Untitled

import 'dart:html';

import 'package:meta/dart2js.dart' as dart2js;

import 'optimizations.dart' show isDevMode;

/// A location in the DOM where CSS-styles are inserted for an application.
///
/// Often this is in `<head>`, but it could be in a different location in
/// test environments where the styles get cleared after every test case.
///
/// This class should not be implemented, extended, or mixed-in.
class CssStyleHost {
  /// Application-level shared style host to shim CSS styles for components.
  ///
  /// By default this is `<head>`, but may be configured in test environments.
  static CssStyleHost sharedHost = CssStyleHost(document.head);

  final HtmlElement _host;
  final Expando<bool> _visited = new Expando();

  CssStyleHost(this._host);

  /// Appends [cssStyles] within this host.
  @dart2js.noInline
  void append(ComponentStyles cssStyles) {
    if (_visited[cssStyles] == null) {
      final sheet = StyleElement()..text = cssStyles._templateStyles;
      if (isDevMode) {
        sheet.setAttribute('from', cssStyles._templateUrl);
      }
      _host.append(sheet);
      _visited[cssStyles] = true;
    }
  }
}

/// Encapsulates the CSS styles configured for a given component.
///
/// This class should not be implemented, extended, or mixed-in in user code.
class ComponentStyles {
  /// Matches the component ID placeholder in encapsulating CSS classes.
  static final RegExp _idPlaceholder = RegExp(r'%ID%');

  final String _templateUrl;
  final String _templateStyles;

  ComponentStyles(
    String uniqueId,
    String templateStyles,
    this._templateUrl,
  ) : _templateStyles = templateStyles.replaceAll(_idPlaceholder, uniqueId);

  factory ComponentStyles.withEncapsulation(
    String uniqueId,
    String templateStyles,
    String templateUrl,
  ) = _EncapsulatedComponentStyles;

  /// Adds content CSS shim classes to a known HTML [element].
  void addContentShimC(HtmlElement element) => element;

  /// Adds content CSS shim classes to an unknown or SVG [element].
  void addContentShimE(Element element) => element;

  /// Adds host CSS shim classes to the root element of a component.
  void addHostShim(HtmlElement element) => element;

  /// Adds a [newClass] to [element], shimming as necessary.
  void addContentClassShimmed(Element element, String newClass) {}

  /// Adds a [newClass] to [element], shimming as necessary.
  void addHostClassShimmed(Element element, String newClass) {}
}

class _EncapsulatedComponentStyles extends ComponentStyles {
  static const _contentClassPrefix = '_ngcontent-';
  static const _hostClassPrefix = '_nghost-';

  final String _contentClass;
  final String _hostClass;

  _EncapsulatedComponentStyles(
    String uniqueId,
    String templateStyles,
    String templateUrl,
  ) :   _contentClass = '$_contentClassPrefix$uniqueId',
        _hostClass = '$_hostClassPrefix$uniqueId',
        super(
          uniqueId,
          templateStyles,
          templateUrl,
        );

  @override
  void addContentShimC(HtmlElement element) {
    element.classes.add(_contentClass);
  }

  @override
  void addContentShimE(Element element) {
    element.classes.add(_contentClass);
  }

  @override
  void addHostShim(HtmlElement element) {
    element.classes.add(_hostClass);
  }

  @override
  void addContentClassShimmed(Element element, String newClass) {
    element.className = '$newClass $_contentClass';
  }

  @override
  void addHostClassShimmed(Element element, String newClass) {
    element.className = '$newClass $_hostClass';
  }
}