// 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.

library computers;

import 'package:analyzer/src/generated/ast.dart';
import 'package:analyzer/src/generated/element.dart';
import 'package:analyzer/src/generated/scanner.dart';
import 'package:analyzer/src/generated/source.dart';


/**
 * A computer for [HighlightRegion]s in a Dart [CompilationUnit].
 */
class DartUnitHighlightsComputer {
  final CompilationUnit _unit;

  final List<Map<String, Object>> _regions = <Map<String, Object>>[];

  DartUnitHighlightsComputer(this._unit);

  /**
   * Returns the computed highlight regions, not `null`.
   */
  List<Map<String, Object>> compute() {
    _unit.accept(new _DartUnitHighlightsComputerVisitor(this));
    return _regions;
  }

  void _addIdentifierRegion(SimpleIdentifier node) {
    if (_addIdentifierRegion_keyword(node)) {
      return;
    }
    if (_addIdentifierRegion_class(node)) {
      return;
    }
    if (_addIdentifierRegion_constructor(node)) {
      return;
    }
    if (_addIdentifierRegion_dynamicType(node)) {
      return;
    }
    if (_addIdentifierRegion_getterSetterDeclaration(node)) {
      return;
    }
    if (_addIdentifierRegion_field(node)) {
      return;
    }
    if (_addIdentifierRegion_function(node)) {
      return;
    }
    if (_addIdentifierRegion_functionTypeAlias(node)) {
      return;
    }
    if (_addIdentifierRegion_importPrefix(node)) {
      return;
    }
    if (_addIdentifierRegion_localVariable(node)) {
      return;
    }
    if (_addIdentifierRegion_method(node)) {
      return;
    }
    if (_addIdentifierRegion_parameter(node)) {
      return;
    }
    if (_addIdentifierRegion_topLevelVariable(node)) {
      return;
    }
    if (_addIdentifierRegion_typeParameter(node)) {
      return;
    }
    _addRegion_node(node, HighlightType.IDENTIFIER_DEFAULT);
  }

  void _addIdentifierRegion_annotation(Annotation node) {
    ArgumentList arguments = node.arguments;
    if (arguments == null) {
      _addRegion_node(node, HighlightType.ANNOTATION);
    } else {
      _addRegion_nodeStart_tokenEnd(node, arguments.beginToken, HighlightType.ANNOTATION);
      _addRegion_token(arguments.endToken, HighlightType.ANNOTATION);
    }
  }

  bool _addIdentifierRegion_class(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! ClassElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.CLASS);
  }

  bool _addIdentifierRegion_constructor(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! ConstructorElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.CONSTRUCTOR);
  }

  bool _addIdentifierRegion_dynamicType(SimpleIdentifier node) {
    // should be variable
    Element element = node.staticElement;
    if (element is! VariableElement) {
      return false;
    }
    // has propagated type
    if (node.propagatedType != null) {
      return false;
    }
    // has dynamic static type
    DartType staticType = node.staticType;
    if (staticType == null || !staticType.isDynamic) {
      return false;
    }
    // OK
    return _addRegion_node(node, HighlightType.DYNAMIC_TYPE);
  }

  bool _addIdentifierRegion_field(SimpleIdentifier node) {
    Element element = node.bestElement;
    if (element is FieldFormalParameterElement) {
      element = (element as FieldFormalParameterElement).field;
    }
    if (element is FieldElement) {
      if ((element as FieldElement).isStatic) {
        return _addRegion_node(node, HighlightType.FIELD_STATIC);
      } else {
        return _addRegion_node(node, HighlightType.FIELD);
      }
    }
    if (element is PropertyAccessorElement) {
      if ((element as PropertyAccessorElement).isStatic) {
        return _addRegion_node(node, HighlightType.FIELD_STATIC);
      } else {
        return _addRegion_node(node, HighlightType.FIELD);
      }
    }
    return false;
  }

  bool _addIdentifierRegion_function(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! FunctionElement) {
      return false;
    }
    HighlightType type;
    if (node.inDeclarationContext()) {
      type = HighlightType.FUNCTION_DECLARATION;
    } else {
      type = HighlightType.FUNCTION;
    }
    return _addRegion_node(node, type);
  }

  bool _addIdentifierRegion_functionTypeAlias(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! FunctionTypeAliasElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.FUNCTION_TYPE_ALIAS);
  }

  bool _addIdentifierRegion_getterSetterDeclaration(SimpleIdentifier node) {
    // should be declaration
    AstNode parent = node.parent;
    if (!(parent is MethodDeclaration || parent is FunctionDeclaration)) {
      return false;
    }
    // should be property accessor
    Element element = node.staticElement;
    if (element is! PropertyAccessorElement) {
      return false;
    }
    // getter or setter
    PropertyAccessorElement propertyAccessorElement = element as PropertyAccessorElement;
    if (propertyAccessorElement.isGetter) {
      return _addRegion_node(node, HighlightType.GETTER_DECLARATION);
    } else {
      return _addRegion_node(node, HighlightType.SETTER_DECLARATION);
    }
  }

  bool _addIdentifierRegion_importPrefix(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! PrefixElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.IMPORT_PREFIX);
  }

  bool _addIdentifierRegion_keyword(SimpleIdentifier node) {
    String name = node.name;
    if (name == "void") {
      return _addRegion_node(node, HighlightType.KEYWORD);
    }
    return false;
  }

  bool _addIdentifierRegion_localVariable(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! LocalVariableElement) {
      return false;
    }
    // OK
    HighlightType type;
    if (node.inDeclarationContext()) {
      type = HighlightType.LOCAL_VARIABLE_DECLARATION;
    } else {
      type = HighlightType.LOCAL_VARIABLE;
    }
    return _addRegion_node(node, type);
  }

  bool _addIdentifierRegion_method(SimpleIdentifier node) {
    Element element = node.bestElement;
    if (element is! MethodElement) {
      return false;
    }
    MethodElement methodElement = element as MethodElement;
    bool isStatic = methodElement.isStatic;
    // OK
    HighlightType type;
    if (node.inDeclarationContext()) {
      if (isStatic) {
        type = HighlightType.METHOD_DECLARATION_STATIC;
      } else {
        type = HighlightType.METHOD_DECLARATION;
      }
    } else {
      if (isStatic) {
        type = HighlightType.METHOD_STATIC;
      } else {
        type = HighlightType.METHOD;
      }
    }
    return _addRegion_node(node, type);
  }

  bool _addIdentifierRegion_parameter(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! ParameterElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.PARAMETER);
  }

  bool _addIdentifierRegion_topLevelVariable(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! TopLevelVariableElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.TOP_LEVEL_VARIABLE);
  }

  bool _addIdentifierRegion_typeParameter(SimpleIdentifier node) {
    Element element = node.staticElement;
    if (element is! TypeParameterElement) {
      return false;
    }
    return _addRegion_node(node, HighlightType.TYPE_PARAMETER);
  }

  void _addRegion(int offset, int length, HighlightType type) {
    _regions.add({'offset': offset, 'length': length, 'type': type.name});
  }

  bool _addRegion_node(AstNode node, HighlightType type) {
    int offset = node.offset;
    int length = node.length;
    _addRegion(offset, length, type);
    return true;
  }

  void _addRegion_nodeStart_tokenEnd(AstNode a, Token b, HighlightType type) {
    int offset = a.offset;
    int end = b.end;
    _addRegion(offset, end - offset, type);
  }

  void _addRegion_token(Token token, HighlightType type) {
    if (token != null) {
      int offset = token.offset;
      int length = token.length;
      _addRegion(offset, length, type);
    }
  }

  void _addRegion_tokenStart_tokenEnd(Token a, Token b, HighlightType type) {
    int offset = a.offset;
    int end = b.end;
    _addRegion(offset, end - offset, type);
  }
}


/**
 * An AST visitor for [DartUnitHighlightsComputer].
 */
class _DartUnitHighlightsComputerVisitor extends RecursiveAstVisitor<Object> {
  final DartUnitHighlightsComputer computer;

  _DartUnitHighlightsComputerVisitor(this.computer);

  @override
  Object visitAnnotation(Annotation node) {
    computer._addIdentifierRegion_annotation(node);
    return super.visitAnnotation(node);
  }

  @override
  Object visitAsExpression(AsExpression node) {
    computer._addRegion_token(node.asOperator, HighlightType.BUILT_IN);
    return super.visitAsExpression(node);
  }

  @override
  Object visitBooleanLiteral(BooleanLiteral node) {
    computer._addRegion_node(node, HighlightType.LITERAL_BOOLEAN);
    return super.visitBooleanLiteral(node);
  }

  @override
  Object visitCatchClause(CatchClause node) {
    computer._addRegion_token(node.onKeyword, HighlightType.BUILT_IN);
    return super.visitCatchClause(node);
  }

  @override
  Object visitClassDeclaration(ClassDeclaration node) {
    computer._addRegion_token(node.abstractKeyword, HighlightType.BUILT_IN);
    return super.visitClassDeclaration(node);
  }

  @override
  Object visitConstructorDeclaration(ConstructorDeclaration node) {
    computer._addRegion_token(node.externalKeyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.factoryKeyword, HighlightType.BUILT_IN);
    return super.visitConstructorDeclaration(node);
  }

  @override
  Object visitDoubleLiteral(DoubleLiteral node) {
    computer._addRegion_node(node, HighlightType.LITERAL_DOUBLE);
    return super.visitDoubleLiteral(node);
  }

  @override
  Object visitExportDirective(ExportDirective node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitExportDirective(node);
  }

  @override
  Object visitFieldDeclaration(FieldDeclaration node) {
    computer._addRegion_token(node.staticKeyword, HighlightType.BUILT_IN);
    return super.visitFieldDeclaration(node);
  }

  @override
  Object visitFunctionDeclaration(FunctionDeclaration node) {
    computer._addRegion_token(node.externalKeyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.propertyKeyword, HighlightType.BUILT_IN);
    return super.visitFunctionDeclaration(node);
  }

  @override
  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitFunctionTypeAlias(node);
  }

  @override
  Object visitHideCombinator(HideCombinator node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitHideCombinator(node);
  }

  @override
  Object visitImplementsClause(ImplementsClause node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitImplementsClause(node);
  }

  @override
  Object visitImportDirective(ImportDirective node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.deferredToken, HighlightType.BUILT_IN);
    computer._addRegion_token(node.asToken, HighlightType.BUILT_IN);
    return super.visitImportDirective(node);
  }

  @override
  Object visitIntegerLiteral(IntegerLiteral node) {
    computer._addRegion_node(node, HighlightType.LITERAL_INTEGER);
    return super.visitIntegerLiteral(node);
  }

  @override
  Object visitLibraryDirective(LibraryDirective node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitLibraryDirective(node);
  }

  @override
  Object visitMethodDeclaration(MethodDeclaration node) {
    computer._addRegion_token(node.externalKeyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.modifierKeyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.operatorKeyword, HighlightType.BUILT_IN);
    computer._addRegion_token(node.propertyKeyword, HighlightType.BUILT_IN);
    return super.visitMethodDeclaration(node);
  }

  @override
  Object visitNativeClause(NativeClause node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitNativeClause(node);
  }

  @override
  Object visitNativeFunctionBody(NativeFunctionBody node) {
    computer._addRegion_token(node.nativeToken, HighlightType.BUILT_IN);
    return super.visitNativeFunctionBody(node);
  }

  @override
  Object visitPartDirective(PartDirective node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitPartDirective(node);
  }

  @override
  Object visitPartOfDirective(PartOfDirective node) {
    computer._addRegion_tokenStart_tokenEnd(node.partToken, node.ofToken, HighlightType.BUILT_IN);
    return super.visitPartOfDirective(node);
  }

  @override
  Object visitShowCombinator(ShowCombinator node) {
    computer._addRegion_token(node.keyword, HighlightType.BUILT_IN);
    return super.visitShowCombinator(node);
  }

  @override
  Object visitSimpleIdentifier(SimpleIdentifier node) {
    computer._addIdentifierRegion(node);
    return super.visitSimpleIdentifier(node);
  }

  @override
  Object visitSimpleStringLiteral(SimpleStringLiteral node) {
    computer._addRegion_node(node, HighlightType.LITERAL_STRING);
    return super.visitSimpleStringLiteral(node);
  }

  @override
  Object visitTypeName(TypeName node) {
    DartType type = node.type;
    if (type != null) {
      if (type.isDynamic && node.name.name == "dynamic") {
        computer._addRegion_node(node, HighlightType.TYPE_NAME_DYNAMIC);
        return null;
      }
    }
    return super.visitTypeName(node);
  }
}


/**
 * Highlighting kinds constants.
 */
class HighlightType {
  static const HighlightType ANNOTATION = const HighlightType('ANNOTATION');
  static const HighlightType BUILT_IN = const HighlightType('BUILT_IN');
  static const HighlightType CLASS = const HighlightType('CLASS');
  static const HighlightType COMMENT_BLOCK = const HighlightType('COMMENT_BLOCK');
  static const HighlightType COMMENT_DOCUMENTATION = const HighlightType('COMMENT_DOCUMENTATION');
  static const HighlightType COMMENT_END_OF_LINE = const HighlightType('COMMENT_END_OF_LINE');
  static const HighlightType CONSTRUCTOR = const HighlightType('CONSTRUCTOR');
  static const HighlightType DIRECTIVE = const HighlightType('DIRECTIVE');
  static const HighlightType DYNAMIC_TYPE = const HighlightType('DYNAMIC_TYPE');
  static const HighlightType FIELD = const HighlightType('FIELD');
  static const HighlightType FIELD_STATIC = const HighlightType('FIELD_STATIC');
  static const HighlightType FUNCTION_DECLARATION = const HighlightType('FUNCTION_DECLARATION');
  static const HighlightType FUNCTION = const HighlightType('FUNCTION');
  static const HighlightType FUNCTION_TYPE_ALIAS = const HighlightType('FUNCTION_TYPE_ALIAS');
  static const HighlightType GETTER_DECLARATION = const HighlightType('GETTER_DECLARATION');
  static const HighlightType KEYWORD = const HighlightType('KEYWORD');
  static const HighlightType IDENTIFIER_DEFAULT = const HighlightType('IDENTIFIER_DEFAULT');
  static const HighlightType IMPORT_PREFIX = const HighlightType('IMPORT_PREFIX');
  static const HighlightType LITERAL_BOOLEAN = const HighlightType('LITERAL_BOOLEAN');
  static const HighlightType LITERAL_DOUBLE = const HighlightType('LITERAL_DOUBLE');
  static const HighlightType LITERAL_INTEGER = const HighlightType('LITERAL_INTEGER');
  static const HighlightType LITERAL_LIST = const HighlightType('LITERAL_LIST');
  static const HighlightType LITERAL_MAP = const HighlightType('LITERAL_MAP');
  static const HighlightType LITERAL_STRING = const HighlightType('LITERAL_STRING');
  static const HighlightType LOCAL_VARIABLE_DECLARATION = const HighlightType('LOCAL_VARIABLE_DECLARATION');
  static const HighlightType LOCAL_VARIABLE = const HighlightType('LOCAL_VARIABLE');
  static const HighlightType METHOD_DECLARATION = const HighlightType('METHOD_DECLARATION');
  static const HighlightType METHOD_DECLARATION_STATIC = const HighlightType('METHOD_DECLARATION_STATIC');
  static const HighlightType METHOD = const HighlightType('METHOD');
  static const HighlightType METHOD_STATIC = const HighlightType('METHOD_STATIC');
  static const HighlightType PARAMETER = const HighlightType('PARAMETER');
  static const HighlightType SETTER_DECLARATION = const HighlightType('SETTER_DECLARATION');
  static const HighlightType TOP_LEVEL_VARIABLE = const HighlightType('TOP_LEVEL_VARIABLE');
  static const HighlightType TYPE_NAME_DYNAMIC = const HighlightType('TYPE_NAME_DYNAMIC');
  static const HighlightType TYPE_PARAMETER = const HighlightType('TYPE_PARAMETER');

  final String name;

  @override
  String toString() => name;

  const HighlightType(this.name);
}


/**
 * A computer for navigation regions in a Dart [CompilationUnit].
 */
class DartUnitNavigationComputer {
  final CompilationUnit _unit;

  List<Map<String, Object>> _regions = [];

  DartUnitNavigationComputer(this._unit);

  /**
   * Returns the computed navigation regions, not `null`.
   */
  List<Map<String, Object>> compute() {
    _unit.accept(new _DartUnitNavigationComputerVisitor(this));
    return new List.from(_regions);
  }

  void _addRegion(int offset, int length, Element element) {
    Map<String, Object> target = _createTarget(element);
    if (target == null) {
      return;
    }
    _regions.add({
      'offset': offset,
      'length': length,
      'targets': [target]
    });
  }

  void _addRegion_nodeStart_nodeEnd(AstNode a, AstNode b, Element element) {
    int offset = a.offset;
    int length = b.end - offset;
    _addRegion(offset, length, element);
  }

  void _addRegion_nodeStart_nodeStart(AstNode a, AstNode b, Element element) {
    int offset = a.offset;
    int length = b.offset - offset;
    _addRegion(offset, length, element);
  }

  void _addRegion_tokenStart_nodeEnd(Token a, AstNode b, Element element) {
    int offset = a.offset;
    int length = b.end - offset;
    _addRegion(offset, length, element);
  }

  void _addRegionForNode(AstNode node, Element element) {
    int offset = node.offset;
    int length = node.length;
    _addRegion(offset, length, element);
  }

  void _addRegionForToken(Token token, Element element) {
    int offset = token.offset;
    int length = token.length;
    _addRegion(offset, length, element);
  }

  /**
   * Returns the JSON for the given [Element], maybe `null` if `null` was given.
   */
  Map<String, Object> _createTarget(Element element) {
    if (element == null) {
      return null;
    }
    if (element is FieldFormalParameterElement) {
      element = (element as FieldFormalParameterElement).field;
    }
    // prepare Source
    Source source = element.source;
    if (source == null) {
      return null;
    }
    // prepare location
    int offset = element.nameOffset;
    int length = element.displayName.length;
    if (element is CompilationUnitElement) {
      offset = 0;
      length = 0;
    }
    // return as JSON
    return {
      'file': source.fullName,
      'offset': offset,
      'length': length,
      'elementId': element.location.encoding
    };
  }
}


class _DartUnitNavigationComputerVisitor extends RecursiveAstVisitor {
  final DartUnitNavigationComputer computer;

  _DartUnitNavigationComputerVisitor(this.computer);

  @override
  visitAssignmentExpression(AssignmentExpression node) {
    computer._addRegionForToken(node.operator, node.bestElement);
    return super.visitAssignmentExpression(node);
  }

  @override
  visitBinaryExpression(BinaryExpression node) {
    computer._addRegionForToken(node.operator, node.bestElement);
    return super.visitBinaryExpression(node);
  }

  @override
  visitConstructorDeclaration(ConstructorDeclaration node) {
    // associate constructor with "T" or "T.name"
    {
      AstNode firstNode = node.returnType;
      AstNode lastNode = node.name;
      if (lastNode == null) {
        lastNode = firstNode;
      }
      if (firstNode != null && lastNode != null) {
        computer._addRegion_nodeStart_nodeEnd(firstNode, lastNode, node.element);
      }
    }
    return super.visitConstructorDeclaration(node);
  }

  @override
  visitExportDirective(ExportDirective node) {
    ExportElement exportElement = node.element;
    if (exportElement != null) {
      Element element = exportElement.exportedLibrary;
      computer._addRegion_tokenStart_nodeEnd(node.keyword, node.uri, element);
    }
    return super.visitExportDirective(node);
  }

  @override
  visitImportDirective(ImportDirective node) {
    ImportElement importElement = node.element;
    if (importElement != null) {
      Element element = importElement.importedLibrary;
      computer._addRegion_tokenStart_nodeEnd(node.keyword, node.uri, element);
    }
    return super.visitImportDirective(node);
  }

  @override
  visitIndexExpression(IndexExpression node) {
    computer._addRegionForToken(node.rightBracket, node.bestElement);
    return super.visitIndexExpression(node);
  }

  @override
  visitInstanceCreationExpression(InstanceCreationExpression node) {
    computer._addRegion_nodeStart_nodeStart(node, node.argumentList, node.staticElement);
    return super.visitInstanceCreationExpression(node);
  }

  @override
  visitPartDirective(PartDirective node) {
    computer._addRegion_tokenStart_nodeEnd(node.keyword, node.uri, node.element);
    return super.visitPartDirective(node);
  }

  @override
  visitPartOfDirective(PartOfDirective node) {
    computer._addRegion_tokenStart_nodeEnd(node.keyword, node.libraryName, node.element);
    return super.visitPartOfDirective(node);
  }

  @override
  visitPostfixExpression(PostfixExpression node) {
    computer._addRegionForToken(node.operator, node.bestElement);
    return super.visitPostfixExpression(node);
  }

  @override
  visitPrefixExpression(PrefixExpression node) {
    computer._addRegionForToken(node.operator, node.bestElement);
    return super.visitPrefixExpression(node);
  }

  @override
  visitSimpleIdentifier(SimpleIdentifier node) {
    if (node.parent is ConstructorDeclaration) {
    } else {
      computer._addRegionForNode(node, node.bestElement);
    }
    return super.visitSimpleIdentifier(node);
  }
}