// 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:analysis_server/src/services/correction/strings.dart';
import 'package:analyzer/dart/analysis/results.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/dart/element/type.dart';
import 'package:analyzer/src/generated/source.dart';
import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';

class Flutter {
  static const _nameCenter = 'Center';
  static const _nameContainer = 'Container';
  static const _namePadding = 'Padding';
  static const _nameState = 'State';
  static const _nameStatefulWidget = 'StatefulWidget';
  static const _nameStatelessWidget = 'StatelessWidget';
  static const _nameStreamBuilder = 'StreamBuilder';
  static const _nameWidget = 'Widget';

  static final mobile = Flutter._('flutter', 'package:flutter');
  static final web = Flutter._('flutter_web', 'package:flutter_web');

  static final _uriFlutterMobileWidgets =
      Uri.parse('package:flutter/widgets.dart');

  static final _uriFlutterWebWidgets =
      Uri.parse('package:flutter_web/widgets.dart');

  final String packageName;
  final String widgetsUri;

  final Uri _uriAsync;
  final Uri _uriBasic;
  final Uri _uriContainer;
  final Uri _uriFramework;
  final Uri _uriWidgetsIcon;
  final Uri _uriWidgetsText;

  factory Flutter.of(ResolvedUnitResult resolvedUnit) {
    var uriConverter = resolvedUnit.session.uriConverter;
    var isMobile = uriConverter.uriToPath(_uriFlutterMobileWidgets) != null;
    var isWeb = uriConverter.uriToPath(_uriFlutterWebWidgets) != null;

    if (isMobile && isWeb) {
      var visitor = _IdentifyMobileOrWeb();
      resolvedUnit.unit.accept(visitor);
      isMobile = visitor.isMobile;
      isWeb = visitor.isWeb;
    }

    if (isMobile) {
      return mobile;
    }

    if (isWeb) {
      return web;
    }

    return mobile;
  }

  Flutter._(this.packageName, String uriPrefix)
      : widgetsUri = '$uriPrefix/widgets.dart',
        _uriAsync = Uri.parse('$uriPrefix/src/widgets/async.dart'),
        _uriBasic = Uri.parse('$uriPrefix/src/widgets/basic.dart'),
        _uriContainer = Uri.parse('$uriPrefix/src/widgets/container.dart'),
        _uriFramework = Uri.parse('$uriPrefix/src/widgets/framework.dart'),
        _uriWidgetsIcon = Uri.parse('$uriPrefix/src/widgets/icon.dart'),
        _uriWidgetsText = Uri.parse('$uriPrefix/src/widgets/text.dart');

  void convertChildToChildren(
      InstanceCreationExpression childArg,
      NamedExpression namedExp,
      String eol,
      Function getNodeText,
      Function getLinePrefix,
      Function getIndent,
      Function getText,
      Function _addInsertEdit,
      Function _addRemoveEdit,
      Function _addReplaceEdit,
      Function rangeNode) {
    int childLoc = namedExp.offset + 'child'.length;
    _addInsertEdit(childLoc, 'ren');
    int listLoc = childArg.offset;
    String childArgSrc = getNodeText(childArg);
    if (!childArgSrc.contains(eol)) {
      _addInsertEdit(listLoc, '<Widget>[');
      _addInsertEdit(listLoc + childArg.length, ']');
    } else {
      int newlineLoc = childArgSrc.lastIndexOf(eol);
      if (newlineLoc == childArgSrc.length) {
        newlineLoc -= 1;
      }
      String indentOld = getLinePrefix(childArg.offset + 1 + newlineLoc);
      String indentNew = '$indentOld${getIndent(1)}';
      // The separator includes 'child:' but that has no newlines.
      String separator =
          getText(namedExp.offset, childArg.offset - namedExp.offset);
      String prefix = separator.contains(eol) ? "" : "$eol$indentNew";
      if (prefix.isEmpty) {
        _addInsertEdit(namedExp.offset + 'child:'.length, ' <Widget>[');
        _addRemoveEdit(new SourceRange(childArg.offset - 2, 2));
      } else {
        _addInsertEdit(listLoc, '<Widget>[');
      }
      String newChildArgSrc = childArgSrc.replaceAll(
          new RegExp("^$indentOld", multiLine: true), "$indentNew");
      newChildArgSrc = "$prefix$newChildArgSrc,$eol$indentOld]";
      _addReplaceEdit(rangeNode(childArg), newChildArgSrc);
    }
  }

  void convertChildToChildren2(
      DartFileEditBuilder builder,
      Expression childArg,
      NamedExpression namedExp,
      String eol,
      Function getNodeText,
      Function getLinePrefix,
      Function getIndent,
      Function getText,
      Function rangeNode) {
    int childLoc = namedExp.offset + 'child'.length;
    builder.addSimpleInsertion(childLoc, 'ren');
    int listLoc = childArg.offset;
    String childArgSrc = getNodeText(childArg);
    if (!childArgSrc.contains(eol)) {
      builder.addSimpleInsertion(listLoc, '<Widget>[');
      builder.addSimpleInsertion(listLoc + childArg.length, ']');
    } else {
      int newlineLoc = childArgSrc.lastIndexOf(eol);
      if (newlineLoc == childArgSrc.length) {
        newlineLoc -= 1;
      }
      String indentOld = getLinePrefix(childArg.offset + 1 + newlineLoc);
      String indentNew = '$indentOld${getIndent(1)}';
      // The separator includes 'child:' but that has no newlines.
      String separator =
          getText(namedExp.offset, childArg.offset - namedExp.offset);
      String prefix = separator.contains(eol) ? "" : "$eol$indentNew";
      if (prefix.isEmpty) {
        builder.addSimpleInsertion(
            namedExp.offset + 'child:'.length, ' <Widget>[');
        builder.addDeletion(new SourceRange(childArg.offset - 2, 2));
      } else {
        builder.addSimpleInsertion(listLoc, '<Widget>[');
      }
      String newChildArgSrc = childArgSrc.replaceAll(
          new RegExp("^$indentOld", multiLine: true), "$indentNew");
      newChildArgSrc = "$prefix$newChildArgSrc,$eol$indentOld]";
      builder.addSimpleReplacement(rangeNode(childArg), newChildArgSrc);
    }
  }

  /**
   * Return the named expression representing the `child` argument of the given
   * [newExpr], or `null` if none.
   */
  NamedExpression findChildArgument(InstanceCreationExpression newExpr) =>
      newExpr.argumentList.arguments
          .firstWhere(isChildArgument, orElse: () => null);

  /**
   * Return the named expression representing the `children` argument of the
   * given [newExpr], or `null` if none.
   */
  NamedExpression findChildrenArgument(InstanceCreationExpression newExpr) =>
      newExpr.argumentList.arguments
          .firstWhere(isChildrenArgument, orElse: () => null);

  /**
   * Return the Flutter instance creation expression that is the value of the
   * 'child' argument of the given [newExpr], or null if none.
   */
  InstanceCreationExpression findChildWidget(
      InstanceCreationExpression newExpr) {
    NamedExpression child = findChildArgument(newExpr);
    return getChildWidget(child);
  }

  /**
   * If the given [node] is a simple identifier, find the named expression whose
   * name is the given [name] that is an argument to a Flutter instance creation
   * expression. Return null if any condition cannot be satisfied.
   */
  NamedExpression findNamedExpression(AstNode node, String name) {
    if (node is! SimpleIdentifier) {
      return null;
    }
    SimpleIdentifier namedArg = node;
    NamedExpression namedExp;
    if (namedArg.parent is Label && namedArg.parent.parent is NamedExpression) {
      namedExp = namedArg.parent.parent;
      if (namedArg.name != name || namedExp.expression == null) {
        return null;
      }
    } else {
      return null;
    }
    if (namedExp.parent?.parent is! InstanceCreationExpression) {
      return null;
    }
    InstanceCreationExpression newExpr = namedExp.parent.parent;
    if (newExpr == null || !isWidgetCreation(newExpr)) {
      return null;
    }
    return namedExp;
  }

  /**
   * Return the expression that is a Flutter Widget that is the value of the
   * given [child], or null if none.
   */
  Expression getChildWidget(NamedExpression child) {
    Expression expression = child?.expression;
    if (isWidgetExpression(expression)) {
      return expression;
    }
    return null;
  }

  /**
   * Return the presentation for the given Flutter `Widget` creation [node].
   */
  String getWidgetPresentationText(InstanceCreationExpression node) {
    ClassElement element = node.staticElement?.enclosingElement;
    if (!isWidget(element)) {
      return null;
    }
    List<Expression> arguments = node.argumentList.arguments;
    if (_isExactWidget(element, 'Icon', _uriWidgetsIcon)) {
      if (arguments.isNotEmpty) {
        String text = arguments[0].toString();
        String arg = shorten(text, 32);
        return 'Icon($arg)';
      } else {
        return 'Icon';
      }
    }
    if (_isExactWidget(element, 'Text', _uriWidgetsText)) {
      if (arguments.isNotEmpty) {
        String text = arguments[0].toString();
        String arg = shorten(text, 32);
        return 'Text($arg)';
      } else {
        return 'Text';
      }
    }
    return element.name;
  }

  /**
   * Return the instance creation expression that surrounds the given
   * [node], if any, else null. The [node] may be the instance creation
   * expression itself or the identifier that names the constructor.
   */
  InstanceCreationExpression identifyNewExpression(AstNode node) {
    InstanceCreationExpression newExpr;
    if (node is SimpleIdentifier) {
      if (node.parent is ConstructorName &&
          node.parent.parent is InstanceCreationExpression) {
        newExpr = node.parent.parent;
      } else if (node.parent?.parent is ConstructorName &&
          node.parent.parent?.parent is InstanceCreationExpression) {
        newExpr = node.parent.parent.parent;
      }
    } else if (node is InstanceCreationExpression) {
      newExpr = node;
    }
    return newExpr;
  }

  /**
   * Attempt to find and return the closest expression that encloses the [node]
   * and is an independent Flutter `Widget`.  Return `null` if nothing found.
   */
  Expression identifyWidgetExpression(AstNode node) {
    for (; node != null; node = node.parent) {
      if (isWidgetExpression(node)) {
        var parent = node.parent;
        if (parent is ArgumentList ||
            parent is ExpressionFunctionBody && parent.expression == node ||
            parent is ListLiteral ||
            parent is NamedExpression && parent.expression == node ||
            parent is Statement) {
          return node;
        }
      }
      if (node is ArgumentList || node is Statement || node is FunctionBody) {
        return null;
      }
    }
    return null;
  }

  /**
   * Return `true` is the given [argument] is the `child` argument.
   */
  bool isChildArgument(Expression argument) =>
      argument is NamedExpression && argument.name.label.name == 'child';

  /**
   * Return `true` is the given [argument] is the `child` argument.
   */
  bool isChildrenArgument(Expression argument) =>
      argument is NamedExpression && argument.name.label.name == 'children';

  /**
   * Return `true` if the given [type] is the Flutter class `StatefulWidget`.
   */
  bool isExactlyStatefulWidgetType(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _nameStatefulWidget, _uriFramework);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `StatelessWidget`.
   */
  bool isExactlyStatelessWidgetType(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _nameStatelessWidget, _uriFramework);
  }

  /// Return `true` if the given [element] is the Flutter class `State`.
  bool isExactState(ClassElement element) {
    return _isExactWidget(element, _nameState, _uriFramework);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `Center`.
   */
  bool isExactWidgetTypeCenter(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _nameCenter, _uriBasic);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `Container`.
   */
  bool isExactWidgetTypeContainer(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _nameContainer, _uriContainer);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `Padding`.
   */
  bool isExactWidgetTypePadding(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _namePadding, _uriBasic);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `StreamBuilder`.
   */
  bool isExactWidgetTypeStreamBuilder(DartType type) {
    return type is InterfaceType &&
        _isExactWidget(type.element, _nameStreamBuilder, _uriAsync);
  }

  /**
   * Return `true` if the given [type] is the Flutter class `Widget`, or its
   * subtype.
   */
  bool isListOfWidgetsType(DartType type) {
    return type is InterfaceType &&
        type.element.library.isDartCore &&
        type.element.name == 'List' &&
        type.typeArguments.length == 1 &&
        isWidgetType(type.typeArguments[0]);
  }

  /// Return `true` if the given [element] has the Flutter class `State` as
  /// a superclass.
  bool isState(ClassElement element) {
    return _hasSupertype(element, _uriFramework, _nameState);
  }

  /**
   * Return `true` if the given [element] is a [ClassElement] that extends
   * the Flutter class `StatefulWidget`.
   */
  bool isStatefulWidgetDeclaration(Element element) {
    if (element is ClassElement) {
      return isExactlyStatefulWidgetType(element.supertype);
    }
    return false;
  }

  /**
   * Return `true` if the given [element] is the Flutter class `Widget`, or its
   * subtype.
   */
  bool isWidget(ClassElement element) {
    if (element == null) {
      return false;
    }
    if (_isExactWidget(element, _nameWidget, _uriFramework)) {
      return true;
    }
    for (InterfaceType type in element.allSupertypes) {
      if (_isExactWidget(type.element, _nameWidget, _uriFramework)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Return `true` if the given [expr] is a constructor invocation for a
   * class that has the Flutter class `Widget` as a superclass.
   */
  bool isWidgetCreation(InstanceCreationExpression expr) {
    ClassElement element = expr?.staticElement?.enclosingElement;
    return isWidget(element);
  }

  /**
   * Return `true` if the given [node] is the Flutter class `Widget`, or its
   * subtype.
   */
  bool isWidgetExpression(AstNode node) {
    if (node == null) {
      return false;
    }
    if (node.parent is TypeName || node.parent?.parent is TypeName) {
      return false;
    }
    if (node.parent is ConstructorName) {
      return false;
    }
    if (node is NamedExpression) {
      return false;
    }
    if (node is Expression) {
      return isWidgetType(node.staticType);
    }
    return false;
  }

  /**
   * Return `true` if the given [type] is the Flutter class `Widget`, or its
   * subtype.
   */
  bool isWidgetType(DartType type) {
    return type is InterfaceType && isWidget(type.element);
  }

  /// Return `true` if the given [element] has a supertype with the [requiredName]
  /// defined in the file with the [requiredUri].
  bool _hasSupertype(
      ClassElement element, Uri requiredUri, String requiredName) {
    if (element == null) {
      return false;
    }
    for (InterfaceType type in element.allSupertypes) {
      if (type.name == requiredName) {
        Uri uri = type.element.source.uri;
        if (uri == requiredUri) {
          return true;
        }
      }
    }
    return false;
  }

  /**
   * Return `true` if the given [element] is the exact [type] defined in the
   * file with the given [uri].
   */
  bool _isExactWidget(ClassElement element, String type, Uri uri) {
    return element != null && element.name == type && element.source.uri == uri;
  }
}

class _IdentifyMobileOrWeb extends GeneralizingAstVisitor<void> {
  bool isMobile = false;
  bool isWeb = false;

  @override
  void visitExpression(Expression node) {
    if (isMobile || isWeb) {
      return;
    }

    if (Flutter.mobile.isWidgetExpression(node)) {
      isMobile = true;
      return;
    }

    if (Flutter.web.isWidgetExpression(node)) {
      isWeb = true;
      return;
    }

    super.visitExpression(node);
  }
}