/*
 * 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.flink.runtime.io.disk;

import static org.junit.Assert.*;

import java.io.EOFException;
import java.util.ArrayList;
import java.util.List;

import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.core.memory.MemoryType;
import org.apache.flink.runtime.io.disk.iomanager.BlockChannelWriter;
import org.apache.flink.runtime.io.disk.iomanager.FileIOChannel;
import org.apache.flink.runtime.io.disk.iomanager.IOManager;
import org.apache.flink.runtime.io.disk.iomanager.IOManagerAsync;
import org.apache.flink.runtime.memory.MemoryManager;
import org.apache.flink.runtime.operators.testutils.DummyInvokable;
import org.junit.Test;


public class SeekableFileChannelInputViewTest {

	@Test
	public void testSeek() {
		final IOManager ioManager = new IOManagerAsync();
		final int PAGE_SIZE = 16 * 1024;
		final int NUM_RECORDS = 120000;
		// integers across 7.x pages (7 pages = 114.688 bytes, 8 pages = 131.072 bytes)
		
		try {
			MemoryManager memMan = new MemoryManager(4 * PAGE_SIZE, 1, PAGE_SIZE, MemoryType.HEAP, true);
			List<MemorySegment> memory = new ArrayList<MemorySegment>();
			memMan.allocatePages(new DummyInvokable(), memory, 4);
			
			FileIOChannel.ID channel = ioManager.createChannel();
			BlockChannelWriter<MemorySegment> writer = ioManager.createBlockChannelWriter(channel);
			FileChannelOutputView out = new FileChannelOutputView(writer, memMan, memory, memMan.getPageSize());
			
			// write some integers across 7.5 pages (7 pages = 114.688 bytes, 8 pages = 131.072 bytes)
			for (int i = 0; i < NUM_RECORDS; i += 4) {
				out.writeInt(i);
			}
			// close for the first time, make sure all memory returns
			out.close();
			assertTrue(memMan.verifyEmpty());
			
			memMan.allocatePages(new DummyInvokable(), memory, 4);
			SeekableFileChannelInputView in = new SeekableFileChannelInputView(ioManager, channel, memMan, memory, out.getBytesInLatestSegment());
			
			// read first, complete
			for (int i = 0; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to the middle of the 3rd page
			int i = 2 * PAGE_SIZE + PAGE_SIZE / 4;
			in.seek(i);
			for (; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to the end
			i = 120000 - 4;
			in.seek(i);
			for (; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to the beginning
			i = 0;
			in.seek(i);
			for (; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to after a page
			i = PAGE_SIZE;
			in.seek(i);
			for (; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to after a page
			i = 3 * PAGE_SIZE;
			in.seek(i);
			for (; i < NUM_RECORDS; i += 4) {
				assertEquals(i, in.readInt());
			}
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek to the end
			i = NUM_RECORDS;
			in.seek(i);
			try {
				in.readInt();
				fail("should throw EOF exception");
			} catch (EOFException ignored) {}
			
			// seek out of bounds
			try {
				in.seek(-10);
				fail("should throw an exception");
			} catch (IllegalArgumentException ignored) {}
			try {
				in.seek(NUM_RECORDS + 1);
				fail("should throw an exception");
			} catch (IllegalArgumentException ignored) {}
		}
		catch (Exception e) {
			e.printStackTrace();
			fail(e.getMessage());
		}
		finally {
			ioManager.shutdown();
		}
	}
}