/*******************************************************************************
 * Copyright (c) 2007, 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.db.layer0.bindings;

import org.simantics.databoard.Datatypes;
import org.simantics.databoard.binding.LongBinding;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.type.Datatype;
import org.simantics.databoard.type.LongType;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.internal.SimanticsInternal;
import org.simantics.db.service.SerialisationSupport;

/**
 * This class binds Resource to LongType
 * 
 * @author toni.kalajainen
 */
public class ResourceBinding extends LongBinding {

    public static final Datatype RESOURCE_TYPE;

    //SerialisationSupport support;

    /**
     * Create resource binding. If session is not provided, this binding cannot instantiate resources.
     * 
     * @param session or null
     */
    public ResourceBinding(Session session) {
        super(Datatypes.LONG);
//        if (session != null) {
//            support = session.peekService(SerialisationSupport.class);
//        }
    }

    public ResourceBinding(SerialisationSupport serializationSupport) {
        super(Datatypes.LONG);
//        this.support = serializationSupport;
    }

    /**
     * @return current {@link SerialisationSupport}
     * @throws BindingException
     *             if not able to return a current {@link SerialisationSupport}
     */
    private SerialisationSupport getCurrentSupport() throws BindingException {
        // FIXME: this is wrong but should be optimized if possible.
//        if (support != null)
//            return support;

        Session s = SimanticsInternal.peekSession();
        if ( s == null ) {
            throw new BindingException("Cannot instantiate Resource without an alive database Session.");
        }
        SerialisationSupport support = s.peekService(SerialisationSupport.class);
        if ( support == null ) {
            throw new BindingException("Cannot instantiate Resource without an alive database Session.");
        }
        return support;
    }

    @Override
    public Object create(long value) throws BindingException {
    	if(value == 0) return null;
    	SerialisationSupport support = getCurrentSupport();
        try {
            return support.getResource(value);
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public Object create(Long value) throws BindingException {
    	SerialisationSupport support = getCurrentSupport();
        try {
            return support.getResource(value.longValue());
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public Object create(Number value) throws BindingException {
    	SerialisationSupport support = getCurrentSupport();
        try {
            return support.getResource(value.longValue());
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public Object create(String value) throws BindingException {
    	SerialisationSupport support = getCurrentSupport();
        try {
            return support.getResource(Long.parseLong(value));
        } catch (NumberFormatException e) {
            throw new BindingException(e);
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public Long getValue(Object o) throws BindingException {
    	SerialisationSupport support = getCurrentSupport();
        // NOTE: r.getResourceId() is unsafe for this purpose, it will just return 0 if it fails, thus corrupting anything serialized with this method
//    	Resource r = (Resource) o;
//    	return r.getResourceId();
        try {
            return support.getRandomAccessId((Resource)o);
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public long getValue_(Object o) throws BindingException {
    	SerialisationSupport support = getCurrentSupport();
        // NOTE: r.getResourceId() is unsafe for this purpose, it will just return 0 if it fails, thus corrupting anything serialized with this method
//    	Resource r = (Resource) o;
//    	return r.getResourceId();
        try {
            return support.getRandomAccessId((Resource)o);
        } catch (DatabaseException e) {
            throw new BindingException(e);
        }
    }

    @Override
    public void setValue(Object obj, Number value) throws BindingException {
        throw new BindingException("Resource is immutable");
    }

    @Override
    public void setValue(Object obj, long value) throws BindingException {
        throw new BindingException("Resource is immutable");
    }
    
    @Override
    public boolean isImmutable() {
    	return true;
    }

    @Override
    public boolean isInstance(Object obj) {
        return obj instanceof Resource;
    }
    
    static {
    	RESOURCE_TYPE = new LongType();
    	RESOURCE_TYPE.metadata.put("resource", "true");
    }
}