var tower = Game.getObjectById('576abeb35663c2990e7fa89b');
    var MAX_HP = 11000;
    if(tower) {
        var closestHostile = tower.pos.findClosestByRange(FIND_HOSTILE_CREEPS);
        if(closestHostile) {
            tower.attack(closestHostile);
        }else{
            var closestDamagedStructure = tower.pos.findClosestByRange(FIND_STRUCTURES, {
                    filter: (structure) => structure.hits+500 < structure.hitsMax && structure.hits < MAX_HP
                });
            // same as  filter: function(structure) { return (structure.hits+500 < structure.hitsMax && structure.hits < MAX_HP); }

            if(closestDamagedStructure) {
                tower.repair(closestDamagedStructure);
            }
        }
    }