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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.io;

import static br.com.objectos.core.lang.Preconditions.checkArgument;

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UncheckedIOException;
import java.net.URL;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;

/**
 * @author [email protected] (Marcio Endo)
 */
public class Resource implements ByteSource, CharSource {

  private final URL url;

  private Resource(URL url) {
    this.url = url;
  }

  public static Resource of(String resourceName) {
    return of(Resource.class, resourceName);
  }

  public static Resource of(Class contextClass, String resourceName) {
    URL url = contextClass.getResource(resourceName);
    checkArgument(url != null, "Resource %s not found.", resourceName);
    return new Resource(url);
  }

  @Override
  public final Stream lines() throws IOException {
    BufferedReader reader = openBufferedReader(Charset.defaultCharset());
    try {
      return reader.lines().onClose(asUncheckedRunnable(reader));
    } catch (Error | RuntimeException e) {
      try {
        reader.close();
      } catch (IOException ex) {
        try {
          e.addSuppressed(ex);
        } catch (Throwable ignore) {
        }
      }
      throw e;
    }
  }

  @Override
  public InputStream openStream() throws IOException {
    return url.openStream();
  }

  @Override
  public final List readAllLines() throws IOException {
    return readAllLines(Charset.defaultCharset());
  }

  @Override
  public final List readAllLines(Charset charset) throws IOException {
    try (BufferedReader reader = openBufferedReader(charset)) {
      List result = new ArrayList<>();
      String line = reader.readLine();
      while (line != null) {
        result.add(line);
        line = reader.readLine();
      }
      return result;
    }
  }

  @Override
  public final String readToString() throws IOException {
    CharBuffer buf = CharBuffer.allocate(4096);
    StringBuilder str = new StringBuilder();
    try (Reader reader = new InputStreamReader(openStream())) {
      while (reader.read(buf) != -1) {
        buf.flip();
        str.append(buf);
        buf.clear();
      }
    }
    return str.toString();
  }

  private BufferedReader openBufferedReader(Charset charset) throws IOException {
    InputStream in = openStream();
    InputStreamReader reader = new InputStreamReader(in, charset);
    return new BufferedReader(reader);
  }

  private Runnable asUncheckedRunnable(Closeable c) {
    return () -> {
      try {
        c.close();
      } catch (IOException e) {
        throw new UncheckedIOException(e);
      }
    };
  }

}