this.recline = this.recline || {};
this.recline.Backend = this.recline.Backend || {};

(function($, my) {
  // ## createDataset
  //
  // Convenience function to create a simple 'in-memory' dataset in one step.
  //
  // @param data: list of hashes for each document/row in the data ({key:
  // value, key: value})
  // @param fields: (optional) list of field hashes (each hash defining a hash
  // as per recline.Model.Field). If fields not specified they will be taken
  // from the data.
  // @param metadata: (optional) dataset metadata - see recline.Model.Dataset.
  // If not defined (or id not provided) id will be autogenerated.
  my.createDataset = function(data, fields, metadata) {
    if (!metadata) {
      var metadata = {};
    }
    if (!metadata.id) {
      metadata.id = String(Math.floor(Math.random() * 100000000) + 1);
    }
    var backend = recline.Model.backends['memory'];
    var datasetInfo = {
      documents: data,
      metadata: metadata
    };
    if (fields) {
      datasetInfo.fields = fields;
    } else {
      if (data) {
        datasetInfo.fields = _.keys(data[0]);
      }
    }
    backend.addDataset(datasetInfo);
    var dataset = new recline.Model.Dataset({id: metadata.id}, 'memory');
    dataset.fetch();
    return dataset;
  };


  // ## Memory Backend - uses in-memory data
  //
  // To use it you should provide in your constructor data:
  // 
  //   * metadata (including fields array)
  //   * documents: list of hashes, each hash being one doc. A doc *must* have an id attribute which is unique.
  //
  // Example:
  // 
  //  <pre>
  //  // Backend setup
  //  var backend = recline.Backend.Memory();
  //  backend.addDataset({
  //    metadata: {
  //      id: 'my-id',
  //      title: 'My Title'
  //    },
  //    fields: [{id: 'x'}, {id: 'y'}, {id: 'z'}],
  //    documents: [
  //        {id: 0, x: 1, y: 2, z: 3},
  //        {id: 1, x: 2, y: 4, z: 6}
  //      ]
  //  });
  //  // later ...
  //  var dataset = Dataset({id: 'my-id'}, 'memory');
  //  dataset.fetch();
  //  etc ...
  //  </pre>
  my.Memory = Backbone.Model.extend({
    initialize: function() {
      this.datasets = {};
    },
    addDataset: function(data) {
      this.datasets[data.metadata.id] = $.extend(true, {}, data);
    },
    sync: function(method, model, options) {
      var self = this;
      if (method === "read") {
        var dfd = $.Deferred();
        if (model.__type__ == 'Dataset') {
          var rawDataset = this.datasets[model.id];
          model.set(rawDataset.metadata);
          model.fields.reset(rawDataset.fields);
          model.docCount = rawDataset.documents.length;
          dfd.resolve(model);
        }
        return dfd.promise();
      } else if (method === 'update') {
        var dfd = $.Deferred();
        if (model.__type__ == 'Document') {
          _.each(self.datasets[model.dataset.id].documents, function(doc, idx) {
            if(doc.id === model.id) {
              self.datasets[model.dataset.id].documents[idx] = model.toJSON();
            }
          });
          dfd.resolve(model);
        }
        return dfd.promise();
      } else if (method === 'delete') {
        var dfd = $.Deferred();
        if (model.__type__ == 'Document') {
          var rawDataset = self.datasets[model.dataset.id];
          var newdocs = _.reject(rawDataset.documents, function(doc) {
            return (doc.id === model.id);
          });
          rawDataset.documents = newdocs;
          dfd.resolve(model);
        }
        return dfd.promise();
      } else {
        alert('Not supported: sync on Memory backend with method ' + method + ' and model ' + model);
      }
    },
    query: function(model, queryObj) {
      var numRows = queryObj.size;
      var start = queryObj.from;
      var dfd = $.Deferred();
      results = this.datasets[model.id].documents;
      // not complete sorting!
      _.each(queryObj.sort, function(sortObj) {
        var fieldName = _.keys(sortObj)[0];
        results = _.sortBy(results, function(doc) {
          var _out = doc[fieldName];
          return (sortObj[fieldName].order == 'asc') ? _out : -1*_out;
        });
      });
      var results = results.slice(start, start+numRows);
      dfd.resolve(results);
      return dfd.promise();
    }
  });
  recline.Model.backends['memory'] = new my.Memory();

}(jQuery, this.recline.Backend));