/* 
 * 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.
 */

namespace ParquetSharp.IO.Api
{
    using System;

    /**
     * Top-level class which should be implemented in order to materialize objects from
     * a stream of Parquet data.
     * 
     * Each record will be wrapped by {@link GroupConverter#start()} and {@link GroupConverter#end()},
     * between which the appropriate fields will be materialized.
     *
     * @author Julien Le Dem
     *
     * @param <T> the materialized object class
     */
    abstract public class RecordMaterializer<T>
    {
        /**
         * @return the result of the conversion
         * @throws RecordMaterializationException to signal that a record cannot be materialized, but can be skipped
         */
        abstract public T getCurrentRecord();

        /**
         * Called if {@link #getCurrentRecord()} isn't going to be called.
         */
        public virtual void skipCurrentRecord() { }

        /**
         * @return the root converter for this tree
         */
        abstract public GroupConverter getRootConverter();

        /**
         * This exception signals that the current record is cannot be converted from parquet columns to a materialized
         * record, but can be skipped if requested. This exception should be used to signal errors like a union with no
         * set values, or an error in converting parquet primitive values to a materialized record. It should not
         * be used to signal unrecoverable errors, like a data column being corrupt or unreadable.
         */
        public class RecordMaterializationException : ParquetDecodingException
        {
            public RecordMaterializationException()
            {
            }

            public RecordMaterializationException(string message, Exception cause)
                : base(message, cause)
            {
            }

            public RecordMaterializationException(string message)
                : base(message)
            {
            }

            public RecordMaterializationException(Exception cause)
                : base(cause.Message, cause)
            {
            }
        }
    }
}
