text: import Ember from 'ember';
  import { deprecate } from 'ember-data/-private/debug';
  
  /**
    @module ember-data
  */
  
  function getDefaultValue(record, options, key) {
    if (typeof options.defaultValue === 'function') {
      return options.defaultValue.apply(null, arguments);
    } else {
      let defaultValue = options.defaultValue;
      deprecate(`Non primitive defaultValues are deprecated because they are shared between all instances. If you would like to use a complex object as a default value please provide a function that returns the complex object.`,
        typeof defaultValue !== 'object' || defaultValue === null, {
          id: 'ds.defaultValue.complex-object',
          until: '3.0.0'
        });
      return defaultValue;
    }
  }
  
  function hasValue(record, key) {
    return key in record._attributes ||
           key in record._inFlightAttributes ||
           key in record._data;
  }
  
  function getValue(record, key) {
    if (key in record._attributes) {
      return record._attributes[key];
    } else if (key in record._inFlightAttributes) {
      return record._inFlightAttributes[key];
    } else {
      return record._data[key];
    }
  }
  
  /**
    `DS.attr` defines an attribute on a [DS.Model](/api/data/classes/DS.Model.html).
    By default, attributes are passed through as-is, however you can specify an
    optional type to have the value automatically transformed.
    Ember Data ships with four basic transform types: `string`, `number`,
    `boolean` and `date`. You can define your own transforms by subclassing
    [DS.Transform](/api/data/classes/DS.Transform.html).
  
    Note that you cannot use `attr` to define an attribute of `id`.
  
    `DS.attr` takes an optional hash as a second parameter, currently
    supported options are:
  
    - `defaultValue`: Pass a string or a function to be called to set the attribute
                      to a default value if none is supplied.
  
    Example
  
    ```app/models/user.js
    import DS from 'ember-data';
  
    export default DS.Model.extend({
      username: DS.attr('string'),
      email: DS.attr('string'),
      verified: DS.attr('boolean', { defaultValue: false })
    });
    ```
  
    Default value can also be a function. This is useful it you want to return
    a new object for each attribute.
  
    ```app/models/user.js
    import DS from 'ember-data';
  
    export default DS.Model.extend({
      username: attr('string'),
      email: attr('string'),
      settings: attr({defaultValue: function() {
        return {};
      }})
    });
    ```
  
    The `options` hash is passed as second argument to a transforms'
    `serialize` and `deserialize` method. This allows to configure a
    transformation and adapt the corresponding value, based on the config:
  
    ```app/models/post.js
    export default DS.Model.extend({
      text: DS.attr('text', {
        uppercase: true
      })
    });
    ```
  
    ```app/transforms/text.js
    export default DS.Transform.extend({
      serialize(value, options) {
        if (options.uppercase) {
          return value.toUpperCase();
        }
  
        return value;
      },
  
      deserialize(value) {
        return value;
      }
    })
    ```
  
    @namespace
    @method attr
    @for DS
    @param {String|Object} type the attribute type
    @param {Object} options a hash of options
    @return {Attribute}
  */
  
  export default function attr(type, options) {
    if (typeof type === 'object') {
      options = type;
      type = undefined;
    } else {
      options = options || {};
    }
  
    let meta = {
      type: type,
      isAttribute: true,
      options: options
    };
  
    return Ember.computed({
      get(key) {
        let internalModel = this._internalModel;
        if (hasValue(internalModel, key)) {
          return getValue(internalModel, key);
        } else {
          return getDefaultValue(this, options, key);
        }
      },
      set(key, value) {
        let internalModel = this._internalModel;
        let oldValue = getValue(internalModel, key);
        let originalValue;
  
        if (value !== oldValue) {
          // Add the new value to the changed attributes hash; it will get deleted by
          // the 'didSetProperty' handler if it is no different from the original value
          internalModel._attributes[key] = value;
  
          if (key in internalModel._inFlightAttributes) {
            originalValue = internalModel._inFlightAttributes[key];
          } else {
            originalValue = internalModel._data[key];
          }
  
          this._internalModel.send('didSetProperty', {
            name: key,
            oldValue: oldValue,
            originalValue: originalValue,
            value: value
          });
        }
  
        return value;
      }
    }).meta(meta);
  }
  