/* Copyright 2004-2005 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.grails.orm.hibernate.metaclass;

import groovy.lang.Closure;
import groovy.lang.MissingMethodException;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.regex.Pattern;

import org.codehaus.groovy.grails.orm.hibernate.exceptions.GrailsQueryException;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.SessionFactoryUtils;

/**
 * Allows the executing of arbitrary HQL updates.
 * <p/>
 * eg. Account.executeUpdate("delete from Account a where a.branch = ?", 'London') or
 * Account.executeUpdate("delete from Account a where a.branch = :branch", [branch:'London'])
 *
 * @author Burt Beckwith
 */
public class ExecuteUpdatePersistentMethod extends AbstractStaticPersistentMethod {

    private static final String METHOD_SIGNATURE = "executeUpdate";
    private static final Pattern METHOD_PATTERN = Pattern.compile("^executeUpdate$");

    public ExecuteUpdatePersistentMethod(SessionFactory sessionFactory, ClassLoader classLoader) {
        super(sessionFactory, classLoader, METHOD_PATTERN);
    }

    @SuppressWarnings("unchecked")
    @Override
    protected Object doInvokeInternal(final Class clazz, final String methodName, Closure additionalCriteria, final Object[] arguments) {

        checkMethodSignature(clazz, arguments);

        return getHibernateTemplate().execute(new HibernateCallback() {
            public Object doInHibernate(Session session) throws HibernateException, SQLException {
                Query q = session.createQuery(arguments[0].toString());
                SessionFactoryUtils.applyTransactionTimeout(q, getHibernateTemplate().getSessionFactory());

                // process positional HQL params
                int index = 0;
                for (Object parameter : extractPositionalParams(arguments)) {
                    q.setParameter(index++, parameter);
                }

                // process named HQL params
                for (Map.Entry entry : (Set<Map.Entry>)extractNamedParams(arguments).entrySet()) {
                    if (!(entry.getKey() instanceof String)) {
                        throw new GrailsQueryException("Named parameter's name must be of type String");
                    }

                    String parameterName = (String)entry.getKey();
                    Object parameterValue = entry.getValue();
                    if (Collection.class.isAssignableFrom(parameterValue.getClass())) {
                        q.setParameterList(parameterName, (Collection)parameterValue);
                    }
                    else if (parameterValue.getClass().isArray()) {
                        q.setParameterList(parameterName, (Object[])parameterValue);
                    }
                    else if (parameterValue instanceof CharSequence) {
                        q.setParameter(parameterName, parameterValue.toString());
                    }
                    else {
                        q.setParameter(parameterName, parameterValue);
                    }
                }
                return q.executeUpdate();
            }
        });
    }

    @SuppressWarnings("unchecked")
    private void checkMethodSignature(Class clazz, Object[] arguments) {
        boolean valid = true;
        if (arguments.length == 0 || arguments.length > 2) {
            valid = false;
        }
        else if (arguments.length == 2 && !(arguments[1] instanceof Map || arguments[1] instanceof Collection)) {
            valid = false;
        }

        if (!valid) {
            throw new MissingMethodException(METHOD_SIGNATURE, clazz, arguments);
        }
    }

    @SuppressWarnings("unchecked")
    private List extractPositionalParams(Object[] arguments) {
        if (arguments.length == 1 || arguments[1] instanceof Map) {
            return Collections.EMPTY_LIST;
        }

        List result = new ArrayList();
        if (arguments[1] instanceof Collection) {
            result.addAll((Collection)arguments[1]);
        }
        else if (arguments[1].getClass().isArray()) {
            result.addAll(Arrays.asList((Object[])arguments[1]));
        }
        else {
            result.add(arguments[1]);
        }

        return result;
    }

    @SuppressWarnings("unchecked")
    private Map extractNamedParams(Object[] arguments) {
        if (arguments.length == 1 || !(arguments[1] instanceof Map)) {
            return Collections.EMPTY_MAP;
        }

        return (Map)arguments[1];
    }
}
