/*******************************************************************************
 *  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.java;

import java.lang.ref.SoftReference;
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.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.adapter.AdapterConstructionException;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.UnionBinding;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.binding.mutable.MutableVariant;
import org.simantics.databoard.type.UnionType;

/**
 * Accessor to Java Object of Union Type
 *
 * @author Toni Kalajainen <toni.kalajainen@vtt.fi>
 */
public class JavaUnion extends JavaObject implements UnionAccessor {

	/** Accessor to childr */
	SoftReference<JavaObject> component;
		
	public JavaUnion(Accessor parent, UnionBinding binding, Object object, AccessorParams params) {
		super(parent, binding, object, params);
	}
	
	@Override
	public UnionType type() {
		return (UnionType) binding.type();
	}
	
	@Override
	public UnionBinding getBinding() {
		return (UnionBinding) binding;
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T extends Accessor> T getComponent(ChildReference reference)
			throws AccessorConstructionException {
		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 by name \""+nr.name+"\" is 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 UnionType");
		} catch (AccessorException ae) {
			throw new AccessorConstructionException(ae);
		}
	}
	
	public int count() throws AccessorException {
		return type().getComponentCount();
	};
	
	/**
	 * Get existing sub-accessor
	 * 
	 * @return sub-accessor or <code>null</code>
	 */
	JavaObject getExistingAccessor() {
		SoftReference<JavaObject> c = component;
		if (c==null) return null;
		return c.get();		
	}

	@Override
	public void setValue(Binding unionBinding, Object newUnionValue)
			throws AccessorException {
		writeLock();
		try {
			UnionBinding newUb = (UnionBinding) unionBinding;
			int tag = newUb.getTag(newUnionValue);
			Binding cb = newUb.getComponentBinding(tag);
			Object cv = newUb.getValue(newUnionValue);
			setComponentValue(tag, cb, cv);
		} catch (BindingException e) {
			throw new AccessorException(e);
		} finally {
			writeUnlock();
		}
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T extends Accessor> T getComponentAccessor() throws AccessorConstructionException {
		try {
			// Get existing or create new
			JavaObject sa = getExistingAccessor();

			if (sa==null) {
				readLock();
				try {
					// Instantiate new accessor
					int tag = getBinding().getTag(object);
					Binding cb = getBinding().getComponentBinding(tag);
					Object cv = getBinding().getValue(object);
					
					// Instantiate correct sub accessor. 
					sa = createSubAccessor(this, cb, cv, params);
					component = new SoftReference<JavaObject>(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;
					}
				} finally {
					readUnlock();
				}

			}
			
			return (T) sa;
		} catch (BindingException be) {
			throw new AccessorConstructionException( be );
		}
	}

	@Override
	public Object getComponentValue(Binding componentBinding) throws AccessorException {
		readLock();
		try {
			int tag = getBinding().getTag(object);
			Binding cb = getBinding().getComponentBinding(tag);
			Object cv = getBinding().getValue(object);		
			return adapt(cv, cb, componentBinding);
		} catch (AdaptException ae) {
			throw new AccessorException( ae );
		} catch (BindingException be) {
			throw new AccessorException( be );
		} catch (AdapterConstructionException e) {
			throw new AccessorException( e );
		} finally {
			readUnlock();
		}
	}

	@Override
	public int getTag() throws AccessorException {
		readLock();
		try {
			return getBinding().getTag(object);
		} catch (BindingException e) {
			throw new AccessorException();
		} finally {
			readUnlock();
		}
	}

	@Override
	public void setComponentValue(int tag, Binding componentBinding,
			Object componentValue) throws AccessorException {
		writeLock();
		try {
			int oldTag = getBinding().getTag(object);
			int newTag = tag;			
			boolean hadSameTag = oldTag == newTag;
			
			// Write to component
			JavaObject 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(componentBinding, componentValue);
				return;
			}
			
			// Write
			Binding cb = getBinding().getComponentBinding(newTag);
			Object cv = adapt(componentValue, componentBinding, cb);
			getBinding().setValue(object, newTag, 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 (BindingException e) {
			throw new AccessorException(e);
		} catch (AdaptException e) {
			throw new AccessorException(e);
		} catch (AdapterConstructionException 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;
			JavaObject 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;
				JavaObject sa = getExistingAccessor();
				if (sa==null) return;
				sa.removeListener(listener);
			}
		}
	}

	@Override
	Event applyLocal(Event e, boolean makeRollback) throws AccessorException {
		try {
			Event rollback = null;
			if (e instanceof ValueAssigned) {
				ValueAssigned va = (ValueAssigned) e;
				if (makeRollback) rollback = new ValueAssigned(getBinding(), getValue(getBinding())); 
				setValue(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);
		
				if (makeRollback) {
					UnionBinding ub = getBinding();
					int tag = getTag();
					Binding cb = ub.getComponentBinding(tag);			
					Object cv = ub.getValue(object);
					MutableVariant v = new MutableVariant(cb, cv);
					rollback = new UnionValueAssigned(tag, v);			
				}
				setComponentValue(ua.tag, ua.newValue.getBinding(), ua.newValue.getValue());		
				return rollback;
			} else {
				throw new AccessorException("Cannot apply "+e.getClass().getName()+" to Union Type");				
			}
		} catch (BindingException be) {
			throw new AccessorException(be);
		}
	}
	
	
}