site/try/project_server.dart - sdk.git - Git at Google

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 library trydart.projectServer;

 import 'dart:io';

 import 'dart:async' show
     Future,
     Stream;

 import 'dart:convert' show
     HtmlEscape,
     JSON,
     UTF8;

 class WatchHandler {
   final WebSocket socket;

   final Set<String> watchedFiles;

   static final Set<WatchHandler> handlers = new Set<WatchHandler>();

   static const Map<int, String> fsEventNames = const <int, String>{
     FileSystemEvent.CREATE: 'create',
     FileSystemEvent.DELETE: 'delete',
     FileSystemEvent.MODIFY: 'modify',
     FileSystemEvent.MOVE: 'move',
   };

   WatchHandler(this.socket, Iterable<String> watchedFiles)
       : this.watchedFiles = watchedFiles.toSet();

   handleFileSystemEvent(FileSystemEvent event) {
     if (event.isDirectory) return;
     String type = fsEventNames[event.type];
     if (type == null) type = 'unknown';
     String path = new Uri.file(event.path).pathSegments.last;
     shouldIgnore(type, path).then((bool ignored) {
       if (ignored) return;
       socket.add(JSON.encode({type: [path]}));
     });
   }

   Future<bool> shouldIgnore(String type, String path) {
     switch (type) {
       case 'create':
         return new Future<bool>.value(!watchedFiles.contains(path));
       case 'delete':
         return Conversation.listProjectFiles().then((List<String> files) {
           watchedFiles
               ..retainAll(files)
               ..addAll(files);
           return watchedFiles.contains(path);
         });
       case 'modify':
         return new Future<bool>.value(false);
       default:
         print('Unhandled fs-event for $path ($type).');
         return new Future<bool>.value(true);
     }
   }

   onData(_) {
     // TODO(ahe): Move POST code here?
   }

   onDone() {
     handlers.remove(this);
   }

   static handleWebSocket(WebSocket socket) {
     Conversation.ensureProjectWatcher();
     Conversation.listProjectFiles().then((List<String> files) {
       socket.add(JSON.encode({'create': files}));
       WatchHandler handler = new WatchHandler(socket, files);
       handlers.add(handler);
       socket.listen(
           handler.onData, cancelOnError: true, onDone: handler.onDone);
     });
   }

   static onFileSystemEvent(FileSystemEvent event) {
     for (WatchHandler handler in handlers) {
       handler.handleFileSystemEvent(event);
     }
   }
 }

 /// Represents a "project" command. These commands are accessed from the URL
 /// "/project?name".
 class ProjectCommand {
   final String name;

   /// For each query parameter, this map describes rules for validating them.
   final Map<String, String> rules;

   final Function handle;

   const ProjectCommand(this.name, this.rules, this.handle);
 }

 class Conversation {
   HttpRequest request;
   HttpResponse response;

   static const String PROJECT_PATH = '/project';

   static const String PACKAGES_PATH = '/packages';

   static const String CONTENT_TYPE = HttpHeaders.CONTENT_TYPE;

   static const String GIT_TAG = 'try_dart_backup';

   static const String COMMIT_MESSAGE = """
 Automated backup.

 It is safe to delete tag '$GIT_TAG' if you don't need the backup.""";

   static Uri documentRoot = Uri.base;

   static Uri projectRoot = Uri.base.resolve('site/try/src/');

   static Uri packageRoot = Uri.base.resolve('sdk/lib/_internal/');

   static const List<ProjectCommand> COMMANDS = const <ProjectCommand>[
       const ProjectCommand('list', const {'list': null}, handleProjectList),
   ];

   static Stream<FileSystemEvent> projectChanges;

   static final Map<String, String> gitEnv = computeGitEnv();

   Conversation(this.request, this.response);

   onClosed(_) {
     if (response.statusCode == HttpStatus.OK) return;
     print('Request for ${request.uri} ${response.statusCode}');
   }

   notFound(path) {
     response.statusCode = HttpStatus.NOT_FOUND;
     response.write(htmlInfo('Not Found',
                             'The file "$path" could not be found.'));
     response.close();
   }

   badRequest(String problem) {
     response.statusCode = HttpStatus.BAD_REQUEST;
     response.write(htmlInfo("Bad request",
                             "Bad request '${request.uri}': $problem"));
     response.close();
   }

   internalError(error, stack) {
     print(error);
     if (stack != null) print(stack);
     response.statusCode = HttpStatus.INTERNAL_SERVER_ERROR;
     response.write(htmlInfo("Internal Server Error",
                             "Internal Server Error: $error\n$stack"));
     response.close();
   }

   bool validate(Map<String, String> parameters, Map<String, String> rules) {
     Iterable<String> problems = rules.keys
         .where((name) => !parameters.containsKey(name))
         .map((name) => "Missing parameter: '$name'.");
     if (!problems.isEmpty) {
       badRequest(problems.first);
       return false;
     }
     Set extra = new Set.from(parameters.keys)..removeAll(rules.keys);
     if (extra.isEmpty) return true;
     String extraString = (extra.toList()..sort()).join("', '");
     badRequest("Extra parameters: '$extraString'.");
     return false;
   }

   static Future<List<String>> listProjectFiles() {
     String nativeDir = projectRoot.toFilePath();
     Directory dir = new Directory(nativeDir);
     var future = dir.list(recursive: true, followLinks: false).toList();
     return future.then((List<FileSystemEntity> entries) {
       return entries
           .map((e) => e.path)
           .where((p) => p.endsWith('.dart') && p.startsWith(nativeDir))
           .map((p) => p.substring(nativeDir.length))
           .map((p) => new Uri.file(p).path).toList();
     });
   }

   static handleProjectList(Conversation self) {
     listProjectFiles().then((List<String> files) {
       self.response
           ..write(JSON.encode(files))
           ..close();
     });
   }

   handleProjectRequest() {
     Map<String, String> parameters = request.uri.queryParameters;
     for (ProjectCommand command in COMMANDS) {
       if (parameters.containsKey(command.name)) {
         if (validate(parameters, command.rules)) {
           (command.handle)(this);
         }
         return;
       }
     }
     String commands = COMMANDS.map((c) => c.name).join("', '");
     badRequest("Valid commands are: '$commands'");
   }

   handleSocket() {
     if (request.uri.path == '/ws/watch') {
       WebSocketTransformer.upgrade(request).then(WatchHandler.handleWebSocket);
     } else {
       response.done
           .then(onClosed)
           .catchError(onError);
       notFound(request.uri.path);
     }
   }

   handle() {
     response.done
       .then(onClosed)
       .catchError(onError);

     Uri uri = request.uri;
     if (uri.path == PROJECT_PATH) {
       return handleProjectRequest();
     }
     if (uri.path.endsWith('/')) {
       uri = uri.resolve('index.html');
     }
     if (uri.path == '/css/fonts/fontawesome-webfont.woff') {
       uri = uri.resolve('/fontawesome-webfont.woff');
     }
     if (uri.path.contains('..') || uri.path.contains('%')) {
       return notFound(uri.path);
     }
     String path = uri.path;
     Uri root = documentRoot;
     String dartType = 'application/dart';
     if (path.startsWith('/project/packages/')) {
       root = packageRoot;
       path = path.substring('/project/packages'.length);
     } else if (path.startsWith('${PROJECT_PATH}/')) {
       root = projectRoot;
       path = path.substring(PROJECT_PATH.length);
       dartType = 'text/plain';
     } else if (path.startsWith('${PACKAGES_PATH}/')) {
       root = packageRoot;
       path = path.substring(PACKAGES_PATH.length);
     }

     String filePath = root.resolve('.$path').toFilePath();
     switch (request.method) {
       case 'GET':
         return handleGet(filePath, dartType);
       case 'POST':
         return handlePost(filePath);
       default:
         String method = const HtmlEscape().convert(request.method);
         return badRequest("Unsupported method: '$method'");
     }
   }

   void handleGet(String path, String dartType) {
     var f = new File(path);
     f.exists().then((bool exists) {
       if (!exists) return notFound(request.uri);
       if (path.endsWith('.html')) {
         response.headers.set(CONTENT_TYPE, 'text/html');
       } else if (path.endsWith('.dart')) {
         response.headers.set(CONTENT_TYPE, dartType);
       } else if (path.endsWith('.js')) {
         response.headers.set(CONTENT_TYPE, 'application/javascript');
       } else if (path.endsWith('.ico')) {
         response.headers.set(CONTENT_TYPE, 'image/x-icon');
       } else if (path.endsWith('.appcache')) {
         response.headers.set(CONTENT_TYPE, 'text/cache-manifest');
       }
       f.openRead().pipe(response).catchError(onError);
     });
   }

   handlePost(String path) {
     // The data is sent using a dart:html HttpRequest (aka XMLHttpRequest).
     // According to http://xhr.spec.whatwg.org/, strings are always encoded as
     // UTF-8.
     request.transform(UTF8.decoder).join().then((String data) {
       // The rest of this method is synchronous. This guarantees that we don't
       // make conflicting git changes in response to multiple POST requests.
       try {
         backup(path);
       } catch (e, stack) {
         return internalError(e, stack);
       }

       new File(path).writeAsStringSync(data);

       response
           ..statusCode = HttpStatus.OK
           ..close();
     });
   }

   // Back up the file [path] using git.
   static void backup(String path) {
     // Reset the index.
     git('read-tree', ['HEAD']);

     // Save modifications in index.
     git('update-index', ['--add', path]);

     // If the file isn't modified, don't back it up.
     if (checkGit('diff', ['--cached', '--quiet'])) return;

     String localModifications = git('write-tree');

     String tag = 'refs/tags/$GIT_TAG';
     var arguments = ['-m', COMMIT_MESSAGE, localModifications];

     if (checkGit('rev-parse',  ['-q', '--verify', tag])) {
       // The tag already exists.

       if (checkGit('diff-tree', ['--quiet', localModifications, tag])) {
         // localModifications are identical to the last backup.
         return;
       }

       // Use the tag as a parent.
       arguments = ['-p', tag]..addAll(arguments);

       String headCommit = git('rev-parse', ['HEAD']);
       String mergeBase = git('merge-base', [tag, 'HEAD']);
       if (headCommit != mergeBase) {
         arguments = ['-p', 'HEAD']..addAll(arguments);
       }
     } else {
       arguments = ['-p', 'HEAD']..addAll(arguments);
     }

     // Commit the local modifcations.
     String commit = git('commit-tree', arguments);

     // Create or update the tag.
     git('tag', ['-f', GIT_TAG, commit]);
   }

   static String git(String command,
                     [List<String> arguments = const <String> []]) {
     ProcessResult result =
         run('git', <String>[command]..addAll(arguments), gitEnv);
     if (result.exitCode != 0) {
       throw 'git error: ${result.stdout}\n${result.stderr}';
     }
     return result.stdout.trim();
   }

   static bool checkGit(String command,
                        [List<String> arguments = const <String> []]) {
     return
         run('git', <String>[command]..addAll(arguments), gitEnv).exitCode == 0;
   }

   static Map<String, String> computeGitEnv() {
     ProcessResult result = run('git', ['rev-parse', '--git-dir'], null);
     if (result.exitCode != 0) {
       throw 'git error: ${result.stdout}\n${result.stderr}';
     }
     String gitDir = result.stdout.trim();
     return <String, String>{ 'GIT_INDEX_FILE': '$gitDir/try_dart_backup' };
   }

   static ProcessResult run(String executable,
                            List<String> arguments,
                            Map<String, String> environment) {
     // print('Running $executable ${arguments.join(" ")}');
     return Process.runSync(executable, arguments, environment: environment);
   }

   static onRequest(HttpRequest request) {
     Conversation conversation = new Conversation(request, request.response);
     if (WebSocketTransformer.isUpgradeRequest(request)) {
       conversation.handleSocket();
     } else {
       conversation.handle();
     }
   }

   static ensureProjectWatcher() {
     if (projectChanges != null) return;
     String nativeDir = projectRoot.toFilePath();
     Directory dir = new Directory(nativeDir);
     projectChanges = dir.watch();
     projectChanges.listen(WatchHandler.onFileSystemEvent);
   }

   static onError(error) {
     if (error is HttpException) {
       print('Error: ${error.message}');
     } else {
       print('Error: ${error}');
     }
   }

   String htmlInfo(String title, String text) {
     // No script injection, please.
     title = const HtmlEscape().convert(title);
     text = const HtmlEscape().convert(text);
     return """
 <!DOCTYPE html>
 <html lang='en'>
 <head>
 <title>$title</title>
 </head>
 <body>
 <h1>$title</h1>
 <p style='white-space:pre'>$text</p>
 </body>
 </html>
 """;
   }
 }

 main(List<String> arguments) {
   if (arguments.length > 0) {
     Conversation.documentRoot = Uri.base.resolve(arguments[0]);
   }
   var host = '127.0.0.1';
   if (arguments.length > 1) {
     host = arguments[1];
   }
   int port = 0;
   if (arguments.length > 2) {
     port = int.parse(arguments[2]);
   }
   if (arguments.length > 3) {
     Conversation.projectRoot = Uri.base.resolve(arguments[3]);
   }
   if (arguments.length > 4) {
     Conversation.packageRoot = Uri.base.resolve(arguments[4]);
   }
   HttpServer.bind(host, port).then((HttpServer server) {
     print('HTTP server started on http://$host:${server.port}/');
     server.listen(Conversation.onRequest, onError: Conversation.onError);
   }).catchError((e) {
     print("HttpServer.bind error: $e");
     exit(1);
   });
 }
	// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	library trydart.projectServer;

	import 'dart:io';

	import 'dart:async' show
	Future,
	Stream;

	import 'dart:convert' show
	HtmlEscape,
	JSON,
	UTF8;

	class WatchHandler {
	final WebSocket socket;

	final Set<String> watchedFiles;

	static final Set<WatchHandler> handlers = new Set<WatchHandler>();

	static const Map<int, String> fsEventNames = const <int, String>{
	FileSystemEvent.CREATE: 'create',
	FileSystemEvent.DELETE: 'delete',
	FileSystemEvent.MODIFY: 'modify',
	FileSystemEvent.MOVE: 'move',
	};

	WatchHandler(this.socket, Iterable<String> watchedFiles)
	: this.watchedFiles = watchedFiles.toSet();

	handleFileSystemEvent(FileSystemEvent event) {
	if (event.isDirectory) return;
	String type = fsEventNames[event.type];
	if (type == null) type = 'unknown';
	String path = new Uri.file(event.path).pathSegments.last;
	shouldIgnore(type, path).then((bool ignored) {
	if (ignored) return;
	socket.add(JSON.encode({type: [path]}));
	});
	}

	Future<bool> shouldIgnore(String type, String path) {
	switch (type) {
	case 'create':
	return new Future<bool>.value(!watchedFiles.contains(path));
	case 'delete':
	return Conversation.listProjectFiles().then((List<String> files) {
	watchedFiles
	..retainAll(files)
	..addAll(files);
	return watchedFiles.contains(path);
	});
	case 'modify':
	return new Future<bool>.value(false);
	default:
	print('Unhandled fs-event for $path ($type).');
	return new Future<bool>.value(true);
	}
	}

	onData(_) {
	// TODO(ahe): Move POST code here?
	}

	onDone() {
	handlers.remove(this);
	}

	static handleWebSocket(WebSocket socket) {
	Conversation.ensureProjectWatcher();
	Conversation.listProjectFiles().then((List<String> files) {
	socket.add(JSON.encode({'create': files}));
	WatchHandler handler = new WatchHandler(socket, files);
	handlers.add(handler);
	socket.listen(
	handler.onData, cancelOnError: true, onDone: handler.onDone);
	});
	}

	static onFileSystemEvent(FileSystemEvent event) {
	for (WatchHandler handler in handlers) {
	handler.handleFileSystemEvent(event);
	}
	}
	}

	/// Represents a "project" command. These commands are accessed from the URL
	/// "/project?name".
	class ProjectCommand {
	final String name;

	/// For each query parameter, this map describes rules for validating them.
	final Map<String, String> rules;

	final Function handle;

	const ProjectCommand(this.name, this.rules, this.handle);
	}

	class Conversation {
	HttpRequest request;
	HttpResponse response;

	static const String PROJECT_PATH = '/project';

	static const String PACKAGES_PATH = '/packages';

	static const String CONTENT_TYPE = HttpHeaders.CONTENT_TYPE;

	static const String GIT_TAG = 'try_dart_backup';

	static const String COMMIT_MESSAGE = """
	Automated backup.

	It is safe to delete tag '$GIT_TAG' if you don't need the backup.""";

	static Uri documentRoot = Uri.base;

	static Uri projectRoot = Uri.base.resolve('site/try/src/');

	static Uri packageRoot = Uri.base.resolve('sdk/lib/_internal/');

	static const List<ProjectCommand> COMMANDS = const <ProjectCommand>[
	const ProjectCommand('list', const {'list': null}, handleProjectList),
	];

	static Stream<FileSystemEvent> projectChanges;

	static final Map<String, String> gitEnv = computeGitEnv();

	Conversation(this.request, this.response);

	onClosed(_) {
	if (response.statusCode == HttpStatus.OK) return;
	print('Request for ${request.uri} ${response.statusCode}');
	}

	notFound(path) {
	response.statusCode = HttpStatus.NOT_FOUND;
	response.write(htmlInfo('Not Found',
	'The file "$path" could not be found.'));
	response.close();
	}

	badRequest(String problem) {
	response.statusCode = HttpStatus.BAD_REQUEST;
	response.write(htmlInfo("Bad request",
	"Bad request '${request.uri}': $problem"));
	response.close();
	}

	internalError(error, stack) {
	print(error);
	if (stack != null) print(stack);
	response.statusCode = HttpStatus.INTERNAL_SERVER_ERROR;
	response.write(htmlInfo("Internal Server Error",
	"Internal Server Error: $error\n$stack"));
	response.close();
	}

	bool validate(Map<String, String> parameters, Map<String, String> rules) {
	Iterable<String> problems = rules.keys
	.where((name) => !parameters.containsKey(name))
	.map((name) => "Missing parameter: '$name'.");
	if (!problems.isEmpty) {
	badRequest(problems.first);
	return false;
	}
	Set extra = new Set.from(parameters.keys)..removeAll(rules.keys);
	if (extra.isEmpty) return true;
	String extraString = (extra.toList()..sort()).join("', '");
	badRequest("Extra parameters: '$extraString'.");
	return false;
	}

	static Future<List<String>> listProjectFiles() {
	String nativeDir = projectRoot.toFilePath();
	Directory dir = new Directory(nativeDir);
	var future = dir.list(recursive: true, followLinks: false).toList();
	return future.then((List<FileSystemEntity> entries) {
	return entries
	.map((e) => e.path)
	.where((p) => p.endsWith('.dart') && p.startsWith(nativeDir))
	.map((p) => p.substring(nativeDir.length))
	.map((p) => new Uri.file(p).path).toList();
	});
	}

	static handleProjectList(Conversation self) {
	listProjectFiles().then((List<String> files) {
	self.response
	..write(JSON.encode(files))
	..close();
	});
	}

	handleProjectRequest() {
	Map<String, String> parameters = request.uri.queryParameters;
	for (ProjectCommand command in COMMANDS) {
	if (parameters.containsKey(command.name)) {
	if (validate(parameters, command.rules)) {
	(command.handle)(this);
	}
	return;
	}
	}
	String commands = COMMANDS.map((c) => c.name).join("', '");
	badRequest("Valid commands are: '$commands'");
	}

	handleSocket() {
	if (request.uri.path == '/ws/watch') {
	WebSocketTransformer.upgrade(request).then(WatchHandler.handleWebSocket);
	} else {
	response.done
	.then(onClosed)
	.catchError(onError);
	notFound(request.uri.path);
	}
	}

	handle() {
	response.done
	.then(onClosed)
	.catchError(onError);

	Uri uri = request.uri;
	if (uri.path == PROJECT_PATH) {
	return handleProjectRequest();
	}
	if (uri.path.endsWith('/')) {
	uri = uri.resolve('index.html');
	}
	if (uri.path == '/css/fonts/fontawesome-webfont.woff') {
	uri = uri.resolve('/fontawesome-webfont.woff');
	}
	if (uri.path.contains('..') \|\| uri.path.contains('%')) {
	return notFound(uri.path);
	}
	String path = uri.path;
	Uri root = documentRoot;
	String dartType = 'application/dart';
	if (path.startsWith('/project/packages/')) {
	root = packageRoot;
	path = path.substring('/project/packages'.length);
	} else if (path.startsWith('${PROJECT_PATH}/')) {
	root = projectRoot;
	path = path.substring(PROJECT_PATH.length);
	dartType = 'text/plain';
	} else if (path.startsWith('${PACKAGES_PATH}/')) {
	root = packageRoot;
	path = path.substring(PACKAGES_PATH.length);
	}

	String filePath = root.resolve('.$path').toFilePath();
	switch (request.method) {
	case 'GET':
	return handleGet(filePath, dartType);
	case 'POST':
	return handlePost(filePath);
	default:
	String method = const HtmlEscape().convert(request.method);
	return badRequest("Unsupported method: '$method'");
	}
	}

	void handleGet(String path, String dartType) {
	var f = new File(path);
	f.exists().then((bool exists) {
	if (!exists) return notFound(request.uri);
	if (path.endsWith('.html')) {
	response.headers.set(CONTENT_TYPE, 'text/html');
	} else if (path.endsWith('.dart')) {
	response.headers.set(CONTENT_TYPE, dartType);
	} else if (path.endsWith('.js')) {
	response.headers.set(CONTENT_TYPE, 'application/javascript');
	} else if (path.endsWith('.ico')) {
	response.headers.set(CONTENT_TYPE, 'image/x-icon');
	} else if (path.endsWith('.appcache')) {
	response.headers.set(CONTENT_TYPE, 'text/cache-manifest');
	}
	f.openRead().pipe(response).catchError(onError);
	});
	}

	handlePost(String path) {
	// The data is sent using a dart:html HttpRequest (aka XMLHttpRequest).
	// According to http://xhr.spec.whatwg.org/, strings are always encoded as
	// UTF-8.
	request.transform(UTF8.decoder).join().then((String data) {
	// The rest of this method is synchronous. This guarantees that we don't
	// make conflicting git changes in response to multiple POST requests.
	try {
	backup(path);
	} catch (e, stack) {
	return internalError(e, stack);
	}

	new File(path).writeAsStringSync(data);

	response
	..statusCode = HttpStatus.OK
	..close();
	});
	}

	// Back up the file [path] using git.
	static void backup(String path) {
	// Reset the index.
	git('read-tree', ['HEAD']);

	// Save modifications in index.
	git('update-index', ['--add', path]);

	// If the file isn't modified, don't back it up.
	if (checkGit('diff', ['--cached', '--quiet'])) return;

	String localModifications = git('write-tree');

	String tag = 'refs/tags/$GIT_TAG';
	var arguments = ['-m', COMMIT_MESSAGE, localModifications];

	if (checkGit('rev-parse', ['-q', '--verify', tag])) {
	// The tag already exists.

	if (checkGit('diff-tree', ['--quiet', localModifications, tag])) {
	// localModifications are identical to the last backup.
	return;
	}

	// Use the tag as a parent.
	arguments = ['-p', tag]..addAll(arguments);

	String headCommit = git('rev-parse', ['HEAD']);
	String mergeBase = git('merge-base', [tag, 'HEAD']);
	if (headCommit != mergeBase) {
	arguments = ['-p', 'HEAD']..addAll(arguments);
	}
	} else {
	arguments = ['-p', 'HEAD']..addAll(arguments);
	}

	// Commit the local modifcations.
	String commit = git('commit-tree', arguments);

	// Create or update the tag.
	git('tag', ['-f', GIT_TAG, commit]);
	}

	static String git(String command,
	[List<String> arguments = const <String> []]) {
	ProcessResult result =
	run('git', <String>[command]..addAll(arguments), gitEnv);
	if (result.exitCode != 0) {
	throw 'git error: ${result.stdout}\n${result.stderr}';
	}
	return result.stdout.trim();
	}

	static bool checkGit(String command,
	[List<String> arguments = const <String> []]) {
	return
	run('git', <String>[command]..addAll(arguments), gitEnv).exitCode == 0;
	}

	static Map<String, String> computeGitEnv() {
	ProcessResult result = run('git', ['rev-parse', '--git-dir'], null);
	if (result.exitCode != 0) {
	throw 'git error: ${result.stdout}\n${result.stderr}';
	}
	String gitDir = result.stdout.trim();
	return <String, String>{ 'GIT_INDEX_FILE': '$gitDir/try_dart_backup' };
	}

	static ProcessResult run(String executable,
	List<String> arguments,
	Map<String, String> environment) {
	// print('Running $executable ${arguments.join(" ")}');
	return Process.runSync(executable, arguments, environment: environment);
	}

	static onRequest(HttpRequest request) {
	Conversation conversation = new Conversation(request, request.response);
	if (WebSocketTransformer.isUpgradeRequest(request)) {
	conversation.handleSocket();
	} else {
	conversation.handle();
	}
	}

	static ensureProjectWatcher() {
	if (projectChanges != null) return;
	String nativeDir = projectRoot.toFilePath();
	Directory dir = new Directory(nativeDir);
	projectChanges = dir.watch();
	projectChanges.listen(WatchHandler.onFileSystemEvent);
	}

	static onError(error) {
	if (error is HttpException) {
	print('Error: ${error.message}');
	} else {
	print('Error: ${error}');
	}
	}

	String htmlInfo(String title, String text) {
	// No script injection, please.
	title = const HtmlEscape().convert(title);
	text = const HtmlEscape().convert(text);
	return """
	<!DOCTYPE html>
	<html lang='en'>
	<head>
	<title>$title</title>
	</head>
	<body>
	<h1>$title</h1>
	<p style='white-space:pre'>$text</p>
	</body>
	</html>
	""";
	}
	}

	main(List<String> arguments) {
	if (arguments.length > 0) {
	Conversation.documentRoot = Uri.base.resolve(arguments[0]);
	}
	var host = '127.0.0.1';
	if (arguments.length > 1) {
	host = arguments[1];
	}
	int port = 0;
	if (arguments.length > 2) {
	port = int.parse(arguments[2]);
	}
	if (arguments.length > 3) {
	Conversation.projectRoot = Uri.base.resolve(arguments[3]);
	}
	if (arguments.length > 4) {
	Conversation.packageRoot = Uri.base.resolve(arguments[4]);
	}
	HttpServer.bind(host, port).then((HttpServer server) {
	print('HTTP server started on http://$host:${server.port}/');
	server.listen(Conversation.onRequest, onError: Conversation.onError);
	}).catchError((e) {
	print("HttpServer.bind error: $e");
	exit(1);
	});
	}