package org.apache.maven.doxia.util;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.

  */

 import java.awt.image.BufferedImage;

 import java.io.File;

 import java.io.IOException;

 import java.io.UnsupportedEncodingException;

 import java.net.URL;

 import java.text.ParseException;

 import java.text.ParsePosition;

 import java.text.SimpleDateFormat;

 import java.util.Date;

 import java.util.Locale;

 import javax.imageio.ImageIO;

 import javax.swing.text.MutableAttributeSet;

 import org.apache.maven.doxia.sink.SinkEventAttributeSet;

 /**

  * General Doxia utility methods. The methods in this class should not assume

  * any specific Doxia module or document format.

  *

  * @author ltheussl

  * @since 1.1

  * @version $Id: DoxiaUtils.java 1185112 2011-10-17 11:33:00Z ltheussl $

  */

 public class DoxiaUtils

 {

     private static final int MINUS_ONE = 0xFF;

     /**

      * Checks if the given string corresponds to an internal link,

      * ie it is a link to an anchor within the same document.

      * If link is not null, then exactly one of the three methods

      * {@link #isInternalLink(java.lang.String)}, {@link #isExternalLink(java.lang.String)} and

      * {@link #isLocalLink(java.lang.String)} will return true.

      *

      * @param link The link to check. Not null.

      * @return True if the link starts with "#".

      *

      * @throws NullPointerException if link is null.

      *

      * @see #isExternalLink(String)

      * @see #isLocalLink(String)

      */

     public static boolean isInternalLink( final String link )

     {

         return link.startsWith( "#" );

     }

     /**

      * Checks if the given string corresponds to an external URI,

      * ie is not a link within the same document nor a relative link

      * to another document (a local link) of the same site.

      * If link is not null, then exactly one of the three methods

      * {@link #isInternalLink(java.lang.String)}, {@link #isExternalLink(java.lang.String)} and

      * {@link #isLocalLink(java.lang.String)} will return true.

      *

      * @param link The link to check. Not null.

      *

      * @return True if the link (ignoring case) starts with either "http:/",

      * "https:/", "ftp:/", "mailto:", "file:/", or contains the string "://".

      * Note that Windows style separators "\" are not allowed

      * for URIs, see  http://www.ietf.org/rfc/rfc2396.txt , section 2.4.3.

      *

      * @throws NullPointerException if link is null.

      *

      * @see #isInternalLink(String)

      * @see #isLocalLink(String)

      */

     public static boolean isExternalLink( final String link )

     {

         String text = link.toLowerCase( Locale.ENGLISH );

         return ( text.startsWith( "http:/" ) || text.startsWith( "https:/" )

             || text.startsWith( "ftp:/" ) || text.startsWith( "mailto:" )

             || text.startsWith( "file:/" ) || text.contains( "://" ) );

     }

     /**

      * Checks if the given string corresponds to a relative link to another document

      * within the same site, ie it is neither an {@link #isInternalLink(String) internal}

      * nor an {@link #isExternalLink(String) external} link.

      * If link is not null, then exactly one of the three methods

      * {@link #isInternalLink(java.lang.String)}, {@link #isExternalLink(java.lang.String)} and

      * {@link #isLocalLink(java.lang.String)} will return true.

      *

      * @param link The link to check. Not null.

      *

      * @return True if the link is neither an external nor an internal link.

      *

      * @throws NullPointerException if link is null.

      *

      * @see #isExternalLink(String)

      * @see #isInternalLink(String)

      */

     public static boolean isLocalLink( final String link )

     {

         return ( !isExternalLink( link ) && !isInternalLink( link ) );

     }

     /**

      * Construct a valid Doxia id.

      *

      * <p>

      *   This method is equivalent to {@link #encodeId(java.lang.String, boolean) encodeId( id, false )}.

      * </p>

      *

      * @param id The id to be encoded.

      *      May be null in which case null is returned.

      *

      * @return The trimmed and encoded id, or null if id is null.

      *

      * @see #encodeId(java.lang.String, boolean)

      */

     public static String encodeId( final String id )

     {

         return encodeId( id, false );

     }

     /**

      * Construct a valid Doxia id.

      *

      * <p>

      *   A valid Doxia id obeys the same constraints as an HTML ID or NAME token.

      *   According to the <a href="http://www.w3.org/TR/html4/types.html#type-name">

      *   HTML 4.01 specification section 6.2 SGML basic types</a>:

      * </p>

      * <p>

      *   <i>ID and NAME tokens must begin with a letter ([A-Za-z]) and may be

      *   followed by any number of letters, digits ([0-9]), hyphens ("-"),

      *   underscores ("_"), colons (":"), and periods (".").</i>

      * </p>

      * <p>

      *   According to <a href="http://www.w3.org/TR/xhtml1/#C_8">XHTML 1.0

      *   section C.8. Fragment Identifiers</a>:

      * </p>

      * <p>

      *   <i>When defining fragment identifiers to be backward-compatible, only

      *   strings matching the pattern [A-Za-z][A-Za-z0-9:_.-]* should be used.</i>

      * </p>

      * <p>

      *   To achieve this we need to convert the <i>id</i> String. Two conversions

      *   are necessary and one is done to get prettier ids:

      * </p>

      * <ol>

      *   <li>Remove whitespace at the start and end before starting to process</li>

      *   <li>If the first character is not a letter, prepend the id with the letter 'a'</li>

      *   <li>Any spaces are replaced with an underscore '_'</li>

      *   <li>

      *     Any characters not matching the above pattern are either dropped,

      *     or replaced according to the rules specified in the

      *     <a href="http://www.w3.org/TR/html4/appendix/notes.html#non-ascii-chars">HTML specs</a>.

      *   </li>

      * </ol>

      * <p>

      *   For letters, the case is preserved in the conversion.

      * </p>

      *

      * <p>

      * Here are some examples:

      * </p>

      * <pre>

      * DoxiaUtils.encodeId( null )        = null

      * DoxiaUtils.encodeId( "" )          = "a"

      * DoxiaUtils.encodeId( "  " )        = "a"

      * DoxiaUtils.encodeId( " _ " )       = "a_"

      * DoxiaUtils.encodeId( "1" )         = "a1"

      * DoxiaUtils.encodeId( "1anchor" )   = "a1anchor"

      * DoxiaUtils.encodeId( "_anchor" )   = "a_anchor"

      * DoxiaUtils.encodeId( "a b-c123 " ) = "a_b-c123"

      * DoxiaUtils.encodeId( "   anchor" ) = "anchor"

      * DoxiaUtils.encodeId( "myAnchor" )  = "myAnchor"

      * </pre>

      *

      * @param id The id to be encoded.

      *      May be null in which case null is returned.

      * @param chop true if non-ASCII characters should be ignored.

      * If false, any non-ASCII characters will be replaced as specified above.

      *

      * @return The trimmed and encoded id, or null if id is null.

      * If id is not null, the return value is guaranteed to be a valid Doxia id.

      *

      * @see #isValidId(java.lang.String)

      *

      * @since 1.1.1

      */

     public static String encodeId( final String id, final boolean chop )

     {

         if ( id == null )

         {

             return null;

         }

         final String idd = id.trim();

         int length = idd.length();

         if ( length == 0 )

         {

             return "a";

         }

         StringBuilder buffer = new StringBuilder( length );

         for ( int i = 0; i < length; ++i )

         {

             char c = idd.charAt( i );

             if ( ( i == 0 ) && ( !isAsciiLetter( c ) ) )

             {

                 buffer.append( 'a' );

             }

             if ( c == ' ' )

             {

                 buffer.append( '_' );

             }

             else if ( isAsciiLetter( c ) || isAsciiDigit( c ) || ( c == '-' ) || ( c == '_' ) || ( c == ':' )

                             || ( c == '.' ) )

             {

                 buffer.append( c );

             }

             else if ( !chop )

             {

                 byte[] bytes;

                 try

                 {

                     bytes = String.valueOf( c ).getBytes( "UTF8" );

                 }

                 catch ( UnsupportedEncodingException cannotHappen )

                 {

                     bytes = new byte[0];

                 }

                 for ( int j = 0; j < bytes.length; ++j )

                 {

                     String hex = byteToHex( bytes[j] );

                     buffer.append( '%' );

                     if ( hex.length() == 1 )

                     {

                         buffer.append( '0' );

                     }

                     buffer.append( hex );

                 }

             }

         }

         return buffer.toString();

     }

     /**

      * Convert a byte to it's hexadecimal equivalent.

      *

      * @param b the byte value.

      * @return the result of Integer.toHexString( b & 0xFF ).

      *

      * @since 1.1.1

      */

     public static String byteToHex( final byte b )

     {

         return Integer.toHexString( b & MINUS_ONE );

     }

     /**

      * Determines if the specified text is a valid id according to the rules

      * laid out in {@link #encodeId(String)}.

      *

      * @param text The text to be tested.

      *      May be null in which case false is returned.

      *

      * @return <code>true</code> if the text is a valid id, otherwise <code>false</code>.

      *

      * @see #encodeId(String)

      */

     public static boolean isValidId( final String text )

     {

         if ( text == null || text.length() == 0 )

         {

             return false;

         }

         for ( int i = 0; i < text.length(); ++i )

         {

             char c = text.charAt( i );

             if ( isAsciiLetter( c ) )

             {

                 continue;

             }

             if ( ( i == 0 ) || ( c == ' ' ) || ( !isAsciiDigit( c ) && c != '-' && c != '_' && c != ':' && c != '.' ) )

             {

                 return false;

             }

         }

         return true;

     }

     private static final SimpleDateFormat DATE_PARSER = new SimpleDateFormat( "", Locale.ENGLISH );

     private static final ParsePosition DATE_PARSE_POSITION = new ParsePosition( 0 );

     private static final String[] DATE_PATTERNS = new String[]

     {

         "yyyy-MM-dd", "yyyy/MM/dd", "yyyyMMdd", "yyyy", "dd.MM.yyyy", "dd MMM yyyy",

         "dd MMM. yyyy", "MMMM yyyy", "MMM. dd, yyyy", "MMM. yyyy", "MMMM dd, yyyy",

         "MMM d, ''yy", "MMM. ''yy", "MMMM ''yy"

     };

     /**

      * <p>Parses a string representing a date by trying different date patterns.</p>

      *

      * <p>The following date patterns are tried (in the given order):</p>

      *

      * <pre>"yyyy-MM-dd", "yyyy/MM/dd", "yyyyMMdd", "yyyy", "dd.MM.yyyy", "dd MMM yyyy",

      *  "dd MMM. yyyy", "MMMM yyyy", "MMM. dd, yyyy", "MMM. yyyy", "MMMM dd, yyyy",

      *  "MMM d, ''yy", "MMM. ''yy", "MMMM ''yy"</pre>

      *

      * <p>A parse is only sucessful if it parses the whole of the input string.

      * If no parse patterns match, a ParseException is thrown.</p>

      *

      * <p>As a special case, the strings <code>"today"</code> and <code>"now"</code>

      * (ignoring case) return the current date.</p>

      *

      * @param str the date to parse, not null.

      *

      * @return the parsed date, or the current date if the input String (ignoring case) was

      *      <code>"today"</code> or <code>"now"</code>.

      *

      * @throws ParseException if no pattern matches.

      * @throws NullPointerException if str is null.

      *

      * @since 1.1.1.

      */

     public static Date parseDate( final String str )

             throws ParseException

     {

         if ( "today".equalsIgnoreCase( str ) || "now".equalsIgnoreCase( str ) )

         {

             return new Date();

         }

         for ( int i = 0; i < DATE_PATTERNS.length; i++ )

         {

             DATE_PARSER.applyPattern( DATE_PATTERNS[i] );

             DATE_PARSE_POSITION.setIndex( 0 );

             final Date date = DATE_PARSER.parse( str, DATE_PARSE_POSITION );

             if ( date != null && DATE_PARSE_POSITION.getIndex() == str.length() )

             {

                 return date;

             }

         }

         throw new ParseException( "Unable to parse date: " + str, -1 );

     }

       //

      // private

     //

     private static boolean isAsciiLetter( final char c )

     {

         return ( ( c >= 'a' && c <= 'z' ) || ( c >= 'A' && c <= 'Z' ) );

     }

     private static boolean isAsciiDigit( final char c )

     {

         return ( c >= '0' && c <= '9' );

     }

     /**

      * Determine width and height of an image. If successful, the returned SinkEventAttributes

      * contain width and height attribute keys whose values are the width and height of the image (as a String).

      *

      * @param logo a String containing either a URL or a path to an image file. Not null.

      *

      * @return a set of SinkEventAttributes, or null if no ImageReader was found to read the image.

      *

      * @throws java.io.IOException if an error occurs during reading.

      * @throws NullPointerException if logo is null.

      *

      * @since 1.1.1

      */

     public static MutableAttributeSet getImageAttributes( final String logo )

             throws IOException

     {

         BufferedImage img = null;

         if ( isExternalLink( logo ) )

         {

             img = ImageIO.read( new URL( logo ) );

         }

         else

         {

             img = ImageIO.read( new File( logo ) );

         }

         if ( img == null )

         {

             return null;

         }

         MutableAttributeSet atts = new SinkEventAttributeSet();

         atts.addAttribute( SinkEventAttributeSet.WIDTH, Integer.toString( img.getWidth() ) );

         atts.addAttribute( SinkEventAttributeSet.HEIGHT, Integer.toString( img.getHeight() ) );

         // add other attributes?

         return atts;

     }

     private DoxiaUtils()

     {

         // utility class

     }

 }