/*******************************************************************************
 * Copyright (c) 2007, 2009 Oracle. 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:
 *     Oracle - initial API and implementation
 ******************************************************************************/
package org.eclipse.jpt.core.internal;

import java.util.ListIterator;
import org.eclipse.jpt.core.JpaPlatformProvider;
import org.eclipse.jpt.core.JpaResourceModelProvider;
import org.eclipse.jpt.core.ResourceDefinition;
import org.eclipse.jpt.core.context.java.JavaAttributeMappingDefinition;
import org.eclipse.jpt.core.context.java.JavaTypeMappingDefinition;
import org.eclipse.jpt.core.context.java.NullDefaultJavaAttributeMappingDefinition;
import org.eclipse.jpt.core.context.java.NullJavaTypeMappingDefinition;
import org.eclipse.jpt.core.context.java.NullSpecifiedJavaAttributeMappingDefinition;
import org.eclipse.jpt.utility.internal.ArrayTools;
import org.eclipse.jpt.utility.internal.iterators.ArrayListIterator;

/**
 * All the state in the JPA platform should be "static" (i.e. unchanging once
 * it is initialized).
 */
public abstract class AbstractJpaPlatformProvider
	implements JpaPlatformProvider
{
	private JpaResourceModelProvider[] resourceModelProviders;

	private JavaTypeMappingDefinition[] javaTypeMappingDefinitions;

	private JavaAttributeMappingDefinition[] specifiedJavaAttributeMappingDefinitions;

	private JavaAttributeMappingDefinition[] defaultJavaAttributeMappingDefinitions;

	private ResourceDefinition[] resourceDefinitions;


	/**
	 * zero-argument constructor
	 */
	protected AbstractJpaPlatformProvider() {
		super();
	}


	// ********** resource models **********
	
	public ListIterator<JpaResourceModelProvider> resourceModelProviders() {
		return new ArrayListIterator<JpaResourceModelProvider>(getResourceModelProviders());
	}
	
	protected synchronized JpaResourceModelProvider[] getResourceModelProviders() {
		if (this.resourceModelProviders == null) {
			this.resourceModelProviders = this.buildResourceModelProviders();
		}
		return this.resourceModelProviders;
	}
	
	protected abstract JpaResourceModelProvider[] buildResourceModelProviders();
	
	
	// ********** Java type mappings **********
	
	public ListIterator<JavaTypeMappingDefinition> javaTypeMappingDefinitions() {
		return new ArrayListIterator<JavaTypeMappingDefinition>(getJavaTypeMappingDefinitions());
	}
	
	protected synchronized JavaTypeMappingDefinition[] getJavaTypeMappingDefinitions() {
		if (this.javaTypeMappingDefinitions == null) {
			this.javaTypeMappingDefinitions = this.buildJavaTypeMappingDefinitions();
		}
		return this.javaTypeMappingDefinitions;
	}
	
	/**
	 * Return an array of mapping definitions to use for analyzing the mapping of a type given all 
	 * annotations on it.  The order is important, as once a mapping definition tests positive for an 
	 * attribute, all following mapping definitions are ignored.
	 * Extenders may either overwrite this method or {@link #buildNonNullJavaTypeMappingDefinitions()}.
	 * Doing the former places the additional requirement on the extender to provide a "null"
	 * mapping definition (@see {@link NullJavaTypeMappingDefinition}.)
	 */
	protected JavaTypeMappingDefinition[] buildJavaTypeMappingDefinitions() {
		return ArrayTools.add(
			buildNonNullJavaTypeMappingDefinitions(), 
			NullJavaTypeMappingDefinition.instance());
	}
	
	/**
	 * No-op implementation of this method. 
	 * @see #buildJavaTypeMappingDefinitions()
	 */
	protected JavaTypeMappingDefinition[] buildNonNullJavaTypeMappingDefinitions() {
		return new JavaTypeMappingDefinition[0];
	}
	
	
	// ********** Java attribute mappings **********
	
	public ListIterator<JavaAttributeMappingDefinition> defaultJavaAttributeMappingDefinitions() {
		return new ArrayListIterator<JavaAttributeMappingDefinition>(getDefaultJavaAttributeMappingDefinitions());
	}
	
	protected synchronized JavaAttributeMappingDefinition[] getDefaultJavaAttributeMappingDefinitions() {
		if (this.defaultJavaAttributeMappingDefinitions == null) {
			this.defaultJavaAttributeMappingDefinitions = this.buildDefaultJavaAttributeMappingDefinitions();
		}
		return this.defaultJavaAttributeMappingDefinitions;
	}
	
	/**
	 * Return an array of mapping definitions to use for analyzing the default mapping of an attribute
	 * in the absence of any annotations.  The order is important, as once a mapping definition tests
	 * positively for a given attribute, all following mapping definitions are ignored.
	 * Extenders may either overwrite this method or 
	 * {@link #buildNonNullDefaultJavaAttributeMappingDefinitions()}.
	 * Doing the former places the additional requirement on the extender to provide a "null"
	 * mapping definition (@see {@link NullDefaultJavaAttributeMappingDefinition}.)
	 */
	protected JavaAttributeMappingDefinition[] buildDefaultJavaAttributeMappingDefinitions() {
		return ArrayTools.add(
			buildNonNullDefaultJavaAttributeMappingDefinitions(), 
			NullDefaultJavaAttributeMappingDefinition.instance());
	}
	
	/**
	 * No-op implementation of this method. 
	 * @see #buildDefaultJavaAttributeMappingDefinitions()
	 */
	protected JavaAttributeMappingDefinition[] buildNonNullDefaultJavaAttributeMappingDefinitions() {
		return new JavaAttributeMappingDefinition[0];
	}
	
	public ListIterator<JavaAttributeMappingDefinition> specifiedJavaAttributeMappingDefinitions() {
		return new ArrayListIterator<JavaAttributeMappingDefinition>(
			getSpecifiedJavaAttributeMappingDefinitions());
	}
	
	protected synchronized JavaAttributeMappingDefinition[] getSpecifiedJavaAttributeMappingDefinitions() {
		if (this.specifiedJavaAttributeMappingDefinitions == null) {
			this.specifiedJavaAttributeMappingDefinitions = this.buildSpecifiedJavaAttributeMappingDefinitions();
		}
		return this.specifiedJavaAttributeMappingDefinitions;
	}
	
	/**
	 * Return an array of mapping definitions to use for analyzing the specified mapping of an attribute
	 * given all annotations on it.  The order is important, as once a mapping definition tests
	 * positively for a given attribute, all following mapping definitions are ignored.
	 * Extenders may either overwrite this method or 
	 * {@link #buildNonNullSpecifiedJavaAttributeMappingDefinitions()}.
	 * Doing the former places the additional requirement on the extender to provide a "null"
	 * mapping definition (@see {@link NullSpecifiedJavaAttributeMappingDefinition}.)
	 */
	protected JavaAttributeMappingDefinition[] buildSpecifiedJavaAttributeMappingDefinitions() {
		return ArrayTools.add(
			buildNonNullSpecifiedJavaAttributeMappingDefinitions(), 
			NullSpecifiedJavaAttributeMappingDefinition.instance());
	}
	
	/**
	 * No-op implementation of this method. 
	 * @see #buildSpecifiedJavaAttributeMappingDefinitions()
	 */
	protected JavaAttributeMappingDefinition[] buildNonNullSpecifiedJavaAttributeMappingDefinitions() {
		return new JavaAttributeMappingDefinition[0];
	}
	
	
	// ********** Mapping Files **********
	
	public ListIterator<ResourceDefinition> resourceDefinitions() {
		return new ArrayListIterator<ResourceDefinition>(getResourceDefinitions());
	}
	
	protected synchronized ResourceDefinition[] getResourceDefinitions() {
		if (this.resourceDefinitions == null) {
			this.resourceDefinitions = this.buildResourceDefinitions();
		}
		return this.resourceDefinitions;
	}
	
	protected abstract ResourceDefinition[] buildResourceDefinitions();
}