/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program 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.
 *
 * Copyright (c) 2006 - 2009 Pentaho Corporation and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.resourceloader;

import java.io.File;
import java.io.Serializable;
import java.net.URL;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.pentaho.reporting.libraries.base.util.ObjectUtilities;

/**
 * The key is an unique identifier for the resource. Most of the time, this may be an URL, but other (especially
 * database based) schemas are possible.
 * <p/>
 * A resource key must provide an 'equals' implementation. ResourceKeys should be implemented as immutable classes, so
 * that they can be safely stored in collections or on external storages (like caches).
 *
 * @author Thomas Morgner
 */
public final class ResourceKey implements Serializable
{
  /**
   * @noinspection StaticCollection
   */
  private static final Map EMPTY_MAP = Collections.unmodifiableMap(new HashMap());

  private Map factoryParameters;
  private Integer hashCode;
  private Object schema;
  private Object identifier;
  private ResourceKey parent;
  private static final long serialVersionUID = -7764107570068726772L;

  public ResourceKey(final Object schema,
                     final Object identifier,
                     final Map factoryParameters)
  {
    if (schema == null)
    {
      throw new NullPointerException();
    }
    if (identifier == null)
    {
      throw new NullPointerException();
    }

    this.schema = schema;
    this.identifier = identifier;
    if (factoryParameters != null)
    {
      this.factoryParameters =
          Collections.unmodifiableMap(new HashMap(factoryParameters));
    }
    else
    {
      this.factoryParameters = EMPTY_MAP;
    }
  }

  public ResourceKey(final ResourceKey parent,
                     final Object schema,
                     final Object identifier,
                     final Map factoryParameters)
  {
    this(schema, identifier, factoryParameters);
    this.parent = parent;
  }

  public ResourceKey getParent()
  {
    return parent;
  }

  public Map getFactoryParameters()
  {
    return Collections.unmodifiableMap(factoryParameters);
  }

  public boolean equals(final Object o)
  {
    if (this == o)
    {
      return true;
    }
    if (o == null || getClass() != o.getClass())
    {
      return false;
    }

    final ResourceKey that = (ResourceKey) o;
    if (parent != that.parent && 
        ObjectUtilities.equal(parent, that.parent) == false)
    {
      return false;
    }
    if (!schema.equals(that.schema))
    {
      return false;
    }
    if (!factoryParameters.equals(that.factoryParameters))
    {
      return false;
    }
    if (identifier instanceof URL)
    {
      if (String.valueOf(identifier).equals(String.valueOf(that.identifier)) == false)
      {
        return false;
      }
    }
    else if (identifier instanceof File && that.identifier instanceof File)
    {
      // File.equals() does not check to see if two File objects refer to the same file ...
      // it checks to make sure they refer to the same file IN THE SAME way (which is deeper than we need)
      if (ObjectUtilities.equals((File) identifier, (File) that.identifier) == false)
      {
        return false;
      }
    }
    else if (!identifier.equals(that.identifier))
    {
      if (identifier instanceof byte[] &&
          that.identifier instanceof byte[])
      {
        final byte[] me = (byte[]) identifier;
        final byte[] he = (byte[]) that.identifier;
        if (Arrays.equals(me, he) == false)
        {
          return false;
        }
      }
      else
      {
        return false;
      }
    }

    return true;
  }

  public int hashCode()
  {
    if (hashCode == null)
    {
      int result = factoryParameters.hashCode();
      result = 29 * result + schema.hashCode();
      result = 29 * result + identifier.hashCode();
      if (parent != null)
      {
        result = 29 * result + parent.hashCode();
      }
      hashCode = new Integer(result);
    }
    return hashCode.intValue();
  }

  public Object getIdentifier()
  {
    return identifier;
  }

  /**
   * Returns a String version of the identifier.
   *
   * @return the identifier as string or null, if the identifier could not be converted easily.
   */
  public String getIdentifierAsString()
  {
    if (identifier instanceof File)
    {
      final File file = (File) identifier;
      return file.getPath();
    }
    if (identifier instanceof URL)
    {
      final URL url = (URL) identifier;
      return url.toExternalForm();
    }
    if (identifier instanceof String)
    {
      return identifier.toString();
    }
    return null;
  }

  /**
   * Returns the schema of this resource key. The schema is an internal identifier to locate the resource-loader
   * implementation that was responsible for creating the key in the first place.
   * <p/>
   * The schema has no meaning outside the resource loading framework.
   *
   * @return
   */
  public Object getSchema()
  {
    return schema;
  }


  public String toString()
  {
    return "ResourceKey{" +
        "schema=" + schema +
        ", identifier=" + identifier +
        ", factoryParameters=" + factoryParameters +
        ", parent=" + parent +
        '}';
  }
}