/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hcatalog.data;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.hadoop.hive.serde2.SerDeException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.typeinfo.ListTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.MapTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.StructTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * ObjectInspectorFactory for HCatRecordObjectInspectors (and associated helper inspectors)
 */
public class HCatRecordObjectInspectorFactory {

    private final static Logger LOG = LoggerFactory.getLogger(HCatRecordObjectInspectorFactory.class);

    static HashMap<TypeInfo, HCatRecordObjectInspector> cachedHCatRecordObjectInspectors =
        new HashMap<TypeInfo, HCatRecordObjectInspector>();
    static HashMap<TypeInfo, ObjectInspector> cachedObjectInspectors =
        new HashMap<TypeInfo, ObjectInspector>();

    /**
     * Returns HCatRecordObjectInspector given a StructTypeInfo type definition for the record to look into
     * @param typeInfo Type definition for the record to look into
     * @return appropriate HCatRecordObjectInspector
     * @throws SerDeException
     */
    public static HCatRecordObjectInspector getHCatRecordObjectInspector(
        StructTypeInfo typeInfo) throws SerDeException {
        HCatRecordObjectInspector oi = cachedHCatRecordObjectInspectors.get(typeInfo);
        if (oi == null) {

            LOG.debug("Got asked for OI for {} [{} ]", typeInfo.getCategory(), typeInfo.getTypeName());
            switch (typeInfo.getCategory()) {
            case STRUCT:
                StructTypeInfo structTypeInfo = (StructTypeInfo) typeInfo;
                List<String> fieldNames = structTypeInfo.getAllStructFieldNames();
                List<TypeInfo> fieldTypeInfos = structTypeInfo.getAllStructFieldTypeInfos();
                List<ObjectInspector> fieldObjectInspectors = new ArrayList<ObjectInspector>(fieldTypeInfos.size());
                for (int i = 0; i < fieldTypeInfos.size(); i++) {
                    fieldObjectInspectors.add(getStandardObjectInspectorFromTypeInfo(fieldTypeInfos.get(i)));
                }
                oi = new HCatRecordObjectInspector(fieldNames, fieldObjectInspectors);

                break;
            default:
                // Hmm.. not good,
                // the only type expected here is STRUCT, which maps to HCatRecord
                // - anything else is an error. Return null as the inspector.
                throw new SerDeException("TypeInfo [" + typeInfo.getTypeName()
                    + "] was not of struct type - HCatRecord expected struct type, got ["
                    + typeInfo.getCategory().toString() + "]");
            }
            cachedHCatRecordObjectInspectors.put(typeInfo, oi);
        }
        return oi;
    }

    public static ObjectInspector getStandardObjectInspectorFromTypeInfo(TypeInfo typeInfo) {


        ObjectInspector oi = cachedObjectInspectors.get(typeInfo);
        if (oi == null) {

            LOG.debug("Got asked for OI for {}, [{}]", typeInfo.getCategory(), typeInfo.getTypeName());
            switch (typeInfo.getCategory()) {
            case PRIMITIVE:
                oi = PrimitiveObjectInspectorFactory.getPrimitiveJavaObjectInspector(
                    ((PrimitiveTypeInfo) typeInfo).getPrimitiveCategory());
                break;
            case STRUCT:
                StructTypeInfo structTypeInfo = (StructTypeInfo) typeInfo;
                List<String> fieldNames = structTypeInfo.getAllStructFieldNames();
                List<TypeInfo> fieldTypeInfos = structTypeInfo.getAllStructFieldTypeInfos();
                List<ObjectInspector> fieldObjectInspectors =
                    new ArrayList<ObjectInspector>(fieldTypeInfos.size());
                for (int i = 0; i < fieldTypeInfos.size(); i++) {
                    fieldObjectInspectors.add(getStandardObjectInspectorFromTypeInfo(fieldTypeInfos.get(i)));
                }
                oi = ObjectInspectorFactory.getStandardStructObjectInspector(
                    fieldNames, fieldObjectInspectors
                );
                break;
            case LIST:
                ObjectInspector elementObjectInspector = getStandardObjectInspectorFromTypeInfo(
                    ((ListTypeInfo) typeInfo).getListElementTypeInfo());
                oi = ObjectInspectorFactory.getStandardListObjectInspector(elementObjectInspector);
                break;
            case MAP:
                ObjectInspector keyObjectInspector = getStandardObjectInspectorFromTypeInfo(
                    ((MapTypeInfo) typeInfo).getMapKeyTypeInfo());
                ObjectInspector valueObjectInspector = getStandardObjectInspectorFromTypeInfo(
                    ((MapTypeInfo) typeInfo).getMapValueTypeInfo());
                oi = ObjectInspectorFactory.getStandardMapObjectInspector(keyObjectInspector, valueObjectInspector);
                break;
            default:
                oi = null;
            }
            cachedObjectInspectors.put(typeInfo, oi);
        }
        return oi;
    }


}