func unmarshalHeader()

in private/protocol/rest/unmarshal.go [190:276]
86 lines of code
29 McCabe index (conditional complexity)

func unmarshalHeader(v reflect.Value, header string, tag reflect.StructTag) error {
	switch tag.Get("type") {
	case "jsonvalue":
		if len(header) == 0 {
			return nil
		}
	case "blob":
		if len(header) == 0 {
			return nil
		}
	default:
		if !v.IsValid() || (header == "" && v.Elem().Kind() != reflect.String) {
			return nil
		}
	}

	switch v.Interface().(type) {
	case *string:
		if tag.Get("suppressedJSONValue") == "true" && tag.Get("location") == "header" {
			b, err := base64.StdEncoding.DecodeString(header)
			if err != nil {
				return fmt.Errorf("failed to decode JSONValue, %v", err)
			}
			header = string(b)
		}
		v.Set(reflect.ValueOf(&header))
	case []byte:
		b, err := base64.StdEncoding.DecodeString(header)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(b))
	case *bool:
		b, err := strconv.ParseBool(header)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(&b))
	case *int64:
		i, err := strconv.ParseInt(header, 10, 64)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(&i))
	case *float64:
		var f float64
		switch {
		case strings.EqualFold(header, floatNaN):
			f = math.NaN()
		case strings.EqualFold(header, floatInf):
			f = math.Inf(1)
		case strings.EqualFold(header, floatNegInf):
			f = math.Inf(-1)
		default:
			var err error
			f, err = strconv.ParseFloat(header, 64)
			if err != nil {
				return err
			}
		}
		v.Set(reflect.ValueOf(&f))
	case *time.Time:
		format := tag.Get("timestampFormat")
		if len(format) == 0 {
			format = protocol.RFC822TimeFormatName
		}
		t, err := protocol.ParseTime(format, header)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(&t))
	case aws.JSONValue:
		escaping := protocol.NoEscape
		if tag.Get("location") == "header" {
			escaping = protocol.Base64Escape
		}
		m, err := protocol.DecodeJSONValue(header, escaping)
		if err != nil {
			return err
		}
		v.Set(reflect.ValueOf(m))
	default:
		err := fmt.Errorf("Unsupported value for param %v (%s)", v.Interface(), v.Type())
		return err
	}
	return nil
}