/*

  * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH

  *

  * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0

  *

  * 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 de.smartics.properties.utils;

 import java.util.Arrays;

 import java.util.HashSet;

 import java.util.Set;

 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 import org.apache.commons.lang.StringUtils;

 /**

  * Utilities to normalize Javadoc comments.

  */

 public final class JavadocCommentHelper

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   /**

    * The pattern matches inline Javadoc tags. In group 1 is the text that is to

    * be used and surrounded with {@link #prefix1} and {@link #suffix1}, if there

    * is no match for group 2. If group 2 is present, the text is to be used

    * without prefix/suffix 2.

    */

   private static final Pattern INLINE_PATTERN = Pattern.compile(

       "\\{@[\\w]+\\s*([#\\.\\w]+(\\([^)]*\\))?)\\s*([^}]+)?\\}",

       Pattern.MULTILINE);

   /**

    * The elements that are of type block.

    */

   private static final Set<String> BLOCK_ELEMENTS = new HashSet<String>(

       Arrays.asList(new String[] { "address", "blockquote", "center", "del",

                                   "dir", "div", "dl", "fieldset", "form", "h1",

                                   "h2", "h3", "h4", "h5", "h5", "hr", "ins",

                                   "isindex", "menu", "noframes", "noscript",

                                   "ol", "p", "pre", "table", "ul" }));

   // --- members --------------------------------------------------------------

   /**

    * The prefix for group 1 match.

    */

   private final String prefix1;

   /**

    * The suffix for group 1 match.

    */

   private final String suffix1;

   /**

    * The prefix for group 2 match.

    */

   private final String prefix2;

   /**

    * The suffix for group 2 match.

    */

   private final String suffix2;

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   /**

    * Default constructor.

    *

    * @param prefix1 the prefix for group 1 match.

    * @param suffix1 the suffix for group 1 match.

    * @param prefix2 the prefix for group 2 match.

    * @param suffix2 the suffix for group 2 match.

    */

   public JavadocCommentHelper(final String prefix1, final String suffix1,

       final String prefix2, final String suffix2)

   {

     this.prefix1 = prefix1;

     this.suffix1 = suffix1;

     this.prefix2 = prefix2;

     this.suffix2 = suffix2;

   }

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- create ---------------------------------------------------------------

   /**

    * Creates a default helper for normalizing in an HTML context.

    *

    * @return the HTML version of the helper.

    */

   public static JavadocCommentHelper createHtml()

   {

     return new JavadocCommentHelper("<tt>", "</tt>", "<i>", "</i>");

   }

   /**

    * Creates a default helper for normalizing in text context.

    *

    * @return the text version of the helper.

    */

   public static JavadocCommentHelper createText()

   {

     return new JavadocCommentHelper("'", "'", "", "");

   }

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   /**

    * Usually the first paragraph in a Javadoc comment is not tagged as a

    * paragraph to reduce the markup. This helper probes if the block tag is

    * present and if not adds it.

    *

    * @param fragment the javadoc fragment to check.

    * @return the cleaned fragment.

    */

   public String expandFirstBlock(final String fragment)

   {

     if (StringUtils.isBlank(fragment))

     {

       return fragment;

     }

     final String norm = fragment.trim();

     if (isStartingWithTag(norm))

     {

       final String elementName = calcElementName(norm);

       if (isBlockElement(elementName))

       {

         final int index = norm.indexOf("</" + elementName);

         return createBlock(norm, index);

       }

     }

     else

     {

       final int index = calcIndexOfFirstBlockElement(norm);

       return createBlock(norm, index);

     }

     return fragment;

   }

   private static int calcIndexOfFirstBlockElement(final String fragment)

   {

     int index = Integer.MAX_VALUE;

     for (final String elementName : BLOCK_ELEMENTS)

     {

       final int currentIndex = fragment.indexOf('<' + elementName);

       if (currentIndex != -1)

       {

         index = Math.min(currentIndex, index);

       }

     }

     return index != Integer.MAX_VALUE ? index : -1;

   }

   private static String createBlock(final String fragment, final int index)

   {

     if (index != -1)

     {

       final String firstBlock = fragment.substring(0, index);

       final String rest = fragment.substring(index);

       return "<p>" + firstBlock + "</p>\n" + rest;

     }

     else

     {

       return "<p>" + fragment + "</p>";

     }

   }

   private static boolean isStartingWithTag(final String fragment)

   {

     return fragment.startsWith("<");

   }

   private static String calcElementName(final String fragment)

   {

     final StringBuilder buffer = new StringBuilder();

     final int end = fragment.length();

     int i = 1;

     while (i < end)

     {

       final char ch = fragment.charAt(i++);

       if (Character.isLetterOrDigit(ch))

       {

         buffer.append(ch);

       }

     }

     final String name = buffer.toString();

     return name;

   }

   private static boolean isBlockElement(final String elementName)

   {

     return BLOCK_ELEMENTS.contains(elementName);

   }

   /**

    * Replaces Javadoc inline tags.

    *

    * @param fragment the fragment with inline tags.

    * @return the normalized fragment.

    */

   public String replaceJavadocInlines(final String fragment)

   {

     if (StringUtils.isBlank(fragment))

     {

       return fragment;

     }

     final StringBuffer buffer = new StringBuffer(fragment.length());

     final Matcher matcher = INLINE_PATTERN.matcher(fragment);

     while (matcher.find())

     {

       final String group2 = matcher.group(3);

       if (group2 != null)

       {

         final String replacement = prefix2 + group2 + suffix2;

         matcher.appendReplacement(buffer, replacement);

       }

       else

       {

         String group1 = matcher.group(1);

         if (group1.length() > 1 && group1.charAt(0) == '#')

         {

           group1 = group1.substring(1);

         }

         final String replacement = prefix1 + group1 + suffix1;

         matcher.appendReplacement(buffer, replacement);

       }

     }

     matcher.appendTail(buffer);

     return buffer.toString();

   }

   // --- object basics --------------------------------------------------------

 }