add client adding logic

database.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"context"
+	"time"
 
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 
@@ -121,3 +123,23 @@ func DbSetGroupById(ctx context.Context, group *Group) error {
 	}
 	return rows.Err()
 }
+
+func DbAddClientsToGroup(ctx context.Context, groupId uint32, clientIds []uint32) error {
+	batch := &pgx.Batch{}
+	now := time.Now()
+	for _, cid := range clientIds {
+		batch.Queue(`
+			INSERT INTO chat_group_members (group_id, user_id, joined_at)
+			VALUES ($1, $2, $3)
+			ON CONFLICT DO NOTHING
+		`, groupId, cid, now)
+	}
+	br := dbConn.SendBatch(ctx, batch)
+	defer br.Close()
+	for range clientIds {
+		if _, err := br.Exec(); err != nil {
+			return err
+		}
+	}
+	return nil
+}