/*
 * 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.loader;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.reporting.libraries.resourceloader.ResourceData;
import org.pentaho.reporting.libraries.resourceloader.ResourceKey;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyData;
import org.pentaho.reporting.libraries.resourceloader.ResourceKeyUtils;
import org.pentaho.reporting.libraries.resourceloader.ResourceLoader;
import org.pentaho.reporting.libraries.resourceloader.ResourceLoadingException;

/**
 * Creation-Date: 05.04.2006, 15:32:36
 *
 * @author Thomas Morgner
 */
public class URLResourceLoader implements ResourceLoader
{
  public static final String SCHEMA_NAME = URLResourceLoader.class.getName();
  private static final Log logger = LogFactory.getLog(URLResourceLoader.class);

  public URLResourceLoader()
  {
  }

  /**
   * Checks, whether this resource loader implementation was responsible for
   * creating this key.
   *
   * @param key
   * @return
   */
  public boolean isSupportedKey(final ResourceKey key)
  {
    if (SCHEMA_NAME.equals(key.getSchema()))
    {
      return true;
    }
    return false;
  }

  /**
   * Creates a new resource key from the given object and the factory keys.
   *
   * @param value
   * @param factoryKeys
   * @return the created key.
   * @throws org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException
   *          if creating the key failed.
   */
  public ResourceKey createKey(final Object value, final Map factoryKeys) throws ResourceKeyCreationException
  {
    if (value instanceof URL)
    {
      return new ResourceKey(SCHEMA_NAME, value, factoryKeys);
    }
    if (value instanceof String)
    {
      final String valueString = (String) value;
      // the 'file' schema is defined to have double-slashes, but the JDK
      // ignores RFC 1738 in that case. So we have to check for these beasts
      // directly ..
      if (valueString.indexOf("://") >= 0 || valueString.startsWith("file:/"))
      {
        try
        {
          return new ResourceKey(SCHEMA_NAME, new URL(valueString), factoryKeys);

        }
        catch (MalformedURLException mfue)
        {
          // we dont take this easy!
          throw new ResourceKeyCreationException("Malformed value: " + value);
        }
      }
    }

    return null;
  }

  /**
   * Derives a new resource key from the given key. If neither a path nor new
   * factory-keys are given, the parent key is returned.
   *
   * @param parent      the parent
   * @param path        the derived path (can be null).
   * @param factoryKeys the optional factory keys (can be null).
   * @return the derived key.
   * @throws org.pentaho.reporting.libraries.resourceloader.ResourceKeyCreationException
   *          if the key cannot be derived for any reason.
   */
  public ResourceKey deriveKey(final ResourceKey parent, final String path, final Map factoryKeys)
      throws ResourceKeyCreationException
  {
    if (isSupportedKey(parent) == false)
    {
      throw new ResourceKeyCreationException("Assertation: Unsupported parent key type");
    }

    try
    {
      final URL url;
      if (path != null)
      {
        url = new URL((URL) parent.getIdentifier(), path);
      }
      else
      {
        url = (URL) parent.getIdentifier();
      }

      final Map map;
      if (factoryKeys != null)
      {
        map = new HashMap();
        map.putAll(parent.getFactoryParameters());
        map.putAll(factoryKeys);
      }
      else
      {
        map = parent.getFactoryParameters();
      }
      return new ResourceKey(parent.getSchema(), url, map);
    }
    catch (MalformedURLException e)
    {
      throw new ResourceKeyCreationException("Malformed value: " + path);
    }
  }

  public URL toURL(final ResourceKey key)
  {
    return (URL) key.getIdentifier();
  }

  public ResourceData load(final ResourceKey key) throws ResourceLoadingException
  {
    if (isSupportedKey(key) == false)
    {
      throw new ResourceLoadingException("Key format is not recognized.");
    }
    return new URLResourceData(key);
  }

  /**
   * Creates a String version of the resource key that can be used to generate a new ResourceKey
   * object via deserialization
   * @param bundleKey
   * @param key
   */
  public String serialize(ResourceKey bundleKey, final ResourceKey key)
  {
    // Validate the parameter
    if (key == null)
    {
      throw new NullPointerException("The ResourceKey can not be null");
    }
    if (isSupportedKey(key) == false)
    {
      throw new IllegalArgumentException("Key format is not recognized.");
    }
    if (!(key.getIdentifier() instanceof URL))
    {
      throw new IllegalArgumentException("ResourceKey is invalid - identifier is not a URL object");
    }

    // Log information
    logger.debug("Serializing a Classloader Resource Key...");
    if (key.getParent() != null)
    {
      logger.warn("Serializing a Classloader Resource Key which contains a parent: key=[" + bundleKey + "] parent=["
          + key.getParent() + "]");
    }

    // Serialize the key
    final URL url = (URL) key.getIdentifier();
    final String result = ResourceKeyUtils.createStringResourceKey
        (key.getSchema().toString(), url.toExternalForm(), key.getFactoryParameters());
    logger.debug("Serialized Classloader Resource Key: [" + result + "]");
    return result;
  }

  /**
   * Parses the input string and returns a newly created ResourceKey based on the string data
   */
  public ResourceKey deserialize(final ResourceKey bundleKey, String stringKey) throws ResourceKeyCreationException
  {
    // Parse the data
    ResourceKeyData keyData = ResourceKeyUtils.parse(stringKey);

    // Validate the data
    if (SCHEMA_NAME.equals(keyData.getSchema()) == false)
    {
      throw new ResourceKeyCreationException("Serialized version of key does not contain correct schema");
    }

    // Create and return a new key
    try
    {
      return createKey(new URL(keyData.getIdentifier()), keyData.getFactoryParameters());
    }
    catch (MalformedURLException mfue)
    {
      throw new ResourceKeyCreationException("Malformed value: " + keyData.getIdentifier());
    }
  }

  public boolean isSupportedDeserializer(String data)
  {
    return SCHEMA_NAME.equals(ResourceKeyUtils.readSchemaFromString(data));
  }
}