"os"
	"syscall"

	"github.com/ncw/directio"
	"golang.org/x/sys/unix"
)

// ODirectPlatform indicates if the platform supports O_DIRECT
const ODirectPlatform = true

// OpenFileDirectIO - bypass kernel cache.
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
	return directio.OpenFile(filePath, flag, perm)
}

// DisableDirectIO - disables directio mode.

const (
	// FlagCRCxxh3 indicates that, the lower 32 bits of xxhash3 of the serialized
	// message will be sent after the serialized message as little endian.
	FlagCRCxxh3 Flags = 1 << iota

	// FlagEOF the stream (either direction) is at EOF.
	FlagEOF

	// FlagStateless indicates the message is stateless.
	// This will retain clients across reconnections or
	// if sequence numbers are unexpected.
	FlagStateless

}

// IsHSTSIncludeSubdomains - is HSTS 'includeSubdomains' directive enabled
func (browseCfg *Config) IsHSTSIncludeSubdomains() string {
	configLock.RLock()
	defer configLock.RUnlock()
	if browseCfg.HSTSSeconds > 0 && browseCfg.HSTSIncludeSubdomains {
		return config.EnableOn
	}
	return config.EnableOff
}

// IsHSTSPreload - is HSTS 'preload' directive enabled
func (browseCfg *Config) IsHSTSPreload() string {

	// Storage class is special, it can be replaced regardless of the
	// metadata directive, if set should be preserved and replaced
	// to the destination metadata.
	sc := r.Header.Get(xhttp.AmzStorageClass)
	if sc == "" {
		sc = r.Form.Get(xhttp.AmzStorageClass)
	}

	// if x-amz-metadata-directive says REPLACE then
	// we extract metadata from the input headers.

		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidMetadataDirective: {
		Code:           "InvalidArgument",
		Description:    "Unknown metadata directive.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidStorageClass: {
		Code:           "InvalidStorageClass",
		Description:    "Invalid storage class.",
		HTTPStatusCode: http.StatusBadRequest,
	},

	"strings"
	"time"
)

const (
	// deadline (in seconds) up to which the go routine leak detection has to be retried.
	leakDetectDeadline = 5
	// pause time (in milliseconds) between each snapshot at the end of the go routine leak detection.
	leakDetectPauseTimeMs = 50
)

// LeakDetect - type with  methods for go routine leak detection.
type LeakDetect struct {
	relevantRoutines map[string]bool
}

	StreamHandlerFn func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr

	// StreamHandler handles fully bidirectional streams,
	// There is flow control in both directions.
	StreamHandler struct {
		// Handle an incoming request. Initial payload is sent.
		// Additional input packets (if any) are streamed to request.
		// Upstream will block when request channel is full.

}

// isDirectiveValid - check if tagging-directive is valid.
func isDirectiveValid(v string) bool {
	// Check if set metadata-directive is valid.
	return isDirectiveCopy(v) || isDirectiveReplace(v)
}

// Check if the directive COPY is requested.
func isDirectiveCopy(value string) bool {
	// By default if directive is not set we
	// treat it as 'COPY' this function returns true.

		}
	}
}

// TestIsRequestPresignedSignatureV4 - Test validates the logic for presign signature version v4 detection.
func TestIsRequestPresignedSignatureV4(t *testing.T) {
	testCases := []struct {
		inputQueryKey   string
		inputQueryValue string
		expectedResult  bool
	}{
		// Test case - 1.

	if err = checkPathLength(filePath); err != nil {
		return err
	}

	flags := os.O_CREATE | os.O_WRONLY | os.O_TRUNC

	var w *os.File
	if sync {
		// Perform DirectIO along with fdatasync for larger xl.meta, mostly when
		// xl.meta has "inlined data" we prefer writing O_DIRECT and then doing
		// fdatasync() at the end instead of opening the file with O_DSYNC.
		//