package main

import (
	"errors"
	"log"
	"time"

	"go.bug.st/serial"
)

const (
	portName    = "/dev/ttyS9"
	baudRate    = 115200
	timeout     = 5 * time.Second
	reopenDelay = 500 * time.Millisecond
)

func main() {
	log.Println("goserial test tool started")
	log.Printf("configuration: port=%s baud=%d", portName, baudRate)

	for {
		if err := runTest(); err != nil {
			log.Printf("test run failed, will reopen port after delay: %v", err)
			time.Sleep(reopenDelay)
			continue
		}
	}
}

func runTest() error {
	log.Println("opening serial port")

	// 打开端口
	port, err := serial.Open(portName, &serial.Mode{
		BaudRate: baudRate,
	})
	if err != nil {
		log.Printf("failed to open serial port %s: %v", portName, err)
		return err
	}
	defer func() {
		log.Println("closing serial port")
		if err := port.Close(); err != nil {
			log.Printf("failed to close serial port: %v", err)
		}
	}()

	// 设置读取超时
	if err := port.SetReadTimeout(timeout); err != nil {
		log.Printf("failed to set read timeout: %v", err)
		return err
	}

	log.Printf("read timeout set: %v", timeout)
	log.Println("start reading from serial port (synchronous mode)")

	// 创建缓冲区用于读取数据
	buffer := make([]byte, 24)

	// 同步读取循环
	for {
		n, err := port.Read(buffer)
		if err != nil {
			// 检查是否是超时错误
			if err.Error() == "i/o timeout" {
				log.Println("serial port read timeout occurred, exiting read loop")
				// 超时后退出循环，重新打开端口
				break
			}

			// 使用类型断言检查是否是PortError
			var portErr *serial.PortError
			if errors.As(err, &portErr) {
				// 检查错误代码是否为PortClosed
				if portErr.Code() == serial.PortClosed {
					log.Println("port closed, exiting read loop")
					break
				}
			}

			// 其他错误
			log.Printf("error reading from serial port: %v", err)
			return err
		}

		if n > 0 {
			log.Printf("data received: bytes=%d data=%v", n, buffer[:n])
		}
	}

	// 正常退出读取循环
	log.Println("read loop exited normally")
	return nil
}