/*
 * 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.sysds.runtime.io;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.sysds.common.Types.ValueType;
import org.apache.sysds.runtime.DMLRuntimeException;
import org.apache.sysds.runtime.data.TensorBlock;
import org.apache.sysds.runtime.util.HDFSTool;

import java.io.EOFException;
import java.io.IOException;

public abstract class TensorReader {
	public abstract TensorBlock readTensorFromHDFS(String fname, long[] dims, int blen, ValueType[] schema)
			throws IOException, DMLRuntimeException;

	protected static void checkValidInputFile(FileSystem fs, Path path)
			throws IOException {
		//check non-existing file
		if (!fs.exists(path))
			throw new IOException("File " + path.toString() + " does not exist on HDFS/LFS.");

		//check for empty file
		if (HDFSTool.isFileEmpty(fs, path))
			throw new EOFException("Empty input file " + path.toString() + ".");
	}
}
