/* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for 
 * full list of contributors). Published under the Clear BSD license.  
 * See http://svn.openlayers.org/trunk/openlayers/license.txt for the
 * full text of the license. */


/**
 * @requires OpenLayers/Layer/Grid.js
 * @requires OpenLayers/Tile/Image.js
 */

/**
 * Class: OpenLayers.Layer.TMS
 * 
 * Inherits from:
 *  - <OpenLayers.Layer.Grid>
 */
OpenLayers.Layer.TMS = OpenLayers.Class(OpenLayers.Layer.Grid, {

    /**
     * APIProperty: serviceVersion
     * {String}
     */
    serviceVersion: "1.0.0",

    /**
     * APIProperty: isBaseLayer
     * {Boolean}
     */
    isBaseLayer: true,

    /**
     * APIProperty: tileOrigin
     * {<OpenLayers.Pixel>}
     */
    tileOrigin: null,

    /**
     * APIProperty: serverResolutions
     * {Array} A list of all resolutions available on the server.  Only set this 
     *     property if the map resolutions differs from the server.
     */
    serverResolutions: null,

    /**
     * APIProperty: zoomOffset
     * {Number} If your cache has more zoom levels than you want to provide
     *     access to with this layer, supply a zoomOffset.  This zoom offset
     *     is added to the current map zoom level to determine the level
     *     for a requested tile.  For example, if you supply a zoomOffset
     *     of 3, when the map is at the zoom 0, tiles will be requested from
     *     level 3 of your cache.  Default is 0 (assumes cache level and map
     *     zoom are equivalent).  Using <zoomOffset> is an alternative to
     *     setting <serverResolutions> if you only want to expose a subset
     *     of the server resolutions.
     */
    zoomOffset: 0,
    
    /**
     * Constructor: OpenLayers.Layer.TMS
     * 
     * Parameters:
     * name - {String}
     * url - {String}
     * options - {Object} Hashtable of extra options to tag onto the layer
     */
    initialize: function(name, url, options) {
        var newArguments = [];
        newArguments.push(name, url, {}, options);
        OpenLayers.Layer.Grid.prototype.initialize.apply(this, newArguments);
    },    

    /**
     * APIMethod:destroy
     */
    destroy: function() {
        // for now, nothing special to do here. 
        OpenLayers.Layer.Grid.prototype.destroy.apply(this, arguments);  
    },

    
    /**
     * APIMethod: clone
     * 
     * Parameters:
     * obj - {Object}
     * 
     * Returns:
     * {<OpenLayers.Layer.TMS>} An exact clone of this <OpenLayers.Layer.TMS>
     */
    clone: function (obj) {
        
        if (obj == null) {
            obj = new OpenLayers.Layer.TMS(this.name,
                                           this.url,
                                           this.getOptions());
        }

        //get all additions from superclasses
        obj = OpenLayers.Layer.Grid.prototype.clone.apply(this, [obj]);

        // copy/set any non-init, non-simple values here

        return obj;
    },    
    
    /**
     * Method: getURL
     * 
     * Parameters:
     * bounds - {<OpenLayers.Bounds>}
     * 
     * Returns:
     * {String} A string with the layer's url and parameters and also the 
     *          passed-in bounds and appropriate tile size specified as 
     *          parameters
     */
    getURL: function (bounds) {
        bounds = this.adjustBounds(bounds);
        var res = this.map.getResolution();
        var x = Math.round((bounds.left - this.tileOrigin.lon) / (res * this.tileSize.w));
        var y = Math.round((bounds.bottom - this.tileOrigin.lat) / (res * this.tileSize.h));
        var z = this.serverResolutions != null ?
            OpenLayers.Util.indexOf(this.serverResolutions, res) :
            this.map.getZoom() + this.zoomOffset;
        var path = this.serviceVersion + "/" + this.layername + "/" + z + "/" + x + "/" + y + "." + this.type; 
        var url = this.url;
        if (url instanceof Array) {
            url = this.selectUrl(path, url);
        }
        return url + path;
    },

    /**
     * Method: addTile
     * addTile creates a tile, initializes it, and adds it to the layer div. 
     * 
     * Parameters:
     * bounds - {<OpenLayers.Bounds>}
     * position - {<OpenLayers.Pixel>}
     * 
     * Returns:
     * {<OpenLayers.Tile.Image>} The added OpenLayers.Tile.Image
     */
    addTile:function(bounds,position) {
        return new OpenLayers.Tile.Image(this, position, bounds, 
                                         null, this.tileSize);
    },

    /** 
     * APIMethod: setMap
     * When the layer is added to a map, then we can fetch our origin 
     *    (if we don't have one.) 
     * 
     * Parameters:
     * map - {<OpenLayers.Map>}
     */
    setMap: function(map) {
        OpenLayers.Layer.Grid.prototype.setMap.apply(this, arguments);
        if (!this.tileOrigin) { 
            this.tileOrigin = new OpenLayers.LonLat(this.map.maxExtent.left,
                                                this.map.maxExtent.bottom);
        }                                       
    },

    CLASS_NAME: "OpenLayers.Layer.TMS"
});
