func (arn ARN) String() string {
	if arn.ID == "" && arn.Name == "" && arn.region == "" {
		return ""
	}

	return "arn:minio:s3-object-lambda:" + arn.region + ":" + arn.TargetID.String()
}

// ParseARN - parses string to ARN.
func ParseARN(s string) (*ARN, error) {
	// ARN must be in the format of arn:minio:s3-object-lambda:<REGION>:<ID>:<TYPE>
	if !strings.HasPrefix(s, "arn:minio:s3-object-lambda:") {
		return nil, &ErrInvalidARN{s}
	}

		{"arn:minio:s3-object-lambda:us-east-1:1:webhook", &ARN{TargetID{"1", "webhook"}, "us-east-1"}, false},
	}

	for i, testCase := range testCases {
		arn, err := ParseARN(testCase.s)
		expectErr := (err != nil)

		if expectErr != testCase.expectErr {
			t.Fatalf("test %v: error: expected: %v, got: %v", i+1, testCase.expectErr, expectErr)
		}

		if !testCase.expectErr {

		{"arn:minio:sqs:us-east-1:1:webhook", &ARN{TargetID{"1", "webhook"}, "us-east-1"}, false},
	}

	for i, testCase := range testCases {
		arn, err := parseARN(testCase.s)
		expectErr := (err != nil)

		if expectErr != testCase.expectErr {
			t.Fatalf("test %v: error: expected: %v, got: %v", i+1, testCase.expectErr, expectErr)
		}

		if !testCase.expectErr {

	}

	return nil
}

// Lookup - checks whether target by target ID exists is valid or not.
func (list *TargetList) Lookup(arnStr string) (Target, error) {
	list.RLock()
	defer list.RUnlock()

	arn, err := ParseARN(arnStr)
	if err != nil {
		return nil, err
	}

	id, found := list.targets[arn.TargetID]
	if !found {
		return nil, &ErrARNNotFound{}
	}
	return id, nil
}