/*******************************************************************************
 * Copyright (c) 2007, 2012 Innoopract Informationssysteme GmbH and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Innoopract Informationssysteme GmbH - initial API and implementation
 *    EclipseSource - ongoing development
 ******************************************************************************/
package org.eclipse.rap.ui.internal.branding;

import java.util.Map;

import org.eclipse.rap.rwt.internal.util.ParamCheck;


/**
 * This data structure represents an HTML tag that goes into the <head>
 * section of the startup page and is used by the branding facility.
 *
 * @see AbstractBranding
 * @since 2.0
 * @noextend This class is not intended to be subclassed by clients.
 */
public final class Header {

  private static final String[] EMPTY_STRINGS = new String[ 0 ];

  private final String tagName;
  private final String[] names;
  private final String[] values;

  /**
   * Constructs a new instance of this class with the given
   * <code>tagName</code>.
   *
   * @param tagName the name of the tag, must either be <code>meta</code> or
   *          <code>link</code>
   * @param attributes the attributes for this tag or <code>null</code> if
   *          there are no attributes.
   * @throws IllegalArgumentException if <code>tagName</code> isn't either
   *           <code>meta</code> or <code>link</code>.
   */
  public Header( String tagName, Map<String, String> attributes ) {
    checkTagName( tagName );
    this.tagName = tagName;
    if( attributes == null ) {
      names = EMPTY_STRINGS;
      values = EMPTY_STRINGS;
    } else {
      int size = attributes.size();
      names = new String[ size ];
      attributes.keySet().toArray( names );
      values = new String[ size ];
      attributes.values().toArray( values );
    }
  }

  /**
   * Constructs a new instance of this class with the given
   * <code>tagName</code>.
   *
   * @param tagName the name of the tag, must either be <code>meta</code> or
   *          <code>link</code>
   * @param attributeNames the attribute names for this tag. Must not be
   *          <code>null</code>.
   * @param attributeValues the attribute values for this tag. Must match the
   *          attribute names given in argument <code>attributeNames</code>
   * @throws IllegalArgumentException if <code>tagName</code> isn't either
   *           <code>meta</code> or <code>link</code>.
   */
  public Header( String tagName, String[] attributeNames, String[] attributeValues ) {
    checkTagName( tagName );
    ParamCheck.notNull( attributeNames, "attributeNames" );
    ParamCheck.notNull( attributeValues, "attributeValues" );
    if( attributeNames.length != attributeValues.length ) {
      String msg
        = "The arguments 'attributeNames' and 'attributeValues' must have "
        + "the same length.";
      throw new IllegalArgumentException( msg );
    }
    this.tagName = tagName;
    names = new String[ attributeNames.length ];
    System.arraycopy( attributeNames, 0, names, 0, attributeNames.length );
    values = new String[ attributeValues.length ];
    System.arraycopy( attributeValues, 0, values, 0, attributeValues.length );
  }

  /**
   * Returns the name of the header tag.
   *
   * @return the tag name
   */
  public String getTagName() {
    return tagName;
  }

  /**
   * Returns the array of attribute names. If no attributes are defined, an
   * empty array is returned.
   * <p>
   * Note: This is not the actual structure used by the receiver to maintain
   * its list of names, so modifying the array will not affect the receiver.
   * </p>
   *
   * @return the attribute names
   */
  public String[] getNames() {
    String[] result = new String[ names.length ];
    System.arraycopy( names, 0, result, 0, names.length );
    return result;
  }

  /**
   * Returns the array of attribute values. If no attributes are defined, an
   * empty array is returned.
   * <p>
   * Note: This is not the actual structure used by the receiver to maintain
   * its list of values, so modifying the array will not affect the receiver.
   * </p>
   *
   * @return the attribute values
   */
  public String[] getValues() {
    String[] result = new String[ values.length ];
    System.arraycopy( values, 0, result, 0, values.length );
    return result;
  }

  private static void checkTagName( String tagName ) {
    if( !"link".equals( tagName ) && !"meta".equals( tagName ) ) {
      String msg = "Invalid tag name. The tag name must be either 'meta' or 'link'.";
      throw new IllegalArgumentException( msg );
    }
  }
}