// ========================================================================
// SproutCore
// copyright 2006-2007 Sprout Systems, Inc.
// ========================================================================

require('controllers/controller') ;
require('foundation/array') ;

/** @class

An Array Controller provides a way to project the contents of an array
out to a view.  You can use this object any place you might use an
array.  Changes to the array will not propogate to the content array
until you call commitChanges().

@extends SC.Controller
@extends SC.Array

*/
SC.ArrayController = SC.Controller.extend(SC.Array, 
/** @scope SC.ArrayController.prototype */
{
  /**
  * The array content that is being managed by the controller.
  * @property
  * @type {Array}
  */
  content: function( key, value )
  {
    if (!this._content) this._content = [];
    if (value !== undefined) 
    {
      // only allow arrays... or array-like objects...
      this._content = ($type(value) == T_ARRAY) || (value && value.objectAt) ? value : [];
    }
    return this._content;
  }.property(),
  
  /**
  * Watches changes to the content property updates the contentClone.
  * @private
  * @observes content
  **/
  _contentObserver: function()
  {
    this.contentCloneReset();
  }.observes('content'),
  

  /**
  * A log of calls to the replace method that will be played back to the content property on commit.
  * @private
  * @property
  * @type {SC.Array}
  */
  changelog: function( key, value )
  {
    if (!this._changelog) this._changelog = [];
    if (value !== undefined) this._changelog = value;
    return this._changelog;
  }.property(),

  /**
  * A collection of all the objects that have been removed using removeObject.
  * On commit, they are deleted.
  * @private
  * @property
  * @type {SC.Array}
  */
  deletions: function( key, value )
  {
    if (!this._deletions) this._deletions = [];
    if (value !== undefined) this._deletions = value;
    return this._deletions;
  }.property(),

  /**
  * The array content that (when committed) will be merged back into the content property.
  * All array methods will take place on this object.
  * @private
  * @property
  * @type {SC.Array}
  */
  contentClone: function( key, value )
  {
    if (value !== undefined)
    {
      this._contentClone = value;
      this.arrayContentDidChange();
    }
    return this._contentClone;
  }.property(),

  /**
  * Clones the content property into the contentClone property.
  * @private
  **/
  contentCloneReset: function()
  {
    this.set('changelog', []);
    this.set('deletions', []);
    this.set('contentClone', null);
  },

  /**
  * SC.Array interface implimentation.
  * 
  * @param {Number} idx 
  *   Starting index in the array to replace.  If idx >= length, then append to 
  *   the end of the array.
  * 
  * @param {Number} amt 
  *   Number of elements that should be removed from the array, starting at 
  *   *idx*.
  * 
  * @param {Array} objects 
  *   An array of zero or more objects that should be inserted into the array at 
  *   *idx* 
  */
  replace: function(idx, amt, objects)
  {
    if (this.get('contentClone') == undefined) this.set('contentClone', this.get('content').clone());

    for (var i=0; i < amt; i++)
    {
      this.get('deletions').push( this._getSourceContent().objectAt(idx + i) );
    }

    this.get('changelog').push({ idx: idx, amt: amt, objects: objects });
    this.get('contentClone').replace(idx, amt, objects);
    
    for (var i=idx, n=idx+amt; i < n; i++)
    {
      if ( this._objControllers && this._objControllers[i] ) 
      {
        this._objControllers[i] = null;
      }
    }
    
    this.editorDidChange() ;
    this.arrayContentDidChange();
    
    return this;
  },
  /**
  * SC.Array interface implimentation.
  * 
  * @param {Number} idx
  *   The index of the item to return.  If idx exceeds the current length, 
  *   return null.
  */
  objectAt: function(idx)
  {
    var obj = this._getSourceContent().objectAt(idx);
    
    if ( !this._objControllers ) this._objControllers = [];
    if ( !this._objControllers[idx] ) this._objControllers[idx] = this.controllerForValue(obj);
    
    return this._objControllers[idx];
  },
  /**
  * SC.Array interface implimentation.
  * @property
  * @type {integer}
  */
  length: function( key, value )
  {
    return this._getSourceContent().get('length');
  }.property(),

  indexOf: function( obj )
  {
    return this._getSourceContent().indexOf(obj);
  },
  _getSourceContent: function()
  {
    return this.get('contentClone') || this.get('content');
  },



  
  /** 
  * @private
  */
  performCommitChanges: function()
  {
    var content = this.get('content');
    var ret     = true;
    
    // cannot commit changes to null content.  Return an error.
    if (!content)
    {
      return $error("No Content");
    }
    
    if (content.beginPropertyChanges) content.beginPropertyChanges();


    // apply all the changes made to the clone
    this.get('changelog').each(function(change)
    {
      content.replace( change.idx, change.amt, change.objects );
    });
    this.get('deletions').each(function(obj)
    {
      if (obj.instanceOf(SC.ObjectController)) obj = obj.get('content');
      if (obj && obj.destroy) 
      {
        obj.destroy();
      }
    });


    if (content.endPropertyChanges) content.endPropertyChanges();
    if (content.commitChanges) ret = content.commitChanges();
    
    if ($ok(ret))
    {
      this.contentCloneReset();
      this.editorDidClearChanges();
    }
    
    return ret;
  },
  /** 
  * @private
  */
  performDiscardChanges: function()
  {
    this.contentCloneReset();
    this.editorDidClearChanges();
    return true;
  }

});