// Copyright (c) 2018, 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 'dart:collection';

import 'package:analyzer/dart/analysis/analysis_context.dart';
import 'package:analyzer/dart/analysis/context_locator.dart';
import 'package:analyzer/dart/analysis/context_root.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/file_system/physical_file_system.dart'
    show PhysicalResourceProvider;
import 'package:analyzer/src/context/builder.dart'
    show ContextBuilder, ContextBuilderOptions;
import 'package:analyzer/src/context/context_root.dart' as old;
import 'package:analyzer/src/dart/analysis/byte_store.dart'
    show MemoryByteStore;
import 'package:analyzer/src/dart/analysis/context_root.dart';
import 'package:analyzer/src/dart/analysis/driver.dart'
    show AnalysisDriver, AnalysisDriverScheduler;
import 'package:analyzer/src/dart/analysis/driver_based_analysis_context.dart';
import 'package:analyzer/src/dart/analysis/file_state.dart'
    show FileContentOverlay;
import 'package:analyzer/src/dart/analysis/performance_logger.dart'
    show PerformanceLog;
import 'package:analyzer/src/dart/sdk/sdk.dart' show FolderBasedDartSdk;
import 'package:analyzer/src/generated/sdk.dart' show DartSdkManager;
import 'package:meta/meta.dart';

/**
 * An implementation of a context locator.
 */
class ContextLocatorImpl implements ContextLocator {
  /**
   * The name of the analysis options file.
   */
  static const String ANALYSIS_OPTIONS_NAME = 'analysis_options.yaml';

  /**
   * The old name of the analysis options file.
   */
  static const String OLD_ANALYSIS_OPTIONS_NAME = '.analysis_options';

  /**
   * The name of the packages file.
   */
  static const String PACKAGES_FILE_NAME = '.packages';

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

  /**
   * Initialize a newly created context locator. If a [resourceProvider] is
   * supplied, it will be used to access the file system. Otherwise the default
   * resource provider will be used.
   */
  ContextLocatorImpl({ResourceProvider resourceProvider})
      : this.resourceProvider =
            resourceProvider ?? PhysicalResourceProvider.INSTANCE;

  /**
   * Return the path to the default location of the SDK.
   */
  String get _defaultSdkPath =>
      FolderBasedDartSdk.defaultSdkDirectory(resourceProvider).path;

  @deprecated
  @override
  List<AnalysisContext> locateContexts(
      {@required List<String> includedPaths,
      List<String> excludedPaths: null,
      String optionsFile: null,
      String packagesFile: null,
      String sdkPath: null}) {
    List<ContextRoot> roots = locateRoots(
        includedPaths: includedPaths,
        excludedPaths: excludedPaths,
        optionsFile: optionsFile,
        packagesFile: packagesFile);
    if (roots.isEmpty) {
      return const <AnalysisContext>[];
    }
    PerformanceLog performanceLog = new PerformanceLog(new StringBuffer());
    AnalysisDriverScheduler scheduler =
        new AnalysisDriverScheduler(performanceLog);
    DartSdkManager sdkManager =
        new DartSdkManager(sdkPath ?? _defaultSdkPath, true);
    scheduler.start();
    ContextBuilderOptions options = new ContextBuilderOptions();
    ContextBuilder builder = new ContextBuilder(
        resourceProvider, sdkManager, null,
        options: options);
    if (packagesFile != null) {
      options.defaultPackageFilePath = packagesFile;
    }
    builder.analysisDriverScheduler = scheduler;
    builder.byteStore = new MemoryByteStore();
    builder.fileContentOverlay = new FileContentOverlay();
    builder.performanceLog = performanceLog;
    List<AnalysisContext> contextList = <AnalysisContext>[];
    for (ContextRoot root in roots) {
      old.ContextRoot contextRoot = new old.ContextRoot(
          root.root.path, root.excludedPaths.toList(),
          pathContext: resourceProvider.pathContext);
      AnalysisDriver driver = builder.buildDriver(contextRoot);
      DriverBasedAnalysisContext context =
          new DriverBasedAnalysisContext(resourceProvider, root, driver);
      contextList.add(context);
    }
    return contextList;
  }

  @override
  List<ContextRoot> locateRoots(
      {@required List<String> includedPaths,
      List<String> excludedPaths: null,
      String optionsFile: null,
      String packagesFile: null}) {
    //
    // Compute the list of folders and files that are to be included.
    //
    List<Folder> includedFolders = <Folder>[];
    List<File> includedFiles = <File>[];
    _resourcesFromPaths(
        includedPaths ?? const <String>[], includedFolders, includedFiles);
    //
    // Compute the list of folders and files that are to be excluded.
    //
    List<Folder> excludedFolders = <Folder>[];
    List<File> excludedFiles = <File>[];
    _resourcesFromPaths(
        excludedPaths ?? const <String>[], excludedFolders, excludedFiles);
    //
    // Use the excluded folders and files to filter the included folders and
    // files.
    //
    includedFolders = includedFolders
        .where((Folder includedFolder) =>
            !_containedInAny(excludedFolders, includedFolder) &&
            !_containedInAny(includedFolders, includedFolder))
        .toList();
    includedFiles = includedFiles
        .where((File includedFile) =>
            !_containedInAny(excludedFolders, includedFile) &&
            !excludedFiles.contains(includedFile) &&
            !_containedInAny(includedFolders, includedFile))
        .toList();
    //
    // We now have a list of all of the files and folders that need to be
    // analyzed. For each, walk the directory structure and figure out where to
    // create context roots.
    //
    File defaultOptionsFile;
    if (optionsFile != null) {
      defaultOptionsFile = resourceProvider.getFile(optionsFile);
      if (!defaultOptionsFile.exists) {
        defaultOptionsFile = null;
      }
    }
    File defaultPackagesFile;
    if (packagesFile != null) {
      defaultPackagesFile = resourceProvider.getFile(packagesFile);
      if (!defaultPackagesFile.exists) {
        defaultPackagesFile = null;
      }
    }
    List<ContextRoot> roots = <ContextRoot>[];
    for (Folder folder in includedFolders) {
      ContextRootImpl root = new ContextRootImpl(resourceProvider, folder);
      root.packagesFile = defaultPackagesFile ?? _findPackagesFile(folder);
      root.optionsFile = defaultOptionsFile ?? _findOptionsFile(folder);
      root.included.add(folder);
      roots.add(root);
      _createContextRootsIn(roots, folder, excludedFolders, root,
          defaultOptionsFile, defaultPackagesFile);
    }
    Map<Folder, ContextRoot> rootMap = <Folder, ContextRoot>{};
    for (File file in includedFiles) {
      Folder parent = file.parent;
      ContextRoot root = rootMap.putIfAbsent(parent, () {
        ContextRootImpl root = new ContextRootImpl(resourceProvider, parent);
        root.packagesFile = defaultPackagesFile ?? _findPackagesFile(parent);
        root.optionsFile = defaultOptionsFile ?? _findOptionsFile(parent);
        roots.add(root);
        return root;
      });
      root.included.add(file);
    }
    return roots;
  }

  /**
   * Return `true` if the given [resource] is contained in one or more of the
   * given [folders].
   */
  bool _containedInAny(Iterable<Folder> folders, Resource resource) =>
      folders.any((Folder folder) => folder.contains(resource.path));

  /**
   * If the given [folder] should be the root of a new analysis context, then
   * create a new context root for it and add it to the list of context [roots].
   * The [containingRoot] is the context root from an enclosing directory and is
   * used to inherit configuration information that isn't overridden.
   *
   * If either the [optionsFile] or [packagesFile] is non-`null` then the given
   * file will be used even if there is a local version of the file.
   *
   * For each directory within the given [folder] that is not in the list of
   * [excludedFolders], recursively search for nested context roots.
   */
  void _createContextRoots(
      List<ContextRoot> roots,
      Folder folder,
      List<Folder> excludedFolders,
      ContextRoot containingRoot,
      File optionsFile,
      File packagesFile) {
    //
    // If the options and packages files are allowed to be locally specified,
    // then look to see whether they are.
    //
    File localOptionsFile;
    if (optionsFile == null) {
      localOptionsFile = _getOptionsFile(folder);
    }
    File localPackagesFile;
    if (packagesFile == null) {
      localPackagesFile = _getPackagesFile(folder);
    }
    //
    // Create a context root for the given [folder] if at least one of the
    // options and packages file is locally specified.
    //
    if (localPackagesFile != null || localOptionsFile != null) {
      if (optionsFile != null) {
        localOptionsFile = optionsFile;
      }
      if (packagesFile != null) {
        localPackagesFile = packagesFile;
      }
      ContextRootImpl root = new ContextRootImpl(resourceProvider, folder);
      root.packagesFile = localPackagesFile ?? containingRoot.packagesFile;
      root.optionsFile = localOptionsFile ?? containingRoot.optionsFile;
      root.included.add(folder);
      containingRoot.excluded.add(folder);
      roots.add(root);
      containingRoot = root;
    }
    _createContextRootsIn(roots, folder, excludedFolders, containingRoot,
        optionsFile, packagesFile);
  }

  /**
   * For each directory within the given [folder] that is not in the list of
   * [excludedFolders], recursively search for nested context roots.
   *
   * If either the [optionsFile] or [packagesFile] is non-`null` then the given
   * file will be used even if there is a local version of the file.
   */
  void _createContextRootsIn(
      List<ContextRoot> roots,
      Folder folder,
      List<Folder> excludedFolders,
      ContextRoot containingRoot,
      File optionsFile,
      File packagesFile) {
    //
    // Check each of the subdirectories to see whether a context root needs to
    // be added for it.
    //
    try {
      for (Resource child in folder.getChildren()) {
        if (child is Folder) {
          if (excludedFolders.contains(folder) ||
              folder.shortName.startsWith('.')) {
            containingRoot.excluded.add(folder);
          } else {
            _createContextRoots(roots, child, excludedFolders, containingRoot,
                optionsFile, packagesFile);
          }
        }
      }
    } on FileSystemException {
      // The directory either doesn't exist or cannot be read. Either way, there
      // are no subdirectories that need to be added.
    }
  }

  /**
   * Return the analysis options file to be used to analyze files in the given
   * [folder], or `null` if there is no analysis options file in the given
   * folder or any parent folder.
   */
  File _findOptionsFile(Folder folder) {
    while (folder != null) {
      File packagesFile = _getOptionsFile(folder);
      if (packagesFile != null) {
        return packagesFile;
      }
      folder = folder.parent;
    }
    return null;
  }

  /**
   * Return the packages file to be used to analyze files in the given [folder],
   * or `null` if there is no packages file in the given folder or any parent
   * folder.
   */
  File _findPackagesFile(Folder folder) {
    while (folder != null) {
      File packagesFile = _getPackagesFile(folder);
      if (packagesFile != null) {
        return packagesFile;
      }
      folder = folder.parent;
    }
    return null;
  }

  /**
   * If the given [directory] contains a file with the given [name], then return
   * the file. Otherwise, return `null`.
   */
  File _getFile(Folder directory, String name) {
    Resource resource = directory.getChild(name);
    if (resource is File && resource.exists) {
      return resource;
    }
    return null;
  }

  /**
   * Return the analysis options file in the given [folder], or `null` if the
   * folder does not contain an analysis options file.
   */
  File _getOptionsFile(Folder folder) =>
      _getFile(folder, ANALYSIS_OPTIONS_NAME) ??
      _getFile(folder, OLD_ANALYSIS_OPTIONS_NAME);

  /**
   * Return the packages file in the given [folder], or `null` if the folder
   * does not contain a packages file.
   */
  File _getPackagesFile(Folder folder) => _getFile(folder, PACKAGES_FILE_NAME);

  /**
   * Add to the given lists of [folders] and [files] all of the resources in the
   * given list of [paths] that exist and are not contained within one of the
   * folders.
   */
  void _resourcesFromPaths(
      List<String> paths, List<Folder> folders, List<File> files) {
    for (String path in _uniqueSortedPaths(paths)) {
      Resource resource = resourceProvider.getResource(path);
      if (resource.exists && !_containedInAny(folders, resource)) {
        if (resource is Folder) {
          folders.add(resource);
        } else if (resource is File) {
          files.add(resource);
        } else {
          // Internal error: unhandled kind of resource.
        }
      }
    }
  }

  /**
   * Return a list of paths that contains all of the unique elements from the
   * given list of [paths], sorted such that shorter paths are first.
   */
  List<String> _uniqueSortedPaths(List<String> paths) {
    Set<String> uniquePaths = new HashSet<String>.from(paths);
    List<String> sortedPaths = uniquePaths.toList();
    sortedPaths.sort((a, b) => a.length - b.length);
    return sortedPaths;
  }
}