/**
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
* 
* Copyright 2005 Richard Heyes
*/

/**
* Global vars
*/
__AutoComplete = new Array();

// Basic UA detection
isIE = document.all ? true : false;
isGecko = navigator.userAgent.toLowerCase().indexOf('gecko') != -1;
isOpera = navigator.userAgent.toLowerCase().indexOf('opera') != -1;


/**
* Attachs the autocomplete object to a form element. Sets
* onkeypress event on the form element.
* 
* @param string formElement Name of form element to attach to
* @param array  data        Array of strings of which to use as the autocomplete data
*/
function AutoComplete_Create (id, data)
{
	__AutoComplete[id] = {'data':data,
						  'isVisible':false,
						  'element':document.getElementById(id),
						  'dropdown':null,
						  'highlighted':null};

	__AutoComplete[id]['element'].setAttribute('autocomplete', 'off');
	__AutoComplete[id]['element'].onkeydown  = function(e) {return AutoComplete_KeyDown(this.getAttribute('id'), e);}
	__AutoComplete[id]['element'].onkeyup    = function(e) {return AutoComplete_KeyUp(this.getAttribute('id'), e);}
	__AutoComplete[id]['element'].onkeypress = function(e) {if (!e) e = window.event; if (e.keyCode == 13 || isOpera) return false;}
	__AutoComplete[id]['element'].ondblclick = function() {AutoComplete_ShowDropdown(this.getAttribute('id'));}
	__AutoComplete[id]['element'].onclick    = function(e) {if (!e) e = window.event; e.cancelBubble = true; e.returnValue = false;}

	// Hides the dropdowns when document clicked
	var docClick = function()
	{
	   for (id in __AutoComplete) {
		   AutoComplete_HideDropdown(id);
	   }
	}

	if (document.addEventListener) {
		document.addEventListener('click', docClick, false);
	} else if (document.attachEvent) {
		document.attachEvent('onclick', docClick, false);
	}


	// Max number of items shown at once
	if (arguments[2] != null) {
		__AutoComplete[id]['maxitems'] = arguments[2];
		__AutoComplete[id]['firstItemShowing'] = 0;
		__AutoComplete[id]['lastItemShowing']  = arguments[2] - 1;
	}
	
	AutoComplete_CreateDropdown(id);
	
	// Prevent select dropdowns showing thru
	if (isIE) {
		__AutoComplete[id]['iframe'] = document.createElement('iframe');
		__AutoComplete[id]['iframe'].id = id +'_iframe';
		__AutoComplete[id]['iframe'].style.position = 'absolute';
		__AutoComplete[id]['iframe'].style.top = '0';
		__AutoComplete[id]['iframe'].style.left = '0';
		__AutoComplete[id]['iframe'].style.width = '0px';
		__AutoComplete[id]['iframe'].style.height = '0px';
		__AutoComplete[id]['iframe'].style.zIndex = '98';
		__AutoComplete[id]['iframe'].style.visibility = 'hidden';
		
		__AutoComplete[id]['element'].parentNode.insertBefore(__AutoComplete[id]['iframe'], __AutoComplete[id]['element']);
	}
}


/**
* Creates the dropdown layer
* 
* @param string id The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_CreateDropdown(id)
{
	var left  = AutoComplete_GetLeft(__AutoComplete[id]['element']);
	var top   = AutoComplete_GetTop(__AutoComplete[id]['element']) + __AutoComplete[id]['element'].offsetHeight;
	var width = __AutoComplete[id]['element'].offsetWidth;

	__AutoComplete[id]['dropdown'] = document.createElement('div');
	__AutoComplete[id]['dropdown'].className = 'autocomplete'; // Don't use setAttribute()

	__AutoComplete[id]['element'].parentNode.insertBefore(__AutoComplete[id]['dropdown'], __AutoComplete[id]['element']);
	
	// Position it
	__AutoComplete[id]['dropdown'].style.left       = left + 'px';
	__AutoComplete[id]['dropdown'].style.top        = top + 'px';
	__AutoComplete[id]['dropdown'].style.width      = width + 'px';
	__AutoComplete[id]['dropdown'].style.zIndex     = '99';
	__AutoComplete[id]['dropdown'].style.visibility = 'hidden';
}


/**
* Gets left coord of given element
* 
* @param object element The element to get the left coord for
*/
function AutoComplete_GetLeft(element)
{
	var curNode = element;
	var left    = 0;

	do {
		left += curNode.offsetLeft;
		curNode = curNode.offsetParent;

	} while(curNode.tagName.toLowerCase() != 'body');

	return left;
}


/**
* Gets top coord of given element
* 
* @param object element The element to get the top coord for
*/
function AutoComplete_GetTop(element)
{
	var curNode = element;
	var top    = 0;

	do {
		top += curNode.offsetTop;
		curNode = curNode.offsetParent;

	} while(curNode.tagName.toLowerCase() != 'body');

	return top;
}


/**
* Shows the dropdown layer
* 
* @param string id The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_ShowDropdown(id)
{
	AutoComplete_HideAll();

	var value = __AutoComplete[id]['element'].value.toLowerCase();
	var toDisplay = new Array();
	var newDiv    = null;
	var text      = null;
	var numItems  = __AutoComplete[id]['dropdown'].childNodes.length;

	// Remove all child nodes from dropdown
	while (__AutoComplete[id]['dropdown'].childNodes.length > 0) {
		__AutoComplete[id]['dropdown'].removeChild(__AutoComplete[id]['dropdown'].childNodes[0]);
	}

	// Go thru data searching for matches
	for (i=0; i<__AutoComplete[id]['data'].length; ++i) {
		if (__AutoComplete[id]['data'][i].substr(0, value.length) == value) {
			toDisplay[toDisplay.length] = __AutoComplete[id]['data'][i];
		}
	}
	
	// No matches?
	if (toDisplay.length == 0) {
		AutoComplete_HideDropdown(id);
		return;
	}



	// Add data to the dropdown layer
	for (i=0; i<toDisplay.length; ++i) {
		newDiv = document.createElement('div');
		newDiv.className = 'autocomplete_item'; // Don't use setAttribute()
		newDiv.setAttribute('id', 'autocomplete_item_' + i);
		newDiv.setAttribute('index', i);
		newDiv.style.zIndex = '99';
		
		 // Scrollbars are on display ?
		if (toDisplay.length > __AutoComplete[id]['maxitems'] && navigator.userAgent.indexOf('MSIE') == -1) {
			newDiv.style.width = __AutoComplete[id]['element'].offsetWidth - 22 + 'px';
		}

		newDiv.onmouseover = function() {AutoComplete_HighlightItem(__AutoComplete[id]['element'].getAttribute('id'), this.getAttribute('index'));};
		newDiv.onclick     = function() {AutoComplete_SetValue(__AutoComplete[id]['element'].getAttribute('id')); AutoComplete_HideDropdown(__AutoComplete[id]['element'].getAttribute('id'));}
		
		text   = document.createTextNode(toDisplay[i]);
		newDiv.appendChild(text);
		
		__AutoComplete[id]['dropdown'].appendChild(newDiv);
	}
	
	
	// Too many items?
	if (toDisplay.length > __AutoComplete[id]['maxitems']) {
		__AutoComplete[id]['dropdown'].style.height = (__AutoComplete[id]['maxitems'] * 15) + 2 + 'px';
	
	} else {
		__AutoComplete[id]['dropdown'].style.height = '';
	}

	
	/**
	* Set left/top in case of document movement/scroll/window resize etc
	*/
	__AutoComplete[id]['dropdown'].style.left = AutoComplete_GetLeft(__AutoComplete[id]['element']);
	__AutoComplete[id]['dropdown'].style.top  = AutoComplete_GetTop(__AutoComplete[id]['element']) + __AutoComplete[id]['element'].offsetHeight;


	// Show the iframe for IE
	if (isIE) {
		__AutoComplete[id]['iframe'].style.top    = __AutoComplete[id]['dropdown'].style.top;
		__AutoComplete[id]['iframe'].style.left   = __AutoComplete[id]['dropdown'].style.left;
		__AutoComplete[id]['iframe'].style.width  = __AutoComplete[id]['dropdown'].offsetWidth;
		__AutoComplete[id]['iframe'].style.height = __AutoComplete[id]['dropdown'].offsetHeight;
		
		__AutoComplete[id]['iframe'].style.visibility = 'visible';
	}


	// Show dropdown
	if (!__AutoComplete[id]['isVisible']) {
		__AutoComplete[id]['dropdown'].style.visibility = 'visible';
		__AutoComplete[id]['isVisible'] = true;
	}

	
	// If now showing less items than before, reset the highlighted value
	if (__AutoComplete[id]['dropdown'].childNodes.length != numItems) {
		__AutoComplete[id]['highlighted'] = null;
	}
}


/**
* Hides the dropdown layer
* 
* @param string id The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_HideDropdown(id)
{
	if (__AutoComplete[id]['iframe']) {
		__AutoComplete[id]['iframe'].style.visibility = 'hidden';
	}


	__AutoComplete[id]['dropdown'].style.visibility = 'hidden';
	__AutoComplete[id]['highlighted'] = null;
	__AutoComplete[id]['isVisible']   = false;
}


/**
* Hides all dropdowns
*/
function AutoComplete_HideAll()
{
	for (id in __AutoComplete) {
		AutoComplete_HideDropdown(id);
	}
}


/**
* Highlights a specific item
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
* @param int    index The index of the element in the dropdown to highlight
*/
function AutoComplete_HighlightItem(id, index)
{
	if (__AutoComplete[id]['dropdown'].childNodes[index]) {
		for (var i=0; i<__AutoComplete[id]['dropdown'].childNodes.length; ++i) {
			if (__AutoComplete[id]['dropdown'].childNodes[i].className == 'autocomplete_item_highlighted') {
				__AutoComplete[id]['dropdown'].childNodes[i].className = 'autocomplete_item';
			}
		}
		
		__AutoComplete[id]['dropdown'].childNodes[index].className = 'autocomplete_item_highlighted';
		__AutoComplete[id]['highlighted'] = index;
	}
}


/**
* Highlights the menu item with the given index
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
* @param int    index The index of the element in the dropdown to highlight
*/
function AutoComplete_Highlight(id, index)
{
	// Out of bounds checking
	if (index == 1 && __AutoComplete[id]['highlighted'] == __AutoComplete[id]['dropdown'].childNodes.length - 1) {
		__AutoComplete[id]['dropdown'].childNodes[__AutoComplete[id]['highlighted']].className = 'autocomplete_item';
		__AutoComplete[id]['highlighted'] = null;
	
	} else if (index == -1 && __AutoComplete[id]['highlighted'] == 0) {
		__AutoComplete[id]['dropdown'].childNodes[0].className = 'autocomplete_item';
		__AutoComplete[id]['highlighted'] = __AutoComplete[id]['dropdown'].childNodes.length;
	}

	// Nothing highlighted at the moment
	if (__AutoComplete[id]['highlighted'] == null) {
		__AutoComplete[id]['dropdown'].childNodes[0].className = 'autocomplete_item_highlighted';
		__AutoComplete[id]['highlighted'] = 0;

	} else {
		if (__AutoComplete[id]['dropdown'].childNodes[__AutoComplete[id]['highlighted']]) {
			__AutoComplete[id]['dropdown'].childNodes[__AutoComplete[id]['highlighted']].className = 'autocomplete_item';
		}

		var newIndex = __AutoComplete[id]['highlighted'] + index;

		if (__AutoComplete[id]['dropdown'].childNodes[newIndex]) {
			__AutoComplete[id]['dropdown'].childNodes[newIndex].className = 'autocomplete_item_highlighted';
			
			__AutoComplete[id]['highlighted'] = newIndex;
		}
	}
}


/**
* Sets the input to a given value
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_SetValue(id)
{
	__AutoComplete[id]['element'].value = __AutoComplete[id]['dropdown'].childNodes[__AutoComplete[id]['highlighted']].innerHTML;
}


/**
* Checks if the dropdown needs scrolling
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_ScrollCheck(id)
{
	// Scroll down, or wrapping around from scroll up
	if (__AutoComplete[id]['highlighted'] > __AutoComplete[id]['lastItemShowing']) {
		__AutoComplete[id]['firstItemShowing'] = __AutoComplete[id]['highlighted'] - (__AutoComplete[id]['maxitems'] - 1);
		__AutoComplete[id]['lastItemShowing']  = __AutoComplete[id]['highlighted'];
	}
	
	// Scroll up, or wrapping around from scroll down
	if (__AutoComplete[id]['highlighted'] < __AutoComplete[id]['firstItemShowing']) {
		__AutoComplete[id]['firstItemShowing'] = __AutoComplete[id]['highlighted'];
		__AutoComplete[id]['lastItemShowing']  = __AutoComplete[id]['highlighted'] + (__AutoComplete[id]['maxitems'] - 1);
	}
	
	__AutoComplete[id]['dropdown'].scrollTop = __AutoComplete[id]['firstItemShowing'] * 15;
}


/**
* Function which handles the keypress event
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_KeyDown(id)
{
	// Mozilla
	if (arguments[1] != null) {
		event = arguments[1];
	}

	var keyCode = event.keyCode;

	switch (keyCode) {

		// Return/Enter
		case 13:
			if (__AutoComplete[id]['highlighted'] != null) {
				AutoComplete_SetValue(id);
				AutoComplete_HideDropdown(id);
			}
			
			event.returnValue = false;
			event.cancelBubble = true;
			break;

		// Escape
		case 27:
			AutoComplete_HideDropdown(id);
			event.returnValue = false;
			event.cancelBubble = true;
			break;
		
		// Up arrow
		case 38:
			if (!__AutoComplete[id]['isVisible']) {
				AutoComplete_ShowDropdown(id);
			}
			
			AutoComplete_Highlight(id, -1);
			AutoComplete_ScrollCheck(id, -1);
			return false;
			break;
		
		// Tab
		case 9:
			if (__AutoComplete[id]['isVisible']) {
				AutoComplete_HideDropdown(id);
			}
			return;
		
		// Down arrow
		case 40:
			if (!__AutoComplete[id]['isVisible']) {
				AutoComplete_ShowDropdown(id);
			}
			
			AutoComplete_Highlight(id, 1);
			AutoComplete_ScrollCheck(id, 1);
			return false;
			break;
	}
}


/**
* Function which handles the keyup event
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_KeyUp(id)
{
	// Mozilla
	if (arguments[1] != null) {
		event = arguments[1];
	}

	var keyCode = event.keyCode;

	switch (keyCode) {
		case 13:
			event.returnValue = false;
			event.cancelBubble = true;
			break;

		case 27:
			AutoComplete_HideDropdown(id);
			event.returnValue = false;
			event.cancelBubble = true;
			break;
		
		case 38:
		case 40:
			return false;
			break;

		default:
			AutoComplete_ShowDropdown(id);
			break;
	}
}

/**
* Returns whether the dropdown is visible
* 
* @param string id    The form elements id. Used to identify the correct dropdown.
*/
function AutoComplete_isVisible(id)
{
	return __AutoComplete[id]['dropdown'].style.visibility == 'visible';
}