package main

import (
	"errors"
	"io"
	"os"
	"runtime"
	"strings"
	"syscall"
	"time"
)

func moveFile(src, dst string) error {
	// zuerst Rename (schnell)
	if err := os.Rename(src, dst); err == nil {
		return nil
	} else {
		// Fallback: Copy+Remove (z.B. bei EXDEV)
		in, err2 := os.Open(src)
		if err2 != nil {
			return err
		}
		defer in.Close()

		out, err2 := os.Create(dst)
		if err2 != nil {
			return err
		}
		if _, err2 := io.Copy(out, in); err2 != nil {
			out.Close()
			return err2
		}
		if err2 := out.Close(); err2 != nil {
			return err2
		}
		return os.Remove(src)
	}
}

const windowsSharingViolation syscall.Errno = 32 // ERROR_SHARING_VIOLATION

func isSharingViolation(err error) bool {
	if runtime.GOOS != "windows" {
		return false
	}
	// Windows: ERROR_SHARING_VIOLATION = 32, ERROR_LOCK_VIOLATION = 33
	var pe *os.PathError
	if errors.As(err, &pe) {
		if errno, ok := pe.Err.(syscall.Errno); ok {
			return errno == syscall.Errno(32) || errno == syscall.Errno(33)
		}
	}
	// Fallback über Text
	s := strings.ToLower(err.Error())
	return strings.Contains(s, "sharing violation") ||
		strings.Contains(s, "used by another process") ||
		strings.Contains(s, "wird von einem anderen prozess verwendet")
}

func removeWithRetry(path string) error {
	var err error
	for i := 0; i < 40; i++ { // ~4s bei 100ms
		err = os.Remove(path)
		if err == nil {
			return nil
		}
		if isSharingViolation(err) {
			time.Sleep(100 * time.Millisecond)
			continue
		}
		return err
	}
	return err
}

func renameWithRetry(oldPath, newPath string) error {
	var err error
	for i := 0; i < 40; i++ {
		err = os.Rename(oldPath, newPath)
		if err == nil {
			return nil
		}
		if isSharingViolation(err) {
			time.Sleep(100 * time.Millisecond)
			continue
		}
		return err
	}
	return err
}