Implement notifications service with shared messaging and email drivers (#36)

backend/notifications/service/service.go

@@ -0,0 +1,109 @@
+package service
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"strings"
+	"time"
+
+	"git.sendico.io/tech/sxchnge/notifications/email"
+	"git.sendico.io/tech/sxchnge/notifications/model"
+	"git.sendico.io/tech/sxchnge/notifications/templates"
+	"git.sendico.io/tech/sxchnge/shared/database/record"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+	mlogger "git.sendico.io/tech/sxchnge/shared/logging"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.uber.org/zap"
+)
+
+type Repository interface {
+	Find(context.Context, string, string) (*model.Notification, error)
+	Get(context.Context, string, string) (*model.Notification, error)
+	Create(context.Context, *model.Notification) (*model.Notification, error)
+	Claim(context.Context, string, time.Time) (*model.Notification, error)
+	Finish(context.Context, *model.Notification) error
+	Recover(context.Context, time.Time) error
+}
+type Service struct {
+	repo    Repository
+	catalog *templates.Catalog
+	sender  email.Sender
+	driver  string
+	logger  mlogger.Logger
+}
+
+func New(repo Repository, catalog *templates.Catalog, sender email.Sender, driver string, logger mlogger.Logger) *Service {
+	return &Service{repo, catalog, sender, driver, mlogger.Named(logger, "notifications")}
+}
+func (s *Service) Send(ctx context.Context, caller string, r model.Request) (*model.Notification, error) {
+	if caller == "" {
+		return nil, merrors.Unauthorized("missing caller")
+	}
+	if r.Key == "" || len(r.Key) > 128 || r.UserID == "" || len(r.UserID) > 128 || !email.ValidAddress(r.Address) || len(r.TemplateID) > 128 || len(r.TemplateVersion) > 64 || len(r.Locale) > 64 || strings.ContainsRune(r.TemplateID+r.TemplateVersion, 0) {
+		return nil, merrors.InvalidArgument("invalid notification request")
+	}
+	if len(r.Parameters) > 64 {
+		return nil, merrors.InvalidArgument("too many parameters")
+	}
+	for k, v := range r.Parameters {
+		if k == "" || len(k) > 64 || len(v) > 4096 {
+			return nil, merrors.InvalidArgument("invalid template parameter")
+		}
+	}
+	payload, err := json.Marshal(r)
+	if err != nil {
+		return nil, merrors.InvalidArgument("invalid request")
+	}
+	if len(payload) > 64<<10 {
+		return nil, merrors.InvalidArgument("request too large")
+	}
+	sum := sha256.Sum256(payload)
+	fingerprint := hex.EncodeToString(sum[:])
+	existing, err := s.repo.Find(ctx, caller, r.Key)
+	if err == nil {
+		return same(existing, fingerprint)
+	}
+	if !errors.Is(err, merrors.ErrNoData) {
+		return nil, err
+	}
+	now := time.Now().UTC()
+	expiry := r.ExpiresAt
+	if expiry.IsZero() {
+		expiry = now.Add(24 * time.Hour)
+	}
+	if !expiry.After(now) || expiry.After(now.Add(24*time.Hour)) {
+		return nil, merrors.InvalidArgument("expiry must be within the next 24 hours")
+	}
+	rendered, err := s.catalog.Render(r)
+	if err != nil {
+		return nil, err
+	}
+	n := &model.Notification{Base: storable.Base{ID: bson.NewObjectID(), CreatedAt: now, UpdatedAt: now}, Caller: caller, Key: r.Key, Fingerprint: fingerprint, UserID: r.UserID, TemplateID: r.TemplateID, TemplateVersion: r.TemplateVersion, Email: rendered, Driver: s.driver, State: model.Queued, ExpiresAt: expiry, NextAttemptAt: now, PurgeAt: now.Add(7 * 24 * time.Hour)}
+	stored, err := s.repo.Create(ctx, n)
+	if err != nil {
+		return nil, err
+	}
+	result, err := same(stored, fingerprint)
+	if err == nil {
+		s.logger.Info("Notification accepted", zap.String("notification_id", stored.ID.Hex()), zap.String("caller", caller))
+	}
+	return result, err
+}
+func same(n *model.Notification, fingerprint string) (*model.Notification, error) {
+	if n.Fingerprint != fingerprint {
+		return nil, merrors.DataConflict("idempotency key already used with a different request")
+	}
+	return n, nil
+}
+func (s *Service) Get(ctx context.Context, caller, id string) (*model.Notification, error) {
+	if caller == "" {
+		return nil, merrors.Unauthorized("missing caller")
+	}
+	if _, err := bson.ObjectIDFromHex(id); err != nil {
+		return nil, merrors.InvalidArgument("invalid notification ID")
+	}
+	return s.repo.Get(ctx, caller, id)
+}