var listItems = [{
  categories: ["lisboa","portugal", "oeiras"],
  id: "praia carcavelos",
  visible: false
},
{
  categories: ["amadora","portugal", "damaia"],
  id: "rua neudel",
  visible: false
}];

var filterItems = [{
	category: "lisboa",
  group: "a",
	selected: false,
  active: true
},
{
	category: "portugal",
  group: "a",
	selected: false,
  active: true
},
{
	category:  "damaia",
  group: "a",
	selected: false,
  active: true
},
{
	category:  "oeiras",
  group: "b",
	selected: true,
  active: true
},
{
	category:  "amadora",
  group: "b",
	selected: true,
  active: true
}
];


var groupBy = function(xs, key) {
  return xs.reduce(function(rv, x) {
    (rv[x[key]] = rv[x[key]] || []).push(x);
    return rv;
  }, {});
};

var respects = function(listItem, filters){
	return true;
}

var teste = function(groupedByFilters){
	debugger;
	listItems.forEach(function(listItem) {
  	listItem.visible = true;
    for(let i = 0; i < groupedByFilters.length; i++){
			if(!respects(listItem, groupedByFilters[i])){
      	listItem.visible = false;
        break;
      }
    }
  })
}

var hasSelectedFilter = filterItems.find(function(element) {
  return element.selected;
})

if(!hasSelectedFilter){
	listItems.forEach(function(element) {
  	element.visible = true;
	});
}else{
	var selectedFilters = filterItems.filter(x => x.selected);
  console.log("selected filter: " + selectedFilters[0].category);
  if(selectedFilters.length > 0){
    teste(groupBy(selectedFilters, 'group'));
  }
//  console.log(selectedFilter[0].category == listItems[1].categories[2]);
}

console.log("Results:");
listItems.forEach(function(element) {
  	if(element.visible){
    	console.log(element);
    }
});

console.log("sdfsdfsdf");
console.log(groupBy(filterItems, 'group'));