// AddNote method adds a note to an alert at OpsGenie.
func (cli *OpsGenieAlertClient) AddNote(req alerts.AddNoteAlertRequest) (*alerts.AddNoteAlertResponse, error) {
	req.APIKey = cli.apiKey
	resp, err := cli.sendRequest(cli.buildPostRequest(addNoteAlertURL, req))

	if resp == nil {
		return nil, err
	}
	defer resp.Body.Close()

	var addNoteAlertResp alerts.AddNoteAlertResponse

	if err = resp.Body.FromJsonTo(&addNoteAlertResp); err != nil {
		message := "Server response can not be parsed, " + err.Error()
		logging.Logger().Warn(message)
		return nil, errors.New(message)
	}
	return &addNoteAlertResp, nil
}