// +build windows

package disk

import (
	"bytes"
	"syscall"
	"unsafe"

	"github.com/StackExchange/wmi"

	common "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/shirou/gopsutil/common"
)

var (
	procGetDiskFreeSpaceExW     = common.Modkernel32.NewProc("GetDiskFreeSpaceExW")
	procGetLogicalDriveStringsW = common.Modkernel32.NewProc("GetLogicalDriveStringsW")
	procGetDriveType            = common.Modkernel32.NewProc("GetDriveTypeW")
	provGetVolumeInformation    = common.Modkernel32.NewProc("GetVolumeInformationW")
)

var (
	FileFileCompression = int64(16)     // 0x00000010
	FileReadOnlyVolume  = int64(524288) // 0x00080000
)

type Win32_PerfFormattedData struct {
	Name                    string
	AvgDiskBytesPerRead     uint64
	AvgDiskBytesPerWrite    uint64
	AvgDiskReadQueueLength  uint64
	AvgDiskWriteQueueLength uint64
	AvgDisksecPerRead       uint64
	AvgDisksecPerWrite      uint64
}

const WaitMSec = 500

func DiskUsage(path string) (*DiskUsageStat, error) {
	ret := &DiskUsageStat{}

	lpFreeBytesAvailable := int64(0)
	lpTotalNumberOfBytes := int64(0)
	lpTotalNumberOfFreeBytes := int64(0)
	diskret, _, err := procGetDiskFreeSpaceExW.Call(
		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(path))),
		uintptr(unsafe.Pointer(&lpFreeBytesAvailable)),
		uintptr(unsafe.Pointer(&lpTotalNumberOfBytes)),
		uintptr(unsafe.Pointer(&lpTotalNumberOfFreeBytes)))
	if diskret == 0 {
		return nil, err
	}
	ret = &DiskUsageStat{
		Path:        path,
		Total:       uint64(lpTotalNumberOfBytes),
		Free:        uint64(lpTotalNumberOfFreeBytes),
		Used:        uint64(lpTotalNumberOfBytes) - uint64(lpTotalNumberOfFreeBytes),
		UsedPercent: (float64(lpTotalNumberOfBytes) - float64(lpTotalNumberOfFreeBytes)) / float64(lpTotalNumberOfBytes) * 100,
		// InodesTotal: 0,
		// InodesFree: 0,
		// InodesUsed: 0,
		// InodesUsedPercent: 0,
	}
	return ret, nil
}

func DiskPartitions(all bool) ([]DiskPartitionStat, error) {
	var ret []DiskPartitionStat
	lpBuffer := make([]byte, 254)
	diskret, _, err := procGetLogicalDriveStringsW.Call(
		uintptr(len(lpBuffer)),
		uintptr(unsafe.Pointer(&lpBuffer[0])))
	if diskret == 0 {
		return ret, err
	}
	for _, v := range lpBuffer {
		if v >= 65 && v <= 90 {
			path := string(v) + ":"
			if path == "A:" || path == "B:" { // skip floppy drives
				continue
			}
			typepath, _ := syscall.UTF16PtrFromString(path)
			typeret, _, _ := procGetDriveType.Call(uintptr(unsafe.Pointer(typepath)))
			if typeret == 0 {
				return ret, syscall.GetLastError()
			}
			// 2: DRIVE_REMOVABLE 3: DRIVE_FIXED 5: DRIVE_CDROM

			if typeret == 2 || typeret == 3 || typeret == 5 {
				lpVolumeNameBuffer := make([]byte, 256)
				lpVolumeSerialNumber := int64(0)
				lpMaximumComponentLength := int64(0)
				lpFileSystemFlags := int64(0)
				lpFileSystemNameBuffer := make([]byte, 256)
				volpath, _ := syscall.UTF16PtrFromString(string(v) + ":/")
				driveret, _, err := provGetVolumeInformation.Call(
					uintptr(unsafe.Pointer(volpath)),
					uintptr(unsafe.Pointer(&lpVolumeNameBuffer[0])),
					uintptr(len(lpVolumeNameBuffer)),
					uintptr(unsafe.Pointer(&lpVolumeSerialNumber)),
					uintptr(unsafe.Pointer(&lpMaximumComponentLength)),
					uintptr(unsafe.Pointer(&lpFileSystemFlags)),
					uintptr(unsafe.Pointer(&lpFileSystemNameBuffer[0])),
					uintptr(len(lpFileSystemNameBuffer)))
				if driveret == 0 {
					if typeret == 5 {
						continue //device is not ready will happen if there is no disk in the drive
					}
					return ret, err
				}
				opts := "rw"
				if lpFileSystemFlags&FileReadOnlyVolume != 0 {
					opts = "ro"
				}
				if lpFileSystemFlags&FileFileCompression != 0 {
					opts += ".compress"
				}

				d := DiskPartitionStat{
					Mountpoint: path,
					Device:     path,
					Fstype:     string(bytes.Replace(lpFileSystemNameBuffer, []byte("\x00"), []byte(""), -1)),
					Opts:       opts,
				}
				ret = append(ret, d)
			}
		}
	}
	return ret, nil
}

func DiskIOCounters() (map[string]DiskIOCountersStat, error) {
	ret := make(map[string]DiskIOCountersStat, 0)
	var dst []Win32_PerfFormattedData

	err := wmi.Query("SELECT * FROM Win32_PerfFormattedData_PerfDisk_LogicalDisk ", &dst)
	if err != nil {
		return ret, err
	}
	for _, d := range dst {
		if len(d.Name) > 3 { // not get _Total or Harddrive
			continue
		}
		ret[d.Name] = DiskIOCountersStat{
			Name:       d.Name,
			ReadCount:  uint64(d.AvgDiskReadQueueLength),
			WriteCount: d.AvgDiskWriteQueueLength,
			ReadBytes:  uint64(d.AvgDiskBytesPerRead),
			WriteBytes: uint64(d.AvgDiskBytesPerWrite),
			ReadTime:   d.AvgDisksecPerRead,
			WriteTime:  d.AvgDisksecPerWrite,
		}
	}
	return ret, nil
}
