/*  suggest ahead by braudel -a-t- ferrarihaines - dot - com 2008 
	
	usage: just add class="suggest_ahead" to the input needed to
	enable and write appropiate backend code to handle the query and reply
	using json
*/



var suggest = function(spec){
    var a, url, input_id, AJAXres, textbox, search_length;
	
	var sg = {
	  init		: function(){
					  this.url		= spec.url;
					  this.input_id	= spec.input_id;
					  this.textbox  = $e(spec.input_id);
					  this.a = new net.CLoader(this.url, 
										   this.a_response,
										   null,
										   null,
										   null);
	  },
	  search		: function() {
					  if ( $e(this.input_id).value.length > 2 
							&& (!this.a.readyState 
								|| this.a.readyState == 4 
								|| this.a.readyState == 0)) {

						this.search_length	= this.textbox.value.length;
						//this.a.loadXMLDoc( this.input_id+'=' + encodeURIComponent( this.last_word() ) );
						this.a.loadXMLDoc( this.input_id+'=' + encodeURIComponent( this.textbox.value ) );
					  }
	  },
	  a_response	: function(){
					  if(this.req.responseText != null){

						  AJAXres = JSON.parse(this.req.responseText);
						  if (AJAXres.id && AJAXres.suggestions && AJAXres.suggestions.length){
							
							if (inputs[AJAXres.id]){
								// some init stuff
								AJAXres.index = 0;
								inputs[AJAXres.id].AJAXres = AJAXres;
								inputs[AJAXres.id].refresh();
							}
						  }
					  }
	  },
	  select_range : function(start , length ){

			if (this.textbox.createTextRange) {
				var range = this.textbox.createTextRange(); 
				range.moveStart("character", start); 
				range.moveEnd("character", length - this.textbox.value.length);      
				range.select();
				
			} else if (this.textbox.setSelectionRange) {
				this.textbox.setSelectionRange(start, length);
			}     

			this.textbox.focus();      
	  },
	  refresh		: function(){

							if (this.textbox.createTextRange || this.textbox.setSelectionRange){
							
								//grab last word
								var vwords	= this.textbox.value.split(/\w+/g);
										
								if (vwords[0]){
									var lword = vwords.pop();
									vwords.push(this.AJAXres.suggestions[this.AJAXres.index]);
										
									this.textbox.value = vwords.join(' '); 
								}
								else {
									this.textbox.value = this.AJAXres.suggestions[this.AJAXres.index];	
								}
								
								this.select_range(this.search_length, this.textbox.value.length);
							 }
	  },
	  last_word		: function(){
							var vwords	= this.textbox.value.split(/\W+/);
							return vwords.pop();
	  }
	}
	sg.init();
	return sg;
}

/* ev handlers */

var keyup_handler = function(ev) {
					var myev = ev || window.event;
					var target = myev.target || myev.srcElement;

					var key = ev.keyCode ? ev.keyCode : ev.charCode;

					if (inputs[target.id]){

					  if (key <= 32 
						|| (key >= 33 && key <= 46) 
						|| (key >= 112 && key <= 123)) {

							if ( inputs[target.id].AJAXres 
								 && inputs[target.id].AJAXres.suggestions ){

							  if (key === 40  
								  && inputs[target.id].AJAXres.index < (inputs[target.id].AJAXres.suggestions.length - 1)){
							   
								  //arrdown show next in array
								  inputs[target.id].AJAXres.index++;
								  if ( inputs[target.id].AJAXres.suggestions[ inputs[target.id].AJAXres.index ] ) {
									  inputs[target.id].refresh();
								  }
								  else {
									  inputs[target.id].AJAXres.index--;
								  }

							  }
							  else if (key === 38 && inputs[target.id].AJAXres.index > 0){
								  //arrup show prev in array
								  inputs[target.id].AJAXres.index--;
								  if ( inputs[target.id].AJAXres.suggestions[ inputs[target.id].AJAXres.index ] ) {
									  inputs[target.id].refresh();
								  }
								  else {
									  inputs[target.id].AJAXres.index++;
								  }

							  }
							}
					  }
					  else {
						   // just search & show first
							 inputs[target.id].search();
					  }
						
					}
}


/* run */
var inputs = new Array();

window.onload=function(){

  var elements = document.getElementsByTagName('input');
  var all = elements.length;

  for (var i = 0; i < all; i++){
	  if ( hasClass(elements[i], 'suggest_ahead') ){
		  inputs[elements[i].id] 
			= suggest({	url:	'http://www.acal-scientia.org/cgi-bin/suggest.pl',
						input_id : elements[i].id
					  });
	  }
  }

	/* attach ev handlers */
	addEventL(window.document, 'keyup', keyup_handler);
}