define(['filters/nodefilter'], function (NodeFilter) {
  'use strict';

  return function () {
    var targets = [];
    var filterObservers = [];
    var filters = [];
    var filteredData;
    var data;

    function remove(d) {
      targets = targets.filter(function (e) {
        return d !== e;
      });
    }

    function add(d) {
      targets.push(d);

      if (filteredData !== undefined) {
        d.setData(filteredData);
      }
    }

    function setData(d) {
      data = d;
      refresh();
    }

    function refresh() {
      if (data === undefined) {
        return;
      }

      var filter = filters.reduce(function (a, f) {
        return function (d) {
          return a(d) && f.run(d);
        };
      }, function () {
        return true;
      });

      filteredData = new NodeFilter(filter)(data);

      targets.forEach(function (t) {
        t.setData(filteredData);
      });
    }

    function notifyObservers() {
      filterObservers.forEach(function (d) {
        d.filtersChanged(filters);
      });
    }

    function addFilter(d) {
      var newItem = true;

      filters.forEach(function (f) {
        if (f.getKey && f.getKey() === d.getKey()) {
          removeFilter(f);
          newItem = false;
        }
      });

      if (newItem) {
        filters.push(d);
        notifyObservers();
        d.setRefresh(refresh);
        refresh();
      }
    }

    function removeFilter(d) {
      filters = filters.filter(function (e) {
        return d !== e;
      });
      notifyObservers();
      refresh();
    }

    function watchFilters(d) {
      filterObservers.push(d);

      d.filtersChanged(filters);

      return function () {
        filterObservers = filterObservers.filter(function (e) {
          return d !== e;
        });
      };
    }

    return {
      add: add,
      remove: remove,
      setData: setData,
      addFilter: addFilter,
      removeFilter: removeFilter,
      watchFilters: watchFilters
    };
  };
});