/*
 * Timemap.js Copyright 2008 Nick Rabinowitz.
 * Licensed under the MIT License (see LICENSE.txt)
 */
 
/**
 * @fileOverview
 * KML Loader
 *
 * @author Nick Rabinowitz (www.nickrabinowitz.com)
 */

/*globals GXml, TimeMap */

/**
 * @class
 * KML loader factory - inherits from remote loader
 *
 * <p>This is a loader class for KML files. Currently supports all geometry
 * types (point, polyline, polygon, and overlay) and multiple geometries.</p>
 *
 * @example Usage in TimeMap.init():
 
    datasets: [
        {
            title: "KML Dataset",
            type: "kml",
            options: {
                url: "mydata.kml"   // Must be local
            }
        }
    ]
 *
 * @param {Object} options          All options for the loader:<pre>
 *   {Array} url                        URL of KML file to load (NB: must be local address)
 *   {Function} preloadFunction         Function to call on data before loading
 *   {Function} transformFunction       Function to call on individual items before loading
 * </pre>
 * @return {TimeMap.loaders.remote} Remote loader configured for KML
 */
TimeMap.loaders.kml = function(options) {
    var loader = new TimeMap.loaders.remote(options);
    loader.parse = TimeMap.loaders.kml.parse;
    return loader;
}

/**
 * Static function to parse KML with time data.
 *
 * @param {XML string} kml      KML to be parsed
 * @return {TimeMapItem Array}  Array of TimeMapItems
 */
TimeMap.loaders.kml.parse = function(kml) {
    var items = [], data, kmlnode, placemarks, pm, i, j;
    kmlnode = GXml.parse(kml);
    
    // get TimeMap utilty functions
    // assigning to variables should compress better
    var util = TimeMap.util;
    var getTagValue = util.getTagValue,
        getNodeList = util.getNodeList,
        makePoint = util.makePoint,
        makePoly = util.makePoly,
        formatDate = util.formatDate;
    
    // recursive time data search
    var findNodeTime = function(n, data) {
        var check = false;
        // look for instant timestamp
        var nList = getNodeList(n, "TimeStamp");
        if (nList.length > 0) {
            data.start = getTagValue(nList[0], "when");
            check = true;
        }
        // otherwise look for span
        else {
            nList = getNodeList(n, "TimeSpan");
            if (nList.length > 0) {
                data.start = getTagValue(nList[0], "begin");
                data.end = getTagValue(nList[0], "end") ||
                    // unbounded spans end at the present time
                    formatDate(new Date());
                check = true;
            }
        }
        // try looking recursively at parent nodes
        if (!check) {
            var pn = n.parentNode;
            if (pn.nodeName == "Folder" || pn.nodeName=="Document") {
                findNodeTime(pn, data);
            }
            pn = null;
        }
    };
    
    // look for placemarks
    placemarks = getNodeList(kmlnode, "Placemark");
    for (i=0; i<placemarks.length; i++) {
        pm = placemarks[i];
        data = { options: {} };
        // get title & description
        data.title = getTagValue(pm, "name");
        data.options.description = getTagValue(pm, "description");
        // get time information
        findNodeTime(pm, data);
        // find placemark(s)
        var nList, coords, pmobj;
        data.placemarks = [];
        // look for marker
        nList = getNodeList(pm, "Point");
        for (j=0; j<nList.length; j++) {
            pmobj = { point: {} };
            // get lat/lon
            coords = getTagValue(nList[j], "coordinates");
            pmobj.point = makePoint(coords, 1);
            data.placemarks.push(pmobj);
        }
        // look for polylines
        nList = getNodeList(pm, "LineString");
        for (j=0; j<nList.length; j++) {
            pmobj = { polyline: [] };
            // get lat/lon
            coords = getTagValue(nList[j], "coordinates");
            pmobj.polyline = makePoly(coords, 1);
            data.placemarks.push(pmobj);
        }
        // look for polygons
        nList = getNodeList(pm, "Polygon");
        for (j=0; j<nList.length; j++) {
            pmobj = { polygon: [] };
            // get lat/lon
            coords = getTagValue(nList[j], "coordinates");
            pmobj.polygon = makePoly(coords, 1);
            // XXX: worth closing unclosed polygons?
            data.placemarks.push(pmobj);
        }
        items.push(data);
    }
    
    // look for ground overlays
    placemarks = getNodeList(kmlnode, "GroundOverlay");
    for (i=0; i<placemarks.length; i++) {
        pm = placemarks[i];
        data = { options: {}, overlay: {} };
        // get title & description
        data.title = getTagValue(pm, "name");
        data.options.description = getTagValue(pm, "description");
        // get time information
        findNodeTime(pm, data);
        // get image
        nList = getNodeList(pm, "Icon");
        data.overlay.image = getTagValue(nList[0], "href");
        // get coordinates
        nList = getNodeList(pm, "LatLonBox");
        data.overlay.north = getTagValue(nList[0], "north");
        data.overlay.south = getTagValue(nList[0], "south");
        data.overlay.east = getTagValue(nList[0], "east");
        data.overlay.west = getTagValue(nList[0], "west");
        items.push(data);
    }
    
    // clean up
    kmlnode = null;
    placemarks = null;
    pm = null;
    nList = null;
    return items;
};