function getTileSourceImplementation( viewer, tileSource, imgOptions, successCallback,
    failCallback ) {
    var _this = viewer;

    //allow plain xml strings or json strings to be parsed here
    if ( $.type( tileSource ) === 'string' ) {
        //xml should start with "<" and end with ">"
        if ( tileSource.match( /^\s*<.*>\s*$/ ) ) {
            tileSource = $.parseXml( tileSource );
        //json should start with "{" or "[" and end with "}" or "]"
        } else if ( tileSource.match(/^\s*[{[].*[}\]]\s*$/ ) ) {
            try {
              var tileSourceJ = $.parseJSON(tileSource);
              tileSource = tileSourceJ;
            } catch (e) {
              //tileSource = tileSource;
            }
        }
    }

    function waitUntilReady(tileSource, originalTileSource) {
        if (tileSource.ready) {
            successCallback(tileSource);
        } else {
            tileSource.addHandler('ready', function () {
                successCallback(tileSource);
            });
            tileSource.addHandler('open-failed', function (event) {
                failCallback({
                    message: event.message,
                    source: originalTileSource
                });
            });
        }
    }

    setTimeout( function() {
        if ( $.type( tileSource ) === 'string' ) {
            //If its still a string it means it must be a url at this point
            tileSource = new $.TileSource({
                url: tileSource,
                crossOriginPolicy: imgOptions.crossOriginPolicy !== undefined ?
                    imgOptions.crossOriginPolicy : viewer.crossOriginPolicy,
                ajaxWithCredentials: viewer.ajaxWithCredentials,
                ajaxHeaders: imgOptions.ajaxHeaders ?
                    imgOptions.ajaxHeaders : viewer.ajaxHeaders,
                splitHashDataForPost: viewer.splitHashDataForPost,
                success: function( event ) {
                    successCallback( event.tileSource );
                }
            });
            tileSource.addHandler( 'open-failed', function( event ) {
                failCallback( event );
            } );

        } else if ($.isPlainObject(tileSource) || tileSource.nodeType) {
            if (tileSource.crossOriginPolicy === undefined &&
                (imgOptions.crossOriginPolicy !== undefined || viewer.crossOriginPolicy !== undefined)) {
                tileSource.crossOriginPolicy = imgOptions.crossOriginPolicy !== undefined ?
                    imgOptions.crossOriginPolicy : viewer.crossOriginPolicy;
            }
            if (tileSource.ajaxWithCredentials === undefined) {
                tileSource.ajaxWithCredentials = viewer.ajaxWithCredentials;
            }

            if ( $.isFunction( tileSource.getTileUrl ) ) {
                //Custom tile source
                var customTileSource = new $.TileSource( tileSource );
                customTileSource.getTileUrl = tileSource.getTileUrl;
                successCallback( customTileSource );
            } else {
                //inline configuration
                var $TileSource = $.TileSource.determineType( _this, tileSource );
                if ( !$TileSource ) {
                    failCallback( {
                        message: "Unable to load TileSource",
                        source: tileSource
                    });
                    return;
                }
                var options = $TileSource.prototype.configure.apply( _this, [ tileSource ] );
                waitUntilReady(new $TileSource(options), tileSource);
            }
        } else {
            //can assume it's already a tile source implementation, force inheritance
            waitUntilReady(tileSource, tileSource);
        }
    });
}
Attempts to initialize a TileSource from various input types and configuration formats.
Handles string URLs, raw XML/JSON strings, inline configuration objects, or custom TileSource implementations.

@function
@private
@param {OpenSeadragon.Viewer} viewer - The OpenSeadragon viewer instance.
@param {string|Object|Element|OpenSeadragon.TileSource} tileSource - The tile source input, which can be a URL string,
       an inline configuration object, raw XML/JSON string, or an existing TileSource instance.
@param {Object} imgOptions - Additional options for tile loading (e.g. CORS policy, headers).
@param {Function} successCallback - Called with the initialized TileSource once ready.
@param {Function} failCallback - Called if initialization fails. Receives an error object with a message and source.