package nl.uvt.commons.oai;

import nl.uvt.commons.lang.InvalidSettingException;
import java.io.*;
import java.net.*;
import java.util.*;

import org.apache.log4j.*;
import org.joda.time.*;

/**
 * DAO that uses properties files for configuration and status.
 * 
 * <p>Simple solution, not to be used for serious production systems.
 * Since the (status) file is simply overwritten, there is a chance
 * that status information can get lost due to some IO error.</p>
 */
public class FilesAdminDAO implements IAdminDAO {

  private File configurationDirectory;
  private File statusDirectory;
  private UUID uuid; // Fake connection handle

  private static Logger logger = Logger.getLogger(FilesAdminDAO.class);
  
  public FilesAdminDAO() {
    this.uuid = UUID.randomUUID();
  }

  @Override
  public void setProperty(String key, String value) throws InvalidSettingException {
    if (key == null) {
      throw new InvalidSettingException("Key is Null");
    }
    else if (key.equals("configurationDirectory")) {
      this.configurationDirectory = new File(value);
      if (! this.configurationDirectory.exists()) {
        logger.fatal("Configuration directory '"+this.configurationDirectory.getAbsolutePath()+"' does not exist");
      }
      else if (! this.configurationDirectory.isDirectory()) {
        logger.fatal("Configuration directory '"+this.configurationDirectory.getAbsolutePath()+"' is not a directory");
      }
    }
    else if (key.equals("statusDirectory")) {
      this.statusDirectory = new File(value);
      if (! this.statusDirectory.exists()) {
        logger.fatal("Status directory '"+this.statusDirectory.getAbsolutePath()+"' does not exist");
      }
      else if (! this.statusDirectory.isDirectory()) {
        logger.fatal("Status directory '"+this.statusDirectory.getAbsolutePath()+"' is not a directory");
      }
    }
    else {
      throw new InvalidSettingException("Unknown setting '"+key+"'");
    }
  }

  @Override
  public void init() { }

  @Override
  public void setupInfrastructure() { }

  @Override
  public void loadDriver() { }

  @Override
  public boolean supportsTransactions() {
    return false;
  }

  @Override
  public boolean guardsConsistency() {
    return false;
  }

  @Override
  public UUID getConnectionHandle() {
    return this.uuid;
  }

  @Override
  public void closeConnection(UUID handle) { }

  @Override
  public void commit(UUID handle) { }

  @Override
  public void rollback(UUID handle) { }

  @Override
  public void putRepository(UUID handle, Repository repository, boolean overwrite)
  throws OAIException {
    try {
      Properties properties = new Properties();
      properties.setProperty("repository.base-url", repository.getBaseURL().toExternalForm());
      File file = this.getRepositoryFile(repository.getId());
      if (file.exists() && overwrite == false)
        throw new OAIException("Trying to overwrite existing repository, id='"+repository.getId()+"'");
      OutputStream os = new FileOutputStream(file);
      properties.store(os, "Updated by "+this.getClass().getName()+" at "+new Date());
      os.close();
    } catch (IOException e) {
      logger.error("IOException occurred while storing configuration for repository with id='"+repository.getId()+"'. Msg="+e.getMessage());
    }
  }

  @Override
  public List<String> getRepositoryIds(UUID handle) {
    return this.getIds("repository");
  }
  
  @Override
  public Repository getRepository(UUID handle, String id) {
    Repository repository = null;
    try {
      Properties properties = new Properties();
      InputStream is = new FileInputStream(this.getRepositoryFile(id));
      properties.load(is);
      is.close();
      String repositoryBaseURL = properties.getProperty("repository.base-url");
      if (repositoryBaseURL != null) {
        repository = new Repository(id, new URL(repositoryBaseURL));
      }
    } catch (IOException e) {
      logger.error("IOException occurred while loading configuration for repository with id='"+id+"'. Msg="+e.getMessage());
    }
    return repository;
  }

  @Override
  public void removeRepository(UUID connectoon, String repositoryId) {
    File file = this.getRepositoryFile(repositoryId);
    file.delete();
  }

  private File getRepositoryFile(String repositoryId) {
    return new File(this.configurationDirectory, repositoryId+".repository");
  }

  @Override
  public void putFeed(UUID handle, Feed feed, boolean overwrite)
  throws OAIException {
    this.saveFeedStatus(feed);
    try {
      Properties properties = new Properties();
      properties.setProperty("repository.id", feed.getRepository().getId());
      properties.setProperty("feed.metadata-prefix", feed.getMetadataPrefix());
      if (feed.getSet() != null)
        properties.setProperty("feed.set", feed.getSet());
      File file = this.getFeedFile(feed.getId());
      if (file.exists() && overwrite == false)
        throw new OAIException("Trying to overwrite existing feed, id='"+feed.getId()+"'");
      OutputStream os = new FileOutputStream(file);
      properties.store(os, "Updated by "+this.getClass().getName()+" at "+new Date());
      os.close();
    } catch (IOException e) {
      logger.error("IOException occurred while storing configuration for feed with id='"+feed.getId()+"'. Msg="+e.getMessage());
    }
  }

  @Override
  public List<String> getFeedIds(UUID handle, String repositoryId) {
    List<String> ids = new ArrayList<String>();
    for (String id : this.getIds("feed")) {
      Feed feed = this.getFeed(handle, id);
      if (feed.getRepository().getId().equals(id))
        ids.add(id);
    }
    return ids;
  }
  
  @Override
  public Feed getFeed(UUID handle, String id) {
    Feed feed = null;
    try {
      Properties properties = new Properties();
      InputStream is = new FileInputStream(this.getFeedFile(id));
      properties.load(is);
      is.close();
      feed = new Feed(id);
      String repositoryId = properties.getProperty("repository.id");
      if (repositoryId != null) {
        Repository repository = this.getRepository(handle, repositoryId);
        feed.setRepository(repository);      
      }
      String metadataPrefix = properties.getProperty("feed.metadata-prefix");
      if (metadataPrefix != null) {
        feed.setMetadataPrefix(metadataPrefix);
      } 
      String set = properties.getProperty("feed.set");
      if (set != null) {
        feed.setSet(set);
      }
      this.loadFeedStatus(feed);
    } catch (IOException e) {
      logger.error("IOException occurred while loading configuration for feed with id='"+id+"'. Msg="+e.getMessage());
    }
    return feed;
  }

  @Override
  public void removeFeed(UUID connectoon, String feedId) {
    File file = this.getFeedFile(feedId);
    file.delete();
  }

  private File getFeedFile(String feedId) {
    return new File(this.configurationDirectory, feedId+".feed");
  }

  private void loadFeedStatus(Feed feed) {
    String timestamp = null;
    try {
      Properties properties = new Properties();
      InputStream is = new FileInputStream(new File(this.statusDirectory, feed.getId()+".feed-status"));
      properties.load(is);
      is.close();

      /*
       * From:
       */
      timestamp = properties.getProperty("feed.from");
      if (timestamp != null) {
        if (timestamp.length() == 0) {
          feed.setFrom(null);
        }
        else {
          if (timestamp.length() == 10)
            timestamp += "T00:00:00Z";
          feed.setFrom(Feed.dateTimeFormat.parseDateTime(timestamp).toDate());
        }
      }
      else {
        feed.setFrom(null);
      }
      
      /*
       * Until:
       */
      timestamp = properties.getProperty("feed.until");
      if (timestamp != null) {
        if (timestamp.length() == 0) {
          feed.setUntil(null);
        }
        else {
          if (timestamp.length() == 10)
            timestamp += "T00:00:00Z";
          feed.setUntil(Feed.dateTimeFormat.parseDateTime(timestamp).toDate());
        }
      }
      else {
        feed.setUntil(null);
      }
      
      /*
       * Resumption token + expirationDate:
       */
      String resumptionToken = properties.getProperty("feed.resumption-token");
      if (resumptionToken != null) {
        if (resumptionToken.length() != 0)
          feed.setResumptionToken(resumptionToken);
        else
          feed.setResumptionToken(null);
      }
      else {
        feed.setResumptionToken(null);
      }
      timestamp = properties.getProperty("feed.resumption-token.expiration-date");
      if (timestamp != null) {
        if (timestamp.length() == 0) {
          feed.setResumptionTokenExpirationDate(null);
        }
        else {
          if (timestamp.length() == 10)
            timestamp += "T00:00:00Z";
          feed.setResumptionTokenExpirationDate(Feed.dateTimeFormat.parseDateTime(timestamp).toDate());
        }
      }
      else {
        feed.setResumptionTokenExpirationDate(null);
      }
    } catch (IOException e) {
      logger.error("IOException occurred while loading status for feed with id='"+feed.getId()+"'. Msg="+e.getMessage());
    }
  }

  private void saveFeedStatus(Feed feed) {
    Properties properties = new Properties();
    if (feed.getFrom() != null) {
      properties.setProperty("feed.from", Feed.dateTimeFormat.print(new DateTime(feed.getFrom())));
    }
    if (feed.getUntil() != null) {
      properties.setProperty("feed.until", Feed.dateTimeFormat.print(new DateTime(feed.getUntil())));
    }
    if (feed.getResumptionToken() != null) {
      properties.setProperty("feed.resumption-token", feed.getResumptionToken());
    }
    if (feed.getResumptionTokenExpirationDate() != null) {
      properties.setProperty(
          "feed.resumption-token.expiration-date",
          Feed.dateTimeFormat.print(new DateTime(feed.getResumptionTokenExpirationDate())));
    }
    try {
      OutputStream os = new FileOutputStream(new File(this.statusDirectory, feed.getId()+".feed-status"));
      properties.store(os, "Written by feed '"+feed.getId()+"' at "+new Date());
    } catch (SecurityException e) {
      logger.error("SecurityException occurred while saving status for feed with id='"+feed.getId()+"'. Msg="+e.getMessage());
    } catch (FileNotFoundException e) {
      logger.error("FileNotFoundException occurred while saving status for feed with id='"+feed.getId()+"'. Msg="+e.getMessage());
    } catch (IOException e) {
      logger.error("IOException occurred while saving status for feed with id='"+feed.getId()+"'. Msg="+e.getMessage());
    }
  }

  /**
   * Returns names of files in configuration directory with certain extension.
   * 
   * <p>Extension is case sensitive.</p>
   * <p>If configuration directory = <code>/var/lib/dodoco</code>, extension = "feed" and
   * configuration directory contains two files with this extension, <code>foo.feed</code>
   * and <code>bar.feed</code>, the method returns [ "bar", "foo" ].</p> 
   * 
   * @param extension filter on this extension (case sensitive)
   * @return sorted list of Ids
   */
  private List<String> getIds(String extension) {
    List<String> ids = new ArrayList<String>();
    for (File file : this.configurationDirectory.listFiles(new ExtensionFileFilter(extension))) {
      // ExtensionFilter class below
      String name = file.getName();
      ids.add(name.substring(0, name.length()-extension.length()-1));
    }
    java.util.Collections.sort(ids);
    return ids;
  }

  private class ExtensionFileFilter implements FileFilter {
    private String extension;
    public ExtensionFileFilter(String extension) {
      this.extension = extension;
    }
    public boolean accept(File file) {
      if (file.getName().endsWith("."+this.extension))
        return true;
      else
        return false;
    }
  }

}