// Copyright (c) 2017, 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.

import 'package:analyzer/dart/analysis/results.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/file_system/overlay_file_system.dart';
import 'package:analyzer/file_system/physical_file_system.dart';
import 'package:analyzer/src/dart/analysis/byte_store.dart';
import 'package:analyzer/src/dart/analysis/driver.dart'
    show AnalysisDriver, AnalysisDriverGeneric, AnalysisDriverScheduler;
import 'package:analyzer/src/dart/analysis/file_byte_store.dart';
import 'package:analyzer/src/dart/analysis/performance_logger.dart';
import 'package:analyzer/src/generated/sdk.dart';
import 'package:analyzer_plugin/channel/channel.dart';
import 'package:analyzer_plugin/protocol/protocol.dart';
import 'package:analyzer_plugin/protocol/protocol_common.dart';
import 'package:analyzer_plugin/protocol/protocol_constants.dart';
import 'package:analyzer_plugin/protocol/protocol_generated.dart';
import 'package:analyzer_plugin/src/protocol/protocol_internal.dart';
import 'package:analyzer_plugin/src/utilities/null_string_sink.dart';
import 'package:analyzer_plugin/utilities/subscriptions/subscription_manager.dart';
import 'package:pub_semver/pub_semver.dart';

/// The abstract superclass of any class implementing a plugin for the analysis
/// server.
///
/// Clients may not implement or mix-in this class, but are expected to extend
/// it.
abstract class ServerPlugin {
  /// A megabyte.
  static const int M = 1024 * 1024;

  /// The communication channel being used to communicate with the analysis
  /// server.
  PluginCommunicationChannel _channel;

  /// The resource provider used to access the file system.
  final OverlayResourceProvider resourceProvider;

  /// The next modification stamp for a changed file in the [resourceProvider].
  int _overlayModificationStamp = 0;

  /// The object used to manage analysis subscriptions.
  final SubscriptionManager subscriptionManager = SubscriptionManager();

  /// The scheduler used by any analysis drivers that are created.
  AnalysisDriverScheduler analysisDriverScheduler;

  /// A table mapping the current context roots to the analysis driver created
  /// for that root.
  final Map<ContextRoot, AnalysisDriverGeneric> driverMap =
      <ContextRoot, AnalysisDriverGeneric>{};

  /// The performance log used by any analysis drivers that are created.
  final PerformanceLog performanceLog = PerformanceLog(NullStringSink());

  /// The byte store used by any analysis drivers that are created, or `null` if
  /// the cache location isn't known because the 'plugin.version' request has not
  /// yet been received.
  ByteStore _byteStore;

  /// The SDK manager used to manage SDKs.
  DartSdkManager _sdkManager;

  /// Initialize a newly created analysis server plugin. If a resource [provider]
  /// is given, then it will be used to access the file system. Otherwise a
  /// resource provider that accesses the physical file system will be used.
  ServerPlugin(ResourceProvider provider)
      : resourceProvider = OverlayResourceProvider(
            provider ?? PhysicalResourceProvider.INSTANCE) {
    analysisDriverScheduler = AnalysisDriverScheduler(performanceLog);
    analysisDriverScheduler.start();
  }

  /// Return the byte store used by any analysis drivers that are created, or
  /// `null` if the cache location isn't known because the 'plugin.version'
  /// request has not yet been received.
  ByteStore get byteStore => _byteStore;

  /// Return the communication channel being used to communicate with the
  /// analysis server, or `null` if the plugin has not been started.
  PluginCommunicationChannel get channel => _channel;

  /// Return the user visible information about how to contact the plugin authors
  /// with any problems that are found, or `null` if there is no contact info.
  String get contactInfo => null;

  /// Return a list of glob patterns selecting the files that this plugin is
  /// interested in analyzing.
  List<String> get fileGlobsToAnalyze;

  /// Return the user visible name of this plugin.
  String get name;

  /// Return the SDK manager used to manage SDKs.
  DartSdkManager get sdkManager => _sdkManager;

  /// Return the version number of the plugin spec required by this plugin,
  /// encoded as a string.
  String get version;

  /// Handle the fact that the file with the given [path] has been modified.
  void contentChanged(String path) {
    // Ignore changes to files.
  }

  /// Return the context root containing the file at the given [filePath].
  ContextRoot contextRootContaining(String filePath) {
    var pathContext = resourceProvider.pathContext;

    /// Return `true` if the given [child] is either the same as or within the
    /// given [parent].
    bool isOrWithin(String parent, String child) {
      return parent == child || pathContext.isWithin(parent, child);
    }

    /// Return `true` if the given context [root] contains the target [file].
    bool ownsFile(ContextRoot root) {
      if (isOrWithin(root.root, filePath)) {
        var excludedPaths = root.exclude;
        for (var excludedPath in excludedPaths) {
          if (isOrWithin(excludedPath, filePath)) {
            return false;
          }
        }
        return true;
      }
      return false;
    }

    for (var root in driverMap.keys) {
      if (ownsFile(root)) {
        return root;
      }
    }
    return null;
  }

  /// Create an analysis driver that can analyze the files within the given
  /// [contextRoot].
  AnalysisDriverGeneric createAnalysisDriver(ContextRoot contextRoot);

  /// Return the driver being used to analyze the file with the given [path].
  AnalysisDriverGeneric driverForPath(String path) {
    var contextRoot = contextRootContaining(path);
    if (contextRoot == null) {
      return null;
    }
    return driverMap[contextRoot];
  }

  /// Return the result of analyzing the file with the given [path].
  ///
  /// Throw a [RequestFailure] is the file cannot be analyzed or if the driver
  /// associated with the file is not an [AnalysisDriver].
  Future<ResolvedUnitResult> getResolvedUnitResult(String path) async {
    var driver = driverForPath(path);
    if (driver is! AnalysisDriver) {
      // Return an error from the request.
      throw RequestFailure(
          RequestErrorFactory.pluginError('Failed to analyze $path', null));
    }
    var result = await (driver as AnalysisDriver).getResult(path);
    var state = result.state;
    if (state != ResultState.VALID) {
      // Return an error from the request.
      throw RequestFailure(
          RequestErrorFactory.pluginError('Failed to analyze $path', null));
    }
    return result;
  }

  /// Handle an 'analysis.getNavigation' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisGetNavigationResult> handleAnalysisGetNavigation(
      AnalysisGetNavigationParams params) async {
    return AnalysisGetNavigationResult(
        <String>[], <NavigationTarget>[], <NavigationRegion>[]);
  }

  /// Handle an 'analysis.handleWatchEvents' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisHandleWatchEventsResult> handleAnalysisHandleWatchEvents(
      AnalysisHandleWatchEventsParams parameters) async {
    for (var event in parameters.events) {
      switch (event.type) {
        case WatchEventType.ADD:
          // TODO(brianwilkerson) Handle the event.
          break;
        case WatchEventType.MODIFY:
          contentChanged(event.path);
          break;
        case WatchEventType.REMOVE:
          // TODO(brianwilkerson) Handle the event.
          break;
        default:
          // Ignore unhandled watch event types.
          break;
      }
    }
    return AnalysisHandleWatchEventsResult();
  }

  /// Handle an 'analysis.setContextRoots' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisSetContextRootsResult> handleAnalysisSetContextRoots(
      AnalysisSetContextRootsParams parameters) async {
    var contextRoots = parameters.roots;
    var oldRoots = driverMap.keys.toList();
    for (var contextRoot in contextRoots) {
      if (!oldRoots.remove(contextRoot)) {
        // The context is new, so we create a driver for it. Creating the driver
        // has the side-effect of adding it to the analysis driver scheduler.
        var driver = createAnalysisDriver(contextRoot);
        driverMap[contextRoot] = driver;
        _addFilesToDriver(
            driver,
            resourceProvider.getResource(contextRoot.root),
            contextRoot.exclude);
      }
    }
    for (var contextRoot in oldRoots) {
      // The context has been removed, so we remove its driver.
      var driver = driverMap.remove(contextRoot);
      // The `dispose` method has the side-effect of removing the driver from
      // the analysis driver scheduler.
      driver.dispose();
    }
    return AnalysisSetContextRootsResult();
  }

  /// Handle an 'analysis.setPriorityFiles' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisSetPriorityFilesResult> handleAnalysisSetPriorityFiles(
      AnalysisSetPriorityFilesParams parameters) async {
    var files = parameters.files;
    var filesByDriver = <AnalysisDriverGeneric, List<String>>{};
    for (var file in files) {
      var contextRoot = contextRootContaining(file);
      if (contextRoot != null) {
        // TODO(brianwilkerson) Which driver should we use if there is no context root?
        var driver = driverMap[contextRoot];
        filesByDriver.putIfAbsent(driver, () => <String>[]).add(file);
      }
    }
    filesByDriver.forEach((AnalysisDriverGeneric driver, List<String> files) {
      driver.priorityFiles = files;
    });
    return AnalysisSetPriorityFilesResult();
  }

  /// Handle an 'analysis.setSubscriptions' request. Most subclasses should not
  /// override this method, but should instead use the [subscriptionManager] to
  /// access the list of subscriptions for any given file.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisSetSubscriptionsResult> handleAnalysisSetSubscriptions(
      AnalysisSetSubscriptionsParams parameters) async {
    var subscriptions = parameters.subscriptions;
    var newSubscriptions = subscriptionManager.setSubscriptions(subscriptions);
    sendNotificationsForSubscriptions(newSubscriptions);
    return AnalysisSetSubscriptionsResult();
  }

  /// Handle an 'analysis.updateContent' request. Most subclasses should not
  /// override this method, but should instead use the [contentCache] to access
  /// the current content of overlaid files.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<AnalysisUpdateContentResult> handleAnalysisUpdateContent(
      AnalysisUpdateContentParams parameters) async {
    Map<String, Object> files = parameters.files;
    files.forEach((String filePath, Object overlay) {
      // Prepare the old overlay contents.
      String oldContents;
      try {
        if (resourceProvider.hasOverlay(filePath)) {
          var file = resourceProvider.getFile(filePath);
          oldContents = file.readAsStringSync();
        }
      } catch (_) {}

      // Prepare the new contents.
      String newContents;
      if (overlay is AddContentOverlay) {
        newContents = overlay.content;
      } else if (overlay is ChangeContentOverlay) {
        if (oldContents == null) {
          // The server should only send a ChangeContentOverlay if there is
          // already an existing overlay for the source.
          throw RequestFailure(
              RequestErrorFactory.invalidOverlayChangeNoContent());
        }
        try {
          newContents = SourceEdit.applySequence(oldContents, overlay.edits);
        } on RangeError {
          throw RequestFailure(
              RequestErrorFactory.invalidOverlayChangeInvalidEdit());
        }
      } else if (overlay is RemoveContentOverlay) {
        newContents = null;
      }

      if (newContents != null) {
        resourceProvider.setOverlay(
          filePath,
          content: newContents,
          modificationStamp: _overlayModificationStamp++,
        );
      } else {
        resourceProvider.removeOverlay(filePath);
      }

      contentChanged(filePath);
    });
    return AnalysisUpdateContentResult();
  }

  /// Handle a 'completion.getSuggestions' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<CompletionGetSuggestionsResult> handleCompletionGetSuggestions(
      CompletionGetSuggestionsParams parameters) async {
    return CompletionGetSuggestionsResult(
        -1, -1, const <CompletionSuggestion>[]);
  }

  /// Handle an 'edit.getAssists' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<EditGetAssistsResult> handleEditGetAssists(
      EditGetAssistsParams parameters) async {
    return EditGetAssistsResult(const <PrioritizedSourceChange>[]);
  }

  /// Handle an 'edit.getAvailableRefactorings' request. Subclasses that override
  /// this method in order to participate in refactorings must also override the
  /// method [handleEditGetRefactoring].
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<EditGetAvailableRefactoringsResult> handleEditGetAvailableRefactorings(
      EditGetAvailableRefactoringsParams parameters) async {
    return EditGetAvailableRefactoringsResult(const <RefactoringKind>[]);
  }

  /// Handle an 'edit.getFixes' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<EditGetFixesResult> handleEditGetFixes(
      EditGetFixesParams parameters) async {
    return EditGetFixesResult(const <AnalysisErrorFixes>[]);
  }

  /// Handle an 'edit.getRefactoring' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<EditGetRefactoringResult> handleEditGetRefactoring(
      EditGetRefactoringParams parameters) async {
    return null;
  }

  /// Handle a 'kythe.getKytheEntries' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<KytheGetKytheEntriesResult> handleKytheGetKytheEntries(
      KytheGetKytheEntriesParams parameters) async {
    return null;
  }

  /// Handle a 'plugin.shutdown' request. Subclasses can override this method to
  /// perform any required clean-up, but cannot prevent the plugin from shutting
  /// down.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<PluginShutdownResult> handlePluginShutdown(
      PluginShutdownParams parameters) async {
    return PluginShutdownResult();
  }

  /// Handle a 'plugin.versionCheck' request.
  ///
  /// Throw a [RequestFailure] if the request could not be handled.
  Future<PluginVersionCheckResult> handlePluginVersionCheck(
      PluginVersionCheckParams parameters) async {
    var byteStorePath = parameters.byteStorePath;
    var sdkPath = parameters.sdkPath;
    var versionString = parameters.version;
    var serverVersion = Version.parse(versionString);
    _byteStore = MemoryCachingByteStore(
        FileByteStore(byteStorePath,
            tempNameSuffix: DateTime.now().millisecondsSinceEpoch.toString()),
        64 * M);
    _sdkManager = DartSdkManager(sdkPath);
    return PluginVersionCheckResult(
        isCompatibleWith(serverVersion), name, version, fileGlobsToAnalyze,
        contactInfo: contactInfo);
  }

  /// Return `true` if this plugin is compatible with an analysis server that is
  /// using the given version of the plugin API.
  bool isCompatibleWith(Version serverVersion) =>
      serverVersion <= Version.parse(version);

  /// The method that is called when the analysis server closes the communication
  /// channel. This method will not be invoked under normal conditions because
  /// the server will send a shutdown request and the plugin will stop listening
  /// to the channel before the server closes the channel.
  void onDone() {}

  /// The method that is called when an error has occurred in the analysis
  /// server. This method will not be invoked under normal conditions.
  void onError(Object exception, StackTrace stackTrace) {}

  /// If the plugin provides folding information, send a folding notification
  /// for the file with the given [path] to the server.
  Future<void> sendFoldingNotification(String path) {
    return Future.value();
  }

  /// If the plugin provides highlighting information, send a highlights
  /// notification for the file with the given [path] to the server.
  Future<void> sendHighlightsNotification(String path) {
    return Future.value();
  }

  /// If the plugin provides navigation information, send a navigation
  /// notification for the file with the given [path] to the server.
  Future<void> sendNavigationNotification(String path) {
    return Future.value();
  }

  /// Send notifications for the services subscribed to for the file with the
  /// given [path].
  ///
  /// This is a convenience method that subclasses can use to send notifications
  /// after analysis has been performed on a file.
  void sendNotificationsForFile(String path) {
    for (var service in subscriptionManager.servicesForFile(path)) {
      _sendNotificationForFile(path, service);
    }
  }

  /// Send notifications corresponding to the given description of
  /// [subscriptions]. The map is keyed by the path of each file for which
  /// notifications should be sent and has values representing the list of
  /// services associated with the notifications to send.
  ///
  /// This method is used when the set of subscribed notifications has been
  /// changed and notifications need to be sent even when the specified files
  /// have already been analyzed.
  void sendNotificationsForSubscriptions(
      Map<String, List<AnalysisService>> subscriptions) {
    subscriptions.forEach((String path, List<AnalysisService> services) {
      for (var service in services) {
        _sendNotificationForFile(path, service);
      }
    });
  }

  /// If the plugin provides occurrences information, send an occurrences
  /// notification for the file with the given [path] to the server.
  Future<void> sendOccurrencesNotification(String path) {
    return Future.value();
  }

  /// If the plugin provides outline information, send an outline notification
  /// for the file with the given [path] to the server.
  Future<void> sendOutlineNotification(String path) {
    return Future.value();
  }

  /// Start this plugin by listening to the given communication [channel].
  void start(PluginCommunicationChannel channel) {
    _channel = channel;
    _channel.listen(_onRequest, onError: onError, onDone: onDone);
  }

  /// Add all of the files contained in the given [resource] that are not in the
  /// list of [excluded] resources to the given [driver].
  void _addFilesToDriver(
      AnalysisDriverGeneric driver, Resource resource, List<String> excluded) {
    var path = resource.path;
    if (excluded.contains(path)) {
      return;
    }
    if (resource is File) {
      driver.addFile(path);
    } else if (resource is Folder) {
      try {
        for (var child in resource.getChildren()) {
          _addFilesToDriver(driver, child, excluded);
        }
      } on FileSystemException {
        // The folder does not exist, so ignore it.
      }
    }
  }

  /// Compute the response that should be returned for the given [request], or
  /// `null` if the response has already been sent.
  Future<Response> _getResponse(Request request, int requestTime) async {
    ResponseResult result;
    switch (request.method) {
      case ANALYSIS_REQUEST_GET_NAVIGATION:
        var params = AnalysisGetNavigationParams.fromRequest(request);
        result = await handleAnalysisGetNavigation(params);
        break;
      case ANALYSIS_REQUEST_HANDLE_WATCH_EVENTS:
        var params = AnalysisHandleWatchEventsParams.fromRequest(request);
        result = await handleAnalysisHandleWatchEvents(params);
        break;
      case ANALYSIS_REQUEST_SET_CONTEXT_ROOTS:
        var params = AnalysisSetContextRootsParams.fromRequest(request);
        result = await handleAnalysisSetContextRoots(params);
        break;
      case ANALYSIS_REQUEST_SET_PRIORITY_FILES:
        var params = AnalysisSetPriorityFilesParams.fromRequest(request);
        result = await handleAnalysisSetPriorityFiles(params);
        break;
      case ANALYSIS_REQUEST_SET_SUBSCRIPTIONS:
        var params = AnalysisSetSubscriptionsParams.fromRequest(request);
        result = await handleAnalysisSetSubscriptions(params);
        break;
      case ANALYSIS_REQUEST_UPDATE_CONTENT:
        var params = AnalysisUpdateContentParams.fromRequest(request);
        result = await handleAnalysisUpdateContent(params);
        break;
      case COMPLETION_REQUEST_GET_SUGGESTIONS:
        var params = CompletionGetSuggestionsParams.fromRequest(request);
        result = await handleCompletionGetSuggestions(params);
        break;
      case EDIT_REQUEST_GET_ASSISTS:
        var params = EditGetAssistsParams.fromRequest(request);
        result = await handleEditGetAssists(params);
        break;
      case EDIT_REQUEST_GET_AVAILABLE_REFACTORINGS:
        var params = EditGetAvailableRefactoringsParams.fromRequest(request);
        result = await handleEditGetAvailableRefactorings(params);
        break;
      case EDIT_REQUEST_GET_FIXES:
        var params = EditGetFixesParams.fromRequest(request);
        result = await handleEditGetFixes(params);
        break;
      case EDIT_REQUEST_GET_REFACTORING:
        var params = EditGetRefactoringParams.fromRequest(request);
        result = await handleEditGetRefactoring(params);
        break;
      case KYTHE_REQUEST_GET_KYTHE_ENTRIES:
        var params = KytheGetKytheEntriesParams.fromRequest(request);
        result = await handleKytheGetKytheEntries(params);
        break;
      case PLUGIN_REQUEST_SHUTDOWN:
        var params = PluginShutdownParams();
        result = await handlePluginShutdown(params);
        _channel.sendResponse(result.toResponse(request.id, requestTime));
        _channel.close();
        return null;
      case PLUGIN_REQUEST_VERSION_CHECK:
        var params = PluginVersionCheckParams.fromRequest(request);
        result = await handlePluginVersionCheck(params);
        break;
    }
    if (result == null) {
      return Response(request.id, requestTime,
          error: RequestErrorFactory.unknownRequest(request.method));
    }
    return result.toResponse(request.id, requestTime);
  }

  /// The method that is called when a [request] is received from the analysis
  /// server.
  Future<void> _onRequest(Request request) async {
    var requestTime = DateTime.now().millisecondsSinceEpoch;
    var id = request.id;
    Response response;
    try {
      response = await _getResponse(request, requestTime);
    } on RequestFailure catch (exception) {
      response = Response(id, requestTime, error: exception.error);
    } catch (exception, stackTrace) {
      response = Response(id, requestTime,
          error: RequestError(
              RequestErrorCode.PLUGIN_ERROR, exception.toString(),
              stackTrace: stackTrace.toString()));
    }
    if (response != null) {
      _channel.sendResponse(response);
    }
  }

  /// Send a notification for the file at the given [path] corresponding to the
  /// given [service].
  void _sendNotificationForFile(String path, AnalysisService service) {
    switch (service) {
      case AnalysisService.FOLDING:
        sendFoldingNotification(path);
        break;
      case AnalysisService.HIGHLIGHTS:
        sendHighlightsNotification(path);
        break;
      case AnalysisService.NAVIGATION:
        sendNavigationNotification(path);
        break;
      case AnalysisService.OCCURRENCES:
        sendOccurrencesNotification(path);
        break;
      case AnalysisService.OUTLINE:
        sendOutlineNotification(path);
        break;
    }
  }
}