// Returns the resulting file or in case of extraction the destination
// directory (for logging).
static Try<string> fetchFromCache(
    const FetcherInfo::Item& item,
    const string& cacheDirectory,
    const string& sandboxDirectory)
{
  LOG(INFO) << "Fetching from cache";

  if (item.uri().has_output_file()) {
    string dirname = Path(item.uri().output_file()).dirname();
    if (dirname != ".") {
      Try<Nothing> result =
        os::mkdir(path::join(sandboxDirectory, dirname), true);

      if (result.isError()) {
        return Error(
          "Unable to create subdirectory " + dirname + "in sandbox");
      }
    }
  }

  Try<string> outputFile = item.uri().has_output_file()
    ? item.uri().output_file()
    : Fetcher::basename(item.uri().value());

  if (outputFile.isError()) {
    return Error(outputFile.error());
  }

  string destinationPath = path::join(sandboxDirectory, outputFile.get());

  // Non-empty cache filename is guaranteed by the callers of this function.
  CHECK(!item.cache_filename().empty());

  string sourcePath = path::join(cacheDirectory, item.cache_filename());

  if (item.uri().executable()) {
    Try<string> copied = copyFile(sourcePath, destinationPath);
    if (copied.isError()) {
      return Error(copied.error());
    }

    return chmodExecutable(copied.get());
  } else if (item.uri().extract()) {
    Try<bool> extracted = extract(sourcePath, sandboxDirectory);
    if (extracted.isError()) {
      return Error(extracted.error());
    } else if (extracted.get()) {
      return sandboxDirectory;
    } else {
      LOG(WARNING) << "Copying instead of extracting resource from URI with "
                   << "'extract' flag, because it does not seem to be an "
                   << "archive: " << item.uri().value();
    }
  }

  return copyFile(sourcePath, destinationPath);
}

// Returns the resulting file or in case of extraction the destination
// directory (for logging).
static Try<string> fetch(
    const FetcherInfo::Item& item,
    const Option<string>& cacheDirectory,
    const string& sandboxDirectory,
    const Option<string>& frameworksHome)
{
  LOG(INFO) << "Fetching URI '" << item.uri().value() << "'";

  if (item.action() == FetcherInfo::Item::BYPASS_CACHE) {
    return fetchBypassingCache(
        item.uri(),
        sandboxDirectory,
        frameworksHome);
  }

  return fetchThroughCache(
      item,
      cacheDirectory,
      sandboxDirectory,
      frameworksHome);
}

// Returns the resulting file or in case of extraction the destination
// directory (for logging).
static Try<string> fetchFromCache(
    const FetcherInfo::Item& item,
    const string& cacheDirectory,
    const string& sandboxDirectory)
{
  LOG(INFO) << "Fetching from cache";

  Try<string> basename = Fetcher::basename(item.uri().value());
  if (basename.isError()) {
    return Error(basename.error());
  }

  string destinationPath = path::join(sandboxDirectory, basename.get());

  string sourcePath = path::join(cacheDirectory, item.cache_filename());

  if (item.uri().executable()) {
    Try<string> copied = copyFile(sourcePath, destinationPath);
    if (copied.isError()) {
      return Error(copied.error());
    }

    return chmodExecutable(copied.get());
  } else if (item.uri().extract()) {
    Try<bool> extracted = extract(sourcePath, sandboxDirectory);
    if (extracted.isError()) {
      return Error(extracted.error());
    } else if (extracted.get()) {
      return sandboxDirectory;
    } else {
      LOG(WARNING) << "Copying instead of extracting resource from URI with "
                   << "'extract' flag, because it does not seem to be an "
                   << "archive: " << item.uri().value();
    }
  }

  return copyFile(sourcePath, destinationPath);
}