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/*
 * Copyright 2016 Objectos, Fábrica de Software LTDA.
 *
 * 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.
 */
package br.com.objectos.flat;

import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.nio.file.NoSuchFileException;
import java.util.Objects;
import java.util.Optional;
import java.util.stream.Stream;

import br.com.objectos.core.io.File;
import br.com.objectos.core.io.FileAppender;
import br.com.objectos.core.lang.Preconditions;

/**
 * @author [email protected] (Marcio Endo)
 */
public class FlatFile {

  private final File delegate;

  private FlatFile(File delegate) {
    this.delegate = Objects.requireNonNull(delegate);
  }

  public static FlatFile of(File file) {
    return new FlatFile(file);
  }

  public FlatFile append(FlatWritable record) {
    try (FlatWriter writer = appender()) {
      record.writeTo(writer);
    }
    return this;
  }

  public void deleteUnchecked() {
    delegate.deleteUnchecked();
  }

  public Optional readerAtLastRecord(int size) {
    Preconditions.checkArgument(size > 0);
    try {
      long filesize = delegate.sizeChecked();
      if (filesize == 0) {
        return Optional.empty();
      }

      if (filesize < size) {
        return Optional.empty();
      }

      long toSkip = filesize - (size + 1);
      InputStream in = delegate.openStreamChecked();
      in.skip(toSkip);
      FlatReader reader = FlatReader.open(in);
      return Optional.of(reader);
    } catch (NoSuchFileException e) {
      return Optional.empty();
    } catch (IOException e) {
      throw new UncheckedIOException(e);
    }
  }

  public Stream stream() {
    try {
      InputStream in = delegate.openStreamChecked();
      return FlatReader.open(in).stream();
    } catch (NoSuchFileException e) {
      return Stream.of();
    } catch (IOException e) {
      throw new UncheckedIOException(e);
    }
  }

  private FlatWriter appender() {
    FileAppender out = FileAppender.of(delegate);
    return FlatWriter.of(out);
  }

}