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/*--------------------------------------------------------------------------
 *  Copyright 2007 Taro L. Saito
 *
 *  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.
 *--------------------------------------------------------------------------*/
//--------------------------------------
// XerialJ Project
//
// RelationBuilder.java
// Since: Apr 18, 2007
//
// $URL$ 
// $Author$
//--------------------------------------
package org.xerial.db.sql;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.xerial.core.XerialException;
import org.xerial.db.Relation;
import org.xerial.db.datatype.DataType;
import org.xerial.json.JSONArray;
import org.xerial.json.JSONErrorCode;
import org.xerial.json.JSONException;
import org.xerial.json.JSONObject;
import org.xerial.util.bean.BeanBinder;
import org.xerial.util.bean.BeanBinderSet;
import org.xerial.util.bean.BeanUtil;
import org.xerial.util.lens.ObjectLens;
import org.xerial.util.lens.impl.ParameterSetter;

/**
 * RelationBuilder creates a Relation instance from a JSON string or a Bean
 * class.
 * 
 * JSON format example. 
 * {"relation":[["id", "integer"], ["name", "string"], ...]}
 * 
 * 
 * @author leo
 * 
 */
public class RelationBuilder
{

    public static List extractBeanParameterList(Class beanClass) throws XerialException {
        ArrayList parameterList = new ArrayList();

        BeanBinderSet outputRuleSet = BeanUtil.getBeanOutputRule(beanClass);
        for (BeanBinder rule : outputRuleSet.getBindRules()) {
            String parameterName = rule.getParameterName();
            parameterList.add(parameterName);
        }
        return parameterList;
    }

    public static JSONObject toJSON(Relation r) {
        JSONObject obj = new JSONObject();
        JSONArray dataTypeList = new JSONArray();
        for (Iterator it = r.getDataTypeList().iterator(); it.hasNext();) {
            DataType dt = (DataType) it.next();
            JSONArray dataTypePair = new JSONArray();
            dataTypePair.add(dt.getName());
            dataTypePair.add(dt.getTypeName());
            dataTypeList.add(dataTypePair);
        }
        obj.put("relation", dataTypeList);
        return obj;
    }

    public static Relation createRelation(String jsonString) throws JSONException {
        Relation r = new Relation();
        JSONObject json = new JSONObject(jsonString);

        JSONArray dataTypeList;
        dataTypeList = json.getJSONArray("relation");
        if (dataTypeList == null)
            throw new JSONException(JSONErrorCode.InvalidJSONData, "no relation is found");
        for (int i = 0; i < dataTypeList.size(); i++) {
            try {
                JSONArray dataType = dataTypeList.getJSONArray(i);
                if (dataType.size() != 2)
                    throw new JSONException(JSONErrorCode.InvalidJSONData);

                String parameterName = dataType.get(0).toString();
                String typeName = dataType.get(1).toString();

                DataType dt = Relation.getDataType(parameterName, typeName);
                r.add(dt);
            }
            catch (JSONException e) {
                throw new JSONException(JSONErrorCode.InvalidJSONData, dataTypeList.toString()
                        + " does not contain a pair of [param_name, data_type_str]");
            }

        }

        return r;
    }

    public static Relation createRelation(Class< ? > beanClass) throws XerialException {
        return new BeanToRelationProcess().createRelation(beanClass);
    }

    private static class BeanToRelationProcess
    {
        private Relation _relation = new Relation();

        public BeanToRelationProcess() {}

        public Relation createRelation(Class< ? > beanClass) throws XerialException {
            if (beanClass == null)
                return _relation;

            ObjectLens lens = ObjectLens.getObjectLens(beanClass);
            for (ParameterSetter setter : lens.getSetterList()) {
                Class< ? > returnType = setter.getParameterType();
                String p = setter.getCanonicalParameterName();

                DataType dt = Relation.getDataType(p, returnType);
                _relation.add(dt);

            }

            return _relation;

        }

    }

}