/*
    * Entagged Audio Tag library
    * Copyright (c) 2003-2005 Raphaël Slinckx <raphael@slinckx.net>
    * 
    * This library is free software; you can redistribute it and/or
    * modify it under the terms of the GNU Lesser General Public
    * License as published by the Free Software Foundation; either
    * version 2.1 of the License, or (at your option) any later version.
    *  
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   * 
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  package entagged.audioformats.generic;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import entagged.audioformats.Tag;
  
  /***
   * This class is the default implementation for
   * {@link entagged.audioformats.Tag} and introduces some more useful
   * functionality to be implemented.<br>
   * 
   * @author Raphaël Slinckx
   */
  public abstract class AbstractTag implements Tag {
  
  	/***
  	 * Stores the amount of {@link TagField} with {@link TagField#isCommon()}
  	 * <code>true</code>.
  	 */
  	protected int commonNumber = 0;
  
  	/***
  	 * This map stores the {@linkplain TagField#getId() ids} of the stored
  	 * fields to the {@linkplain TagField fields} themselves.<br>
  	 */
  	protected HashMap fields = new HashMap();
  
  	/***
  	 * (overridden) The use of this method is not recommended. One must know the
  	 * underlying audio files implementation.
  	 * 
  	 * @see entagged.audioformats.Tag#add(entagged.audioformats.generic.TagField)
  	 */
  	/***
  	 * (overridden)
  	 * 
  	 * @see entagged.audioformats.Tag#add(entagged.audioformats.generic.TagField)
  	 */
  	public void add(TagField field) {
  		if (field == null || field.isEmpty())
  			return;
  
  		List list = (List) fields.get(field.getId());
  
  		// There was no previous item
  		if (list == null) {
  			list = new ArrayList();
  			list.add(field);
  			fields.put(field.getId(), list);
  			if (field.isCommon())
  				commonNumber++;
  		} else {
  			// We append to existing list
  			list.add(field);
  		}
  	}
  
  	/***
  	 * (overridden)
  	 * 
  	 * @see entagged.audioformats.Tag#addAlbum(java.lang.String)
  	 */
  	public void addAlbum(String s) {
  		add(createAlbumField(s));
  	}
  
  	/***
  	 * (overridden)
  	 * 
  	 * @see entagged.audioformats.Tag#addArtist(java.lang.String)
  	 */
  	public void addArtist(String s) {
  		add(createArtistField(s));
  	}
  
  	/***
  	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#addComment(java.lang.String)
 	 */
 	public void addComment(String s) {
 		add(createCommentField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#addGenre(java.lang.String)
 	 */
 	public void addGenre(String s) {
 		add(createGenreField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#addTitle(java.lang.String)
 	 */
 	public void addTitle(String s) {
 		add(createTitleField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#addTrack(java.lang.String)
 	 */
 	public void addTrack(String s) {
 		add(createTrackField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#addYear(java.lang.String)
 	 */
 	public void addYear(String s) {
 		add(createYearField(s));
 	}
 
 	/***
 	 * Creates a field which represents the &quot;album&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;album&quot;
 	 */
 	protected abstract TagField createAlbumField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;artist&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;artist&quot;
 	 */
 	protected abstract TagField createArtistField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;comment&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;comment&quot;
 	 */
 	protected abstract TagField createCommentField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;genre&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;genre&quot;
 	 */
 	protected abstract TagField createGenreField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;title&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;title&quot;
 	 */
 	protected abstract TagField createTitleField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;track&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;track&quot;
 	 */
 	protected abstract TagField createTrackField(String content);
 
 	/***
 	 * Creates a field which represents the &quot;year&quot;.<br>
 	 * The field will already contain the given content.
 	 * 
 	 * @param content
 	 *            The content of the created field.
 	 * @return tagfield representing the &quot;year&quot;
 	 */
 	protected abstract TagField createYearField(String content);
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#get(java.lang.String)
 	 */
 	public List get(String id) {
 		List list = (List) fields.get(id);
 
 		if (list == null)
 			return new ArrayList();
 
 		return list;
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getAlbum()
 	 */
 	public List getAlbum() {
 		return get(getAlbumId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;album&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;album&quot; field.
 	 */
 	protected abstract String getAlbumId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getArtist()
 	 */
 	public List getArtist() {
 		return get(getArtistId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;artist&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;artist&quot; field.
 	 */
 	protected abstract String getArtistId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getComment()
 	 */
 	public List getComment() {
 		return get(getCommentId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;comment&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;comment&quot; field.
 	 */
 	protected abstract String getCommentId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFields()
 	 */
 	public Iterator getFields() {
 		final Iterator it = this.fields.entrySet().iterator();
 		return new Iterator() {
 			private Iterator fieldsIt;
 
 			private void changeIt() {
 				if (!it.hasNext())
 					return;
 
 				List l = (List) ((Map.Entry) it.next()).getValue();
 				fieldsIt = l.iterator();
 			}
 
 			public boolean hasNext() {
 				if (fieldsIt == null) {
 					changeIt();
 				}
 				return it.hasNext() || (fieldsIt != null && fieldsIt.hasNext());
 			}
 
 			public Object next() {
 				if (!fieldsIt.hasNext())
 					changeIt();
 
 				return fieldsIt.next();
 			}
 
 			public void remove() {
 				fieldsIt.remove();
 			}
 		};
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstAlbum()
 	 */
 	public String getFirstAlbum() {
 		List l = get(getAlbumId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstArtist()
 	 */
 	public String getFirstArtist() {
 		List l = get(getArtistId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstComment()
 	 */
 	public String getFirstComment() {
 		List l = get(getCommentId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstGenre()
 	 */
 	public String getFirstGenre() {
 		List l = get(getGenreId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstTitle()
 	 */
 	public String getFirstTitle() {
 		List l = get(getTitleId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstTrack()
 	 */
 	public String getFirstTrack() {
 		List l = get(getTrackId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getFirstYear()
 	 */
 	public String getFirstYear() {
 		List l = get(getYearId());
 		return (l.size() != 0) ? ((TagTextField) l.get(0)).getContent() : "";
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getGenre()
 	 */
 	public List getGenre() {
 		return get(getGenreId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;genre&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;genre&quot; field.
 	 */
 	protected abstract String getGenreId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getTitle()
 	 */
 	public List getTitle() {
 		return get(getTitleId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;title&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;title&quot; field.
 	 */
 	protected abstract String getTitleId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getTrack()
 	 */
 	public List getTrack() {
 		return get(getTrackId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;track&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;track&quot; field.
 	 */
 	protected abstract String getTrackId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#getYear()
 	 */
 	public List getYear() {
 		return get(getYearId());
 	}
 
 	/***
 	 * Returns the identifier for a field representing the &quot;year&quot;<br>
 	 * 
 	 * @see TagField#getId()
 	 * @return identifier for the &quot;year&quot; field.
 	 */
 	protected abstract String getYearId();
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#hasCommonFields()
 	 */
 	public boolean hasCommonFields() {
 		return commonNumber != 0;
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#hasField(java.lang.String)
 	 */
 	public boolean hasField(String id) {
 		return get(id).size() != 0;
 	}
 
 	/***
 	 * Determines whether the given charset encoding may be used for the
 	 * represented tagging system.
 	 * 
 	 * @param enc
 	 *            charset encoding.
 	 * @return <code>true</code> if the given encoding can be used.
 	 */
 	protected abstract boolean isAllowedEncoding(String enc);
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#isEmpty()
 	 */
 	public boolean isEmpty() {
 		return fields.size() == 0;
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#merge(entagged.audioformats.Tag)
 	 */
 	public void merge(Tag tag) {
 		// FIXME: Improve me, for the moment,
 		// it overwrites this tag with other values
 		// FIXME: TODO: an abstract method that merges particular things for
 		// each
 		// format
 		if (getTitle().size() == 0)
 			setTitle(tag.getFirstTitle());
 		if (getArtist().size() == 0)
 			setArtist(tag.getFirstArtist());
 		if (getAlbum().size() == 0)
 			setAlbum(tag.getFirstAlbum());
 		if (getYear().size() == 0)
 			setYear(tag.getFirstYear());
 		if (getComment().size() == 0)
 			setComment(tag.getFirstComment());
 		if (getTrack().size() == 0)
 			setTrack(tag.getFirstTrack());
 		if (getGenre().size() == 0)
 			setGenre(tag.getFirstGenre());
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#set(entagged.audioformats.generic.TagField)
 	 */
 	public void set(TagField field) {
 		if (field == null)
 			return;
 
 		// If an empty field is passed, we delete all the previous ones
 		if (field.isEmpty()) {
 			Object removed = fields.remove(field.getId());
 			if (removed != null && field.isCommon())
 				commonNumber--;
 			return;
 		}
 
 		// If there is already an existing field with same id
 		// and both are TextFields, we update the first element
 		List l = (List) fields.get(field.getId());
 		if (l != null) {
 			TagField f = (TagField) l.get(0);
 			f.copyContent(field);
 			return;
 		}
 
 		// Else we put the new field in the fields.
 		l = new ArrayList();
 		l.add(field);
 		fields.put(field.getId(), l);
 		if (field.isCommon())
 			commonNumber++;
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setAlbum(java.lang.String)
 	 */
 	public void setAlbum(String s) {
 		set(createAlbumField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setArtist(java.lang.String)
 	 */
 	public void setArtist(String s) {
 		set(createArtistField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setComment(java.lang.String)
 	 */
 	public void setComment(String s) {
 		set(createCommentField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setEncoding(java.lang.String)
 	 */
 	public boolean setEncoding(String enc) {
 		if (!isAllowedEncoding(enc)) {
 			return false;
 		}
 
 		Iterator it = getFields();
 		while (it.hasNext()) {
 			TagField field = (TagField) it.next();
 			if (field instanceof TagTextField) {
 				((TagTextField) field).setEncoding(enc);
 			}
 		}
 
 		return true;
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setGenre(java.lang.String)
 	 */
 	public void setGenre(String s) {
 		set(createGenreField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setTitle(java.lang.String)
 	 */
 	public void setTitle(String s) {
 		set(createTitleField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setTrack(java.lang.String)
 	 */
 	public void setTrack(String s) {
 		set(createTrackField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see entagged.audioformats.Tag#setYear(java.lang.String)
 	 */
 	public void setYear(String s) {
 		set(createYearField(s));
 	}
 
 	/***
 	 * (overridden)
 	 * 
 	 * @see java.lang.Object#toString()
 	 */
 	public String toString() {
 		StringBuffer out = new StringBuffer();
 		out.append("Tag content:\n");
 		Iterator it = getFields();
 		while (it.hasNext()) {
 			TagField field = (TagField) it.next();
 			out.append("\t");
 			out.append(field.getId());
 			out.append(" : ");
 			out.append(field.toString());
 			out.append("\n");
 		}
 		return out.toString().substring(0, out.length() - 1);
 	}
 }