package com.c2kernel.persistency;

import java.util.ArrayList;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Map;

import com.c2kernel.entity.C2KLocalObject;
import com.c2kernel.process.auth.Authenticator;
import com.c2kernel.utils.Logger;

public class MemoryOnlyClusterStorage extends ClusterStorage {

    HashMap<Integer, Map<String, C2KLocalObject>> memoryCache = new HashMap<Integer, Map<String, C2KLocalObject>>();
	/**
	 * 
	 */
	public MemoryOnlyClusterStorage() {
		memoryCache = new HashMap<Integer, Map<String,C2KLocalObject>>();
	}

	@Override
	public void open(Authenticator auth) throws ClusterStorageException {

	}

	@Override
	public void close() throws ClusterStorageException {
	}

	@Override
	public short queryClusterSupport(String clusterType) {
		return ClusterStorage.READWRITE;
	}

	@Override
	public String getName() {
		return "Memory Cache";
	}

	@Override
	public String getId() {
		return "Memory Cache";
	}

	@Override
	public C2KLocalObject get(Integer sysKey, String path)
			throws ClusterStorageException {
        Map<String, C2KLocalObject> sysKeyMemCache = memoryCache.get(sysKey);
        if (sysKeyMemCache != null)
            return sysKeyMemCache.get(path);
        return null;
	}

	@Override
	public void put(Integer sysKey, C2KLocalObject obj)
			throws ClusterStorageException {

		// create item cache if not present
        Map<String, C2KLocalObject> sysKeyMemCache;
        synchronized (memoryCache) {
        	if (memoryCache.containsKey(sysKey))
        		sysKeyMemCache = memoryCache.get(sysKey);
        	else {
        		sysKeyMemCache = new HashMap<String, C2KLocalObject>();
        		memoryCache.put(sysKey, sysKeyMemCache);
            }
        }
        
        // store object in the cache
        String path = ClusterStorage.getPath(obj);
        synchronized(sysKeyMemCache) {
	        sysKeyMemCache.put(path, obj);
        }

	}

	@Override
	public void delete(Integer sysKey, String path)
			throws ClusterStorageException {
        Map<String, C2KLocalObject> sysKeyMemCache = memoryCache.get(sysKey);
        if (sysKeyMemCache != null) {
        	synchronized (sysKeyMemCache) {
        		if (sysKeyMemCache.containsKey(path)) {
        			sysKeyMemCache.remove(path);
        			if (sysKeyMemCache.isEmpty()) {
        				synchronized (memoryCache) {
        					memoryCache.remove(sysKey);
        				}
        			}
        		}
        	}
        }
	}

	@Override
	public String[] getClusterContents(Integer sysKey, String path)
			throws ClusterStorageException {
		Map<String, C2KLocalObject> sysKeyMemCache = memoryCache.get(sysKey);
		ArrayList<String> result = new ArrayList<String>();
        if (sysKeyMemCache != null) {
        	while (path.endsWith("/")) 
        		path = path.substring(0,path.length()-1);
        	path = path+"/";
        	for (String thisPath : sysKeyMemCache.keySet()) {
				if (thisPath.startsWith(path)) {
					String end = thisPath.substring(path.length());
					int slash = end.indexOf('/');
					String suffix = slash>-1?end.substring(0, slash):end;
					if (!result.contains(suffix)) result.add(suffix);
				}
			}
        }
        return result.toArray(new String[result.size()]);
	}
	
    public void dumpContents(int sysKey) {
        synchronized(memoryCache) {
			Logger.msg(0, "Cached Objects of Entity "+sysKey);
			Map<String, C2KLocalObject> sysKeyMemCache = memoryCache.get(sysKey);
			if (sysKeyMemCache == null) {
				Logger.msg(0, "No cache found");
				return;
			}
            try {
                synchronized(sysKeyMemCache) {
             for (Object name : sysKeyMemCache.keySet()) {
               String path = (String) name;
               try {
                 Logger.msg(0, "    Path "+path+": "+sysKeyMemCache.get(path).getClass().getName());
               } catch (NullPointerException e) {
                 Logger.msg(0, "    Path "+path+": reaped");
               }
             }
                }
            } catch (ConcurrentModificationException ex) {
                Logger.msg(0, "Cache modified - aborting");
            }
		}
        Logger.msg(0, "Total number of cached entities: "+memoryCache.size());
    }
}