Attorney General Buddy Caldwell filed a lawsuit Tuesday against State Farm, alleging Louisiana’s largest auto insurer is illegally steering customers involved in car accidents to repair shops that use junkyard parts and choose cheap fixes over safety. The lawsuit, filed in state district court in Baton Rouge, accused the insurance company of violating Louisiana’s unfair trade practices act with a systematic effort to lower its costs at the expense of its customers. Caldwell said his office’s investigation started in March after receiving complaints from around the state about shoddy repair work.