nikoksr/notify

package twilio

import (
    "context"
    "fmt"
    "net/url"

    "github.com/kevinburke/twilio-go"
)

// Compile-time check that twilio.MessageService satisfies twilioClient interface.
var _ twilioClient = &twilio.MessageService{}

// twilioClient abstracts twilio-go MessageService for writing unit tests.
type twilioClient interface {
    SendMessage(from, to, body string, mediaURLs []*url.URL) (*twilio.Message, error)
}

// Service encapsulates the Twilio Message Service client along with internal state for storing recipient phone numbers.
type Service struct {
    client twilioClient

    fromPhoneNumber string
    toPhoneNumbers  []string
}

// New returns a new instance of Twilio notification service.
func New(accountSID, authToken, fromPhoneNumber string) (*Service, error) {
    client := twilio.NewClient(accountSID, authToken, nil)

    s := &Service{
        client:          client.Messages,
        fromPhoneNumber: fromPhoneNumber,
        toPhoneNumbers:  []string{},
    }
    return s, nil
}

// AddReceivers takes strings of recipient phone numbers and appends them to the internal phone numbers slice.
// The Send method will send a given message to all those phone numbers.
func (s *Service) AddReceivers(phoneNumbers ...string) {
    s.toPhoneNumbers = append(s.toPhoneNumbers, phoneNumbers...)
}

// Send takes a message subject and a message body and sends them to all previously set phone numbers.
func (s *Service) Send(ctx context.Context, subject, message string) error {
    body := subject + "\n" + message

    for _, toPhoneNumber := range s.toPhoneNumbers {
        select {
        case <-ctx.Done():
            return ctx.Err()
        default:

            _, err := s.client.SendMessage(s.fromPhoneNumber, toPhoneNumber, body, []*url.URL{})
            if err != nil {
                return fmt.Errorf("send message to recipient %q: %w", toPhoneNumber, err)
            }
        }
    }

    return nil
}