package at.gv.egovernment.moa.id.auth.modules.eidas.engine;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Timer;

import javax.xml.namespace.QName;

import org.opensaml.saml2.metadata.EntitiesDescriptor;
import org.opensaml.saml2.metadata.EntityDescriptor;
import org.opensaml.saml2.metadata.RoleDescriptor;
import org.opensaml.saml2.metadata.provider.ChainingMetadataProvider;
import org.opensaml.saml2.metadata.provider.FilesystemMetadataProvider;
import org.opensaml.saml2.metadata.provider.HTTPMetadataProvider;
import org.opensaml.saml2.metadata.provider.MetadataFilter;
import org.opensaml.saml2.metadata.provider.MetadataProvider;
import org.opensaml.saml2.metadata.provider.MetadataProviderException;
import org.opensaml.saml2.metadata.provider.ObservableMetadataProvider;
import org.opensaml.xml.XMLObject;
import org.springframework.stereotype.Service;

import at.gv.egovernment.moa.id.auth.IDestroyableObject;
import at.gv.egovernment.moa.id.auth.IGarbageCollectorProcessing;
import at.gv.egovernment.moa.id.auth.IPostStartupInitializable;
import at.gv.egovernment.moa.id.auth.modules.eidas.Constants;
import at.gv.egovernment.moa.id.protocols.pvp2x.metadata.IMOARefreshableMetadataProvider;
import at.gv.egovernment.moa.id.protocols.pvp2x.metadata.SimpleMOAMetadataProvider;
import at.gv.egovernment.moa.id.protocols.pvp2x.verification.metadata.MOASPMetadataSignatureFilter;
import at.gv.egovernment.moa.id.saml2.MetadataFilterChain;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.FileUtils;
import at.gv.egovernment.moa.util.MiscUtil;
import eu.eidas.auth.engine.AbstractProtocolEngine;

@Service("eIDASMetadataProvider")
public class MOAeIDASChainingMetadataProvider extends SimpleMOAMetadataProvider implements ObservableMetadataProvider, 
	IGarbageCollectorProcessing, IDestroyableObject, IMOARefreshableMetadataProvider, IPostStartupInitializable{

	private Timer timer = null;
	
	private MetadataProvider internalProvider;
	private Map<String, Date> lastAccess = null;
	
	
//	public static MOAeIDASChainingMetadataProvider getInstance() {
//		if (instance == null) {
//			synchronized (mutex) {
//				if (instance == null) {
//					instance = new MOAeIDASChainingMetadataProvider();
//					MOAGarbageCollector.addModulForGarbageCollection(instance);
//				}
//			}
//		}
//		return instance;
//	}
	
	
	public MOAeIDASChainingMetadataProvider() {
		internalProvider = new ChainingMetadataProvider();
		lastAccess = new HashMap<String, Date>();
				
	}

	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.auth.IPostStartupInitializable#executeAfterStartup()
	 */
	@Override
	public void executeAfterStartup() {
		initializeEidasMetadataFromFileSystem();
		
	}
	
	protected void initializeEidasMetadataFromFileSystem() {
		Map<String, String> metadataToLoad = authConfig.getBasicMOAIDConfigurationWithPrefix(Constants.CONIG_PROPS_EIDAS_METADATA_URLS_LIST_PREFIX);
		if (!metadataToLoad.isEmpty()) {
			Logger.info("Load static configurated eIDAS metadata ... ");			
			for (String metaatalocation : metadataToLoad.values()) {
				String absMetadataLocation = FileUtils.makeAbsoluteURL(metaatalocation, authConfig.getRootConfigFileDir());				
				Logger.info("  Load eIDAS metadata from: " + absMetadataLocation);
				refreshMetadataProvider(absMetadataLocation);
				
			}
			
			Logger.info("Load static configurated eIDAS metadata finished ");
		}		
	}
	
	
	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.auth.IDestroyableObject#fullyDestroy()
	 */
	@Override
	public void fullyDestroy() {
		
		if (timer != null)
			timer.cancel();
		
		Map<String, HTTPMetadataProvider> loadedproviders = getAllActuallyLoadedProviders();
		if (loadedproviders != null) {
			for (Entry<String, HTTPMetadataProvider> el : loadedproviders.entrySet()) {
				try {
					el.getValue().destroy();
					Logger.debug("Destroy eIDAS Matadataprovider: " + el.getKey() + " finished");
					
				} catch (Exception e) {
					Logger.warn("Destroy eIDAS Matadataprovider: " + el.getKey() + " FAILED");
					
				}
			}
		}		
	}
	
	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.config.auth.IGarbageCollectorProcessing#runGarbageCollector()
	 */
	@Override
	public void runGarbageCollector() {
		if (!lastAccess.isEmpty()) {
			Date now = new Date();
			Date expioredate = new Date(now.getTime() - 
					Constants.CONFIG_PROPS_METADATA_GARBAGE_TIMEOUT);
			Logger.debug("Starting eIDAS Metadata garbag collection (Expioredate:" 
					+ expioredate + ")");
			
			List<String> expiredEntities = new ArrayList<String>();
			
			Iterator<Entry<String, Date>> lastAccessInterator = lastAccess.entrySet().iterator();
			while(lastAccessInterator.hasNext()) {
				Entry<String, Date> element = lastAccessInterator.next();
				if (element.getValue().before(expioredate)) {
					Logger.debug("Remove unused eIDAS Metadate: " + element.getKey());
					expiredEntities.add(element.getKey());
					
				}								
			}
		
			ChainingMetadataProvider chainProvider = (ChainingMetadataProvider) internalProvider;
			boolean isUpdateRequired = false;
			
			//get all actually loaded metadata providers
			Map<String, HTTPMetadataProvider> loadedproviders = getAllActuallyLoadedProviders();
						
			if (!expiredEntities.isEmpty()) {										
				for (String expired : expiredEntities) {
					if (loadedproviders.containsKey(expired)) {
						HTTPMetadataProvider provider = loadedproviders.get(expired);
					
						//destroy metadata provider
						provider.destroy();
					
						//remove from map
						loadedproviders.remove(expired);
						isUpdateRequired = true;
						
						/*OpenSAML ChainingMetadataProvider can not remove a MetadataProvider (UnsupportedOperationException)
						 *The ChainingMetadataProvider use internal a unmodifiableList to hold all registrated MetadataProviders.*/
						//chainProvider.removeMetadataProvider(provider);					
						Logger.info("Remove not used eIDAS MetadataProvider " + expired 
								+ " after timeout.");
										
					} else
						Logger.info("eIDAS metadata for EntityID: " + expired 
								+ " is marked as expired, but no currently loaded HTTPMetadataProvider metadata provider is found.");
				
				}			
			}
			
			//check signature of all metadata which are actually loaded
			List<String> nonValidMetadataProvider = new ArrayList<String>();
			for (HTTPMetadataProvider provider : loadedproviders.values()) {
				try {
					provider.refresh();
					
					//provider.getMetadataFilter().doFilter(provider.getMetadata());
					
				} catch (MetadataProviderException e) {
					Logger.info("eIDAS MetadataProvider: " + provider.getMetadataURI() 
						+ " is not valid any more. Reason:" + e.getMessage());
					if (Logger.isDebugEnabled())
						Logger.warn("Reason", e);

					nonValidMetadataProvider.add(provider.getMetadataURI());
										
				}										
			}			
			for (String el : nonValidMetadataProvider) {
				HTTPMetadataProvider provider = loadedproviders.get(el);
				
				//destroy metadata provider
				if (provider != null) {
					provider.destroy();
					loadedproviders.remove(el);
					isUpdateRequired = true;
					
				} else {
					Logger.error("Can not destroy eIDAS metadata for: " + el + " Reason: !!!!!NOT FOUND ANY MORE!!!!!!");
					
				}
				
			}

			//update chaining metadata-provider if it is required
			if (isUpdateRequired) {
				try {
					synchronized (chainProvider) {
						chainProvider.setProviders(new ArrayList<MetadataProvider>(loadedproviders.values()));
				
						emitChangeEvent();	
					}
				
				} catch (MetadataProviderException e) {
					Logger.warn("ReInitalize eIDASA MetaDataProvider is not possible! MOA-ID Instance has to be restarted manualy", e);
			
				}
			}
		}					
	}
	
		
	private MetadataProvider createNewHTTPMetaDataProvider(String metadataURL) {		
		if (timer == null)
			timer = new Timer(true);
		
		//add Metadata filters
		MetadataFilterChain filter = new MetadataFilterChain();
		filter.addFilter(new MOASPMetadataSignatureFilter(
				authConfig.getBasicMOAIDConfiguration(Constants.CONIG_PROPS_EIDAS_METADATA_VALIDATION_TRUSTSTORE)));
		
		return createNewMoaMetadataProvider(metadataURL, filter, 
					"eIDAS metadata-provider", 
					timer, AbstractProtocolEngine.getSecuredParserPool());
			
	}

	private Map<String, HTTPMetadataProvider> getAllActuallyLoadedProviders() {
		Map<String, HTTPMetadataProvider> loadedproviders = new HashMap<String, HTTPMetadataProvider>();
		ChainingMetadataProvider chainProvider = (ChainingMetadataProvider) internalProvider;
			
		//make a Map of all actually loaded HTTPMetadataProvider
		List<MetadataProvider> providers = chainProvider.getProviders();
		for (MetadataProvider provider : providers) {
			if (provider instanceof HTTPMetadataProvider) {
				HTTPMetadataProvider httpprovider = (HTTPMetadataProvider) provider;
				loadedproviders.put(httpprovider.getMetadataURI(), httpprovider);
			
			} else if (provider instanceof FilesystemMetadataProvider) {
				String entityID = "'!!NO-ENTITYID!!'";
				try {
					if (provider.getMetadata() instanceof EntityDescriptor)
						entityID = ((EntityDescriptor)provider.getMetadata()).getEntityID();
										
					Logger.debug("Skip eIDAS metadata: " + entityID + " because it is loaded from local Filesystem");	
					
				} catch (MetadataProviderException e) {
					Logger.info("Collect currently loaded eIDAS metadata provider has an internel process error: " + e.getMessage());
					
				}
								
			} else
				Logger.info("Skip " + provider.getClass().getName() + " from list of currently loaded "
						+ "eIDAS metadata provider");
			
		}
		
		Logger.debug("Find #" + loadedproviders.size() + " eIDAS metadata provider");
		
		return loadedproviders;		
	}
	
	public boolean refreshMetadataProvider(String metadataURL) {
		try {
			if (MiscUtil.isNotEmpty(metadataURL)) {
				Map<String, HTTPMetadataProvider> actuallyLoadedProviders = getAllActuallyLoadedProviders();

				// check if MetadataProvider is actually loaded
				if (actuallyLoadedProviders.containsKey(metadataURL)) {
					actuallyLoadedProviders.get(metadataURL).refresh();						
					Logger.info("eIDAS metadata for " 
							+ metadataURL + " is refreshed.");
					return true;
					
				} else {
					//load new Metadata Provider				
					ChainingMetadataProvider chainProvider = (ChainingMetadataProvider) internalProvider;						
					MetadataProvider newMetadataProvider = createNewHTTPMetaDataProvider(metadataURL);	
					
					if (newMetadataProvider != null) {
						chainProvider.addMetadataProvider(newMetadataProvider);
					
						emitChangeEvent();
						Logger.info("eIDAS metadata for " 
								+ metadataURL + " is added.");
						return true;
						
					} else
						Logger.warn("Can not load eIDAS metadata from URL: " + metadataURL);
				}
														
			} else
				Logger.debug("Can not refresh eIDAS metadata: NO eIDAS metadata URL.");
																								
		} catch (MetadataProviderException e) {
			Logger.warn("Refresh eIDAS metadata for " 
					+ metadataURL + " FAILED.", e);
			
		}
		
		return false;
		
	}
	
	
	public boolean requireValidMetadata() {
		return internalProvider.requireValidMetadata();
	}

	public void setRequireValidMetadata(boolean requireValidMetadata) {
		internalProvider.setRequireValidMetadata(requireValidMetadata);
	}

	public MetadataFilter getMetadataFilter() {
		return internalProvider.getMetadataFilter();
	}

	public void setMetadataFilter(MetadataFilter newFilter)
			throws MetadataProviderException {
		internalProvider.setMetadataFilter(newFilter);
	}

	public XMLObject getMetadata() throws MetadataProviderException {
		return internalProvider.getMetadata();
	}

	public EntitiesDescriptor getEntitiesDescriptor(String entitiesID)
			throws MetadataProviderException {
		Logger.warn("eIDAS metadata not support 'EntitiesDescriptor' elements!");		
		return null;
		
	}

	public EntityDescriptor getEntityDescriptor(String entityID)
			throws MetadataProviderException {
		EntityDescriptor entityDesc = null;
		try {
			entityDesc = internalProvider.getEntityDescriptor(entityID);
			if (entityDesc == null) {
				Logger.debug("Can not find eIDAS metadata for entityID: " + entityID 
						+ " Start refreshing process ...");
				if (refreshMetadataProvider(entityID))
					entityDesc =  internalProvider.getEntityDescriptor(entityID);
									
			} else {
				if (!entityDesc.isValid())
					if (refreshMetadataProvider(entityID))
						entityDesc = internalProvider.getEntityDescriptor(entityID);
									
			}
			
			
		} catch (MetadataProviderException e) {
			Logger.debug("Can not find eIDAS metadata for entityID: " + entityID 
					+ " Start refreshing process ...");
			if (refreshMetadataProvider(entityID))
				entityDesc = internalProvider.getEntityDescriptor(entityID);
			
		}
		
		if (entityDesc != null)
			lastAccess.put(entityID, new Date());
		
		return entityDesc;
	}

	public List<RoleDescriptor> getRole(String entityID, QName roleName)
			throws MetadataProviderException {
		EntityDescriptor entityDesc = getEntityDescriptor(entityID);
		if (entityDesc != null)
			return entityDesc.getRoleDescriptors(roleName);
		
		else
			return null;
	}

	public RoleDescriptor getRole(String entityID, QName roleName,
			String supportedProtocol) throws MetadataProviderException {
		EntityDescriptor entityDesc = getEntityDescriptor(entityID);
		if (entityDesc != null)		
			return internalProvider.getRole(entityID, roleName, supportedProtocol);
		
		else
			return null;
	}

	/* (non-Javadoc)
	 * @see org.opensaml.saml2.metadata.provider.ObservableMetadataProvider#getObservers()
	 */
	@Override
	public List<Observer> getObservers() {
		return ((ChainingMetadataProvider) internalProvider).getObservers();
	}

	protected void emitChangeEvent() {
		if ((getObservers() == null) || (getObservers().size() == 0)) {
			return;
		}

		List<Observer> tempObserverList = new ArrayList<Observer>(getObservers());
		for (ObservableMetadataProvider.Observer observer : tempObserverList)
			if (observer != null)
				observer.onEvent(this);
	}

}