[MM-41998] Channel Info RHS: display number of files for a channel (#19822)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/app_iface.go

@@ -561,6 +561,7 @@ type AppIface interface {
 	GetChannelByName(channelName, teamID string, includeDeleted bool) (*model.Channel, *model.AppError)
 	GetChannelByNameForTeamName(channelName, teamName string, includeDeleted bool) (*model.Channel, *model.AppError)
 	GetChannelCounts(teamID string, userID string) (*model.ChannelCounts, *model.AppError)
+	GetChannelFileCount(channelID string) (int64, *model.AppError)
 	GetChannelGuestCount(channelID string) (int64, *model.AppError)
 	GetChannelMember(ctx context.Context, channelID string, userID string) (*model.ChannelMember, *model.AppError)
 	GetChannelMemberCount(channelID string) (int64, *model.AppError)

app/channel.go

@@ -2009,6 +2009,15 @@ func (a *App) GetChannelMemberCount(channelID string) (int64, *model.AppError) {
 	return count, nil
 }
 
+func (a *App) GetChannelFileCount(channelID string) (int64, *model.AppError) {
+	count, err := a.Srv().Store.Channel().GetFileCount(channelID)
+	if err != nil {
+		return 0, model.NewAppError("SqlChannelStore.GetFileCount", "app.channel.get_file_count.app_error", nil, err.Error(), http.StatusInternalServerError)
+	}
+
+	return count, nil
+}
+
 func (a *App) GetChannelGuestCount(channelID string) (int64, *model.AppError) {
 	count, err := a.Srv().Store.Channel().GetGuestCount(channelID, true)
 	if err != nil {

app/opentracing/opentracing_layer.go

@@ -4890,6 +4890,28 @@ func (a *OpenTracingAppLayer) GetChannelCounts(teamID string, userID string) (*m
 	return resultVar0, resultVar1
 }
 
+func (a *OpenTracingAppLayer) GetChannelFileCount(channelID string) (int64, *model.AppError) {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetChannelFileCount")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0, resultVar1 := a.app.GetChannelFileCount(channelID)
+
+	if resultVar1 != nil {
+		span.LogFields(spanlog.Error(resultVar1))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0, resultVar1
+}
+
 func (a *OpenTracingAppLayer) GetChannelGroupUsers(channelID string) ([]*model.User, *model.AppError) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetChannelGroupUsers")