feat: add chat

internal/service/social_graph_service.go

@@ -71,10 +71,13 @@ type SocialGraphService struct {
 	reports *repository.ReportRepo
 	posts   *repository.PostRepo
 	users   *repository.UserRepo
-	notif   *NotificationService
-	mail    mailer.Mailer
-	admins  []string
-	logger  *zap.Logger
+	// chat answers "may the viewer open a DM with this profile?" — the same
+	// rule OpenDM enforces, so the button and the action can't disagree.
+	chat   *repository.ChatRepo
+	notif  *NotificationService
+	mail   mailer.Mailer
+	admins []string
+	logger *zap.Logger
 }
 
 func NewSocialGraphService(
@@ -83,6 +86,7 @@ func NewSocialGraphService(
 	reports *repository.ReportRepo,
 	posts *repository.PostRepo,
 	users *repository.UserRepo,
+	chat *repository.ChatRepo,
 	notif *NotificationService,
 	mail mailer.Mailer,
 	admins []string,
@@ -90,7 +94,8 @@ func NewSocialGraphService(
 ) *SocialGraphService {
 	return &SocialGraphService{
 		follows: follows, blocks: blocks, reports: reports, posts: posts,
-		users: users, notif: notif, mail: mail, admins: admins, logger: logger,
+		users: users, chat: chat, notif: notif, mail: mail, admins: admins,
+		logger: logger,
 	}
 }
 
@@ -294,6 +299,33 @@ func (s *SocialGraphService) Relationship(ctx context.Context, viewerID, targetI
 	}
 	out.Blocked = viewerBlocked
 	out.BlockedBy = blockedByTarget
+
+	// A block closes messaging in either direction; otherwise the target's own
+	// "who can message you" rule decides. Asking the chat repository — rather
+	// than reimplementing the rule here — is what keeps the offered button and
+	// the eventual OpenDM in agreement.
+	switch {
+	case viewerID == "" || viewerID == targetID:
+		out.CanMessage = false
+	case viewerBlocked || blockedByTarget:
+		out.CanMessage = false
+		out.MessageRestriction = "blocked"
+	case s.chat == nil:
+		out.CanMessage = true
+	default:
+		allowed, err := s.chat.CanStartConversation(ctx, viewerID, targetID)
+		if err != nil {
+			return nil, err
+		}
+		out.CanMessage = allowed
+		if !allowed {
+			settings, err := s.chat.Settings(ctx, targetID)
+			if err != nil {
+				return nil, err
+			}
+			out.MessageRestriction = settings.WhoCanMessage
+		}
+	}
 	return out, nil
 }