/**
 * 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.
 *
 * Modified by Tuukka Lehtonen - Semantum Oy
 *  - allow extracting native library to designated directory
 */
package net.jpountz.util;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;

/** FOR INTERNAL USE ONLY */
public enum Native {
  ;

  private enum OS {
    // Even on Windows, the default compiler from cpptasks (gcc) uses .so as a shared lib extension
    WINDOWS("win32", "dll"), LINUX("linux", "so"), MAC("darwin", "dylib"), SOLARIS("solaris", "so");
    public final String name, libExtension;

    private OS(String name, String libExtension) {
      this.name = name;
      this.libExtension = libExtension;
    }
  }

  private static String arch() {
    return System.getProperty("os.arch");
  }

  private static OS os() {
    String osName = System.getProperty("os.name");
    if (osName.contains("Linux")) {
      return OS.LINUX;
    } else if (osName.contains("Mac")) {
      return OS.MAC;
    } else if (osName.contains("Windows")) {
      return OS.WINDOWS;
    } else if (osName.contains("Solaris") || osName.contains("SunOS")) {
      return OS.SOLARIS;
    } else {
      throw new UnsupportedOperationException("Unsupported operating system: "
          + osName);
    }
  }

  private static String resourceName() {
    OS os = os();
    String packagePrefix = Native.class.getPackage().getName().replace('.', '/');

    return "/" + packagePrefix + "/" + os.name + "/" + arch() + "/liblz4-java." + os.libExtension;
  }

  private static boolean loaded = false;
  private static boolean failedToLoad = false;

  public static synchronized boolean isLoaded() {
    return loaded;
  }

  public static boolean failedToLoad() {
    return failedToLoad;
  }

  public static synchronized void load() {
    load(NativeParameters.extractionPath);
  }

  public static synchronized void load(Path extractionPath) {
    if (loaded)
      return;
    if (failedToLoad)
      throw new UnsatisfiedLinkError("Native LZ4 dynamic library loading failed already. Not retrying.");

    String resourceName = resourceName();
    URL libraryUrl = Native.class.getResource(resourceName);
    if (libraryUrl == null)
      throw new UnsupportedOperationException("Unsupported OS/arch, cannot find " + resourceName + ". Please try building from source.");

    try {
      Path tempFile = null, out;
      boolean extract = true;

      try {
        if (extractionPath == null) {
          out = tempFile = Files.createTempFile("liblz4-java", "." + os().libExtension);
        } else {
          out = extractionPath.resolve("liblz4-java." + os().libExtension);
          if (Files.exists(out)) {
            byte[] sourceHash = ChecksumUtil.computeSum(libraryUrl);
            byte[] targetHash = ChecksumUtil.computeSum(out);
            extract = !Arrays.equals(sourceHash, targetHash);
          }
        }
        if (extract)
          copy(libraryUrl, out);
        System.load(out.toString());
        loaded = true;
      } finally {
        if (tempFile != null && Files.exists(tempFile)) {
          if (!loaded) {
            Files.deleteIfExists(tempFile);
          } else {
            // This probably doesn't work on Windows at all.
            tempFile.toFile().deleteOnExit();
          }
        }
      }
    } catch (UnsatisfiedLinkError e) {
      failedToLoad = true;
      throw e;
    } catch (IOException e) {
      failedToLoad = true;
      throw new ExceptionInInitializerError("Cannot unpack liblz4-java");
    }
  }

  private static long copy(URL url, Path to) throws IOException {
    try (InputStream in = url.openStream()) {
      return Files.copy(in, to);
    }
  }

}