feat: add web push and sadhna tracker

internal/service/push_sender.go

@@ -0,0 +1,98 @@
+package service
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+
+	webpush "github.com/SherClockHolmes/webpush-go"
+	"github.com/prabhupadasays/spsays-bff/internal/repository"
+	"go.uber.org/zap"
+)
+
+// PushPayload is the JSON the service worker receives in its `push` event.
+type PushPayload struct {
+	Title string `json:"title"`
+	Body  string `json:"body"`
+	URL   string `json:"url,omitempty"`
+	Icon  string `json:"icon,omitempty"`
+	Tag   string `json:"tag,omitempty"`
+}
+
+// PushSender delivers Web Push messages via VAPID. Construct with
+// NewPushSender; it returns nil when VAPID isn't configured, and every method
+// is nil-safe so callers needn't branch.
+type PushSender struct {
+	repo    *repository.PushRepo
+	pub     string
+	priv    string
+	subject string
+	logger  *zap.Logger
+}
+
+// NewPushSender returns nil if the VAPID keys are absent (push disabled).
+func NewPushSender(repo *repository.PushRepo, publicKey, privateKey, subject string, logger *zap.Logger) *PushSender {
+	if publicKey == "" || privateKey == "" || repo == nil {
+		return nil
+	}
+	return &PushSender{repo: repo, pub: publicKey, priv: privateKey, subject: subject, logger: logger}
+}
+
+// PublicKey is the VAPID application server key the browser subscribes with.
+func (p *PushSender) PublicKey() string {
+	if p == nil {
+		return ""
+	}
+	return p.pub
+}
+
+// Enabled reports whether push delivery is configured.
+func (p *PushSender) Enabled() bool { return p != nil }
+
+// SendToUser pushes a payload to every subscription the user has, pruning any
+// endpoint the push service reports as gone (404/410). Best-effort: failures
+// are logged, never returned.
+func (p *PushSender) SendToUser(ctx context.Context, userID string, payload PushPayload) {
+	if p == nil {
+		return
+	}
+	subs, err := p.repo.ListByUser(ctx, userID)
+	if err != nil {
+		p.logger.Warn("push: list subscriptions failed", zap.String("user", userID), zap.Error(err))
+		return
+	}
+	if len(subs) == 0 {
+		return
+	}
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return
+	}
+	for _, s := range subs {
+		sub := &webpush.Subscription{
+			Endpoint: s.Endpoint,
+			Keys:     webpush.Keys{P256dh: s.P256dh, Auth: s.Auth},
+		}
+		resp, err := webpush.SendNotification(body, sub, &webpush.Options{
+			Subscriber:      p.subject,
+			VAPIDPublicKey:  p.pub,
+			VAPIDPrivateKey: p.priv,
+			TTL:             60,
+			Urgency:         webpush.UrgencyNormal,
+		})
+		if err != nil {
+			p.logger.Warn("push: send failed", zap.String("user", userID), zap.Error(err))
+			continue
+		}
+		status := resp.StatusCode
+		_ = resp.Body.Close()
+		// Subscription expired/gone — drop it so we stop trying.
+		if status == http.StatusNotFound || status == http.StatusGone {
+			if derr := p.repo.DeleteByEndpoint(ctx, s.Endpoint); derr != nil {
+				p.logger.Warn("push: prune failed", zap.Error(derr))
+			}
+		} else if status >= 400 {
+			p.logger.Warn("push: non-2xx", zap.Int("status", status), zap.String("user", userID))
+		}
+	}
+}