Simple WGET clone in WSH

wgets.wsf

<job>
    <runtime>
        <description>A non-interactive web retriever script.

Copyright (c) Atif Aziz. All rights reserved.
Written by Atif Aziz, http://www.raboof.com/

Creative Commons Attribution-ShareAlike 3.0 Unported License.
  http://creativecommons.org/licenses/by-sa/3.0/
</description>
        <named name="od" helpstring="Output directory." type="string" required="false" />
        <named name="status" helpstring="Report status only." type="simple" required="false" />
        <named name="headers" helpstring="Report headers only." type="simple" required="false" />
        <named name="test" helpstring="Runs internal tests." type="simple" required="false" />
        <named name="logo" helpstring="Information about this script." type="simple" required="false" />
        <unnamed name="URL" helpstring="URL of the resource to retrieve" type="string" required="true" />
        <unnamed name="LOCALFILE" helpstring="Path to local file where to save the resource." type="string" required="true" />
        <example>
Example: wgets http://www.example.com/ -</example>
    </runtime>
    <script language="JavaScript">
//
// Global variables
//

var stdin  = WScript.StdIn;
var stdout = WScript.StdOut;
var stderr = WScript.StdErr;

var About =
{
    name         : "WGETS",
    version      : "1.1",
    majorVersion : 1,
    minorVersion : 1,
    copyright    : "Copyright (c) Atif Aziz. All rights reserved.",
    authors      : [
        { name: "Atif Aziz", href: "http://www.raboof.com/" }
    ],
    description  : "A non-interactive web retriever script.",
    license      : { 
        title: "Creative Commons Attribution-ShareAlike 3.0 Unported License.",
        href : "http://creativecommons.org/licenses/by-sa/3.0/"
    },
    write : function(writeln)
    {
        writeln(this.name + ' ' + this.version + ' - ' + this.description);
        writeln(this.copyright);
        writeln();
        if (this.authors.length)
        {
            var author = function() { return this.name + ', ' + this.href; };
            if (this.authors.length > 1)
            {
                writeln('Written by:');
                for (var i = 0; i < this.authors.length; i++)
                    writeln('- ' + author.apply(this.authors[i]));
            }
            else
            {
                writeln('Written by ' + author.apply(this.authors[0]));
            }
            writeln();
        }
        writeln(this.license.title);
        writeln(' ' + this.license.href);
        writeln();
    }
}

//
// Global functions
//

function writeln(s) { stdout.WriteLine(s); }
function write(s)   { stdout.Write(s); }
function alert(s)   { echo(s); }
function echo(s)    { WScript.Echo(s); }

//
// ADO Constants
//

var ADO = 
{
    SaveOptionsEnum : 
    {
        adSaveCreateNotExist : 1,
        adSaveCreateOverWrite : 2
    },
    StreamTypeEnum : 
    {
        adTypeBinary : 1,
        adTypeText : 2
    }
};

//
// Mask
//

var Mask = 
{
    nullString : function(s) 
    {
        return s == null ? "" : s;
    },
    emptyString : function (s, mask)
    {
        return s == null || s.length == 0 ? mask : s;
    },
    nullObject : function(o, mask)
    {
        return o == null ? mask : o;
    }
};

//
// Path
//

var Path =
{
    combine : function(path1, path2)
    {
        path1 = Mask.nullString(path1);
        path2 = Mask.nullString(path2);
        
        var sb = [];
        sb.push(path1);
        if (path1.slice(-1) != "\\")
            sb.push("\\");
        sb.push(path2.indexOf("\\") == 0 ? path2.substring(1) : path2);
        return sb.join("");
    }
};

//
// Test
//

var Test =
{
    assertEquals : function(expected, actual, message)
    {
        if (actual != expected)
            throw new Exception("Equality assertion test failed. " + Mask.nullString(message));
    }
};

//
// Reflection
//

var Reflection =
{
    getFunctionName : function(f) 
    {
        var match = f.toString().match(/function\s+(\w*)/);
        return match == null ? "(anonymous)" : match[1];
    }
};

//
// Diagnostics
//

var Diagnostics =
{
    trace : function(s)
    {
        echo("TRACE: " + s);
    },
    here : function()
    {
        this.trace("I am here!");
    },
    stackTrace : function() 
    {
        var trace = "";
        
        for (var aCaller = arguments.caller; aCaller != null; aCaller = aCaller.caller)
        {
            trace += "-> " + Reflection.getFunctionName(aCaller.callee) + "\n";

            if (aCaller.caller == aCaller) 
            {
                trace += "*"; 
                break;
            }
        }
        
        return trace;
    }
};

//
// HTTP
//

var HTTP = 
{
    getResponseHeaders : function(http)
    {
        var headersText = http.getAllResponseHeaders();
        
        var parser = /^([^\:\r]+)\:\s*(.+)$/gm;
        var match;
        var headers = {};
        
        while ((match = parser.exec(headersText)) != null)
        {
            var name = match[1].trim().toLowerCase();
            var value = match[2].trim();
            headers[name] = value;
        }
        
        return headers;
    }
};

//
// String (extensions)
//

String.prototype.mask = function(mask)
{
    return Mask.emptyString(this, mask);
}

String.prototype.trim = function()
{
    return this.replace(/^[\s]+/, "").replace(/[\s]+$/, "");
}

String.prototype.clipLeft = function(width, decoration)
{
    decoration = Mask.emptyString(decoration, "...");
    
    if (this.length <= width)
        return this;
    
    return decoration + this.slice(-width);
}

//
// Exception
//

function Exception(message)
{
    this.init(message);
}

Exception.prototype.init = function(message)
{
    this.message = Mask.emptyString(message, "A general error has occurred.");
    this.stackTrace = Diagnostics.stackTrace();
}

Exception.prototype.toString = function()
{
    return this.message;
}

//
// ProgramArgumentException extends Exception
//

ProgramArgumentException.prototype = new Exception();
ProgramArgumentException.prototype.constructor = ProgramArgumentException;
ProgramArgumentException.base = Exception.prototype;

function ProgramArgumentException(message) 
{
    message = Mask.emptyString(message, "Error with program argument.") + 
        " Use the /? for help.";
        
    ProgramArgumentException.base.init.call(this, message);
}

try
{
    var wshargs = WScript.Arguments;
    var args = [];
    for (var i = 0; i < wshargs.length; i++)
        args.push(wshargs(i));
        
    args.unnamed = [];

    for (var i = 0; i < wshargs.Unnamed.Count; i++)
        args.unnamed.push(wshargs.Unnamed.Item(i));

    args.getNamed  = function(name) { return WScript.Arguments.Named.Item(name); }    
    args.isFlagged = function(name) { return WScript.Arguments.Named.Exists(name); }

    if (args.isFlagged("test"))
        test();
    else          
        main(args);
}
catch (e)
{
    stderr.WriteLine(e.message == null ? e.toString() : e.message);
    WScript.Quit(-1);
}

function main(args)
{
    var logo = args.isFlagged('logo');
    if (logo)
        About.write(function(s) { stderr.WriteLine(s); });
        
    if (args.unnamed.length == 0)
    {
        if (logo) return;
        throw new ProgramArgumentException("Missing URL.");
    }
    
    var url = args.unnamed[0];

    var outputFileName
    var useStandardOutput = false;
    var httpStatusOnly = args.isFlagged("status");
    var httpHeadersOnly = args.isFlagged("headers");
    var dontOutputEntity = httpStatusOnly || httpHeadersOnly;
    
    if (!dontOutputEntity)
    {
        if (args.unnamed.length > 1)
        {
            outputFileName = args.unnamed[1];
            useStandardOutput = outputFileName == "-";
        }
        else
        {
            outputFileName = getFileNameFromURL(url, "");
            
            if (outputFileName.length == 0)
                throw new Exception("Unable to guess the output file name from the URL.");
        }
    }
    
    var http = new ActiveXObject("Microsoft.XMLHTTP");
    http.open(dontOutputEntity ? "HEAD" : "GET", url, false);
    http.send();
    
    var httpStatus = http.status + " " + http.statusText;

    if (httpStatusOnly)
        writeln(httpStatus);
    if (httpHeadersOnly)
        write(http.getAllResponseHeaders());

    if (dontOutputEntity)
        return;

    var headers = HTTP.getResponseHeaders(http);
    var contentLength = parseInt(Mask.nullObject(headers["content-length"], -1));
    
    var outputDirectory = Mask.nullString(args.getNamed("od"));
    var outputPath = outputDirectory.length > 0 ?
        Path.combine(outputDirectory, outputFileName) : outputFileName;
        
    if (http.status != 200)
        throw new Exception(httpStatus);

    if (useStandardOutput)
    {
        write(http.responseText);
    }
    else
    {        
        var stream = new ActiveXObject("ADODB.Stream");
        stream.Type = ADO.StreamTypeEnum.adTypeBinary;
        stream.Open();
        stream.Write(http.responseBody);
        stream.SaveToFile(outputPath, ADO.SaveOptionsEnum.adSaveCreateOverWrite);
        
        write("Saved " + url.clipLeft(30) + " to " + outputPath);
        if (contentLength >= 0)
            write(" [" + contentLength + " byte(s)]");
        writeln(".");
    }
}

function getFileNameFromURL(url, defaultFileName)
{
    var qIndex = url.indexOf('?');

    var path = qIndex >= 0 ? url.substring(0, qIndex) : url;
        
    var lastSlashIndex = path.lastIndexOf('/');
    var result = path.substring(lastSlashIndex + 1);

    return result.length > 0 ? result : defaultFileName;
}

function getScriptNameFromHost()
{
    var name = WScript.ScriptName;
    var dotIndex = name.lastIndexOf('.');
    return dotIndex >= 0 ? name = name.substring(0, dotIndex) : name;
}

function test() {}
    </script>
</job>