// Copyright (c) 2014, 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:async';

import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
import 'package:analysis_server/src/services/completion/dart/completion_manager.dart'
    show DartCompletionRequest;
import 'package:analysis_server/src/services/completion/dart/suggestion_builder.dart';
import 'package:analysis_server/src/services/completion/dart/utilities.dart';
import 'package:analyzer/dart/analysis/results.dart';
import 'package:analyzer/src/dartdoc/dartdoc_directive_info.dart';
import 'package:analyzer_plugin/protocol/protocol_common.dart';
import 'package:collection/collection.dart';
import 'package:meta/meta.dart';
import 'package:test/test.dart';

import '../../../abstract_context.dart';

SuggestionMatcher suggestionHas(
        {required String completion,
        ElementKind? element,
        CompletionSuggestionKind? kind}) =>
    (CompletionSuggestion s) {
      if (s.completion == completion) {
        if (element != null && s.element?.kind != element) {
          return false;
        }
        if (kind != null && s.kind != kind) {
          return false;
        }
        return true;
      }
      return false;
    };

typedef SuggestionMatcher = bool Function(CompletionSuggestion suggestion);

/// Base class for tests that validate individual [DartCompletionContributor]
/// suggestions.
abstract class DartCompletionContributorTest
    extends _BaseDartCompletionContributorTest {
  @nonVirtual
  @override
  Future<List<CompletionSuggestion>> computeContributedSuggestions(
      DartCompletionRequest request) async {
    var builder = SuggestionBuilder(request);
    var contributor = createContributor(request, builder);
    await contributor.computeSuggestions();
    return builder.suggestions.toList();
  }

  DartCompletionContributor createContributor(
    DartCompletionRequest request,
    SuggestionBuilder builder,
  );
}

abstract class _BaseDartCompletionContributorTest extends AbstractContextTest {
  static const String _UNCHECKED = '__UNCHECKED__';
  late String testFile;
  int _completionOffset = -1;
  late int replacementOffset;
  late int replacementLength;

  late ResolvedUnitResult result;

  /// The Dartdoc information passed to requests.
  final DartdocDirectiveInfo dartdocInfo = DartdocDirectiveInfo();

  late DartCompletionRequest request;

  late List<CompletionSuggestion> suggestions;

  /// Return the offset at which completion was requested.
  int get completionOffset {
    if (_completionOffset < 0) {
      fail('Must call addTestSource exactly once');
    }
    return _completionOffset;
  }

  /// If `true` and `null` is specified as the suggestion's expected returnType
  /// then the actual suggestion is expected to have a `dynamic` returnType.
  /// Newer tests return `false` so that they can distinguish between
  /// `dynamic` and `null`.
  /// Eventually all tests should be converted and this getter removed.
  bool get isNullExpectedReturnTypeConsideredDynamic => true;

  /// Return `true` if contributors should suggest constructors in contexts
  /// where there is no `new` or `const` keyword.
  bool get suggestConstructorsWithoutNew => true;

  void addTestSource(String content) {
    expect(_completionOffset, lessThan(0),
        reason: 'Must call addTestSource exactly once');
    _completionOffset = content.indexOf('^');
    expect(_completionOffset, greaterThanOrEqualTo(0), reason: 'missing ^');
    var nextOffset = content.indexOf('^', _completionOffset + 1);
    expect(nextOffset, equals(-1), reason: 'too many ^');
    content = content.substring(0, _completionOffset) +
        content.substring(_completionOffset + 1);
    addSource(testFile, content);
  }

  /// A variant of [addTestSource] that can be invoked more than once,
  /// and will notify the driver that the file changed.
  void addTestSource2(String content) {
    _completionOffset = content.indexOf('^');
    expect(_completionOffset, greaterThanOrEqualTo(0), reason: 'missing ^');
    var nextOffset = content.indexOf('^', _completionOffset + 1);
    expect(nextOffset, equals(-1), reason: 'too many ^');
    content = content.substring(0, _completionOffset) +
        content.substring(_completionOffset + 1);
    addSource(testFile, content);
    driverFor(testFile).changeFile(testFile);
  }

  void assertCoreTypeSuggestions() {
    assertSuggestClass('Comparable');
    assertSuggestTypeAlias(
      'Comparator',
      aliasedType: 'int Function(T, T)',
      returnType: 'int',
    );
    assertSuggestClass('DateTime');
    assertSuggestClass('Deprecated');
    assertSuggestClass('Duration');
    assertSuggestClass('Error');
    assertSuggestClass('Exception');
    assertSuggestClass('FormatException');
    assertSuggestClass('Function');
    assertSuggestClass('Future');
    assertSuggestClass('Invocation');
    assertSuggestClass('Iterable');
    assertSuggestClass('Iterator');
    assertSuggestClass('List');
    assertSuggestClass('Map');
    assertSuggestClass('MapEntry');
    assertSuggestClass('Null');
    assertSuggestClass('Object');
    assertSuggestClass('Pattern');
    assertSuggestClass('RegExp');
    assertSuggestClass('Set');
    assertSuggestClass('StackTrace');
    assertSuggestClass('Stream');
    assertSuggestClass('String');
  }

  void assertHasNoParameterInfo(CompletionSuggestion suggestion) {
    expect(suggestion.parameterNames, isNull);
    expect(suggestion.parameterTypes, isNull);
    expect(suggestion.requiredParameterCount, isNull);
    expect(suggestion.hasNamedParameters, isNull);
  }

  void assertHasParameterInfo(CompletionSuggestion suggestion) {
    var parameterNames = suggestion.parameterNames!;
    var parameterTypes = suggestion.parameterTypes!;
    expect(parameterNames.length, parameterTypes.length);
    expect(suggestion.requiredParameterCount,
        lessThanOrEqualTo(parameterNames.length));
    expect(suggestion.hasNamedParameters, isNotNull);
  }

  void assertNoSuggestions({CompletionSuggestionKind? kind}) {
    if (kind == null) {
      if (suggestions.isNotEmpty) {
        failedCompletion('Expected no suggestions', suggestions);
      }
      return;
    }
    var suggestion = suggestions
        .firstWhereOrNull((CompletionSuggestion cs) => cs.kind == kind);
    if (suggestion != null) {
      failedCompletion('did not expect completion: $completion\n  $suggestion');
    }
  }

  void assertNotSuggested(String completion, {ElementKind? elemKind}) {
    var suggestion = suggestions.firstWhereOrNull((CompletionSuggestion cs) {
      if (elemKind == null) {
        return cs.completion == completion;
      } else {
        return cs.completion == completion && cs.element!.kind == elemKind;
      }
    });
    if (suggestion != null) {
      failedCompletion('did not expect completion: $completion\n  $suggestion');
    }
  }

  CompletionSuggestion assertSuggest(String completion,
      {CompletionSuggestionKind csKind = CompletionSuggestionKind.INVOCATION,
      ElementKind? elemKind,
      bool isDeprecated = false,
      bool isPotential = false,
      String? elemFile,
      int? elemOffset,
      int? selectionOffset,
      String? paramName,
      String? paramType,
      String? defaultArgListString = _UNCHECKED,
      List<int>? defaultArgumentListTextRanges,
      bool isSynthetic = false,
      bool skipLocationCheck = false}) {
    var cs =
        getSuggest(completion: completion, csKind: csKind, elemKind: elemKind);
    if (cs == null) {
      failedCompletion('expected $completion $csKind $elemKind', suggestions);
    }
    expect(cs.kind, equals(csKind));
    expect(cs.selectionOffset, equals(selectionOffset ?? completion.length));
    expect(cs.selectionLength, equals(0));
    expect(cs.isDeprecated, equals(isDeprecated));
    expect(cs.isPotential, equals(isPotential));
    var element = cs.element;
    if (!isSynthetic && element != null && !skipLocationCheck) {
      var location = element.location!;
      expect(location.file, isNotNull);
      expect(location.offset, isNotNull);
      expect(location.length, isNotNull);
      expect(location.startColumn, isNotNull);
      expect(location.startLine, isNotNull);
    }
    if (elemFile != null) {
      expect(element!.location!.file, convertPath(elemFile));
    }
    if (elemOffset != null) {
      expect(element!.location!.offset, elemOffset);
    }
    if (paramName != null) {
      expect(cs.parameterName, paramName);
    }
    if (paramType != null) {
      expect(cs.parameterType, paramType);
    }
    if (defaultArgListString != _UNCHECKED) {
      expect(cs.defaultArgumentListString, defaultArgListString);
    }
    if (defaultArgumentListTextRanges != null) {
      expect(cs.defaultArgumentListTextRanges, defaultArgumentListTextRanges);
    }
    return cs;
  }

  CompletionSuggestion assertSuggestClass(String name,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.IDENTIFIER,
      bool isDeprecated = false,
      String? elemFile,
      String? elemName,
      int? elemOffset}) {
    var cs = assertSuggest(name,
        csKind: kind,
        isDeprecated: isDeprecated,
        elemFile: elemFile,
        elemKind: ElementKind.CLASS,
        elemOffset: elemOffset);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.CLASS));
    expect(element.name, equals(elemName ?? name));
    expect(element.parameters, isNull);
    expect(element.returnType, isNull);
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestClassTypeAlias(String name,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION}) {
    var cs = assertSuggest(name, csKind: kind);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.CLASS_TYPE_ALIAS));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    expect(element.returnType, isNull);
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestConstructor(String suggestion,
      {String? elementName,
      int? elemOffset,
      String defaultArgListString = _UNCHECKED,
      List<int>? defaultArgumentListTextRanges}) {
    elementName ??= suggestion;
    var cs = assertSuggest(suggestion,
        elemKind: ElementKind.CONSTRUCTOR,
        elemOffset: elemOffset,
        defaultArgListString: defaultArgListString,
        defaultArgumentListTextRanges: defaultArgumentListTextRanges);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.CONSTRUCTOR));
    expect(element.name, elementName);
    return cs;
  }

  CompletionSuggestion assertSuggestEnum(String completion,
      {bool isDeprecated = false}) {
    var suggestion = assertSuggest(
      completion,
      isDeprecated: isDeprecated,
      csKind: CompletionSuggestionKind.IDENTIFIER,
    );
    expect(suggestion.isDeprecated, isDeprecated);
    expect(suggestion.element!.kind, ElementKind.ENUM);
    return suggestion;
  }

  CompletionSuggestion assertSuggestEnumConst(String completion,
      {bool isDeprecated = false}) {
    var suggestion = assertSuggest(completion, isDeprecated: isDeprecated);
    expect(suggestion.completion, completion);
    expect(suggestion.isDeprecated, isDeprecated);
    expect(suggestion.element!.kind, ElementKind.ENUM_CONSTANT);
    return suggestion;
  }

  CompletionSuggestion assertSuggestField(String name, String? type,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
      bool isDeprecated = false}) {
    var cs = assertSuggest(name,
        csKind: kind, elemKind: ElementKind.FIELD, isDeprecated: isDeprecated);
    // The returnType represents the type of a field
    expect(cs.returnType, type ?? 'dynamic');
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.FIELD));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    // The returnType represents the type of a field
    expect(element.returnType, type ?? 'dynamic');
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestFunction(String name, String? returnType,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
      bool isDeprecated = false,
      String? defaultArgListString = _UNCHECKED,
      List<int>? defaultArgumentListTextRanges}) {
    var cs = assertSuggest(name,
        csKind: kind,
        isDeprecated: isDeprecated,
        defaultArgListString: defaultArgListString,
        defaultArgumentListTextRanges: defaultArgumentListTextRanges);
    if (returnType != null) {
      expect(cs.returnType, returnType);
    } else if (isNullExpectedReturnTypeConsideredDynamic) {
      expect(cs.returnType, 'dynamic');
    }
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.FUNCTION));
    expect(element.name, equals(name));
    expect(element.isDeprecated, equals(isDeprecated));
    var param = element.parameters!;
    expect(param[0], equals('('));
    expect(param[param.length - 1], equals(')'));
    if (returnType != null) {
      expect(element.returnType, returnType);
    } else if (isNullExpectedReturnTypeConsideredDynamic) {
      expect(element.returnType, 'dynamic');
    }
    assertHasParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestGetter(String name, String? returnType,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
      bool isDeprecated = false}) {
    var cs = assertSuggest(name,
        csKind: kind, elemKind: ElementKind.GETTER, isDeprecated: isDeprecated);
    expect(cs.returnType, returnType ?? 'dynamic');
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.GETTER));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    expect(element.returnType, equals(returnType ?? 'dynamic'));
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestLocalVariable(
      String name, String? returnType) {
    // Local variables should only be suggested by LocalReferenceContributor
    var cs = assertSuggest(name, csKind: CompletionSuggestionKind.INVOCATION);
    expect(cs.returnType, returnType ?? 'dynamic');
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.LOCAL_VARIABLE));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    expect(element.returnType, returnType ?? 'dynamic');
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestMethod(
      String name, String? declaringType, String? returnType,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
      bool isDeprecated = false,
      String? defaultArgListString = _UNCHECKED,
      List<int>? defaultArgumentListTextRanges,
      bool skipLocationCheck = false}) {
    var cs = assertSuggest(name,
        csKind: kind,
        isDeprecated: isDeprecated,
        defaultArgListString: defaultArgListString,
        defaultArgumentListTextRanges: defaultArgumentListTextRanges,
        skipLocationCheck: skipLocationCheck);
    expect(cs.declaringType, equals(declaringType));
    expect(cs.returnType, returnType ?? 'dynamic');
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.METHOD));
    expect(element.name, equals(name));
    var param = element.parameters!;
    expect(param[0], equals('('));
    expect(param[param.length - 1], equals(')'));
    expect(element.returnType, returnType ?? 'dynamic');
    assertHasParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestMixin(String name,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.IDENTIFIER,
      bool isDeprecated = false,
      String? elemFile,
      String? elemName,
      int? elemOffset}) {
    var cs = assertSuggest(name,
        csKind: kind,
        isDeprecated: isDeprecated,
        elemFile: elemFile,
        elemKind: ElementKind.MIXIN,
        elemOffset: elemOffset);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.MIXIN));
    expect(element.name, equals(elemName ?? name));
    expect(element.parameters, isNull);
    expect(element.returnType, isNull);
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestName(String name,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.IDENTIFIER,
      bool isDeprecated = false}) {
    var cs = assertSuggest(name, csKind: kind, isDeprecated: isDeprecated);
    expect(cs.completion, equals(name));
    expect(cs.element, isNull);
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestParameter(String name, String? returnType) {
    var cs = assertSuggest(name, csKind: CompletionSuggestionKind.INVOCATION);
    expect(cs.returnType, returnType ?? 'dynamic');
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.PARAMETER));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    expect(element.returnType, equals(returnType ?? 'dynamic'));
    return cs;
  }

  CompletionSuggestion assertSuggestSetter(String name,
      {CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION}) {
    var cs = assertSuggest(name, csKind: kind, elemKind: ElementKind.SETTER);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.SETTER));
    expect(element.name, equals(name));
    // TODO (danrubel) assert setter param
    //expect(element.parameters, isNull);
    // TODO (danrubel) it would be better if this was always null
    if (element.returnType != null) {
      expect(element.returnType, 'dynamic');
    }
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestTopLevelVar(
    String name,
    String? returnType, {
    CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
  }) {
    var cs = assertSuggest(name, csKind: kind);
    if (returnType != null) {
      expect(cs.returnType, returnType);
    } else if (isNullExpectedReturnTypeConsideredDynamic) {
      expect(cs.returnType, 'dynamic');
    }
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.TOP_LEVEL_VARIABLE));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    if (returnType != null) {
      expect(element.returnType, returnType);
    } else if (isNullExpectedReturnTypeConsideredDynamic) {
      expect(element.returnType, 'dynamic');
    }
    assertHasNoParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestTypeAlias(
    String name, {
    String? aliasedType,
    String? returnType,
    bool isDeprecated = false,
    CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
  }) {
    var cs = assertSuggest(name, csKind: kind, isDeprecated: isDeprecated);
    if (returnType != null) {
      expect(cs.returnType, returnType);
    } else if (aliasedType != null) {
      // Just to don't fall into the next 'if'.
    } else if (isNullExpectedReturnTypeConsideredDynamic) {
      expect(cs.returnType, 'dynamic');
    } else {
      expect(cs.returnType, isNull);
    }
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.TYPE_ALIAS));
    expect(element.name, equals(name));
    expect(element.isDeprecated, equals(isDeprecated));
    // TODO (danrubel) Determine why params are null
    //    String param = element.parameters;
    //    expect(param, isNotNull);
    //    expect(param[0], equals('('));
    //    expect(param[param.length - 1], equals(')'));
    expect(element.aliasedType, aliasedType);
    expect(element.returnType, returnType);
    // TODO (danrubel) Determine why param info is missing
    //    assertHasParameterInfo(cs);
    return cs;
  }

  CompletionSuggestion assertSuggestTypeParameter(String name) {
    var cs = assertSuggest(name, csKind: CompletionSuggestionKind.IDENTIFIER);
    expect(cs.returnType, isNull);
    var element = cs.element!;
    expect(element.kind, equals(ElementKind.TYPE_PARAMETER));
    expect(element.name, equals(name));
    expect(element.parameters, isNull);
    expect(element.returnType, isNull);
    return cs;
  }

  Future<List<CompletionSuggestion>> computeContributedSuggestions(
      DartCompletionRequest request);

  Future computeSuggestions({int times = 200}) async {
    result = await session.getResolvedUnit(testFile) as ResolvedUnitResult;

    // Build the request
    var request = DartCompletionRequest.forResolvedUnit(
      resolvedUnit: result,
      offset: completionOffset,
      dartdocDirectiveInfo: dartdocInfo,
    );

    var range = request.target.computeReplacementRange(request.offset);
    replacementOffset = range.offset;
    replacementLength = range.length;

    // Request completions
    suggestions = await computeContributedSuggestions(request);
    expect(suggestions, isNotNull, reason: 'expected suggestions');
  }

  Never failedCompletion(String message,
      [Iterable<CompletionSuggestion>? completions]) {
    var sb = StringBuffer(message);
    if (completions != null) {
      sb.write('\n  found');
      completions.toList()
        ..sort(completionComparator)
        ..forEach((CompletionSuggestion suggestion) {
          sb.write('\n    ${suggestion.completion} -> $suggestion');
        });
    }
    fail(sb.toString());
  }

  CompletionSuggestion? getSuggest(
      {String? completion,
      CompletionSuggestionKind? csKind,
      ElementKind? elemKind}) {
    CompletionSuggestion? cs;
    suggestions.forEach((CompletionSuggestion s) {
      if (completion != null && completion != s.completion) {
        return;
      }
      if (csKind != null && csKind != s.kind) {
        return;
      }
      if (elemKind != null) {
        var element = s.element;
        if (element == null || elemKind != element.kind) {
          return;
        }
      }
      if (cs == null) {
        cs = s;
      } else {
        failedCompletion('expected exactly one $cs',
            suggestions.where((s) => s.completion == completion));
      }
    });
    return cs;
  }

  Future<E> performAnalysis<E>(int times, Completer<E> completer) async {
    // Await a microtask. Otherwise the futures are chained and would
    // resolve linearly using up the stack.
    await null;
    if (completer.isCompleted) {
      return completer.future;
    }
    // We use a delayed future to allow microtask events to finish. The
    // Future.value or Future.microtask() constructors use scheduleMicrotask
    // themselves and would therefore not wait for microtask callbacks that
    // are scheduled after invoking this method.
    return Future(() => performAnalysis(times - 1, completer));
  }

  void resolveSource(String path, String content) {
    addSource(path, content);
  }

  @override
  void setUp() {
    super.setUp();
    testFile = convertPath('$testPackageLibPath/test.dart');
  }

  CompletionSuggestion suggestionWith(
      {required String completion,
      ElementKind? element,
      CompletionSuggestionKind? kind}) {
    final matches = suggestions.where(
        suggestionHas(completion: completion, element: element, kind: kind));
    expect(matches, hasLength(1));
    return matches.first;
  }
}