// Copyright (C) 2016 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.

// +build windows

package osutil

import (
	"bytes"
	"fmt"
	"syscall"
	"unsafe"
)

func GetFilesystemRoots() ([]string, error) {
	kernel32, err := syscall.LoadDLL("kernel32.dll")
	if err != nil {
		return nil, err
	}
	getLogicalDriveStringsHandle, err := kernel32.FindProc("GetLogicalDriveStringsA")
	if err != nil {
		return nil, err
	}

	buffer := [1024]byte{}
	bufferSize := uint32(len(buffer))

	hr, _, _ := getLogicalDriveStringsHandle.Call(uintptr(unsafe.Pointer(&bufferSize)), uintptr(unsafe.Pointer(&buffer)))
	if hr == 0 {
		return nil, fmt.Errorf("Syscall failed")
	}

	var drives []string
	parts := bytes.Split(buffer[:], []byte{0})
	for _, part := range parts {
		if len(part) == 0 {
			break
		}
		drives = append(drives, string(part))
	}

	return drives, nil
}