/*******************************************************************************
 * Copyright (c) 2011, 2013 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 * 		dclarke/tware - initial 
 ******************************************************************************/
package org.eclipse.persistence.jpa.rs.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.dynamic.DynamicEntity;
import org.eclipse.persistence.internal.descriptors.PersistenceEntity;
import org.eclipse.persistence.internal.dynamic.DynamicEntityImpl;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.internal.jpa.CMP3Policy;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.jpa.JpaHelper;
import org.eclipse.persistence.jpa.rs.PersistenceContext;
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.OneToOneMapping;
import org.eclipse.persistence.queries.FetchGroupTracker;
import org.eclipse.persistence.sessions.DatabaseSession;


/**
 * EclipseLink helper class used for converting composite key values passed into
 * JAX-RS calls as query or matrix parameters into a value that can be used in a
 * find.
 * 
 * @author dclarke
 * @since EclipseLink 2.4.0
 */
public class IdHelper {

    private static final String SEPARATOR_STRING = "+";

    @SuppressWarnings("rawtypes")
    public static Object buildId(PersistenceContext app, String entityName, String idString) {
        DatabaseSession session = app.getJpaSession();
        ClassDescriptor descriptor = app.getDescriptor(entityName);
        List<DatabaseMapping> pkMappings = descriptor.getObjectBuilder().getPrimaryKeyMappings();
        List<SortableKey> pkIndices = new ArrayList<SortableKey>();
        int index = 0;
        int multitenantPKMappings = 0;
        for (DatabaseMapping mapping: pkMappings){
            if (mapping.isMultitenantPrimaryKeyMapping()){
                multitenantPKMappings++;
            } else {
                pkIndices.add(new SortableKey(mapping, index));
                index++;
            }
        }
        Collections.sort(pkIndices);

        // Handle composite key in map
        Object[] keyElements = new Object[pkMappings.size() - multitenantPKMappings];
        StringTokenizer tokenizer = new StringTokenizer(idString, SEPARATOR_STRING);
        int tokens = tokenizer.countTokens();
        if (tokens + multitenantPKMappings != pkMappings.size()){
            throw new RuntimeException("Failed, incorrect number of keys values");
        }
        index = 0;
        Iterator<SortableKey> iterator = pkIndices.iterator();
        while (tokenizer.hasMoreTokens()){
            SortableKey key = iterator.next();
            String token = tokenizer.nextToken();
            DatabaseMapping mapping = key.getMapping();
            Class attributeClasification = mapping.getAttributeClassification();
            if (attributeClasification == null) {
                if ((mapping.getFields() != null) && (!mapping.getFields().isEmpty())) {
                    attributeClasification = mapping.getFields().get(0).getType();
                }
            }
            
            Object idValue = session.getDatasourcePlatform().getConversionManager().convertObject(token, attributeClasification);
            keyElements[key.getIndex()] = idValue;
            index++;
        }

        if (descriptor.hasCMPPolicy()) {
            CMP3Policy policy = (CMP3Policy) descriptor.getCMPPolicy();
            return policy.createPrimaryKeyInstanceFromPrimaryKeyValues((AbstractSession) session, new int[]{0}, keyElements);
        }

        if (keyElements.length == 1) {
            return keyElements[0];
        }
        return keyElements;
    }

    public static String stringifyId(Object entity, String typeName, PersistenceContext app) {
        ClassDescriptor descriptor = app.getDescriptor(typeName);
        List<DatabaseMapping> pkMappings = descriptor.getObjectBuilder().getPrimaryKeyMappings();
        if (pkMappings.isEmpty()) {
            return "";
        }
        List<SortableKey> pkIndices = new ArrayList<SortableKey>();
        int index = 0;
        for (DatabaseMapping mapping : pkMappings) {
            pkIndices.add(new SortableKey(mapping, index));
            index++;
        }
        Collections.sort(pkIndices);
        StringBuffer key = new StringBuffer();
        Iterator<SortableKey> sortableKeys = pkIndices.iterator();
        List<DatabaseField> refObjectdbFields = null;
        while (sortableKeys.hasNext()) {
            DatabaseMapping mapping = sortableKeys.next().getMapping();
            ClassDescriptor refDesc = mapping.getReferenceDescriptor();
            List<DatabaseField> dbFields = mapping.getDescriptor().getPrimaryKeyFields();
            if (refDesc != null) {
                refObjectdbFields = refDesc.getFields();
            }

            if ((refObjectdbFields != null) && (!refObjectdbFields.isEmpty())) {
                for (DatabaseField dbField : dbFields) {
                    String dbFieldName = dbField.getName();
                    String refObjectDbFieldName = null;
                    if (refDesc != null) {
                        for (DatabaseField refObjectDbField : refObjectdbFields) {
                            refObjectDbFieldName = refObjectDbField.getName();
                            if ((refObjectDbFieldName != null) && (dbFieldName != null)) {
                                if (dbFieldName.equals(refObjectDbFieldName)) {
                                    List<DatabaseMapping> refMappings = refDesc.getMappings();
                                    for (DatabaseMapping refMapping : refMappings) {//
                                        DatabaseField field = refMapping.getField();
                                        if (field != null) {
                                            String fieldName = field.getName();
                                            if (mapping instanceof OneToOneMapping) {
                                                Map<DatabaseField, DatabaseField> targetToSourceKeyFields = ((OneToOneMapping) mapping).getTargetToSourceKeyFields();
                                                Map<DatabaseField, DatabaseField> sourceToTargetFields = ((OneToOneMapping) mapping).getTargetToSourceKeyFields();
                                                if ((targetToSourceKeyFields != null) && (!targetToSourceKeyFields.isEmpty())) {
                                                    if (targetToSourceKeyFields.containsKey(refObjectDbField)) {
                                                        if ((sourceToTargetFields != null) && (!sourceToTargetFields.isEmpty())) {
                                                            if (sourceToTargetFields.containsKey(field)) {
                                                                if ((fieldName != null) && (dbFieldName.equals(fieldName))) {
                                                                    Object value = descriptor.getObjectBuilder().getBaseValueForField(dbField, entity);
                                                                    Object realAttributeValue = refMapping.getRealAttributeValueFromAttribute(refMapping.getAttributeValueFromObject(value), value, (AbstractSession) app.getJpaSession());
                                                                    key.append(realAttributeValue);
                                                                }
                                                            }
                                                        }
                                                    }
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            } else {
                Object part = mapping.getAttributeValueFromObject(entity);
                key.append(part);
            }
            if (sortableKeys.hasNext()) {
                key.append(SEPARATOR_STRING);
                refObjectdbFields = null;
            }
        }
        return key.toString();
    }

    /**
     * build a shell of an object based on a primary key.  The object shell will be an instance of the object with
     * only primary key populated
     * @param context
     * @param entityType
     * @param id
     * @return
     */
    public static Object buildObjectShell(PersistenceContext context,  String entityType, Object id) {
        ClassDescriptor descriptor = context.getDescriptor(entityType);
        List<DatabaseMapping> pkMappings = descriptor.getObjectBuilder().getPrimaryKeyMappings();
        Object entity = null;
        if (descriptor.hasCMPPolicy()) {
            CMP3Policy policy = (CMP3Policy) descriptor.getCMPPolicy();
            entity = policy.createBeanUsingKey(id, (AbstractSession) context.getJpaSession());
        } else if (entity instanceof DynamicEntity) {
            DynamicEntityImpl dynamicEntity = (DynamicEntityImpl) context.newEntity(entityType);
            // if there is only one PK mapping, we assume the id object
            // represents the value of that mapping
            if (pkMappings.size() == 1) {
                dynamicEntity.set(pkMappings.get(0).getAttributeName(), id);
            } else {
                // If there are more that one PK, we assume an array as produced
                // by buildId() above with the keys
                // based on a sorted order of PK fields
                List<SortableKey> pkIndices = new ArrayList<SortableKey>();
                int index = 0;
                for (DatabaseMapping mapping : pkMappings) {
                    pkIndices.add(new SortableKey(mapping, index));
                    index++;
                }
                Collections.sort(pkIndices);
                Object[] keyElements = (Object[]) id;
                for (SortableKey key : pkIndices) {
                    dynamicEntity.set(key.getMapping().getAttributeName(), keyElements[key.getIndex()]);
                }
            }
            entity = dynamicEntity;
        } else {
            throw new RuntimeException("Could not create shell for entity.");
        }

        if (entity instanceof PersistenceEntity) {
            ((PersistenceEntity) entity)._persistence_setId(id);
        }
        if (entity instanceof FetchGroupTracker) {
            ((FetchGroupTracker) entity)._persistence_setSession(JpaHelper.getDatabaseSession(context.getEmf()));
        }

        return entity;
    }


    private static class SortableKey implements Comparable<SortableKey>{

        private DatabaseMapping mapping;
        private int index;

        public SortableKey(DatabaseMapping mapping, int index){
            this.mapping = mapping;
            this.index = index;
        }

        public int compareTo(SortableKey o){
            return mapping.getAttributeName().compareTo(o.getMapping().getAttributeName());
        }

        public DatabaseMapping getMapping(){
            return mapping;
        }

        public int getIndex(){
            return index;
        }

    }
}