refactor notifications

Signed-off-by: Christian Richter <crichter@owncloud.com>

extensions/notifications/pkg/channels/channels.go

@@ -0,0 +1,105 @@
+// Package channels provides different communication channels to notify users.
+package channels
+
+import (
+	"context"
+	"net/smtp"
+
+	gateway "github.com/cs3org/go-cs3apis/cs3/gateway/v1beta1"
+	groups "github.com/cs3org/go-cs3apis/cs3/identity/group/v1beta1"
+	rpc "github.com/cs3org/go-cs3apis/cs3/rpc/v1beta1"
+	"github.com/cs3org/reva/v2/pkg/rgrpc/todo/pool"
+	"github.com/owncloud/ocis/extensions/notifications/pkg/config"
+	"github.com/owncloud/ocis/ocis-pkg/log"
+	"github.com/pkg/errors"
+)
+
+// Channel defines the methods of a communication channel.
+type Channel interface {
+	// SendMessage sends a message to users.
+	SendMessage(userIDs []string, msg string) error
+	// SendMessageToGroup sends a message to a group.
+	SendMessageToGroup(groupdID *groups.GroupId, msg string) error
+}
+
+// NewMailChannel instantiates a new mail communication channel.
+func NewMailChannel(cfg config.Config, logger log.Logger) (Channel, error) {
+	gc, err := pool.GetGatewayServiceClient(cfg.Notifications.RevaGateway)
+	if err != nil {
+		logger.Error().Err(err).Msg("could not get gateway client")
+		return nil, err
+	}
+	return Mail{
+		gatewayClient: gc,
+		conf:          cfg,
+		logger:        logger,
+	}, nil
+}
+
+// Mail is the communcation channel for email.
+type Mail struct {
+	gatewayClient gateway.GatewayAPIClient
+	conf          config.Config
+	logger        log.Logger
+}
+
+// SendMessage sends a message to all given users.
+func (m Mail) SendMessage(userIDs []string, msg string) error {
+	to, err := m.getReceiverAddresses(userIDs)
+	if err != nil {
+		return err
+	}
+	body := []byte(msg)
+
+	smtpConf := m.conf.Notifications.SMTP
+	auth := smtp.PlainAuth("", smtpConf.Sender, smtpConf.Password, smtpConf.Host)
+	if err := smtp.SendMail(smtpConf.Host+":"+smtpConf.Port, auth, smtpConf.Sender, to, body); err != nil {
+		return errors.Wrap(err, "could not send mail")
+	}
+	return nil
+}
+
+// SendMessageToGroup sends a message to all members of the given group.
+func (m Mail) SendMessageToGroup(groupID *groups.GroupId, msg string) error {
+	// TODO We need an authenticated context here...
+	res, err := m.gatewayClient.GetGroup(context.Background(), &groups.GetGroupRequest{GroupId: groupID})
+	if err != nil {
+		return err
+	}
+	if res.Status.Code != rpc.Code_CODE_OK {
+		return errors.New("could not get group")
+	}
+
+	members := make([]string, 0, len(res.Group.Members))
+	for _, id := range res.Group.Members {
+		members = append(members, id.OpaqueId)
+	}
+
+	return m.SendMessage(members, msg)
+}
+
+func (m Mail) getReceiverAddresses(receivers []string) ([]string, error) {
+	addresses := make([]string, 0, len(receivers))
+	for _, id := range receivers {
+		// Authenticate is too costly but at the moment our only option to get the user.
+		// We don't have an authenticated context so calling `GetUser` doesn't work.
+		res, err := m.gatewayClient.Authenticate(context.Background(), &gateway.AuthenticateRequest{
+			Type:         "machine",
+			ClientId:     "userid:" + id,
+			ClientSecret: m.conf.Notifications.MachineAuthSecret,
+		})
+		if err != nil {
+			return nil, err
+		}
+		if res.Status.Code != rpc.Code_CODE_OK {
+			m.logger.Error().
+				Interface("status", res.Status).
+				Str("receiver_id", id).
+				Msg("could not get user")
+			continue
+		}
+		addresses = append(addresses, res.User.Mail)
+	}
+
+	return addresses, nil
+}