// Copyright 2008 Google Inc.
//
// 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 com.google.gerrit.git;

import org.spearce.jgit.lib.Repository;

import java.io.File;
import java.io.IOException;
import java.util.Random;

public class GitMetaUtil {
  private static final int SLEEP_MIN = 100; // milliseconds
  private static final int SLEEP_MAX = 2 * 60 * 1000; // milliseconds
  private static final ThreadLocal<Random> SLEEP_RNG =
      new ThreadLocal<Random>() {
        @Override
        protected Random initialValue() {
          return new Random();
        }
      };

  private static int waitTime() {
    return SLEEP_MIN + SLEEP_RNG.get().nextInt(SLEEP_MAX - SLEEP_MIN);
  }

  public static void randomSleep() {
    try {
      Thread.sleep(waitTime());
    } catch (InterruptedException ie) {
      // Just let the thread continue anyway.
    }
  }

  public static boolean isGitRepository(final File gitdir) {
    return new File(gitdir, "config").isFile()
        && new File(gitdir, "HEAD").isFile()
        && new File(gitdir, "objects").isDirectory()
        && new File(gitdir, "refs/heads").isDirectory();
  }

  public static Repository open(final File gitdir) throws IOException {
    if (isGitRepository(gitdir)) {
      return new Repository(gitdir);
    }

    if (isGitRepository(new File(gitdir, ".git"))) {
      return new Repository(new File(gitdir, ".git"));
    }

    final String name = gitdir.getName();
    final File parent = gitdir.getParentFile();
    if (isGitRepository(new File(parent, name + ".git"))) {
      return new Repository(new File(parent, name + ".git"));
    }

    return null;
  }
}