// 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 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer/error/listener.dart';
import 'package:analyzer/src/dart/scanner/reader.dart';
import 'package:analyzer/src/dart/scanner/scanner.dart';
import 'package:analyzer/src/generated/parser.dart';
import 'package:analyzer/src/generated/source.dart';
import 'package:analyzer/src/generated/utilities_dart.dart';
import 'package:analyzer/src/summary/format.dart';
import 'package:analyzer/src/summary/idl.dart';
import 'package:analyzer/src/summary/link.dart';
import 'package:analyzer/src/summary/package_bundle_reader.dart';
import 'package:analyzer/src/summary/prelink.dart';
import 'package:analyzer/src/summary/summarize_ast.dart';
import 'package:analyzer/src/summary/summarize_elements.dart';
import 'package:path/path.dart' show posix;
import 'package:test/test.dart';

import '../context/mock_sdk.dart';

/**
 * Convert the given Posix style file [path] to the corresponding absolute URI.
 */
String absUri(String path) {
  String absolutePath = posix.absolute(path);
  return posix.toUri(absolutePath).toString();
}

/**
 * Instances of the class [LinkerInputs] encapsulate the necessary information
 * to pass to the summary linker.
 */
class LinkerInputs {
  final bool _allowMissingFiles;
  final Map<String, UnlinkedUnit> _uriToUnit;
  final Uri testDartUri;
  final UnlinkedUnit unlinkedDefiningUnit;
  final Map<String, LinkedLibrary> _dependentLinkedLibraries;
  final Map<String, UnlinkedUnit> _dependentUnlinkedUnits;

  LinkerInputs(
      this._allowMissingFiles,
      this._uriToUnit,
      this.testDartUri,
      this.unlinkedDefiningUnit,
      this._dependentLinkedLibraries,
      this._dependentUnlinkedUnits);

  Set<String> get linkedLibraries => _uriToUnit.keys.toSet();

  String getDeclaredVariable(String name) {
    return null;
  }

  LinkedLibrary getDependency(String absoluteUri) {
    Map<String, LinkedLibrary> sdkLibraries =
        SerializedMockSdk.instance.uriToLinkedLibrary;
    LinkedLibrary linkedLibrary =
        sdkLibraries[absoluteUri] ?? _dependentLinkedLibraries[absoluteUri];
    if (linkedLibrary == null && !_allowMissingFiles) {
      Set<String> librariesAvailable = sdkLibraries.keys.toSet();
      librariesAvailable.addAll(_dependentLinkedLibraries.keys);
      fail('Linker unexpectedly requested LinkedLibrary for "$absoluteUri".'
          '  Libraries available: ${librariesAvailable.toList()}');
    }
    return linkedLibrary;
  }

  UnlinkedUnit getUnit(String absoluteUri) {
    if (absoluteUri == null) {
      return null;
    }
    UnlinkedUnit unit = _uriToUnit[absoluteUri] ??
        SerializedMockSdk.instance.uriToUnlinkedUnit[absoluteUri] ??
        _dependentUnlinkedUnits[absoluteUri];
    if (unit == null && !_allowMissingFiles) {
      fail('Linker unexpectedly requested unit for "$absoluteUri".');
    }
    return unit;
  }
}

/**
 * [SerializedMockSdk] is a singleton class representing the result of
 * serializing the mock SDK to summaries.  It is computed once and then shared
 * among test invocations so that we don't bog down the tests.
 *
 * Note: should an exception occur during computation of [instance], it will
 * silently be set to null to allow other tests to complete quickly.
 */
class SerializedMockSdk {
  static final SerializedMockSdk instance = _serializeMockSdk();

  final Map<String, UnlinkedUnit> uriToUnlinkedUnit;

  final Map<String, LinkedLibrary> uriToLinkedLibrary;
  SerializedMockSdk._(this.uriToUnlinkedUnit, this.uriToLinkedLibrary);

  static SerializedMockSdk _serializeMockSdk() {
    try {
      Map<String, UnlinkedUnit> uriToUnlinkedUnit = <String, UnlinkedUnit>{};
      Map<String, LinkedLibrary> uriToLinkedLibrary = <String, LinkedLibrary>{};
      PackageBundle bundle = new MockSdk().getLinkedBundle();
      for (int i = 0; i < bundle.unlinkedUnitUris.length; i++) {
        String uri = bundle.unlinkedUnitUris[i];
        uriToUnlinkedUnit[uri] = bundle.unlinkedUnits[i];
      }
      for (int i = 0; i < bundle.linkedLibraryUris.length; i++) {
        String uri = bundle.linkedLibraryUris[i];
        uriToLinkedLibrary[uri] = bundle.linkedLibraries[i];
      }
      return new SerializedMockSdk._(uriToUnlinkedUnit, uriToLinkedLibrary);
    } catch (_) {
      return null;
    }
  }
}

/// Abstract base class for tests involving summaries.
///
/// Test classes should not extend this class directly; they should extend a
/// class that implements this class with methods that drive summary generation.
/// The tests themselves can then be provided via mixin, allowing summaries to
/// be tested in a variety of ways.
abstract class SummaryBaseTestStrategy {
  LinkerInputs get linkerInputs;

  /**
   * Add the given source file so that it may be referenced by the file under
   * test.
   */
  Source addNamedSource(String filePath, String contents);
}

/// Abstract base class for black-box tests of summaries.
///
/// Test classes should not extend this class directly; they should extend a
/// class that implements this class with methods that drive summary generation.
/// The tests themselves can then be provided via mixin, allowing summaries to
/// be tested in a variety of ways.
abstract class SummaryBlackBoxTestStrategy extends SummaryBaseTestStrategy {
  /**
   * A test will set this to `true` if it contains `import`, `export`, or
   * `part` declarations that deliberately refer to non-existent files.
   */
  void set allowMissingFiles(bool value);

  /**
   * Get access to the linked summary that results from serializing and
   * then deserializing the library under test.
   */
  LinkedLibrary get linked;

  /**
   * `true` if the linked portion of the summary only contains prelinked data.
   * This happens because we don't yet have a full linker; only a prelinker.
   */
  bool get skipFullyLinkedData;

  /**
   * Get access to the unlinked compilation unit summaries that result from
   * serializing and deserializing the library under test.
   */
  List<UnlinkedUnit> get unlinkedUnits;

  /**
   * Serialize the given library [text], then deserialize it and store its
   * summary in [lib].
   */
  void serializeLibraryText(String text, {bool allowErrors: false});
}

/// Implementation of [SummaryBlackBoxTestStrategy] that drives summary
/// generation using the old two-phase API, and exercises the pre-linker only.
class SummaryBlackBoxTestStrategyPrelink
    extends _SummaryBlackBoxTestStrategyTwoPhase
    implements SummaryBlackBoxTestStrategy {
  @override
  bool get skipFullyLinkedData => true;

  @override
  void serializeLibraryText(String text, {bool allowErrors: false}) {
    super.serializeLibraryText(text, allowErrors: allowErrors);

    UnlinkedUnit getPart(String absoluteUri) {
      return linkerInputs.getUnit(absoluteUri);
    }

    UnlinkedPublicNamespace getImport(String absoluteUri) {
      return getPart(absoluteUri)?.publicNamespace;
    }

    linked = new LinkedLibrary.fromBuffer(prelink(
        linkerInputs.testDartUri.toString(),
        linkerInputs.unlinkedDefiningUnit,
        getPart,
        getImport,
        (String declaredVariable) => null).toBuffer());
    _validateLinkedLibrary(linked);
  }
}

/// Implementation of [SummaryBlackBoxTestStrategy] that drives summary
/// generation using the old two-phase API, and exercises full summary
/// generation.
class SummaryBlackBoxTestStrategyTwoPhase
    extends _SummaryBlackBoxTestStrategyTwoPhase
    implements SummaryBlackBoxTestStrategy {
  @override
  bool get skipFullyLinkedData => false;
}

/// Abstract base class for unit tests of the summary linker.
///
/// Test classes should not extend this class directly; they should extend a
/// class that implements this class with methods that drive summary generation.
/// The tests themselves can then be provided via mixin, allowing summaries to
/// be tested in a variety of ways.
abstract class SummaryLinkerTestStrategy extends SummaryBaseTestStrategy {
  Linker get linker;

  LibraryElementInBuildUnit get testLibrary;

  /**
   * Add the given package bundle as a dependency so that it may be referenced
   * by the files under test.
   */
  void addBundle(String path, PackageBundle bundle);

  void createLinker(String text, {String path: '/test.dart'});

  /**
   * Link together the given file, along with any other files passed to
   * [addNamedSource], to form a package bundle.  Reset the state of the buffers
   * accumulated by [addNamedSource] and [addBundle] so that further bundles
   * can be created.
   */
  PackageBundleBuilder createPackageBundle(String text,
      {String path: '/test.dart', String uri});
}

/// Implementation of [SummaryLinkerTestStrategy] that drives summary generation
/// using the old two-phase API.
class SummaryLinkerTestStrategyTwoPhase extends _SummaryBaseTestStrategyTwoPhase
    implements SummaryLinkerTestStrategy {
  LibraryElementInBuildUnit _testLibrary;

  @override
  Linker linker;

  @override
  LibraryElementInBuildUnit get testLibrary => _testLibrary ??=
      linker.getLibrary(linkerInputs.testDartUri) as LibraryElementInBuildUnit;

  @override
  bool get _allowMissingFiles => false;

  @override
  void addBundle(String path, PackageBundle bundle) {
    _filesToLink.summaryDataStore.addBundle(path, bundle);
  }

  @override
  void createLinker(String text, {String path: '/test.dart'}) {
    linkerInputs = createLinkerInputs(text, path: path);
    Map<String, LinkedLibraryBuilder> linkedLibraries = setupForLink(
        linkerInputs.linkedLibraries,
        linkerInputs.getUnit,
        linkerInputs.getDeclaredVariable);
    linker = new Linker(
        linkedLibraries, linkerInputs.getDependency, linkerInputs.getUnit);
  }

  @override
  PackageBundleBuilder createPackageBundle(String text,
      {String path: '/test.dart', String uri}) {
    PackageBundleAssembler assembler = new PackageBundleAssembler();
    LinkerInputs linkerInputs = createLinkerInputs(text, path: path, uri: uri);
    Map<String, LinkedLibraryBuilder> linkedLibraries = link(
        linkerInputs.linkedLibraries,
        linkerInputs.getDependency,
        linkerInputs.getUnit,
        linkerInputs.getDeclaredVariable);
    linkedLibraries.forEach(assembler.addLinkedLibrary);
    linkerInputs._uriToUnit.forEach((String uri, UnlinkedUnit unit) {
      assembler.addUnlinkedUnitViaUri(uri, unit);
    });
    return assembler.assemble();
  }
}

/**
 * [_FilesToLink] stores information about a set of files to be linked together.
 * This information is grouped into a class to allow it to be reset easily when
 * [_SummaryBaseTestStrategyTwoPhase.createLinkerInputs] is called.
 */
class _FilesToLink {
  /**
   * Map from absolute URI to the [UnlinkedUnit] for each compilation unit
   * passed to [addNamedSource].
   */
  Map<String, UnlinkedUnitBuilder> uriToUnit = <String, UnlinkedUnitBuilder>{};

  /**
   * Information about summaries to be included in the link process.
   */
  SummaryDataStore summaryDataStore = new SummaryDataStore([]);
}

/// Implementation of [SummaryBaseTestStrategy] that drives summary generation
/// using the old two-phase API.
abstract class _SummaryBaseTestStrategyTwoPhase
    implements SummaryBaseTestStrategy {
  /**
   * Information about the files to be linked.
   */
  _FilesToLink _filesToLink = new _FilesToLink();

  @override
  LinkerInputs linkerInputs;

  bool get _allowMissingFiles;

  @override
  Source addNamedSource(String filePath, String contents) {
    CompilationUnit unit = _parseText(contents);
    UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(unit);
    _filesToLink.uriToUnit[absUri(filePath)] = unlinkedUnit;
    // Tests using SummaryLinkerTest don't actually need the returned
    // Source, so we can safely return `null`.
    return null;
  }

  LinkerInputs createLinkerInputs(String text,
      {String path: '/test.dart', String uri}) {
    uri ??= absUri(path);
    Uri testDartUri = Uri.parse(uri);
    UnlinkedUnitBuilder unlinkedDefiningUnit =
        createUnlinkedSummary(testDartUri, text);
    _filesToLink.uriToUnit[testDartUri.toString()] = unlinkedDefiningUnit;
    LinkerInputs linkerInputs = new LinkerInputs(
        _allowMissingFiles,
        _filesToLink.uriToUnit,
        testDartUri,
        unlinkedDefiningUnit,
        _filesToLink.summaryDataStore.linkedMap,
        _filesToLink.summaryDataStore.unlinkedMap);
    // Reset _filesToLink in case the test needs to start a new package bundle.
    _filesToLink = new _FilesToLink();
    return linkerInputs;
  }

  UnlinkedUnitBuilder createUnlinkedSummary(Uri uri, String text) =>
      serializeAstUnlinked(_parseText(text));

  CompilationUnit _parseText(String text) {
    CharSequenceReader reader = new CharSequenceReader(text);
    Scanner scanner =
        new Scanner(null, reader, AnalysisErrorListener.NULL_LISTENER);
    Token token = scanner.tokenize();
    Parser parser = new Parser(
        NonExistingSource.unknown, AnalysisErrorListener.NULL_LISTENER);
    (parser as ParserAdapter).fastaParser.isMixinSupportEnabled = true;
    CompilationUnit unit = parser.parseCompilationUnit(token);
    unit.lineInfo = new LineInfo(scanner.lineStarts);
    return unit;
  }
}

/// Implementation of [SummaryBlackBoxTestStrategy] that drives summary
/// generation using the old two-phase API.
///
/// Not intended to be used directly; instead use a derived class that either
/// exercises the full summary algorithmm or just pre-linking.
abstract class _SummaryBlackBoxTestStrategyTwoPhase
    extends _SummaryBaseTestStrategyTwoPhase
    implements SummaryBlackBoxTestStrategy {
  @override
  List<UnlinkedUnit> unlinkedUnits;

  @override
  LinkedLibrary linked;

  @override
  bool _allowMissingFiles = false;

  @override
  void set allowMissingFiles(bool value) {
    _allowMissingFiles = value;
  }

  @override
  void serializeLibraryText(String text, {bool allowErrors: false}) {
    Map<String, UnlinkedUnitBuilder> uriToUnit = this._filesToLink.uriToUnit;
    linkerInputs = createLinkerInputs(text);
    linked = link(
        linkerInputs.linkedLibraries,
        linkerInputs.getDependency,
        linkerInputs.getUnit,
        (name) => null)[linkerInputs.testDartUri.toString()];
    expect(linked, isNotNull);
    _validateLinkedLibrary(linked);
    unlinkedUnits = <UnlinkedUnit>[linkerInputs.unlinkedDefiningUnit];
    for (String relativeUriStr
        in linkerInputs.unlinkedDefiningUnit.publicNamespace.parts) {
      Uri relativeUri;
      try {
        relativeUri = Uri.parse(relativeUriStr);
      } on FormatException {
        unlinkedUnits.add(new UnlinkedUnitBuilder());
        continue;
      }

      UnlinkedUnit unit = uriToUnit[
          resolveRelativeUri(linkerInputs.testDartUri, relativeUri).toString()];
      if (unit == null) {
        if (!_allowMissingFiles) {
          fail('Test referred to unknown unit $relativeUriStr');
        }
      } else {
        unlinkedUnits.add(unit);
      }
    }
  }

  /**
   * Verify invariants of the given [linkedLibrary].
   */
  void _validateLinkedLibrary(LinkedLibrary linkedLibrary) {
    for (LinkedUnit unit in linkedLibrary.units) {
      for (LinkedReference reference in unit.references) {
        switch (reference.kind) {
          case ReferenceKind.classOrEnum:
          case ReferenceKind.topLevelPropertyAccessor:
          case ReferenceKind.topLevelFunction:
          case ReferenceKind.typedef:
            // This reference can have either a zero or a nonzero dependency,
            // since it refers to top level element which might or might not be
            // imported from another library.
            break;
          case ReferenceKind.prefix:
            // Prefixes should have a dependency of 0, since they come from the
            // current library.
            expect(reference.dependency, 0,
                reason: 'Nonzero dependency for prefix');
            break;
          case ReferenceKind.unresolved:
            // Unresolved references always have a dependency of 0.
            expect(reference.dependency, 0,
                reason: 'Nonzero dependency for undefined');
            break;
          default:
            // This reference should have a dependency of 0, since it refers to
            // an element that is contained within some other element.
            expect(reference.dependency, 0,
                reason: 'Nonzero dependency for ${reference.kind}');
        }
      }
    }
  }
}