/*
 * Copyright (c) 2006-2008, KNOPFLERFISH project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 * - Neither the name of the KNOPFLERFISH project nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.knopflerfish.bundle.component;

import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Dictionary;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.Constants;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.SynchronousBundleListener;

import org.osgi.service.cm.Configuration;
import org.osgi.service.cm.ConfigurationAdmin;
import org.osgi.service.cm.ConfigurationEvent;
import org.osgi.service.cm.ConfigurationListener;

import org.osgi.service.component.ComponentConstants;

class SCR implements SynchronousBundleListener {

  private Hashtable bundleConfigs = new Hashtable();

  private Collection components = new ArrayList();
  private Hashtable factoryConfigs = new Hashtable();


  private Hashtable serviceConfigs = new Hashtable();

  private static long componentId = 0;
  private static SCR instance;

  public static void init(BundleContext bc) {
    if (instance == null) {
      instance = new SCR(bc);

      Bundle[] bundles = bc.getBundles();
      for(int i=0;i<bundles.length;i++){
        if (bundles[i].getState() == Bundle.ACTIVE) {
          instance.bundleChanged(new BundleEvent(BundleEvent.STARTED, bundles[i]));
        }
      }
    }
  }

  public static SCR getInstance() {
    return instance;
  }

  private SCR(BundleContext bc) {
    bc.addBundleListener(this);
    bc.registerService(ConfigurationListener.class.getName(),
                       new CMListener(),
                       new Hashtable());
  }

  public synchronized void shutdown() {

    for (Enumeration e = bundleConfigs.keys();
         e.hasMoreElements();) {

      Bundle bundle = (Bundle) e.nextElement();
      bundleChanged(new BundleEvent(BundleEvent.STOPPING, bundle));

    }

    instance = null;
  }

  public synchronized void bundleChanged(BundleEvent event) {
    Bundle bundle = event.getBundle();
    String manifestEntry = (String) bundle.getHeaders().get(ComponentConstants.SERVICE_COMPONENT);
    if (manifestEntry == null) {
      return;
    }

    switch (event.getType()) {
    case BundleEvent.STARTED:

      // Create components
      Collection addedConfigs = new ArrayList();
      String[] manifestEntries = Parser.splitwords(manifestEntry, ",");

      for (int i = 0; i < manifestEntries.length; i++) {
        URL resourceURL = bundle.getResource(manifestEntries[i]);
        if (resourceURL == null) {
          Activator.log.error("Resource not found: " + manifestEntries[i]);
          continue;
        }
        try {
          Collection configs = Parser.readXML(bundle, resourceURL);
          if (configs.isEmpty()) {
            System.err.println("Declarative Services: Warning: xml-file did not contain any valid component declarations");

          }
          addedConfigs.addAll(configs);

        } catch (Throwable e) {
          Activator.log.error("Failed to parse " + resourceURL +": " + e.getCause());
          e.printStackTrace();
        }
      }

      bundleConfigs.put(bundle, new ArrayList());
      for (Iterator iter = addedConfigs.iterator(); iter.hasNext();) {
        Config config = (Config) iter.next();

        if (config.isAutoEnabled()) {
          Component component = config.createComponent();
          component.enable();
        }

        // Add to cycle finder:
        String[] services = config.getServices();
        if (services != null) {
          for (int i=0; i<services.length; i++) {
            ArrayList existing = (ArrayList) serviceConfigs.get(services[i]);
            if (existing == null) {
              existing = new ArrayList();
              serviceConfigs.put(services[i], existing);
            }
            existing.add(config);
          }
          // Find cycles:
          ArrayList cycle = new ArrayList();
          if (findCycle(config, cycle)) {
            String message = "Possible cycle found in references of " + config.getName() + ": ";
            Iterator citer = cycle.iterator();
            if (citer.hasNext()) {
              Config cycleItem = (Config) citer.next();
              message += cycleItem.getName();
              while (citer.hasNext()) {
                cycleItem = (Config) citer.next();
                message += " references " + cycleItem.getName();
              }
            }
            Activator.log.error(message);
          }
        }
      }

      Collection tmp = (Collection)bundleConfigs.get(bundle);
      tmp.addAll(addedConfigs);
      bundleConfigs.put(bundle, tmp);
      //bundleConfigs.put(bundle, addedConfigs);
      break;
    case BundleEvent.STOPPING:
      if (Activator.log.doDebug()) {
        Activator.log.debug("Bundle is STOPPING. Disable components.");
      }

      Collection removedConfigs = (Collection) bundleConfigs.remove(bundle);
      if (removedConfigs != null) {
        for (Iterator iter = removedConfigs.iterator(); iter.hasNext();) {
          Config config = (Config) iter.next();
          config.disable();
          // Remove from cycle finder:
          String[] services = config.getServices();
          if (services != null) {
            for (int i=0; i<services.length; i++) {
              ArrayList existing = (ArrayList) serviceConfigs.get(services[i]);
              if (existing == null) continue;
              existing.remove(config);
              if (existing.size() == 0) {
                serviceConfigs.remove(services[i]);
              }
            }
          }
        }
      }
      break;
    }
  }

  private boolean findCycle(Config config, ArrayList visited) {
    if (visited.contains(config)) {
      visited.add(config);
      return true;
    }
    visited.add(config);
    ArrayList references = config.getReferences();
    for (Iterator riter = references.iterator(); riter.hasNext();) {
      Reference ref = (Reference) riter.next();
      if (ref.isSatisfied()) continue;
      String service = ref.getInterfaceName();
      ArrayList providers = (ArrayList) serviceConfigs.get(service);
      if (providers != null) {
        for (Iterator piter = providers.iterator(); piter.hasNext();) {
          Config provider = (Config) piter.next();
          if (findCycle(provider, visited)) {
            return true;
          }
        }
      }
    }
    visited.remove(config);
    return false;
  }

  public Collection getComponents(Bundle bundle) {
    return (Collection)bundleConfigs.get(bundle);
  }

  public synchronized void initComponent(Component component) {
    component.setComponentId(new Long(++componentId));
    initConfig(component);
    components.add(component);
    // build graph here.
  }

  public synchronized void removeComponent(Component component) {
    if (component != null) {
      removeConfig(component);
      components.remove(component);
    }
  }

  private ConfigurationAdmin getCM(Component component) {

    BundleContext bc = component.getBundleContext();
    ServiceReference ref = bc.getServiceReference(ConfigurationAdmin.class.getName());

    if (ref == null)
      return null;

    return (ConfigurationAdmin) bc.getService(ref);
  }

  private synchronized void removeConfig(Component component) {
    Config config = component.getConfig();
    Dictionary dict = (Dictionary)factoryConfigs.get(config.getName());

    if (dict != null) {
      for (Enumeration e = dict.keys();
           e.hasMoreElements();) {
        Object key = e.nextElement();

        if (dict.get(key) == component) {
          dict.remove(key);
          break;
        }
      }

      if (dict.isEmpty()) {
        factoryConfigs.remove(config.getName());
      }
    }
  }

  private synchronized void initConfig(Component component) {

    Config config = component.getConfig();
    ConfigurationAdmin admin = getCM(component);
    String name = config.getName();

    if (admin == null)
      return ;

    try {
      Configuration[] conf =
        admin.listConfigurations("(" + ConfigurationAdmin.SERVICE_FACTORYPID +
                                 "=" + name + ")");

      if (conf != null) {
        Dictionary table = (Dictionary)factoryConfigs.get(name);

        if (table == null) {
          table = new Hashtable();
          factoryConfigs.put(name, table);
        }

        Collection configs = (Collection)bundleConfigs.get(config.getBundle());

        if (table.get(conf[0].getPid()) == null) {
          component.cmUpdated(conf[0].getProperties());
          table.put(conf[0].getPid(), component);
        }


        for (int i = conf.length - 1; i >= 0; i--) {
          String pid = conf[i].getPid();
          Component instance = (Component)table.get(pid);

          if (instance == null) {
            Config copy = config.copy();
            instance = copy.createComponent();
            instance.cmUpdated(conf[i].getProperties());
            table.put(pid, instance);
            configs.add(copy);
            instance.enable();
          }
        }

        // end factory configuration
      } else {

        // regular single configuration
        conf =
          admin.listConfigurations("(" + Constants.SERVICE_PID + "=" + name + ")");

        if (conf != null &&
            conf.length == 1) {
          component.cmUpdated(conf[0].getProperties());
        }
      }

    } catch (InvalidSyntaxException e) {
      Activator.log.error("The name (" + name + ") must have screwed up the filter.", e);
    } catch (IOException e) {
      Activator.log.error("Declarative Services could not retrieve " +
                          "the configuration for component " + name +
                          ". Got IOException.", e);
    }
  }

  private class CMListener implements ConfigurationListener {


    private Configuration getConfiguration(Component component, String pid) {

      ConfigurationAdmin admin = getCM(component);

      if (admin == null)
        return null;

      try {
        Configuration[] conf =
          admin.listConfigurations("(" + Constants.SERVICE_PID +
                                   "=" + pid + ")");

        return conf == null ? null : conf[0];
      } catch (InvalidSyntaxException e) {
        Activator.log.error("The PID (" + pid + ") must have screwed up the filter.", e);
        return null;
      } catch (IOException e) {
        Activator.log.error("Declarative Services could not retrieve " +
                            "the configuration for component with pid " + pid +
                            ". Got IOException.", e);
        return null;
      }

    }

    private void restart(Component component) {
      restart(component, null);
    }

    private void restart(Component component, Configuration configuration) {

      component.deactivate();
      component.unregisterService();

      if (configuration != null) {
        component.cmUpdated(configuration.getProperties());
      } else {
        component.cmDeleted();
        removeConfig(component);
      }

      component.registerService();
      component.activate();

    }

    public void configurationEvent(ConfigurationEvent evt) {

      String factoryPid = evt.getFactoryPid();
      String pid = evt.getPid();

      synchronized(SCR.getInstance()){
        if (factoryPid != null) {

          Dictionary table = (Dictionary) factoryConfigs.get(factoryPid);

          if (table != null) {
            Component component = (Component)table.get(pid);
            if (component != null) {
              if (evt.getType() == ConfigurationEvent.CM_DELETED) {
                table.remove(pid);

                if (table.isEmpty()) {

                  factoryConfigs.remove(factoryPid);
                  restart(component);

                } else {

                  component.disable();

                }

              } else {

                Configuration conf = getConfiguration(component, pid);
                if (conf == null)
                  return ;

                restart(component, conf);
              }


            } else { // we need to create a new component

              Object key = table.keys().nextElement();
              Component src = (Component)table.get(key);
              Config config = src.getConfig();
              Config copy = config.copy();

              Component instance = copy.createComponent();
              Configuration conf =
                getConfiguration(instance, pid);

              if (conf == null)
                return ;

              instance.cmUpdated(conf.getProperties());
              Collection collection = (Collection)bundleConfigs.get(copy.getBundle());
              collection.add(copy);
              instance.enable();

            }
          } else {

            for (Iterator i = components.iterator();
                 i.hasNext(); ) { // start looking for a potential target.

              Component component = (Component)i.next();
              Config config = component.getConfig();

              if (factoryPid.equals(config.getName())) {
                  // this is a new factory configuration (and has a corresponding component)
                  Configuration conf =
                    getConfiguration(component, pid);

                  if (conf == null)
                    continue; // does not have permission.

                  table = new Hashtable();
                  factoryConfigs.put(factoryPid, table);
                  table.put(evt.getPid(), component);
                  restart(component, conf);

//                }
              }
            }
          }

        } else { // just a regular Single Configuration.

          for (Iterator i = components.iterator();
             i.hasNext(); ) { // start looking for a potential target.

            Component component = (Component)i.next();
            Config config = component.getConfig();

            if (pid.equals(config.getName())) {

              if (evt.getType() == ConfigurationEvent.CM_DELETED) {
                restart(component);
              }

              Configuration conf =
                getConfiguration(component, pid);

              if (conf == null)
                continue ; // might not have permission

              restart(component, conf);
              // note that there might be other that matches as well..
            }
          }
        }
      }
    }
  }
}