serviceSTS serviceType = "sts"
)

// getCanonicalHeaders generate a list of request headers with their values
func getCanonicalHeaders(signedHeaders http.Header) string {
	var headers []string
	vals := make(http.Header)
	for k, vv := range signedHeaders {
		k = strings.ToLower(k)
		headers = append(headers, k)
		vals[k] = vv
	}
	sort.Strings(headers)

	var buf bytes.Buffer
	for _, k := range headers {

	if len(signedHdrFields) != 2 {
		return nil, ErrMissingFields
	}
	if signedHdrFields[0] != "SignedHeaders" {
		return nil, ErrMissingSignHeadersTag
	}
	if signedHdrFields[1] == "" {
		return nil, ErrMissingFields
	}
	signedHeaders := strings.Split(signedHdrFields[1], ";")
	return signedHeaders, ErrNone
}

// signValues data type represents structured form of AWS Signature V4 header.

			// validating signed headers.
			if strings.Join(testCase.expectedPreSignValues.SignedHeaders, ",") != strings.Join(parsedPreSign.SignedHeaders, ",") {
				t.Errorf("Test %d: Expected the result to be \"%v\", but got \"%v\". ", i+1, testCase.expectedPreSignValues.SignedHeaders, parsedPreSign.SignedHeaders)
			}
			// validating signature field.

func TestExtractSignedHeaders(t *testing.T) {
	signedHeaders := []string{"host", "x-amz-content-sha256", "x-amz-date", "transfer-encoding"}

	// If the `expect` key exists in the signed headers then golang server would have stripped out the value, expecting the `expect` header set to `100-continue` in the result.
	signedHeaders = append(signedHeaders, "expect")
	// expected header values.
	expectedHost := "play.min.io:9000"

				"X-Amz-Algorithm":     signV4Algorithm,
				"X-Amz-Date":          now.Format(iso8601Format),
				"X-Amz-Expires":       "60",
				"X-Amz-Signature":     "badsignature",
				"X-Amz-SignedHeaders": "host;x-amz-content-sha256;x-amz-date",
				"X-Amz-Credential":    fmt.Sprintf(credentialTemplate, "Z7IXGOO6BZ0REAN1Q26I", now.Format(yyyymmdd), "us-west-1"),
			},
			region:   "us-west-1",

	if err != nil {
		t.Fatal(err)
	}
	req.RequestURI = "/?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=USWUXHGYZQYFYFFIT3RE%2F20170529%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20170529T190139Z&X-Amz-Expires=600&X-Amz-Signature=19b58080999df54b446fc97304eb8dda60d3df1812ae97f3e8783351bfd9781d&X-Amz-SignedHeaders=host&prefix=Hello%2AWorld%2A"

// extractSignedHeaders extract signed headers from Authorization header
func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header, APIErrorCode) {
	reqHeaders := r.Header
	reqQueries := r.Form
	// find whether "host" is part of list of signed headers.
	// if not return ErrUnsignedHeaders. "host" is mandatory.
	if !slices.Contains(signedHeaders, "host") {
		return nil, ErrUnsignedHeaders
	}

	//  <HTTPMethod>\n
	//  <CanonicalURI>\n
	//  <CanonicalQueryString>\n
	//  <CanonicalHeaders>\n
	//  <SignedHeaders>\n
	//  <HashedPayload>
	//
	canonicalRequest := strings.Join([]string{
		req.Method,
		canonicalURI,
		req.URL.RawQuery,
		canonicalHeaders,
		signedHeaders,
		hashedPayload,
	}, "\n")

	// Get scope.
	scope := strings.Join([]string{
		currTime.Format(yyyymmdd),

    "groups": null,
    "action": "s3:ListBucket",
    "bucket": "test",
    "conditions": {
      "Authorization": [
        "AWS4-HMAC-SHA256 Credential=minio/20220507/us-east-1/s3/aws4_request, SignedHeaders=host;x-amz-content-sha256;x-amz-date, Signature=62012db6c47d697620cf6c68f0f45f6e34894589a53ab1faf6dc94338468c78a"
      ],
      "CurrentTime": [
        "2022-05-07T18:31:41Z"
      ],
      "Delimiter": [
        "/"

  "userAgent": "MinIO (linux; amd64) minio-go/v7.0.15 mc/DEVELOPMENT.2021-10-06T23-39-34Z",
  "requestHeader": {
    "Authorization": "AWS4-HMAC-SHA256 Credential=minio/20211008/us-east-1/s3/aws4_request,SignedHeaders=host;x-amz-content-sha256;x-amz-date;x-amz-decoded-content-length,Signature=4c60a59e5eb3b0a68693c7fee9dbb5a8a509e0717668669194d37bf182fde031",
    "Content-Length": "380",
    "Content-Type": "application/octet-stream",