nikoksr/notify

package rocketchat

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

    "github.com/RocketChat/Rocket.Chat.Go.SDK/models"
    "github.com/RocketChat/Rocket.Chat.Go.SDK/rest"
)

// RocketChat struct holds necessary data to communicate with the RocketChat API.
type RocketChat struct {
    client       *rest.Client
    channelNames []string
}

// New returns a new instance of a RocketChat notification service.
// serverURL is the endpoint of server i.e "localhost" , scheme is protocol i.e "http/https"
// userID and token of the user sending the message.
func New(serverURL, scheme, userID, token string) (*RocketChat, error) {
    u := url.URL{
        Scheme: scheme,
        Host:   serverURL,
    }
    authInfo := models.UserCredentials{
        ID:    userID,
        Token: token,
    }

    c := rest.NewClient(&u, false)
    if err := c.Login(&authInfo); err != nil {
        return nil, err
    }

    rc := RocketChat{
        client:       c,
        channelNames: []string{},
    }

    return &rc, nil
}

// AddReceivers takes rocketchat channel names and adds them to the internal channel list. The Send method will send
// a given message to all channels in the list.
func (r *RocketChat) AddReceivers(channelNames ...string) {
    r.channelNames = append(r.channelNames, channelNames...)
}

// Send takes a message subject and a message body and sends them to all previously set channels.
// user used for sending the message has to be a member of the channel.
// https://docs.rocket.chat/api/rest-api/methods/chat/postmessage
func (r *RocketChat) Send(ctx context.Context, subject, message string) error {
    fullMessage := subject + "\n" + message // Treating subject as message title

    for _, channelName := range r.channelNames {
        select {
        case <-ctx.Done():
            return ctx.Err()
        default:
            msg := models.PostMessage{
                Channel: channelName,
                Text:    fullMessage,
            }
            _, err := r.client.PostMessage(&msg)
            if err != nil {
                return fmt.Errorf("send message to channel %q: %w", channelName, err)
            }
        }
    }

    return nil
}