feat: chat notification

internal/service/chat_service.go

@@ -1,12 +1,14 @@
 package service
 
 import (
+	"bytes"
 	"context"
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"html/template"
 	"net/url"
 	"path"
 	"strings"
@@ -14,6 +16,7 @@ import (
 
 	"github.com/prabhupadasays/spsays-bff/internal/model"
 	"github.com/prabhupadasays/spsays-bff/internal/repository"
+	"github.com/prabhupadasays/spsays-bff/pkg/mailer"
 	"github.com/prabhupadasays/spsays-bff/pkg/realtime"
 	"github.com/prabhupadasays/spsays-bff/pkg/unfurl"
 	"go.uber.org/zap"
@@ -69,14 +72,18 @@ type ChatService struct {
 	posts *repository.PostRepo
 	// push, prefs and users deliver out-of-band message alerts. All optional:
 	// nil means no push, never a failed send.
-	push   *PushSender
-	prefs  *repository.NotificationPrefsRepo
-	users  *repository.UserRepo
-	rt     *realtime.SoketiClient
-	r2     *repository.R2
-	links  *unfurl.Fetcher
-	cache  *repository.Redis
-	logger *zap.Logger
+	push  *PushSender
+	prefs *repository.NotificationPrefsRepo
+	users *repository.UserRepo
+	// mail nudges someone who has never used this thread and isn't connected.
+	// Optional: nil disables first-contact email and nothing else.
+	mail        mailer.Mailer
+	frontendURL string
+	rt          *realtime.SoketiClient
+	r2          *repository.R2
+	links       *unfurl.Fetcher
+	cache       *repository.Redis
+	logger      *zap.Logger
 }
 
 func NewChatService(
@@ -86,6 +93,8 @@ func NewChatService(
 	push *PushSender,
 	prefs *repository.NotificationPrefsRepo,
 	users *repository.UserRepo,
+	mail mailer.Mailer,
+	frontendURL string,
 	rt *realtime.SoketiClient,
 	r2 *repository.R2,
 	cache *repository.Redis,
@@ -93,7 +102,8 @@ func NewChatService(
 ) *ChatService {
 	return &ChatService{
 		chat: chat, blocks: blocks, posts: posts,
-		push: push, prefs: prefs, users: users, rt: rt, r2: r2,
+		push: push, prefs: prefs, users: users, mail: mail,
+		frontendURL: frontendURL, rt: rt, r2: r2,
 		links: unfurl.New(), cache: cache, logger: logger,
 	}
 }
@@ -1926,6 +1936,14 @@ func (s *ChatService) notifyNewMessage(ctx context.Context, conv *model.Conversa
 		if c.MutedUntil != nil && c.MutedUntil.After(now) {
 			continue
 		}
+		// First contact: push only reaches a device that has already opted
+		// in, which someone who has never used chat almost certainly hasn't.
+		// Email is the one channel that reaches them — and only the FIRST
+		// message qualifies, since after that the thread exists and push
+		// carries it.
+		if msg.Seq == 1 && !s.online(ctx, c.UserID) {
+			s.emailFirstContact(ctx, c.UserID, senderID, conv)
+		}
 		s.pushTo(ctx, conv, c.UserID, title, body)
 	}
 }
@@ -1962,6 +1980,68 @@ func (s *ChatService) pushTo(ctx context.Context, conv *model.Conversation, user
 	})
 }
 
+// emailFirstContact tells someone a conversation has been opened with them,
+// when nothing else would reach them.
+//
+// Deliberately says nothing about the message itself: an email subject line is
+// the least private surface in the product, and "you have a message" is enough
+// to bring someone back.
+func (s *ChatService) emailFirstContact(ctx context.Context, recipientID, senderID string, conv *model.Conversation) {
+	if s.mail == nil || s.users == nil {
+		return
+	}
+	// The same preference as chat push, on its email channel — so turning
+	// Messages off silences both rather than leaving one leaking through.
+	if s.prefs != nil {
+		if off, err := s.prefs.DisabledSet(ctx, recipientID); err == nil &&
+			prefOff(off, NotifChatMessage, repository.ChannelEmail) {
+			return
+		}
+	}
+
+	recipient, err := s.users.FindByID(ctx, recipientID)
+	if err != nil || recipient == nil ||
+		recipient.Email == nil || strings.TrimSpace(*recipient.Email) == "" {
+		// OAuth-only accounts may have no address on file.
+		return
+	}
+	sender, err := s.users.FindByID(ctx, senderID)
+	if err != nil || sender == nil {
+		return
+	}
+
+	var buf bytes.Buffer
+	if err := firstContactEmailTpl.Execute(&buf, map[string]any{
+		"RecipientName": recipient.Name,
+		"SenderName":    actorDisplay(sender),
+		"SenderHandle":  sender.Handle,
+		"ChatURL":       s.frontendURL + "/chats/" + conv.ID,
+	}); err != nil {
+		s.logger.Warn("chat: first-contact email render failed", zap.Error(err))
+		return
+	}
+	subject := actorDisplay(sender) + " sent you a message — Prabhupāda Says"
+	if err := s.mail.Send(strings.TrimSpace(*recipient.Email), subject, buf.String()); err != nil {
+		s.logger.Warn("chat: first-contact email failed",
+			zap.String("recipient", recipientID), zap.Error(err))
+	}
+}
+
+// Styled to match the follow-request email so the two read as one product.
+var firstContactEmailTpl = template.Must(template.New("firstContact").Parse(`<div style="font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;color:#2a2118;max-width:560px;margin:0 auto;font-size:17px;line-height:1.7">
+  <p style="font-size:18px;color:#9a6b2f;letter-spacing:0.04em;margin-bottom:1em">Hare Kṛṣṇa{{if .RecipientName}}, {{.RecipientName}}{{end}} 🙏</p>
+
+  <p><strong>{{.SenderName}}</strong> (@{{.SenderHandle}}) has sent you a message.
+  Reply to them on Prabhupāda Says.</p>
+
+  <p style="margin:1.6em 0">
+    <a href="{{.ChatURL}}" style="background:#9a6b2f;color:#fff;text-decoration:none;padding:12px 22px;border-radius:8px;font-weight:600;display:inline-block">Open the conversation</a>
+  </p>
+
+  <p style="font-size:14px;color:#7a6a55">You are receiving this because someone started a conversation with you.
+  You can turn these off under Settings → Notifications.</p>
+</div>`))
+
 // pushCopy builds the lock-screen text.
 func (s *ChatService) pushCopy(ctx context.Context, conv *model.Conversation, senderID string, msg *model.Message) (title, body string) {
 	sender := "Someone"

internal/service/chat_service_test.go

@@ -44,7 +44,7 @@ func testChatService(t *testing.T) (*ChatService, *repository.ChatRepo, *reposit
 	// no-ops — these tests are about the rules, and none of those services are
 	// reachable from a test run.
 	return NewChatService(chat, repository.NewBlockRepo(pg), repository.NewPostRepo(pg),
-		nil, nil, nil, nil, nil, nil, zap.NewNop()), chat, pg
+		nil, nil, nil, nil, "", nil, nil, nil, zap.NewNop()), chat, pg
 }
 
 // chatUserWithHandle returns both identifiers: ids for authoring, handles for
@@ -1928,7 +1928,7 @@ func TestSharedPosts_ResolutionDoesNotScaleWithShareCount(t *testing.T) {
 
 	pg := &repository.Postgres{Pool: pool}
 	svc := NewChatService(repository.NewChatRepo(pg), repository.NewBlockRepo(pg),
-		repository.NewPostRepo(pg), nil, nil, nil, nil, nil, nil, zap.NewNop())
+		repository.NewPostRepo(pg), nil, nil, nil, nil, "", nil, nil, nil, zap.NewNop())
 
 	// measure returns the statement count for reading a thread carrying
 	// `shares` distinct shared posts.

internal/service/notification_service.go

@@ -65,8 +65,8 @@ var PrefCategories = map[string][]string{
 	"post_interactions": {NotifPostLike, NotifPostMention, NotifPostComment, NotifCommentReply},
 	"sadhna_reminders":  {NotifChantReminder, NotifQuoteReminder, NotifChantIncomplete},
 	"community":         {NotifDiscipleJoined},
-	// Push only: in-app delivery for chat is the inbox itself, and there is
-	// no such thing as an emailed chat message.
+	// Push, plus email for FIRST contact only — see ChatService.emailFirstContact.
+	// In-app delivery for chat is the inbox itself, so it isn't offered here.
 	"messages": {NotifChatMessage},
 }