/static/scripts/mvc/collection/collection-model.js

define([
    "mvc/dataset/dataset-model",
    "mvc/base-mvc",
    "utils/localization"
], function( DATASET_MODEL, BASE_MVC, _l ){
//==============================================================================
/*
Notes:

Terminology:
    DatasetCollection/DC : a container of datasets or nested DatasetCollections
    Element/DatasetCollectionElement/DCE : an item contained in a DatasetCollection
    HistoryDatasetCollectionAssociation/HDCA: a DatasetCollection contained in a history


This all seems too complex unfortunately:

- Terminology collision between DatasetCollections (DCs) and Backbone Collections.
- In the DatasetCollections API JSON, DC Elements use a 'Has A' stucture to *contain*
    either a dataset or a nested DC. This would make the hierarchy much taller. I've
    decided to merge the contained JSON with the DC element json - making the 'has a'
    relation into an 'is a' relation. This seems simpler to me and allowed a lot of
    DRY in both models and views, but may make tracking or tracing within these models
    more difficult (since DatasetCollectionElements are now *also* DatasetAssociations
    or DatasetCollections (nested)). This also violates the rule of thumb about
    favoring aggregation over inheritance.
- Currently, there are three DatasetCollection subclasses: List, Pair, and ListPaired.
    These each should a) be usable on their own, b) be usable in the context of
    nesting within a collection model (at least in the case of ListPaired), and
    c) be usable within the context of other container models (like History or
    LibraryFolder, etc.). I've tried to separate/extract classes in order to
    handle those three situations, but it's proven difficult to do in a simple,
    readable manner.
- Ideally, histories and libraries would inherit from the same server models as
    dataset collections do since they are (in essence) dataset collections themselves -
    making the whole nested structure simpler. This would be a large, error-prone
    refactoring and migration.

Many of the classes and heirarchy are meant as extension points so, while the
relations and flow may be difficult to understand initially, they'll allow us to
handle the growth or flux dataset collection in the future (w/o actually implementing
any YAGNI).

*/
//_________________________________________________________________________________________________ ELEMENTS
/** @class mixin for Dataset collection elements.
 *      When collection elements are passed from the API, the underlying element is
 *          in a sub-object 'object' (IOW, a DCE representing an HDA will have HDA json in element.object).
 *      This mixin uses the constructor and parse methods to merge that JSON with the DCE attribtues
 *          effectively changing a DCE from a container to a subclass (has a --> is a).
 */
var DatasetCollectionElementMixin = {

    /** default attributes used by elements in a dataset collection */
    defaults : {
        model_class         : 'DatasetCollectionElement',
        element_identifier  : null,
        element_index       : null,
        element_type        : null
    },

    /** merge the attributes of the sub-object 'object' into this model */
    _mergeObject : function( attributes ){
        _.extend( attributes, attributes.object );
        delete attributes.object;
        return attributes;
    },

    /** override to merge this.object into this */
    constructor : function( attributes, options ){
        this.debug( '\t DatasetCollectionElement.constructor:', attributes, options );
        attributes = this._mergeObject( attributes );
        Backbone.Model.apply( this, arguments );
    },

    /** when the model is fetched, merge this.object into this */
    parse : function( response, options ){
        var attributes = response;
        attributes = this._mergeObject( attributes );
        return attributes;
    }
};

//TODO: unused?
/** @class Concrete class of Generic DatasetCollectionElement */
var DatasetCollectionElement = Backbone.Model
    .extend( BASE_MVC.LoggableMixin )
    .extend( DatasetCollectionElementMixin );

    
//==============================================================================
/** @class Base/Abstract Backbone collection for Generic DCEs. */
var DCECollection = Backbone.Collection.extend( BASE_MVC.LoggableMixin ).extend(
/** @lends DCECollection.prototype */{
    model: DatasetCollectionElement,

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

//TODO: unused?
    /** Set up.
     *  @see Backbone.Collection#initialize
     */
    initialize : function( attributes, options ){
        this.debug( this + '(DCECollection).initialize:', attributes, options );
        options = options || {};
        //this._setUpListeners();
    },

    /** String representation. */
    toString : function(){
         return ([ 'DatasetCollectionElementCollection(', this.length, ')' ].join( '' ));
    }
});


//==============================================================================
/** @class Backbone model for a dataset collection element that is a dataset (HDA).
 */
var DatasetDCE = DATASET_MODEL.DatasetAssociation.extend( BASE_MVC.mixin( DatasetCollectionElementMixin,
/** @lends DatasetDCE.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    defaults : _.extend( {},
        DATASET_MODEL.DatasetAssociation.prototype.defaults,
        DatasetCollectionElementMixin.defaults
    ),

    // because all objects have constructors (as this hashmap would even if this next line wasn't present)
    //  the constructor in hcontentMixin won't be attached by BASE_MVC.mixin to this model
    //  - re-apply manually it now
    /** call the mixin constructor */
    constructor : function( attributes, options ){
        this.debug( '\t DatasetDCE.constructor:', attributes, options );
        //DATASET_MODEL.DatasetAssociation.prototype.constructor.call( this, attributes, options );
        DatasetCollectionElementMixin.constructor.call( this, attributes, options );
    },

//TODO: unused?
    /** set up */
    initialize : function( attributes, options ){
        this.debug( this + '(DatasetDCE).initialize:', attributes, options );
        DATASET_MODEL.DatasetAssociation.prototype.initialize.call( this, attributes, options );
    },

    /** String representation. */
    toString : function(){
        var objStr = this.get( 'element_identifier' );
        return ([ 'DatasetDCE(', objStr, ')' ].join( '' ));
    }
}));


//==============================================================================
/** @class DCECollection of DatasetDCE's (a list of datasets, a pair of datasets).
 */
var DatasetDCECollection = DCECollection.extend(
/** @lends DatasetDCECollection.prototype */{
    model: DatasetDCE,

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

//TODO: unused?
    /** set up */
    initialize : function( attributes, options ){
        this.debug( this + '(DatasetDCECollection).initialize:', attributes, options );
        DCECollection.prototype.initialize.call( this, attributes, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'DatasetDCECollection(', this.length, ')' ].join( '' ));
    }
});


//_________________________________________________________________________________________________ COLLECTIONS
/** @class Backbone model for Dataset Collections.
 *      The DC API returns an array of JSON objects under the attribute elements.
 *      This model:
 *          - removes that array/attribute ('elements') from the model,
 *          - creates a bbone collection (of the class defined in the 'collectionClass' attribute),
 *          - passes that json onto the bbone collection
 *          - caches the bbone collection in this.elements
 */
var DatasetCollection = Backbone.Model
        .extend( BASE_MVC.LoggableMixin )
        .extend( BASE_MVC.SearchableModelMixin )
.extend(/** @lends DatasetCollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    /** default attributes for a model */
    defaults : {
        /* 'list', 'paired', or 'list:paired' */
        collection_type     : null,
        //??
        deleted             : false
    },

    /** Which class to use for elements */
    collectionClass : DCECollection,

    /** set up: create elements instance var and (on changes to elements) update them  */
    initialize : function( model, options ){
        this.debug( this + '(DatasetCollection).initialize:', model, options, this );
        //historyContent.HistoryContent.prototype.initialize.call( this, attrs, options );
        this.elements = this._createElementsModel();
        this.on( 'change:elements', function(){
            this.log( 'change:elements' );
//TODO: prob. better to update the collection instead of re-creating it
            this.elements = this._createElementsModel();
        });
    },

    /** move elements model attribute to full collection */
    _createElementsModel : function(){
        this.debug( this + '._createElementsModel', this.collectionClass, this.get( 'elements' ), this.elements );
//TODO: same patterns as DatasetCollectionElement _createObjectModel - refactor to BASE_MVC.hasSubModel?
        var elements = this.get( 'elements' ) || [];
        this.unset( 'elements', { silent: true });
        this.elements = new this.collectionClass( elements );
        //this.debug( 'collectionClass:', this.collectionClass + '', this.elements );
        return this.elements;
    },

    // ........................................................................ common queries
    /** pass the elements back within the model json when this is serialized */
    toJSON : function(){
        var json = Backbone.Model.prototype.toJSON.call( this );
        if( this.elements ){
            json.elements = this.elements.toJSON();
        }
        return json;
    },

    /** is the collection done with updates and ready to be used? (finished running, etc.) */
    inReadyState : function(){
//TODO: state currenly unimplemented for collections
        return true;
    },

    //TODO:?? the following are the same interface as DatasetAssociation - can we combine?
    /** Does the DC contain any elements yet? Is a fetch() required? */
    hasDetails : function(){
//TODO: this is incorrect for (accidentally) empty collections
        this.debug( 'hasDetails:', this.elements.length );
        return this.elements.length !== 0;
    },

    /** Given the filters, what models in this.elements would be returned? */
    getVisibleContents : function( filters ){
        // filters unused for now
        return this.elements;
    },

    // ........................................................................ ajax
    /** save this dataset, _Mark_ing it as deleted (just a flag) */
    'delete' : function( options ){
        if( this.get( 'deleted' ) ){ return jQuery.when(); }
        return this.save( { deleted: true }, options );
    },
    /** save this dataset, _Mark_ing it as undeleted */
    undelete : function( options ){
        if( !this.get( 'deleted' ) || this.get( 'purged' ) ){ return jQuery.when(); }
        return this.save( { deleted: false }, options );
    },

    /** Is this collection deleted or purged? */
    isDeletedOrPurged : function(){
        return ( this.get( 'deleted' ) || this.get( 'purged' ) );
    },

    // ........................................................................ searchable
    /** searchable attributes for collections */
    searchAttributes : [
        'name'
    ],

    // ........................................................................ misc
    /** String representation */
    toString : function(){
        var idAndName = [ this.get( 'id' ), this.get( 'name' ) || this.get( 'element_identifier' ) ];
        return 'DatasetCollection(' + ( idAndName.join(',') ) + ')';
    }
});


//==============================================================================
/** Model for a DatasetCollection containing datasets (non-nested).
 */
var ListDatasetCollection = DatasetCollection.extend(
/** @lends ListDatasetCollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    /** override since we know the collection will only contain datasets */
    collectionClass : DatasetDCECollection,

//TODO: unused?
    initialize : function( attrs, options ){
        this.debug( this + '(ListDatasetCollection).initialize:', attrs, options );
        DatasetCollection.prototype.initialize.call( this, attrs, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'ListDatasetCollection(', this.get( 'name' ), ')' ].join( '' ));
    }
});


//==============================================================================
/** Model for a DatasetCollection containing fwd/rev datasets (a list of 2).
 */
var PairDatasetCollection = ListDatasetCollection.extend(
/** @lends PairDatasetCollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

//TODO: unused?
    /**  */
    initialize : function( attrs, options ){
        this.debug( this + '(PairDatasetCollection).initialize:', attrs, options );
        ListDatasetCollection.prototype.initialize.call( this, attrs, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'PairDatasetCollection(', this.get( 'name' ), ')' ].join( '' ));
    }
});


//_________________________________________________________________________________________________ NESTED COLLECTIONS
// this is where things get weird, man. Weird.
//TODO: it might be possible to compact all the following...I think.
//==============================================================================
/** @class Backbone model for a Generic DatasetCollectionElement that is also a DatasetCollection
 *      (a nested collection). Currently only list:paired.
 */
var NestedDCDCE = DatasetCollection.extend( BASE_MVC.mixin( DatasetCollectionElementMixin,
/** @lends NestedDCDCE.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    // because all objects have constructors (as this hashmap would even if this next line wasn't present)
    //  the constructor in hcontentMixin won't be attached by BASE_MVC.mixin to this model
    //  - re-apply manually it now
    /** call the mixin constructor */
    constructor : function( attributes, options ){
        this.debug( '\t NestedDCDCE.constructor:', attributes, options );
        DatasetCollectionElementMixin.constructor.call( this, attributes, options );
    },
    
    /** String representation. */
    toString : function(){
        var objStr = ( this.object )?( '' + this.object ):( this.get( 'element_identifier' ) );
        return ([ 'NestedDCDCE(', objStr, ')' ].join( '' ));
    }
}));


//==============================================================================
/** @class Backbone collection containing Generic NestedDCDCE's (nested dataset collections).
 */
var NestedDCDCECollection = DCECollection.extend(
/** @lends NestedDCDCECollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,
    
    /** This is a collection of nested collections */
    model: NestedDCDCE,

//TODO: unused?
    /** set up */
    initialize : function( attrs, options ){
        this.debug( this + '(NestedDCDCECollection).initialize:', attrs, options );
        DCECollection.prototype.initialize.call( this, attrs, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'NestedDCDCECollection(', this.length, ')' ].join( '' ));
    }
});


//==============================================================================
/** @class Backbone model for a paired dataset collection within a list:paired dataset collection.
 */
var NestedPairDCDCE = PairDatasetCollection.extend( BASE_MVC.mixin( DatasetCollectionElementMixin,
/** @lends NestedPairDCDCE.prototype */{
//TODO:?? possibly rename to NestedDatasetCollection?

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    // because all objects have constructors (as this hashmap would even if this next line wasn't present)
    //  the constructor in hcontentMixin won't be attached by BASE_MVC.mixin to this model
    //  - re-apply manually it now
    /** This is both a collection and a collection element - call the constructor */
    constructor : function( attributes, options ){
        this.debug( '\t NestedPairDCDCE.constructor:', attributes, options );
        //DatasetCollection.constructor.call( this, attributes, options );
        DatasetCollectionElementMixin.constructor.call( this, attributes, options );
    },

    /** String representation. */
    toString : function(){
        var objStr = ( this.object )?( '' + this.object ):( this.get( 'element_identifier' ) );
        return ([ 'NestedPairDCDCE(', objStr, ')' ].join( '' ));
    }
}));


//==============================================================================
/** @class Backbone collection for a backbone collection containing paired dataset collections.
 */
var NestedPairDCDCECollection = NestedDCDCECollection.extend(
/** @lends PairDCDCECollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    /** We know this collection is composed of only nested pair collections */
    model: NestedPairDCDCE,

//TODO: unused?
    /** set up */
    initialize : function( attrs, options ){
        this.debug( this + '(NestedPairDCDCECollection).initialize:', attrs, options );
        NestedDCDCECollection.prototype.initialize.call( this, attrs, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'NestedPairDCDCECollection(', this.length, ')' ].join( '' ));
    }
});


//==============================================================================
/** @class Backbone Model for a DatasetCollection (list) that contains DatasetCollections (pairs).
 */
var ListPairedDatasetCollection = DatasetCollection.extend(
/** @lends ListPairedDatasetCollection.prototype */{

    /** logger used to record this.log messages, commonly set to console */
    //logger              : console,

    /** list:paired is the only collection that itself contains collections */
    collectionClass : NestedPairDCDCECollection,

//TODO: unused?
    /** set up */
    initialize : function( attributes, options ){
        this.debug( this + '(ListPairedDatasetCollection).initialize:', attributes, options );
        DatasetCollection.prototype.initialize.call( this, attributes, options );
    },

    /** String representation. */
    toString : function(){
         return ([ 'ListPairedDatasetCollection(', this.get( 'name' ), ')' ].join( '' ));
    }
});


//==============================================================================
    return {
        ListDatasetCollection               : ListDatasetCollection,
        PairDatasetCollection               : PairDatasetCollection,
        ListPairedDatasetCollection         : ListPairedDatasetCollection
    };
});