// Copyright (C) 2013 The Android Open Source Project
//
// 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.server.securestore;

import com.google.gerrit.common.FileUtil;
import com.google.gerrit.server.config.SitePaths;
import com.google.inject.Inject;
import com.google.inject.Singleton;

import org.eclipse.jgit.internal.storage.file.LockFile;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.storage.file.FileBasedConfig;
import org.eclipse.jgit.util.FS;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

@Singleton
public class DefaultSecureStore extends SecureStore {
  private final FileBasedConfig sec;

  @Inject
  DefaultSecureStore(SitePaths site) {
    sec = new FileBasedConfig(site.secure_config.toFile(), FS.DETECTED);
    try {
      sec.load();
    } catch (Exception e) {
      throw new RuntimeException("Cannot load secure.config", e);
    }
  }

  @Override
  public String[] getList(String section, String subsection, String name) {
    return sec.getStringList(section, subsection, name);
  }

  @Override
  public void setList(String section, String subsection, String name,
      List<String> values) {
    if (values != null) {
      sec.setStringList(section, subsection, name, values);
    } else {
      sec.unset(section, subsection, name);
    }
    save();
  }

  @Override
  public void unset(String section, String subsection, String name) {
    sec.unset(section, subsection, name);
    save();
  }

  @Override
  public Iterable<EntryKey> list() {
    List<EntryKey> result = new ArrayList<>();
    for (String section : sec.getSections()) {
      for (String subsection : sec.getSubsections(section)) {
        for (String name : sec.getNames(section, subsection)) {
          result.add(new EntryKey(section, subsection, name));
        }
      }
      for (String name : sec.getNames(section)) {
        result.add(new EntryKey(section, null, name));
      }
    }
    return result;
  }

  private void save() {
    try {
      saveSecure(sec);
    } catch (IOException e) {
      throw new RuntimeException("Cannot save secure.config", e);
    }
  }

  private static void saveSecure(final FileBasedConfig sec) throws IOException {
    if (FileUtil.modified(sec)) {
      final byte[] out = Constants.encode(sec.toText());
      final File path = sec.getFile();
      final LockFile lf = new LockFile(path);
      if (!lf.lock()) {
        throw new IOException("Cannot lock " + path);
      }
      try {
        FileUtil.chmod(0600, new File(path.getParentFile(), path.getName()
            + ".lock"));
        lf.write(out);
        if (!lf.commit()) {
          throw new IOException("Cannot commit write to " + path);
        }
      } finally {
        lf.unlock();
      }
    }
  }
}