package dnsforward

import (
	"fmt"
	"net"
	"os"
	"path"
	"runtime"
	"strings"
)

func isConnClosed(err error) bool {
	if err == nil {
		return false
	}
	nerr, ok := err.(*net.OpError)
	if !ok {
		return false
	}

	if strings.Contains(nerr.Err.Error(), "use of closed network connection") {
		return true
	}

	return false
}

// ---------------------
// debug logging helpers
// ---------------------
func _Func() string {
	pc := make([]uintptr, 10) // at least 1 entry needed
	runtime.Callers(2, pc)
	f := runtime.FuncForPC(pc[0])
	return path.Base(f.Name())
}

func trace(format string, args ...interface{}) {
	pc := make([]uintptr, 10) // at least 1 entry needed
	runtime.Callers(2, pc)
	f := runtime.FuncForPC(pc[0])
	var buf strings.Builder
	buf.WriteString(fmt.Sprintf("%s(): ", path.Base(f.Name())))
	text := fmt.Sprintf(format, args...)
	buf.WriteString(text)
	if len(text) == 0 || text[len(text)-1] != '\n' {
		buf.WriteRune('\n')
	}
	fmt.Fprint(os.Stderr, buf.String())
}