/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
 * license.  See http://svn.openlayers.org/trunk/openlayers/license.txt for the
 * full text of the license. */

/**
 * @requires OpenLayers/Geometry/MultiPoint.js
 */

/**
 * Class: OpenLayers.Geometry.Curve
 * A Curve is a MultiPoint, whose points are assumed to be connected. To 
 * this end, we provide a "getLength()" function, which iterates through 
 * the points, summing the distances between them. 
 * 
 * Inherits: 
 *  - <OpenLayers.Geometry.MultiPoint>
 */
OpenLayers.Geometry.Curve = OpenLayers.Class(OpenLayers.Geometry.MultiPoint, {

    /**
     * Property: componentTypes
     * {Array(String)} An array of class names representing the types of 
     *                 components that the collection can include.  A null 
     *                 value means the component types are not restricted.
     */
    componentTypes: ["OpenLayers.Geometry.Point"],

    /**
     * Constructor: OpenLayers.Geometry.Curve
     * 
     * Parameters:
     * point - {Array(<OpenLayers.Geometry.Point>)}
     */
    initialize: function(points) {
        OpenLayers.Geometry.MultiPoint.prototype.initialize.apply(this, 
                                                                  arguments);
    },
    
    /**
     * APIMethod: getLength
     * 
     * Returns:
     * {Float} The length of the curve
     */
    getLength: function() {
        var length = 0.0;
        if ( this.components && (this.components.length > 1)) {
            for(var i=1, len=this.components.length; i<len; i++) {
                length += this.components[i-1].distanceTo(this.components[i]);
            }
        }
        return length;
    },

    /**
     * APIMethod: getGeodesicLength
     * Calculate the approximate length of the geometry were it projected onto
     *     the earth.
     *
     * projection - {<OpenLayers.Projection>} The spatial reference system
     *     for the geometry coordinates.  If not provided, Geographic/WGS84 is
     *     assumed.
     * 
     * Returns:
     * {Float} The appoximate geodesic length of the geometry in meters.
     */
    getGeodesicLength: function(projection) {
        var geom = this;  // so we can work with a clone if needed
        if(projection) {
            var gg = new OpenLayers.Projection("EPSG:4326");
            if(!gg.equals(projection)) {
                geom = this.clone().transform(projection, gg);
            }
        }
        var length = 0.0;
        if(geom.components && (geom.components.length > 1)) {
            var p1, p2;
            for(var i=1, len=geom.components.length; i<len; i++) {
                p1 = geom.components[i-1];
                p2 = geom.components[i];
                // this returns km and requires lon/lat properties
                length += OpenLayers.Util.distVincenty(
                    {lon: p1.x, lat: p1.y}, {lon: p2.x, lat: p2.y}
                );
            }
        }
        // convert to m
        return length * 1000;
    },

    CLASS_NAME: "OpenLayers.Geometry.Curve"
});
