dev/ttyUSB0)")
	baud := flag.Int("baud", defaultBaud, "UART baud rate")
	flag.Parse()

	if *portName == "" {
		fmt.Fprintln(os.Stderr, "usage: gotool -port /dev/ttyUSB0")
		flag.PrintDefaults()
		os.Exit(2)
	}

	mode := &serial.Mode{
		BaudRate: *baud,
		DataBits: 8,
		Parity:   serial.NoParity,
		StopBits: serial.OneStopBit,
	}

	port, err := serial.Open(*portName, mode)
	if err != nil {
		log.Fatalf("open serial: %v", err)
	}
	defer port.Close()

	if err := port.SetReadTimeout(readTimeout); err != nil {
		log.Fatalf("set read timeout: %v", err)
	}

	frame, err := uartframe.EncodeFrame([]byte{versionCmdID})
	if err != nil {
		log.Fatalf("encode frame: %v", err)
	}

	log.Printf("sending VERSION command (%d bytes): % x", len(frame), frame)
	if _, err := port.Write(frame); err != nil {
		log.Fatalf("write: %v", err)
	}

	payload, err := uartframe.ReadFrame(port, nil)
	if err != nil {
		log.Fatalf("read response: %v", err)
	}

	log.Printf("response payload (%d bytes): % x", len(payload), payload)
	if len(payload) == 0 {
		log.Fatal("empty response payload")
	}
	if payload[0] != versionCmdID {
		log.Fatalf("unexpected command id 0x%02x (want 0x%02x)", payload[0], versionCmdID)
	}

	var msg pb.UartMessage
	if err := proto.Unmarshal(payload[1:], &msg); err != nil {
		log.Fatalf("decode protobuf: %v", err)
	}

	if msg.GetType() != pb.MessageType_VERSION {
		log.Fatalf("unexpected message type %v", msg.GetType())
	}

	ver := msg.GetVersionResponse()
	if ver == nil {
		log.Fatal("response missing version_response")
	}

	fmt.Printf("version:  %d\n", ver.GetVersion())
	fmt.Printf("git_hash: %s\n", ver.GetGitHash())
}