Db.Form = new Class
({
	Extends: Vn.Object
	,Implements: Db.Iterator
	,Tag: 'db-form'
	,Child: 'model'
	,Properties:
	{
		/**
		 * The model associated to this form.
		 **/
		model:
		{ 
			type: Db.Model
			,set: function (x)
			{
				this.link ({_model: x},
				{
					 'status-changed': this.onModelChange
					,'row-updated': this.onRowUpdate
				});
			}
			,get: function ()
			{
				return this._model;
			}
		},
		/**
		 * The row where the form positioned, has -1 if the row is unselected.
		 **/
		row:
		{ 
			type: Number
			,set: function (x)
			{
				if (!this._model || this._model.numRows <= x || x < -1)
					x = -1;
				if (x == this._row)
					return;

				this._row = x;
				this.iterChanged ();
			}
			,get: function ()
			{
				return this._row;
			}
		},
		/**
		 * The number of rows in the form.
		 **/
		numRows:
		{
			type: Number
			,get: function ()
			{
				if (this._model)
					return this._model.numRows;

				return 0;
			}
		},
		/**
		 * Checks if the form data is ready.
		 **/
		ready:
		{
			type: Boolean
			,get: function ()
			{
				return this._ready;
			}
		}
	}
	
	,lastRow: 0
	,_model: null
	,_row: -1
	,_ready: false

	,onModelChange: function ()
	{
		var ready = this._model && this._model.ready;
		
		if (ready != this._ready)
		{
			if (this._row != -1)
				this.lastRow = this._row;
	
			this._ready = ready;
			this.signalEmit ('status-changed');
			
			if (this._row == -1)
				this.row = this.lastRow;
				
			if (ready)
				this.signalEmit ('ready');
		}
	}

	,onRowUpdate: function (model, row, column)
	{
		if (row == this._row)
			this.iterChanged ();
	}
});