/*
 * Copyright (c) 2012, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.core.html;

import com.google.dart.tools.core.DartCore;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * A comprehensive list of html keywords and attributes. This class reads its content from the
 * html.txt file.
 * 
 * @coverage dart.tools.core
 */
public class HtmlKeywords {
  private static List<String> globalAttributes;
  private static List<String> eventAttributes;

  private static List<String> keywords;
  private static Map<String, List<String>> attributeMap;

  private static Set<String> SELF_CLOSING = new HashSet<String>(Arrays.asList(new String[] {
      "area", "base", "basefont", "br", "col", "frame", "hr", "img", "input", "link", "meta",
      "param", "!"}));

  static {
    init();
  }

  public static List<String> getAttributes(String entityName) {
    if (attributeMap.containsKey(entityName)) {
      List<String> atts = new ArrayList<String>();

      atts.addAll(attributeMap.get(entityName));
      atts.addAll(globalAttributes);

      return atts;
    } else {
      return Collections.emptyList();
    }
  }

  public static List<String> getEventAttributes() {
    return eventAttributes;
  }

  public static List<String> getKeywords() {
    return keywords;
  }

  public static boolean isSelfClosing(String entityName) {
    return SELF_CLOSING.contains(entityName);
  }

  public static boolean isValidEventAttribute(String name) {
    name = processEventAttribute(name);

    return eventAttributes.contains(name);
  }

  private static void init() {
    try {
      keywords = new ArrayList<String>();
      attributeMap = new HashMap<String, List<String>>();
      globalAttributes = Collections.emptyList();

      BufferedReader reader = new BufferedReader(new InputStreamReader(
          HtmlKeywords.class.getResourceAsStream("html.txt")));

      // handle the global attributes
      String line = reader.readLine();
      line = line.substring(1, line.length() - 1);
      globalAttributes = Collections.unmodifiableList(Arrays.asList(line.split(",")));

      // handle the event attributes
      line = reader.readLine();
      line = line.substring(1, line.length() - 1);
      eventAttributes = Collections.unmodifiableList(Arrays.asList(line.split(",")));

      line = reader.readLine();

      while (line != null) {
        line = line.trim();

        if (line.length() > 0 && line.charAt(0) != '#') {
          List<String> atts = Collections.emptyList();
          String keyword = line;

          if (line.indexOf('=') != -1) {
            String[] strs = line.split("=");

            keyword = strs[0];
            atts = Collections.unmodifiableList(Arrays.asList(strs[1].split(",")));
          }

          attributeMap.put(keyword, atts);
        }

        line = reader.readLine();
      }

      reader.close();

      keywords.addAll(attributeMap.keySet());
      Collections.sort(keywords);
    } catch (IOException ioe) {
      DartCore.logError(ioe);
    }
  }

  private static String processEventAttribute(String name) {
    name = name.toLowerCase();

    int index = name.indexOf('-');

    while (index != -1) {
      name = name.substring(0, index) + name.substring(index + 1);

      index = name.indexOf('-');
    }

    return name;
  }

  private HtmlKeywords() {

  }

}