module.exports = function(options) {
  // ## BaseCollection
  // -----------------

  // The BaseCollection is the base Collection for storing instances of models
  // for Bottlecap. It is the same as a normal Backbone.Collection, but with
  // a few alterations:
  //
  // - It keeps a reference to the event bus upon construction
  // - It can reply to DataStore API requests on that event bus, if a
  //   namespace option is passed to it.

  // ### Dependencies
  // ----------------
  var Backbone = options.Backbone;
  var _ = options._;
  var FilterCollection = options.FilterCollection;

  // ### BaseCollection
  // ------------------
  var BaseCollection = Backbone.Collection.extend({
    // The DataStore API events
    dataStoreAPI: [
      'all', 'find', 'where', 'filter', 'build'
    ],

    // Creates a BaseCollection and returns it. Accepts `models`, and
    // `options` parameters. The `options` parameter should contain an
    // instance of the application event bus. If you want this BaseCollection
    // to be able to respond to DataStore API requests on the event bus, you
    // should also pass a `namespace` property on the `options` object.
    constructor: function(models, options) {
      Backbone.Collection.apply(this, arguments);

      models = models || [];
      options = options || {};

      this._vent = options.vent;

      if (!this.namespace) {
        this.namespace = options.namespace;
      }

      if (this.namespace) {
        var locals = _.map(this.dataStoreAPI, function(name) {
          return '_' + name;
        });

        _.bindAll(this, locals);
        this._setupDSBindings(this.namespace, this.dataStoreAPI);
      }

      return this;
    },

    // ### DataStore API functions
    _subcollection: function(options) {
      var col = new FilterCollection({
        filter: options.filter,
        parent: this
      });
      return col;
    },

    _build: function(attrs, options, cb) {
      var args = Array.prototype.slice.call(arguments);

      if (args.length === 1) {
        cb = args[0];
        attrs = {};
        options = {};
      } else if (args.length === 2) {
        attrs = args[0];
        options = {};
        cb = args[1];
      }

      var model = new this.model(attrs, options);
      return cb (null, model);
    },

    _all: function(cb) {
      var filter = function(model) { return true; };
      var all = this._subcollection({filter: filter});
      return cb(null, all);
    },

    _find: function(attrs, cb) {
      this._where(attrs, function(err, data) {
        if (err) { return cb(err); }

        if (data.length < 1) {
          err = new Error('DSNotFoundError');
          return cb(err);
        }

        var model = data.at(0);
        return cb(null, model);
      });
    },

    _where: function(attrs, cb) {
      var filter = function(model) {
        for (var key in attrs) {
          var modelValue = model.get(key);
          var value = attrs[key];

          if ((value instanceof Array) && (modelValue instanceof Array)) {
            if (value !== modelValue) { return false; }
          } else if (value instanceof Array) {
            if (!_.contains(value, modelValue)) { return false; }
          } else if (modelValue instanceof Array) {
            if (!_.contains(modelValue, value)) { return false; }
          } else {
            if (modelValue !== value) { return false; }
          }
        }
        return true;
      };
      var col = this._subcollection({filter: filter});
      return cb(null, col);
    },

    _filter: function(filter, cb) {
      var col = this._subcollection({filter: filter});
      return cb(null, col);
    },

    // Binds DataStore API message names to functions on this instance. For
    // example, ds:contacts:all -> this._all
    _setupDSBindings: function(namespace, dsEvents) {
      _.each(dsEvents, function(name) {
        var messageName = 'ds:' + namespace + ':' + name;
        var ourFunc = this['_' + name];
        this._vent.handle(messageName, ourFunc);
      }, this);
    }
  });

  // ### Exports
  // -----------
  return BaseCollection;
};