/**
 * Copyright 2010 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 org.waveprotocol.box.server.persistence.file;

import com.google.inject.Inject;
import com.google.inject.name.Named;

import org.waveprotocol.box.server.CoreSettings;
import org.waveprotocol.box.server.persistence.AttachmentStore;
import org.waveprotocol.box.server.persistence.AttachmentUtil;
import org.waveprotocol.wave.model.util.CharBase64;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Date;

/**
 * An implementation of AttachmentStore which uses files on disk
 *
 * @author josephg@gmail.com (Joseph Gentle)
 */
public class FileAttachmentStore implements AttachmentStore {
  /**
   * The directory in which the attachments are stored. This directory is created lazily
   * when the first attachment is stored.
   */
  private String basePath;

  @Inject
  public FileAttachmentStore(@Named(CoreSettings.ATTACHMENT_STORE_DIRECTORY) String basePath) {
    this.basePath = basePath;
  }

  private static String encodeId(String id) {
    try {
      return CharBase64.encode(id.getBytes("UTF-8"));
    } catch (UnsupportedEncodingException e) {
      throw new RuntimeException(e);
    }
  }

  private String getAttachmentPath(String id) {
    return basePath + File.separatorChar + encodeId(id);
  }

  /** Gets the file which stores an attachment with the specified ID. */
  private File getAttachmentFile(String id, boolean createDir) {
    File file = new File(getAttachmentPath(id));
    if (!file.exists() && createDir) {
      file.getParentFile().mkdirs();
    }

    return file;
  }

  @Override
  public AttachmentData getAttachment(String id) {
    final File file = getAttachmentFile(id, false);

    if (!file.exists() || !file.canRead()) {
      return null;
    }

    return new AttachmentData() {
      @Override
      public Date getLastModifiedDate() {
        return new Date(file.lastModified());
      }

      @Override
      public InputStream getInputStream() throws IOException {
        return new FileInputStream(file);
      }

      @Override
      public long getContentSize() {
        return file.length();
      }

      @Override
      public void writeDataTo(OutputStream out) throws IOException {
        InputStream is = getInputStream();
        AttachmentUtil.writeTo(is, out);
        is.close();
      }
    };
  }

  @Override
  public boolean storeAttachment(String id, InputStream data) throws IOException {
    File file = getAttachmentFile(id, true);

    if (file.exists()) {
      return false;
    } else {
      FileOutputStream stream = new FileOutputStream(file);
      AttachmentUtil.writeTo(data, stream);
      stream.close();
      return true;
    }
  }

  @Override
  public void deleteAttachment(String id) {
    File file = new File(getAttachmentPath(id));
    if (file.exists()) {
      file.delete();
    }
  }
}