/*******************************************************************************
 *  Copyright (c) 2010 Association for Decentralized Information Management in
 *  Industry THTH ry.
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  which accompanies this distribution, and is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *
 *  Contributors:
 *      VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.databoard.accessor.binary;

import gnu.trove.map.hash.TObjectIntHashMap;

import java.io.IOException;
import java.lang.ref.SoftReference;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executor;

import org.simantics.databoard.accessor.Accessor;
import org.simantics.databoard.accessor.UnionAccessor;
import org.simantics.databoard.accessor.error.AccessorConstructionException;
import org.simantics.databoard.accessor.error.AccessorException;
import org.simantics.databoard.accessor.error.ReferenceException;
import org.simantics.databoard.accessor.event.Event;
import org.simantics.databoard.accessor.event.UnionValueAssigned;
import org.simantics.databoard.accessor.event.ValueAssigned;
import org.simantics.databoard.accessor.file.FileUnionAccessor;
import org.simantics.databoard.accessor.impl.AccessorParams;
import org.simantics.databoard.accessor.impl.ListenerEntry;
import org.simantics.databoard.accessor.interestset.InterestSet;
import org.simantics.databoard.accessor.interestset.UnionInterestSet;
import org.simantics.databoard.accessor.reference.ChildReference;
import org.simantics.databoard.accessor.reference.ComponentReference;
import org.simantics.databoard.accessor.reference.IndexReference;
import org.simantics.databoard.accessor.reference.LabelReference;
import org.simantics.databoard.accessor.reference.NameReference;
import org.simantics.databoard.adapter.AdaptException;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.UnionBinding;
import org.simantics.databoard.binding.error.BindingConstructionException;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.binding.mutable.MutableVariant;
import org.simantics.databoard.serialization.Serializer;
import org.simantics.databoard.serialization.SerializerConstructionException;
import org.simantics.databoard.type.Datatype;
import org.simantics.databoard.type.UnionType;
import org.simantics.databoard.util.binary.Blob;
import org.simantics.databoard.util.binary.Endian;

public class BinaryUnion extends BinaryObject implements UnionAccessor, FileUnionAccessor {

	/** Accessor to childr */
	SoftReference<BinaryObject> component;	
	
	public BinaryUnion(BinaryObject parent, Blob blob, Datatype type, AccessorParams params) {
		super(parent, blob, type, params);
	}
	
	public UnionType type() {
		return (UnionType) type;
	}

	@Override
	public int count() {
		return type().getComponentCount();
	}

	@Override
	public void setValueNoflush(Binding binding, Object newValue)
			throws AccessorException {
		assert b.isOpen();
		writeLock();
		try {
			UnionBinding ub = (UnionBinding) binding;
			int tag = ub.getTag(newValue);
			Binding cb = ub.getComponentBinding(tag);
			Object cv = ub.getValue(newValue);
			setComponentValueNoflush(tag, cb, cv);
		} catch (BindingException e) {
			throw new AccessorException(e);
		} finally {
			writeUnlock();
		}
	}
	
	@SuppressWarnings("unchecked")
	@Override
	public <T extends Accessor> T getComponentAccessor()
			throws AccessorConstructionException {
		assert b.isOpen();
		readLock();
		try {
			// Get existing or create new
			BinaryObject sa = getExistingAccessor();

			if (sa==null) {
				// Read Value				
				b.position(0L);
				int tag = Endian.getUInt(b, count()-1);
				int tagLen = (int) b.position();
				Datatype ct = type().getComponent(tag).type;
				
				// Instantiate sub accessor. 
				sa = createSubAccessor(ct, tagLen, b.length()-tagLen, params);
				component = new SoftReference<BinaryObject>(sa);
				
				// Add listener to component, if it is in our interest set
				ListenerEntry le = listeners;
				while (le!=null) {				
					UnionInterestSet is = le.getInterestSet();
					InterestSet cis = is.getComponentInterest(tag);
					if (cis != null) {
						try {
							ChildReference childPath = ChildReference.concatenate(le.path, new ComponentReference() );
							sa.addListener(le.listener, cis, childPath, le.executor);
						} catch (AccessorException e) {
							throw new AccessorConstructionException(e);
						}
					}
					le = le.next;
				}				

			}
			
			return (T) sa;
		} catch (IOException e) {
			throw new AccessorConstructionException( e );
		} finally {
			readUnlock();
		}
	}
	
	/**
	 * Get existing sub-accessor
	 * 
	 * @return sub-accessor or <code>null</code>
	 */
	BinaryObject getExistingAccessor() {
		SoftReference<BinaryObject> c = component;
		if (c==null) return null;
		return c.get();		
	}	

	@Override
	public Object getComponentValue(Binding componentBinding)
			throws AccessorException {
		assert b.isOpen();
		readLock();
		try {
			b.position( 0L );
			int tag = Endian.getUInt(b, count()-1);
			Datatype ct = type().getComponent(tag).type; 
			if ( !ct.equals(componentBinding.type()) ) {
				throw new AccessorException("Binding of "+ct+" expected.");
			}
			
			List<Object> ids = new ArrayList<Object>(0);
			Serializer s = params.serializerScheme.getSerializer( componentBinding );
			return s.deserialize(b, ids);
		} catch (IOException e) {
			throw new AccessorException(e);
		} catch (SerializerConstructionException e) {
			throw new AccessorException(e);
		} finally {
			readUnlock();
		}
	}

	@Override
	public int getTag() throws AccessorException {
		assert b.isOpen();
		readLock();
		try {
			b.position(0L);
			return Endian.getUInt(b, count()-1);
		} catch (IOException e) {
			throw new AccessorException(e);
		} finally {
			readUnlock();
		}
	}

	@Override
	public void setComponentValue(int tag, Binding componentBinding,
			Object componentValue) throws AccessorException {
		assert b.isOpen();
		writeLock();
		try {
			setComponentValueNoflush(tag, componentBinding, componentValue);
			flush();
		} finally {
			writeUnlock();
		}
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T extends Accessor> T getComponent(ChildReference reference)
			throws AccessorConstructionException {
		assert b.isOpen();
		readLock();
		try {
			if (reference==null) return (T) this;
			
			if (reference instanceof LabelReference) {
				LabelReference lr = (LabelReference) reference;
				Integer tag = type().getComponentIndex( lr.label );
				
				if (tag==null && lr.label.equals("uv")) {
					Accessor result = getComponentAccessor();
					if (reference.getChildReference() != null)
						result = result.getComponent(reference.getChildReference());
					return (T) result;
				} else if (tag==null) {
					throw new ReferenceException("Tag \""+lr.label+"\" not found");
				}
				
				if (tag != getTag()) throw new ReferenceException("The union isn't currently assigned with the expected type ("+type().getComponent(tag).name+")");
				Accessor result = getComponentAccessor();
				if (reference.getChildReference() != null)
					result = result.getComponent(reference.getChildReference());
				return (T) result;				
			}
			
			if (reference instanceof ComponentReference) {
				Accessor result = getComponentAccessor();
				if (reference.getChildReference() != null)
					result = result.getComponent(reference.getChildReference());
				return (T) result;
			} 
			
			if (reference instanceof IndexReference) {
				IndexReference ir = (IndexReference) reference;
				if (ir.index<0 || ir.index>=type().getComponentCount()) throw new ReferenceException("Tag index out of bounds");
				if (ir.index != getTag()) throw new ReferenceException("The union isn't currently assigned with the expected type ("+type().getComponent(ir.index).name+")");
				Accessor result = getComponentAccessor();
				if (reference.getChildReference() != null)
					result = result.getComponent(reference.getChildReference());
				return (T) result;
			} 
			
			if (reference instanceof NameReference) {
				NameReference nr = (NameReference) reference;
				Integer tag = type().getComponentIndex( nr.name );
				if (tag==null) throw new ReferenceException("Tag \""+nr.name+"\" not found");
				if (tag != getTag()) throw new ReferenceException("The union isn't currently assigned with the expected type ("+type().getComponent(tag).name+")");
				Accessor result = getComponentAccessor();
				if (reference.getChildReference() != null)
					result = result.getComponent(reference.getChildReference());
				return (T) result;				
			}
			
			throw new ReferenceException(reference.getClass()+" is not a reference of OptionalType");
		} catch (AccessorException ae) {
			throw new AccessorConstructionException(ae);
		} finally {
			readUnlock();
		}
	}

	@Override
	public void setComponentValueNoflush(int tag, Binding cb,
			Object cv) throws AccessorException {
		assert b.isOpen();
		writeLock();
		try {
			int oldTag = getTag();
			int newTag = tag;			
			boolean hadSameTag = oldTag == newTag;
			
			// Write to component
			BinaryObject sa = getExistingAccessor();
			
			// Tag type changes, invalidate old accessor
			if (sa!=null && !hadSameTag) {
				component = null;
				sa.invalidatedNotification();
			}
			
			// Tag type remains the same
			if (sa!=null && hadSameTag) {
				sa.setValue(cb, cv);
				return;
			}
			
			// Write
			UnionType ut = type();
			Datatype ct = ut.getComponent(tag).type;
			if (!ct.equals(cb.type())) {
				throw new AccessorException("Binding of "+ct+" expected.");
			}
			TObjectIntHashMap<Object> ids = new TObjectIntHashMap<Object>(0);
			int len = Endian.getUIntLength(count()-1);
			
			Serializer s = params.serializerScheme.getSerializer( cb );
			len += s.getSize(cv, ids);
			ids.clear();
			
			b.setLength(len);
			b.position(0L);
			Endian.putUInt(b, tag, count()-1);
			s.serialize(b, ids, cv);
			
			// Notify Listeners
			ListenerEntry le = listeners;
			while (le!=null) {				
				UnionInterestSet is = le.getInterestSet();
				if (is.inNotificationsOf(tag)) {
					MutableVariant newComponentValue = null;
					if (is.inValuesOf(tag)) newComponentValue = new MutableVariant(cb, cb.isImmutable() ? cv : cb.clone(cv));
					UnionValueAssigned e = new UnionValueAssigned(newTag, newComponentValue);
					emitEvent(le, e);
				}
				
				// Attach component listener
//				InterestSet cis = is.getComponentInterest(newTag);
//				if (cis!=null && getExistingAccessor()==null) {
//					sa = getComponentAccessor();
//				}
				
				le = le.next;
			}
			
		} catch (IOException e) {
			throw new AccessorException(e);
		} catch (AdaptException e) {
			throw new AccessorException(e);
		} catch (SerializerConstructionException e) {
			throw new AccessorException(e);
		} finally {
			writeUnlock();
		}
		
	}

	@Override
	public void addListener(Listener listener, InterestSet interestSet,
			ChildReference path, Executor executor) throws AccessorException {
		super.addListener(listener, interestSet, path, executor);
		UnionInterestSet is = (UnionInterestSet) interestSet;		
		if (is.componentInterests!=null) {
			int tag = getTag();
			InterestSet cis = is.componentInterests[tag];
			if (cis==null) return;
			BinaryObject sa = getExistingAccessor();
			if (sa==null) return;
			ChildReference childPath = ChildReference.concatenate(path, new IndexReference(tag) );
			sa.addListener(listener, cis, childPath, executor);
		}
	}	
	
	@Override
	public void removeListener(Listener listener) throws AccessorException {
		ListenerEntry e = detachListener(listener);
		if (e==null) return;
		UnionInterestSet is = (UnionInterestSet) e.interestSet;
		
		if (is.componentInterests!=null) {
			for (int i=0; i<is.componentInterests.length; i++) {
				InterestSet cis = is.componentInterests[i];
				if (cis==null) continue;
				BinaryObject sa = getExistingAccessor();
				if (sa==null) return;
				sa.removeListener(listener);
			}
		}
	}
	
	@Override
	Event applyLocal(Event e, boolean makeRollback) throws AccessorException {
		Event rollback = null;
		if (makeRollback) {
			try {
				UnionType ut = type();
				int tag = getTag();
				Datatype ct = ut.getComponent(tag).type;
				Binding cb = params.bindingScheme.getBinding(ct);
				Object cv = getComponentValue(cb);
				MutableVariant v = new MutableVariant(cb, cv);
				rollback = new UnionValueAssigned(tag, v);
			} catch (BindingConstructionException e2) {
				throw new AccessorException( e2 );
			}
		}
		
		if (e instanceof ValueAssigned) {
			ValueAssigned va = (ValueAssigned) e;
			setValueNoflush(va.newValue.getBinding(), va.newValue.getValue());
			return rollback;
		} else	
		if (e instanceof UnionValueAssigned) {		
			UnionValueAssigned ua = (UnionValueAssigned) e;
			if (ua.tag<0 || ua.tag>=type().getComponentCount()) throw new AccessorException("Tag index ("+ua.tag+") out of bounds.");
			if (!ua.newValue.type().equals( type().getComponent(ua.tag).type ) )
					throw new AccessorException("Cannot assign "+ua.newValue.type()+" to "+type().getComponent(ua.tag).type);
	
			setComponentValueNoflush(ua.tag, ua.newValue.getBinding(), ua.newValue.getValue());		
			return rollback;
		} else {
			throw new AccessorException("Cannot apply "+e.getClass().getName()+" to Union Type");
		}
	}
	
}