// 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.

// TODO(jmesserly): everything in this file is copied straight from "dart:html".
library html.dom.src;

import 'dart:collection';

import 'package:html/dom.dart';

class ElementCssClassSet extends _CssClassSetImpl {
  final Element _element;

  ElementCssClassSet(this._element);

  Set<String> readClasses() {
    var s = new LinkedHashSet<String>();
    var classname = _element.className;

    for (String name in classname.split(' ')) {
      String trimmed = name.trim();
      if (trimmed.isNotEmpty) {
        s.add(trimmed);
      }
    }
    return s;
  }

  void writeClasses(Set<String> s) {
    _element.className = s.join(' ');
  }
}

/** A Set that stores the CSS class names for an element. */
abstract class CssClassSet implements Set<String> {
  /**
   * Adds the class [value] to the element if it is not on it, removes it if it
   * is.
   *
   * If [shouldAdd] is true, then we always add that [value] to the element. If
   * [shouldAdd] is false then we always remove [value] from the element.
   */
  bool toggle(String value, [bool shouldAdd]);

  /**
   * Returns [:true:] if classes cannot be added or removed from this
   * [:CssClassSet:].
   */
  bool get frozen;

  /**
   * Determine if this element contains the class [value].
   *
   * This is the Dart equivalent of jQuery's
   * [hasClass](http://api.jquery.com/hasClass/).
   */
  bool contains(Object value);

  /**
   * Add the class [value] to element.
   *
   * This is the Dart equivalent of jQuery's
   * [addClass](http://api.jquery.com/addClass/).
   *
   * If this corresponds to one element. Returns true if [value] was added to
   * the set, otherwise false.
   *
   * If this corresponds to many elements, null is always returned.
   */
  bool add(String value);

  /**
   * Remove the class [value] from element, and return true on successful
   * removal.
   *
   * This is the Dart equivalent of jQuery's
   * [removeClass](http://api.jquery.com/removeClass/).
   */
  bool remove(Object value);

  /**
   * Add all classes specified in [iterable] to element.
   *
   * This is the Dart equivalent of jQuery's
   * [addClass](http://api.jquery.com/addClass/).
   */
  void addAll(Iterable<String> iterable);

  /**
   * Remove all classes specified in [iterable] from element.
   *
   * This is the Dart equivalent of jQuery's
   * [removeClass](http://api.jquery.com/removeClass/).
   */
  void removeAll(Iterable<Object> iterable);

  /**
   * Toggles all classes specified in [iterable] on element.
   *
   * Iterate through [iterable]'s items, and add it if it is not on it, or
   * remove it if it is. This is the Dart equivalent of jQuery's
   * [toggleClass](http://api.jquery.com/toggleClass/).
   * If [shouldAdd] is true, then we always add all the classes in [iterable]
   * element. If [shouldAdd] is false then we always remove all the classes in
   * [iterable] from the element.
   */
  void toggleAll(Iterable<String> iterable, [bool shouldAdd]);
}

abstract class _CssClassSetImpl extends SetBase<String> implements CssClassSet {
  String toString() {
    return readClasses().join(' ');
  }

  /**
   * Adds the class [value] to the element if it is not on it, removes it if it
   * is.
   *
   * If [shouldAdd] is true, then we always add that [value] to the element. If
   * [shouldAdd] is false then we always remove [value] from the element.
   */
  bool toggle(String value, [bool shouldAdd]) {
    Set<String> s = readClasses();
    bool result = false;
    if (shouldAdd == null) shouldAdd = !s.contains(value);
    if (shouldAdd) {
      s.add(value);
      result = true;
    } else {
      s.remove(value);
    }
    writeClasses(s);
    return result;
  }

  /**
   * Returns [:true:] if classes cannot be added or removed from this
   * [:CssClassSet:].
   */
  bool get frozen => false;

  Iterator<String> get iterator => readClasses().iterator;

  int get length => readClasses().length;

  // interface Set - BEGIN
  /**
   * Determine if this element contains the class [value].
   *
   * This is the Dart equivalent of jQuery's
   * [hasClass](http://api.jquery.com/hasClass/).
   */
  bool contains(Object value) => readClasses().contains(value);

  /** Lookup from the Set interface. Not interesting for a String set. */
  String lookup(Object value) => contains(value) ? value as String : null;

  Set<String> toSet() => readClasses().toSet();

  /**
   * Add the class [value] to element.
   *
   * This is the Dart equivalent of jQuery's
   * [addClass](http://api.jquery.com/addClass/).
   */
  bool add(String value) {
    // TODO - figure out if we need to do any validation here
    // or if the browser natively does enough.
    return _modify((s) => s.add(value));
  }

  /**
   * Remove the class [value] from element, and return true on successful
   * removal.
   *
   * This is the Dart equivalent of jQuery's
   * [removeClass](http://api.jquery.com/removeClass/).
   */
  bool remove(Object value) {
    if (value is! String) return false;
    Set<String> s = readClasses();
    bool result = s.remove(value);
    writeClasses(s);
    return result;
  }

  /**
   * Toggles all classes specified in [iterable] on element.
   *
   * Iterate through [iterable]'s items, and add it if it is not on it, or
   * remove it if it is. This is the Dart equivalent of jQuery's
   * [toggleClass](http://api.jquery.com/toggleClass/).
   * If [shouldAdd] is true, then we always add all the classes in [iterable]
   * element. If [shouldAdd] is false then we always remove all the classes in
   * [iterable] from the element.
   */
  void toggleAll(Iterable<String> iterable, [bool shouldAdd]) {
    iterable.forEach((e) => toggle(e, shouldAdd));
  }

  /**
   * Helper method used to modify the set of css classes on this element.
   *
   *   f - callback with:
   *   s - a Set of all the css class name currently on this element.
   *
   *   After f returns, the modified set is written to the
   *       className property of this element.
   */
  bool _modify(bool f(Set<String> s)) {
    Set<String> s = readClasses();
    var ret = f(s);
    writeClasses(s);
    return ret;
  }

  /**
   * Read the class names from the Element class property,
   * and put them into a set (duplicates are discarded).
   * This is intended to be overridden by specific implementations.
   */
  Set<String> readClasses();

  /**
   * Join all the elements of a set into one string and write
   * back to the element.
   * This is intended to be overridden by specific implementations.
   */
  void writeClasses(Set<String> s);
}