page.replace_html :sidebar_title, 'Data'
page.replace_html :sidebar_content, :partial => 'start'
page << <<EOJ
    
    var gml, sf, objList, currentFeature, featureList, mode = "auto", currentBounds, browsing;
    OpenLayers.Feature.Vector.style['default'].strokeWidth = 3;
    OpenLayers.Feature.Vector.style['default'].cursor = "pointer";
    
    function start() {
        openSidebar({ onclose: stopBrowse });
        var vectors = new OpenLayers.Layer.Vector();
    
        box = new OpenLayers.Control.DrawFeature(vectors, OpenLayers.Handler.RegularPolygon, { 
          handlerOptions: {
            sides: 4,
            snapAngle: 90,
            irregular: true,
            persist: true,
            callbacks: { done: endDrag }
          }
        });
        map.addControl(box);
        map.events.register("moveend", map, showData);
        map.events.triggerEvent("moveend");
        browsing = true;
    }

    function showData() {
        if (mode == "manual") { return; }
        if (map.getZoom() >= 15) {
            useMap();
        } else {
            $("status").innerHTML = "Zoom in or Select an area of the map to view.";
        }    
    }
    
    function stopBrowse() {
        if (gml) {
            gml.destroy();
            gml = null; 
        } 
        if (sf) {   
            sf.destroy();  
            sf = null;
        } 
        if (currentFeature) {
            currentFeature.destroy(); 
            currentFeature = null; 
        } 
        map.events.unregister("moveend", map, showData);
        browsing = false; 
    }
    
    function startDrag() {
      $("drag_box").innerHTML='Drag a box on the map to select an area';
       box.activate(); 
       return false;
    };
    $("drag_box").onclick = startDrag;
    
    function useMap() {
        var bounds = map.getExtent();
        var projected = bounds.clone().transform(map.getProjectionObject(), epsg4326);
        if (!currentBounds || !currentBounds.containsBounds(projected)) {
            var center = bounds.getCenterLonLat();
            var tileWidth = bounds.getWidth() * 1.2;
            var tileHeight = bounds.getHeight() * 1.2;
            var tileBounds =
                new OpenLayers.Bounds(center.lon - (tileWidth / 2),
                                      center.lat - (tileHeight / 2),
                                      center.lon + (tileWidth / 2),
                                      center.lat + (tileHeight / 2));

            currentBounds = tileBounds;
            getData(tileBounds);
            mode = "auto";
            $("use_map").style.display="none";
        }
        return false;
    }
    $("use_map").onclick = useMap;
    
    function endDrag(bbox) {
        var bounds = bbox.getBounds();
        box.deactivate();
        getData(bounds);
        $("drag_box").innerHTML = "Manually select a different area";
        mode = "manual";  
        $("use_map").style.display="inline";
    }
    
    function displayFeatureWarning() {
        $("status").innerHTML = "";
        var div = document.createElement("div");
        var p = document.createElement("p");
        p.appendChild(document.createTextNode("You have loaded an area which contains " + featureList.length + " features. In general, some browsers may not cope well with displaying this quantity of data. Generally, browsers work best at displaying less than 100 features at a time: doing anything else may make your browser slow/unresponsive. If you are sure you want to display this data, you may do so by clicking the button below.")); 
        div.appendChild(p);
        var input = document.createElement("input");
        input.type = "submit";
        input.value = "Load Data";
        input.onclick = loadFeatureList;
        div.appendChild(input); 
        $("object").innerHTML="";
        $("object").appendChild(div);
    }
    
    function loadFeatureList() {
        gml.addFeatures(featureList);
        gml.events.triggerEvent("loadend");
        return false;
    }    

    function customDataLoader(request) { 
        if (!browsing) { return; } 
        var doc = request.responseXML;
        
        if (!doc || !doc.documentElement) {
            doc = request.responseText;
        }
        
        var options = {};
        
        OpenLayers.Util.extend(options, this.formatOptions);
        if (this.map && !this.projection.equals(this.map.getProjectionObject())) {
            options.externalProjection = this.projection;
            options.internalProjection = this.map.getProjectionObject();
        }    
        
        var gml = this.format ? new this.format(options) : new OpenLayers.Format.GML(options);
        var features = gml.read(doc);
        if (!this.maxFeatures || features.length <= this.maxFeatures) {
            this.addFeatures(features);
            this.events.triggerEvent("loadend");
            featureList = []; 
        } else {
            featureList = features;
            displayFeatureWarning();
        }
    }

    function getData(bounds) {
        
        bounds.transform(new OpenLayers.Projection("EPSG:900913"), new OpenLayers.Projection("EPSG:4326"));
        var size = bounds.getWidth() * bounds.getHeight(); 
        if (size > 0.25) {
            $("status").innerHTML = "Unable to load: Bounding box size of " + size + " is too large. (Must be smaller than 0.25)<br />"; 
            return;
        }

        var url = "/api/0.5/map?bbox="+bounds.toBBOX();
        
        loadGML(url);
    }
    function loadGML(url) {
        $("status").innerHTML = "Loading...";
        $("object").innerHTML = "";
        if (!gml) {
            var style = new OpenLayers.Style();
            style.addRules([new OpenLayers.Rule( 
              {'symbolizer': 
                {"Polygon": {'fillColor': '#ff0000', 'strokeColor': '#ff0000'},
                 "Line": {'fillColor': '#ffff00', 'strokeColor': '#000000', strokeOpacity: '0.4'},
                 "Point": {'fillColor': '#00ff00', 'strokeColor': '#00ff00'}}
              }
            )]);
            gml = new OpenLayers.Layer.GML("Data",url, 
                    {format: OpenLayers.Format.OSM, formatOptions: {checkTags: true},
                     maxFeatures: 100, requestSuccess: customDataLoader,
                     styleMap: new OpenLayers.StyleMap({'default': style, 'select': {'strokeColor': '#0000ff', strokeWidth: 8}})
                    }
            );
            gml.events.register("loadend", gml, dataLoaded );
            map.addLayer(gml);
            
            sf = new OpenLayers.Control.SelectFeature(gml, {'onSelect': onFeatureSelect});
            sf.handler.stopDown = false;
            sf.handler.stopUp = false;
            map.addControl(sf);
            sf.activate();
             
        } else {
            gml.setUrl(url);
        }

        currentFeature = null;
    }
    function dataLoaded() {
        if (!browsing) { return; } 
        $("status").innerHTML = "Loaded " + this.features.length + " features. (<a href='"+ this.url+"'>API</a>)";
        
        objList = document.createElement("ul");
        for (var i = 0; i < this.features.length; i++) {
            var feature = this.features[i]; 
            
            // Type, for linking
            var type ="way";
            if (feature.geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
                type = "node";
            }   
            var nice_name = type.substr(0,1).toUpperCase() + type.substr(1,type.length); 
            var li = document.createElement("li");
            li.appendChild(document.createTextNode(nice_name + " "));
            
            // Link, for viewing in the tab
            var link = document.createElement("a");
            link.href =  "/browse/" + type + "/" + feature.osm_id; 
            var name = feature.attributes.name || feature.osm_id;
            link.appendChild(document.createTextNode(name));
            link.feature = feature;
            link.onclick = OpenLayers.Function.bind(viewFeatureLink, link);   
            li.appendChild(link);

            objList.appendChild(li);
        }
        $("object").innerHTML = "";
        $("object").appendChild(objList); 
    }
    
    function viewFeatureLink() {
        var layer = this.feature.layer;
        for (var i = 0; i < layer.selectedFeatures.length; i++) {
            var f = layer.selectedFeatures[i]; 
            layer.drawFeature(f, layer.styleMap.createSymbolizer(f, "default"));
        }
        onFeatureSelect(this.feature);
        if (mode != "auto") {
            map.setCenter(this.feature.geometry.getBounds().getCenterLonLat()); 
        }
        return false;
    }
    
    function loadObjList() {
        $("object").innerHTML="";
        $("object").appendChild(objList);
        return false;
    }
      
    function onFeatureSelect(feature) {
        // Unselect previously selected feature
        if (currentFeature) {
          currentFeature.layer.drawFeature(
            currentFeature, currentFeature.layer.styleMap.createSymbolizer(currentFeature, "default")
          );
        }

        // Redraw in selected style
        feature.layer.drawFeature(
          feature, feature.layer.styleMap.createSymbolizer(feature, "select")
        );

        // If the current object is the list, don't innerHTML="", since that could clar it.   
        if ($("object").firstChild == objList) { 
            $("object").removeChild(objList);
        } else { 
            $("object").innerHTML = "";
        }   
        
        // Create a link back to the object list
        var div = document.createElement("div");
        var link = document.createElement("a");
        link.href="#";
        link.onclick = loadObjList;
        link.appendChild(document.createTextNode("Back to Object List"));
        div.appendChild(link)
        $("object").appendChild(div);    
        
        // Now the list of attributes
        var ul = document.createElement("ul");
        var type = "way";
        if (feature.geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
            type = "node";
        }    
        var li = document.createElement("li");
        var link = document.createElement("a");   
        link.href =  "/browse/"+type+"/"+feature.osm_id;
        link.appendChild(document.createTextNode(feature.osm_id));
        li.appendChild(link);
        ul.appendChild(li);
        for (var key in feature.attributes) {
            var li = document.createElement("li");
            var b = document.createElement("b");
            b.appendChild(document.createTextNode(key));
            li.appendChild(b);
            li.appendChild(document.createTextNode(": " + feature.attributes[key]));
            ul.appendChild(li);
        }
        
        var li = document.createElement("li");
        var link = document.createElement("a");   
        link.href =  "/browse/"+type+"/"+feature.osm_id+"/history";
        link.appendChild(document.createTextNode("History"));
        li.appendChild(link);
        ul.appendChild(li);
        link.onclick = OpenLayers.Function.bind(loadHistory, {type: type, feature: feature, link: link});
        $("object").appendChild(ul);
        
        
        // Stash the currently drawn feature
        currentFeature = feature; 
    }   
    function loadHistory() {
        this.link.href = "";
        this.link.innerHTML = "Wait...";
        new Ajax.Request("/api/0.5/"+this.type+"/"+this.feature.osm_id+"/history", {onComplete: OpenLayers.Function.bind(displayHistory, this)});
        return false;
    }
    function displayHistory(request) {
        if (currentFeature.osm_id != this.feature.osm_id || $("object").firstChild == objList)  { 
            return false;
        } 
        this.link.parentNode.parentNode.removeChild(this.link.parentNode);
        var doc = request.responseXML;
        var div = document.createElement("div");
        var h3 = document.createElement("h3"); 
        h3.appendChild(document.createTextNode("History"));
        div.appendChild(h3);
        var nodes = doc.getElementsByTagName(this.type);
        var history = document.createElement("ul");  
        for (var i = nodes.length - 1; i >= 0; i--) {
            var user = nodes[i].getAttribute("user") || "private user";
            var timestamp = nodes[i].getAttribute("timestamp");
            var item = document.createElement("li");
            item.appendChild(document.createTextNode("Edited by " + user + " at " + timestamp));
            history.appendChild(item);
        }
        div.appendChild(history);
        var link = document.createElement("a");
        link.appendChild(document.createTextNode("History"));
        link.href = "/browse/"+this.type+"/"+this.feature.osm_id+"/history";
        div.appendChild(link);
        $("object").appendChild(div); 
    }
    
    start();
EOJ