//FILTERS
var filterItems = [{
	category: "lisboa",
  group: "a",
	selected: true,
  active: true
},
{
	category: "portugal",
  group: "a",
	selected: true,
  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
},
{
	category:  "almada",
  group: "c",
	selected: false,
  active: true
}
];

//LIST OF ITEMS
var listItems = [{
	id: "praia carcavelos",
  categories: ["lisboa","portugal", "oeiras"],
  visible: false
},
{
	id: "rua neudel",
  categories: ["amadora","portugal", "damaia"],
  visible: false
},
{
	id: "fronteira",
  categories: ["amadora","portugal", "lisboa"],
  visible: false
},
{
	id: "em almada",
  categories: ["almada", "oeiras"],
  visible: false
}
];



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

var matchesAtLeastOneFilter = function(listItem, filters){
  for(var prop in filters){
  	if(listItem.categories.includes(filters[prop].category)){
    	return true;
    }
  }
	return false;
}

var setListItemsVisibility = function(groupedByFilters){
	listItems.forEach(function(listItem) {
  	listItem.visible = true;
    for(var group in groupedByFilters){//must be true for all groups
      var filterList = groupedByFilters[group];
      //debugger;
      if(!matchesAtLeastOneFilter(listItem, filterList)){
      	listItem.visible = false;
        break;
      }
  	}
  })
}

var updateVisibleItems = function(){
  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);
    if(selectedFilters.length > 0){
      setListItemsVisibility(groupBy(selectedFilters, 'group'));
    }
  //  console.log(selectedFilter[0].category == listItems[1].categories[2]);
  }
}

var getVisibleItems = function(){
	var ret = [];
	for(var prop in listItems){
  	if(listItems[prop].visible){
    	ret.push(listItems[prop].id);
    }
  }
  return ret;
}

function arraysEqual(_arr1, _arr2) {
    if (!Array.isArray(_arr1) || ! Array.isArray(_arr2) || _arr1.length !== _arr2.length)
      return false;
    var arr1 = _arr1.concat().sort();
    var arr2 = _arr2.concat().sort();
    for (var i = 0; i < arr1.length; i++) {
        if (arr1[i] !== arr2[i])
            return false;
    }
    return true;
}

function updateFiltersActiveState(visibleItems) {
	for(var prop in filterItems){
    var filterItem = filterItems[prop];
    if(!filterItem.selected){
      filterItem.selected = true;
    }else{
      continue;
    }
    updateVisibleItems();
    filterItem.selected = false;
    var visibleItemsWithOneMoreActiveFilter = getVisibleItems();
    if(!listItems.find(function(element) {
      return element.visible;
    }) || arraysEqual(visibleItems, visibleItemsWithOneMoreActiveFilter)){
      filterItem.active = false;
    }
	}
}

var selectedFilters = filterItems.filter(x => x.selected);
if(selectedFilters.length > 0){
  for(var prop in selectedFilters){
    console.log("selected filter: " + selectedFilters[prop].category + " - group: " + selectedFilters[prop].group);
  }
}

//MAIN PROGRAM
updateVisibleItems();
updateFiltersActiveState(getVisibleItems());

updateVisibleItems();

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

console.log("Filter states:");
filterItems.forEach(function(element) {
    	console.log(element.category + " (" + element.group + ") active: " + element.active);
});
debugger;