io.github.oliviercailloux.gitjfs.impl.GitPathRootRefImpl Maven / Gradle / Ivy

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package io.github.oliviercailloux.gitjfs.impl;

import static com.google.common.base.Preconditions.checkArgument;

import io.github.oliviercailloux.gitjfs.GitPathRootRef;
import java.io.IOException;
import java.nio.file.NoSuchFileException;
import java.util.Optional;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.revwalk.RevCommit;

public class GitPathRootRefImpl extends GitPathRootImpl implements GitPathRootRef {

  private GitPathRootShaImpl sha;

  protected GitPathRootRefImpl(GitFileSystemImpl fileSystem, GitRev gitRev) {
    super(fileSystem, gitRev);
    checkArgument(gitRev.isRef());
    sha = null;
  }

  @Override
  public GitPathRootShaImpl toSha() throws IOException, NoSuchFileException {
    refreshCache();
    if (sha == null) {
      throw new NoSuchFileException(toString());
    }
    return sha;
  }

  private void refreshCache() throws IOException, NoSuchFileException {
    final Optional newIdOpt = getFileSystem().getObjectId(getGitRef());
    final GitPathRootShaImpl newSha;
    if (newIdOpt.isPresent()) {
      final ObjectId newId = newIdOpt.get();
      /*
       * We try to hold to our existing reference if possible, because it may contain valuable cache
       * data.
       */
      if (sha == null || !sha.getStaticCommitId().equals(newId)) {
        newSha = getFileSystem().getPathRoot(newId);
      } else {
        newSha = sha;
      }
    } else {
      newSha = null;
    }
    sha = newSha;
  }

  @Override
  RevCommit getRevCommit() throws IOException, NoSuchFileException {
    return toSha().getRevCommit();
  }
}