var YWSID = "pCx6OSKGDVbm48ReioI9Cw"; // common required parameter (api key)

    var map = null;
    var icon = null;
    var popWin = true;

    /*
     * Creates the map object and calls setCenterAndBounds
     * to instantiate it.
     */
    function loadYelp(lat, lng, zoom) {
        map = new GMap2(document.getElementById("map"));
        //GEvent.addListener(map, "load", function() {updateMap();});    
        if (!zoom) {
        	zoom = 15;
        }
        map.setCenter(new GLatLng(lat, lng), zoom);
        map.addControl(new GMapTypeControl());
        map.addControl(new GLargeMapControl());
        //map.setMapType(G_HYBRID_MAP);
          
        //if (window.attachEvent) window.attachEvent("onresize", function() { map.checkResize()} );
        //else if (window.addEventListener) window.addEventListener("resize", function() { map.checkResize()}, false);

        // setup our marker icon
        icon = new GIcon();
        icon.image = "/img/yelp/marker_star.png";
        icon.shadow = "/img/yelp/marker_shadow.png";
        icon.iconSize = new GSize(20, 29);
        icon.shadowSize = new GSize(38, 29);
        icon.iconAnchor = new GPoint(15, 29);
        icon.infoWindowAnchor = new GPoint(15, 3);
        
        // setup callbacks for map actions
        GEvent.bind(map, 'dragend', this, updateMap);
	 	GEvent.bind(map, 'zoomend', this, updateMap);
    }

    /*
     * Construct the URL to call for the API request
     */
    function constructYelpURL() {
        var mapBounds = map.getBounds();
        var URL = "http://api.yelp.com/" +
            "business_review_search?"+
            "callback=" + "handleResults" +
            "&term=" + document.getElementById("term").value + 
            "&num_biz_requested=10" +
            "&tl_lat=" + mapBounds.getSouthWest().lat() +
            "&tl_long=" + mapBounds.getSouthWest().lng() + 
            "&br_lat=" + mapBounds.getNorthEast().lat() + 
            "&br_long=" + mapBounds.getNorthEast().lng() +
            "&ywsid=" + YWSID;
        return encodeURI(URL);
    }

    /*
     * Called on the form submission: updates the map by
     * placing markers on it at the appropriate places
     */
    function updateMap(doPopWin) {
        // turn on spinner animation
        document.getElementById("spinner").style.visibility = 'visible';

        var yelpRequestURL = constructYelpURL();

        /* clear existing markers */
        map.clearOverlays();
        
        /* do the api request */
        var script = document.createElement('script');
        script.src = yelpRequestURL;
        script.type = 'text/javascript';
        var head = document.getElementsByTagName('head').item(0);
        head.appendChild(script);
        if (doPopWin) {
        	popWin = true;
        }
        return false;
    }

    /*
     * If a sucessful API response is received, place
     * markers on the map.  If not, display an error.
     */
    function handleResults(data) {
        // turn off spinner animation
        document.getElementById("spinner").style.visibility = 'hidden';
        if(data.message.text == "OK") {
            if (data.businesses.length == 0) {
                alert("Error: No businesses were found near that location");
                return;
            }
            for(var i=0; i<data.businesses.length; i++) {
                biz = data.businesses[i];
                createMarker(biz, new GLatLng(biz.latitude, biz.longitude), i);
            }
        }
        else {
            alert("Error: " + data.message.text);
        }
    }

    /*
     * Formats and returns the Info Window HTML 
     * (displayed in a balloon when a marker is clicked)
     */
    function generateInfoWindowHtml(biz) {
        var text = '<div class="marker">';

        // image and rating
        text += '<img class="businessimage" src="'+biz.photo_url+'"/>';

        // div start
        text += '<div class="businessinfo">';
        // name/url
        text += '<a href="'+biz.url+'" target="_blank">'+biz.name+'</a><br/>';
        // stars
        text += '<img class="ratingsimage" src="'+biz.rating_img_url_small+'"/>&nbsp;based&nbsp;on&nbsp;';
        // reviews
        text += biz.review_count + '&nbsp;reviews<br/><br />';
        // categories
        text += formatCategories(biz.categories);
        // neighborhoods
        if(biz.neighborhoods.length)
            text += formatNeighborhoods(biz.neighborhoods);
        // address
        text += biz.address1 + '<br/>';
        // address2
        if(biz.address2.length) 
            text += biz.address2+ '<br/>';
        // city, state and zip
        text += biz.city + ',&nbsp;' + biz.state + '&nbsp;' + biz.zip + '<br/>';
        // phone number
        if(biz.phone.length)
            text += formatPhoneNumber(biz.phone);
        // Read the reviews
        text += '<br/><a href="'+biz.url+'" target="_blank">Read the reviews »</a><br/>';
        // div end
        text += '</div></div>'
        return text;
    }

    /*
     * Formats the categories HTML
     */
    function formatCategories(cats) {
        var s = 'Categories: ';
        for(var i=0; i<cats.length; i++) {
            s+= cats[i].name;
            if(i != cats.length-1) s += ', ';
        }
        s += '<br/>';
        return s;
    }

    /*
     * Formats the neighborhoods HTML
     */
    function formatNeighborhoods(neighborhoods) {
        s = 'Neighborhoods: ';
        for(var i=0; i<neighborhoods.length; i++) {
            s += '<a href="' + neighborhoods[i].url + '" target="_blank">' + neighborhoods[i].name + '</a>';
            if (i != neighborhoods.length-1) s += ', ';
        }
        s += '<br/>';
        return s;
    }

    /*
     * Formats the phone number HTML
     */
    function formatPhoneNumber(num) {
        if(num.length != 10) return '';
        return '(' + num.slice(0,3) + ') ' + num.slice(3,6) + '-' + num.slice(6,10) + '<br/>';
    }
    
    /*
     * Creates a marker for the given business and point
     */
    function createMarker(biz, point, markerNum) {
        var infoWindowHtml = generateInfoWindowHtml(biz)
        var marker = new GMarker(point, icon);
        map.addOverlay(marker);
        GEvent.addListener(marker, "click", function() {
            marker.openInfoWindowHtml(infoWindowHtml, {maxWidth:400});
        });
        // automatically open first marker
        if (markerNum == 0 && popWin)
            marker.openInfoWindowHtml(infoWindowHtml, {maxWidth:400});
            popWin = false;
    }