page.replace_html :sidebar_title, 'Data'
page.replace_html :sidebar_content, :partial => 'start'
page << <<EOJ
  var browseBoxControl;
  var browseActive;
  var browseMode = "auto";
  var browseBounds;
  var browseFeatureList;
  var browseActiveFeature;
  var browseDataLayer;
  var browseSelectControl;
  var browseObjectList;

  OpenLayers.Feature.Vector.style['default'].strokeWidth = 3;
  OpenLayers.Feature.Vector.style['default'].cursor = "pointer";
    
  function startBrowse() {
    browseActive = true;

    openSidebar({ onclose: stopBrowse });

    var vectors = new OpenLayers.Layer.Vector();
    
    browseBoxControl = new OpenLayers.Control.DrawFeature(vectors, OpenLayers.Handler.RegularPolygon, { 
      handlerOptions: {
        sides: 4,
        snapAngle: 90,
        irregular: true,
        persist: true,
        callbacks: { done: endDrag }
      }
    });
    map.addControl(browseBoxControl);

    map.events.register("moveend", map, showData);
    map.events.triggerEvent("moveend");
  }

  function showData() {
    if (browseMode == "auto") {
      if (map.getZoom() >= 15) {
          useMap();
      } else {
          setStatus("Zoom in or select an area of the map to view");
      }    
    }
  }

  function stopBrowse() {
    if (browseActive) {
      browseActive = false;

      if (browseDataLayer) {
        browseDataLayer.destroy();
        browseDataLayer = null; 
      } 

      if (browseSelectControl) {   
        browseSelectControl.destroy();  
        browseSelectControl = null;
      } 

      if (browseBoxControl) {
    	browseBoxControl.destroy();
	browseBoxControl = null;
      }		

      if (browseActiveFeature) {
        browseActiveFeature.destroy(); 
        browseActiveFeature = null; 
      }

      map.dataLayer.setVisibility(false);
      map.events.unregister("moveend", map, showData);
    }    
  }

  function startDrag() {
    $("browse_select_box").innerHTML='Drag a box on the map to select an area';

    browseBoxControl.activate();

    return false;
  };

  $("browse_select_box").onclick = startDrag;

  function useMap() {
    var bounds = map.getExtent();
    var projected = bounds.clone().transform(map.getProjectionObject(), epsg4326);

    if (!browseBounds || !browseBounds.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));

      browseBounds = tileBounds;
      getData(tileBounds);

      browseMode = "auto";

      $("browse_select_view").style.display = "none";
    }

    return false;
  }

  $("browse_select_view").onclick = useMap;

  function endDrag(bbox) {
    var bounds = bbox.getBounds();
    var projected = bounds.clone().transform(map.getProjectionObject(), epsg4326);

    browseBoxControl.deactivate();
    browseBounds = projected;
    getData(bounds);

    browseMode = "manual";  

    $("browse_select_box").innerHTML = "Manually select a different area";
    $("browse_select_view").style.display = "inline";
  }

  function displayFeatureWarning() {
    clearStatus();

    var div = document.createElement("div");

    var p = document.createElement("p");
    p.appendChild(document.createTextNode("You have loaded an area which contains " + browseFeatureList.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); 

    $("browse_content").innerHTML = "";
    $("browse_content").appendChild(div);
  }

  function loadFeatureList() {
    browseDataLayer.addFeatures(browseFeatureList);
    browseDataLayer.events.triggerEvent("loadend");

    browseFeatureList = []; 

    return false;
  }    

  function customDataLoader(request) {
    if (browseActive) {
      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);

      browseFeatureList = gml.read(doc);

      if (!this.maxFeatures || browseFeatureList.length <= this.maxFeatures) {
        loadFeatureList();
      } else {
        displayFeatureWarning();
      }
    }
  }

  function getData(bounds) {
    var projected = bounds.clone().transform(new OpenLayers.Projection("EPSG:900913"), new OpenLayers.Projection("EPSG:4326"));
    var size = projected.getWidth() * projected.getHeight();

    if (size > 0.25) {
      setStatus("Unable to load: Bounding box size of " + size + " is too large (must be smaller than 0.25)");
    } else {
      loadGML("/api/0.5/map?bbox=" + projected.toBBOX());
    }
  }

  function loadGML(url) {
    setStatus("Loading...");
    $("browse_content").innerHTML = "";

    if (!browseDataLayer) {
      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' }
        }
      })]);

      browseDataLayer = new OpenLayers.Layer.GML("Data", url, {
        format: OpenLayers.Format.OSM,
        formatOptions: { checkTags: true },
        maxFeatures: 100,
        requestSuccess: customDataLoader,
        displayInLayerSwitcher: false,
        styleMap: new OpenLayers.StyleMap({
          'default': style,
          'select': { strokeColor: '#0000ff', strokeWidth: 8 }
        })
      });
      browseDataLayer.events.register("loadend", browseDataLayer, dataLoaded );
      map.addLayer(browseDataLayer);
            
      browseSelectControl = new OpenLayers.Control.SelectFeature(browseDataLayer, { onSelect: onFeatureSelect });
      browseSelectControl.handlers.feature.stopDown = false;
      browseSelectControl.handlers.feature.stopUp = false;
      map.addControl(browseSelectControl);
      browseSelectControl.activate();
    } else {
      browseDataLayer.setUrl(url);
    }

    browseActiveFeature = null;
  }

  function dataLoaded() {
    if (browseActive) {
      clearStatus();
        
      browseObjectList = document.createElement("div")

      var heading = document.createElement("p");
      heading.className = "browse_heading";
      heading.appendChild(document.createTextNode("Object list"));
      browseObjectList.appendChild(heading);

      var list = document.createElement("ul");

      for (var i = 0; i < this.features.length; i++) {
        var feature = this.features[i]; 
            
        // Type, for linking
        var type = featureType(feature);
        var typeName = ucFirst(type);
        var li = document.createElement("li");
        li.appendChild(document.createTextNode(typeName + " "));
            
        // 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);

        list.appendChild(li);
      }

      browseObjectList.appendChild(list)

      var link = document.createElement("a");
      link.href = this.url;
      link.appendChild(document.createTextNode("API"));
      browseObjectList.appendChild(link);

      $("browse_content").innerHTML = "";
      $("browse_content").appendChild(browseObjectList); 
    }
  }
    
  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 (browseMode != "auto") {
      map.setCenter(this.feature.geometry.getBounds().getCenterLonLat()); 
    }

    return false;
  }
    
  function loadObjectList() {
    $("browse_content").innerHTML="";
    $("browse_content").appendChild(browseObjectList);

    return false;
  }
      
  function onFeatureSelect(feature) {
    // Unselect previously selected feature
    if (browseActiveFeature) {
      browseActiveFeature.layer.drawFeature(
        browseActiveFeature, 
        browseActiveFeature.layer.styleMap.createSymbolizer(browseActiveFeature, "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 clear it.
    if ($("browse_content").firstChild == browseObjectList) { 
      $("browse_content").removeChild(browseObjectList);
    } else { 
      $("browse_content").innerHTML = "";
    }   
        
    // Create a link back to the object list
    var div = document.createElement("div");
    div.style.textAlign = "center";
    div.style.marginBottom = "20px";
    $("browse_content").appendChild(div);
    var link = document.createElement("a");
    link.href = "#";
    link.onclick = loadObjectList;
    link.appendChild(document.createTextNode("Display object list"));
    div.appendChild(link);

    var table = document.createElement("table");
    table.width = "100%";
    table.className = "browse_heading";
    $("browse_content").appendChild(table);

    var tr = document.createElement("tr");
    table.appendChild(tr);

    var heading = document.createElement("td");
    heading.appendChild(document.createTextNode(featureName(feature)));
    tr.appendChild(heading);

    var td = document.createElement("td");
    td.align = "right";
    tr.appendChild(td);

    var type = featureType(feature);
    var link = document.createElement("a");   
    link.href = "/browse/" + type + "/" + feature.osm_id;
    link.appendChild(document.createTextNode("Details"));
    td.appendChild(link);

    var div = document.createElement("div");
    div.className = "browse_details";

    $("browse_content").appendChild(div);

    // Now the list of attributes
    var ul = document.createElement("ul");
    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);
    }
        
    div.appendChild(ul);
        
    var link = document.createElement("a");   
    link.href =  "/browse/" + type + "/" + feature.osm_id + "/history";
    link.appendChild(document.createTextNode("Show history"));
    link.onclick = OpenLayers.Function.bind(loadHistory, {
      type: type, feature: feature, link: link
    });
        
    div.appendChild(link);

    // Stash the currently drawn feature
    browseActiveFeature = 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 (browseActiveFeature.osm_id != this.feature.osm_id || $("browse_content").firstChild == browseObjectList)  { 
        return false;
    } 

    this.link.parentNode.removeChild(this.link);

    var doc = request.responseXML;

    var table = document.createElement("table");
    table.width = "100%";
    table.className = "browse_heading";
    $("browse_content").appendChild(table);

    var tr = document.createElement("tr");
    table.appendChild(tr);

    var heading = document.createElement("td");
    heading.appendChild(document.createTextNode("History for " + featureName(this.feature)));
    tr.appendChild(heading);

    var td = document.createElement("td");
    td.align = "right";
    tr.appendChild(td);

    var link = document.createElement("a");   
    link.href = "/browse/" + this.type + "/" + this.feature.osm_id + "/history";
    link.appendChild(document.createTextNode("Details"));
    td.appendChild(link);

    var div = document.createElement("div");
    div.className = "browse_details";

    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);

    $("browse_content").appendChild(div); 
  }

  function featureType(feature) {
    if (feature.geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
      return "node";
    } else {
      return "way";
    }
  }
  
  function featureName(feature) {
    if (feature.attributes.name) {
      return feature.attributes.name;
    } else {
      return ucFirst(featureType(feature)) + " " + feature.osm_id;
    }
  }

  function setStatus(status) {
    $("browse_status").innerHTML = status;
    $("browse_status").style.display = "block";
  }
  
  function clearStatus() {
    $("browse_status").innerHTML = "";
    $("browse_status").style.display = "none";
  }

  function ucFirst(str) {
    return str.substr(0,1).toUpperCase() + str.substr(1,str.length);
  }

  startBrowse();
EOJ