michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = [
michael@0:   "DownloadPaths",
michael@0: ];
michael@0: 
michael@0: /**
michael@0:  * This module provides the DownloadPaths object which contains methods for
michael@0:  * giving names and paths to files being downloaded.
michael@0:  *
michael@0:  * List of methods:
michael@0:  *
michael@0:  * nsILocalFile
michael@0:  * createNiceUniqueFile(nsILocalFile aLocalFile)
michael@0:  *
michael@0:  * [string base, string ext]
michael@0:  * splitBaseNameAndExtension(string aLeafName)
michael@0:  */
michael@0: 
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: const Cu = Components.utils;
michael@0: const Cr = Components.results;
michael@0: 
michael@0: this.DownloadPaths = {
michael@0:   /**
michael@0:    * Creates a uniquely-named file starting from the name of the provided file.
michael@0:    * If a file with the provided name already exists, the function attempts to
michael@0:    * create nice alternatives, like "base(1).ext" (instead of "base-1.ext").
michael@0:    *
michael@0:    * If a unique name cannot be found, the function throws the XPCOM exception
michael@0:    * NS_ERROR_FILE_TOO_BIG. Other exceptions, like NS_ERROR_FILE_ACCESS_DENIED,
michael@0:    * can also be expected.
michael@0:    *
michael@0:    * @param aTemplateFile
michael@0:    *        nsILocalFile whose leaf name is going to be used as a template. The
michael@0:    *        provided object is not modified.
michael@0:    * @returns A new instance of an nsILocalFile object pointing to the newly
michael@0:    *          created empty file. On platforms that support permission bits, the
michael@0:    *          file is created with permissions 644.
michael@0:    */
michael@0:   createNiceUniqueFile: function DP_createNiceUniqueFile(aTemplateFile) {
michael@0:     // Work on a clone of the provided template file object.
michael@0:     var curFile = aTemplateFile.clone().QueryInterface(Ci.nsILocalFile);
michael@0:     var [base, ext] = DownloadPaths.splitBaseNameAndExtension(curFile.leafName);
michael@0:     // Try other file names, for example "base(1).txt" or "base(1).tar.gz",
michael@0:     // only if the file name initially set already exists.
michael@0:     for (let i = 1; i < 10000 && curFile.exists(); i++) {
michael@0:       curFile.leafName = base + "(" + i + ")" + ext;
michael@0:     }
michael@0:     // At this point we hand off control to createUnique, which will create the
michael@0:     // file with the name we chose, if it is valid. If not, createUnique will
michael@0:     // attempt to modify it again, for example it will shorten very long names
michael@0:     // that can't be created on some platforms, and for which a normal call to
michael@0:     // nsIFile.create would result in NS_ERROR_FILE_NOT_FOUND. This can result
michael@0:     // very rarely in strange names like "base(9999).tar-1.gz" or "ba-1.gz".
michael@0:     curFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, 0644);
michael@0:     return curFile;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Separates the base name from the extension in a file name, recognizing some
michael@0:    *  double extensions like ".tar.gz".
michael@0:    *
michael@0:    * @param aLeafName
michael@0:    *        The full leaf name to be parsed. Be careful when processing names
michael@0:    *        containing leading or trailing dots or spaces.
michael@0:    * @returns [base, ext]
michael@0:    *          The base name of the file, which can be empty, and its extension,
michael@0:    *          which always includes the leading dot unless it's an empty string.
michael@0:    *          Concatenating the two items always results in the original name.
michael@0:    */
michael@0:   splitBaseNameAndExtension: function DP_splitBaseNameAndExtension(aLeafName) {
michael@0:     // The following regular expression is built from these key parts:
michael@0:     //  .*?                      Matches the base name non-greedily.
michael@0:     //  \.[A-Z0-9]{1,3}          Up to three letters or numbers preceding a
michael@0:     //                           double extension.
michael@0:     //  \.(?:gz|bz2|Z)           The second part of common double extensions.
michael@0:     //  \.[^.]*                  Matches any extension or a single trailing dot.
michael@0:     var [, base, ext] = /(.*?)(\.[A-Z0-9]{1,3}\.(?:gz|bz2|Z)|\.[^.]*)?$/i
michael@0:                         .exec(aLeafName);
michael@0:     // Return an empty string instead of undefined if no extension is found.
michael@0:     return [base, ext || ""];
michael@0:   }
michael@0: };