//package spo.src.JDBC;

import java.io.*;
import java.net.*;
import java.util.Vector;
import java.util.StringTokenizer;

/**
 *
 * Class <TT>XConnection<TT> is java class, which allows client to
 * connect to the SPDBMS data server.
 *
 * <br>
 * @author <A HREF="http://www.cs.uky.edu/~wzhao0">Wenzhong Zhao</A>
 * @version 1.0
 */

  public class XConnection {
    /* The connection to the server */
    private Socket sock = null;
    private PrintWriter out = null;
    private BufferedReader in = null;

    private static boolean success = false;	//Indicate whether the latest command succeeds or not.

    //Default host and port
    final static String DEFAULT_HOST = "alphaville.csr.uky.edu";
    final static int DEFAULT_PORT = 2000;

    /**
     * Default constructor
     *
     * Initialize the XConnection
     */
    public XConnection() { }

    /**
     * Use default host and port to connect
     */
    public void connect() {
	connect(DEFAULT_HOST, DEFAULT_PORT);
    }

    /**
     * Connect to the data server with (host, port)
     *
     * @param host data server name
     * @param port the prot number which the server is listening
     */
    public void connect(String host, int port) {
        try {
            sock = new Socket(host, port);
            out = new PrintWriter(sock.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(sock.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: " +host);
	    success = false;
            //System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: " +host);
	    success = false;
            //System.exit(1);
        }

	success = true;
   }

   /**
    * Close the connection to the data server
    */
   public void close() {
     //Inform the server to close the thread
     out.println("exit");

     //Close all the streams
     try {
        out.close();
        in.close();
        sock.close();
     } catch (IOException ie) {
       System.out.println("Problem with closing socket.");
       success = false;
     }

     success = true;
   }

  //SPDB simple API functions
  /**
   * Get the names of relations in the data server
   */
  public Vector getRelNames() throws IOException {
     //Execute it
     executeUpdate("GET RELATION NAMES");
     String temp = in.readLine();
     if (temp.startsWith("FAILED:")) {
        success = false;
	return null;
     }
     else {
	Vector names = new Vector();
	StringTokenizer tokens = new StringTokenizer(temp, " ");
	while(tokens.hasMoreTokens()) {
	   names.add(tokens.nextToken());
	}

	if (names.size() == 0) {
	   success = false;
	   return null;
	}
	else {
	   success = true;
	   return names;
	}
     }
  }

  /**
   * Get the dependency config file of the relation
   */
  public String getContext(String relName) throws IOException {
     if (relName == null) {
        success = false;
        return "FAILED: Please input a relation name.";
     }

     //Execute it
     String temp = executeQuery("GETXC " +relName);
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Get the dependency config file of the relation
   */
  public String getConfig(String relName) throws IOException {
     if (relName == null) {
        success = false;
        return "FAILED: Please input a relation name.";
     }

     //Execute it
     String temp = executeQuery("GETX " +relName);
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Create the relation in the data server
   *
   * @param relName name of the relation
   * @param schemaURL URL string of the schema
   */
  public String create(String relName, String schemaURL) throws IOException {
     if (relName == null) {
        success = false;
        return "FAILED: Please input a relation name.";
     }

     StringBuffer sb = new StringBuffer();
     if (schemaURL == null)
        sb.append("CREATE " +relName);
     else
        sb.append("CREATE " +relName+ " " +schemaURL);

     //Execute it
     executeUpdate(sb.toString());
     String temp = in.readLine();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Drop the relation
   *
   * @param relName name of the relation
   */
  public String drop(String relName) throws IOException {
     if (relName == null) {
        success = false;
        return "FAILED: Please input a relation name.";
     }

     StringBuffer sb = new StringBuffer();
     sb.append("DROP " +relName);

     //Execute it
     executeUpdate(sb.toString());
     String temp = in.readLine();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Insert a dependency config file for the relation
   *
   * @param relName name of the relation
   * @param cfgName name the dependency config file
   */
  public String setConfig(String relName, String cfgName)
                          throws IOException {
     if (relName == null || cfgName == null) {
        success = false;
        return "FAILED: Please input both a relation name and a dependency file name.";
     }

     StringBuffer sb = new StringBuffer();
     sb.append("INSERTX INTO " +relName);
     executeUpdate(sb.toString());

     //Check if server is ready to receive the XML data
     String isReady = null;
     while (!in.ready()) {;} //Waits for the stream to be ready

     isReady = in.readLine();
     if (!isReady.equals("Ready")) {
        return isReady;
     }

     //Get the XML stream and send to server
     BufferedReader br = new BufferedReader(new FileReader(cfgName));

     String aLine = br.readLine();
     while (aLine != null) {
         out.println(aLine);
         aLine = br.readLine();
     }

     //Close br
     br.close();

     //No need to set the end of stream
     //Expected 'EOF' from the parser if more char after the closing root tag!!!
     //Tell the server that the xml file ends
     //Important!!!
     out.println("null");

     //Get response
     String temp = getRespond();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Insert a dependency config file for the relation
   *
   * @param relName name of the relation
   * @param cfgName name the dependency config file
   */
  public String setContext(String relName, String cfgName)
                          throws IOException {
     if (relName == null || cfgName == null) {
        success = false;
        return "FAILED: Please input both a relation name and a dependency file name.";
     }

     StringBuffer sb = new StringBuffer();
     sb.append("INSERTXC INTO " +relName);
     executeUpdate(sb.toString());

     //Check if server is ready to receive the XML data
     String isReady = null;
     while (!in.ready()) {;} //Waits for the stream to be ready

     isReady = in.readLine();
     if (!isReady.equals("Ready")) {
        return isReady;
     }

     //Get the XML stream and send to server
     BufferedReader br = new BufferedReader(new FileReader(cfgName));

     String aLine = br.readLine();
     while (aLine != null) {
         out.println(aLine);
         aLine = br.readLine();
     }

     //Close br
     br.close();

     //No need to set the end of stream
     //Expected 'EOF' from the parser if more char after the closing root tag!!!
     //Tell the server that the xml file ends
     //Important!!!
     out.println("null");

     //Get response
     String temp = getRespond();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Insert a xml file into the relation
   *
   * @param relName name of the relation
   * @param xmlFile name the xml file
   */
  public String insert(String relName, String xmlFile) throws IOException {
     if (relName == null || xmlFile == null) {
        success = false;
        return "FAILED: Please input both a relation name and XML file name.";
     }

     StringBuffer sb = new StringBuffer();
     sb.append("INSERT INTO " +relName);
     executeUpdate(sb.toString());

     //Check if server is ready to receive the XML data
     String isReady = null;
//     while ((isReady = in.readLine()) == null) {;}
//     try {
        while (!in.ready()) {;} //Waits for the stream to be ready
//     } catch (InterruptedException ie) {;}

     isReady = in.readLine();
     if (!isReady.equals("Ready")) {
        return isReady;
     }

     //Get the XML stream and send to server
     BufferedReader br = new BufferedReader(new FileReader(xmlFile));

     String aLine = br.readLine();
     while (aLine != null) {
         out.println(aLine);
         aLine = br.readLine();
     }

     //Close br
     br.close();

     //No need to set the end of stream
     //Expected 'EOF' from the parser if more char after the closing root tag!!!
     //Tell the server that the xml file ends
     //Important!!!
     out.println("null");

     //Get response
     String temp = getRespond();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
     * Insert a xml stream into the relation
     *
     * @param relName name of the relation
     * @param xmldata
     * author : Krol Mathias
   */
  public String insertdata(String relName, String xmldata) throws IOException
  {
       if (relName == null || xmldata == null)
       {
          success = false;
          return "FAILED: Please input both a relation name and data.";
       }

       StringBuffer sb = new StringBuffer();
       sb.append("INSERT INTO " +relName);
       executeUpdate(sb.toString());

       //Check if server is ready to receive the XML data
       String isReady = null;
  //     while ((isReady = in.readLine()) == null) {;}
 //      try {
          while (!in.ready()) {;} //Waits for the stream to be ready
 //      } catch (InterruptedException ie) {;}

       isReady = in.readLine();
       if (!isReady.equals("Ready")) {
          return isReady;
       }

       // send the xmldata string
       //System.out.println(xmldata);
       out.println(xmldata);

       //No need to set the end of stream
       //Expected 'EOF' from the parser if more char after the closing root tag!!!
       //Tell the server that the xml file ends
       //Important!!!
       out.println("null");

       //Get response
       String temp = getRespond();
       if (temp.startsWith("FAILED:")) {
          success = false;
       }
       else {
          success = true;
       }

       return temp;
  }

  /**
   * Delete from the relation SPOs which satisfy the condition
   *
   * @param relName name of the relation
   * @param condition the condition string
   */
  public String delete(String relName, String condition) throws IOException {
     if (relName == null || condition == null) {
        success = false;
        return "FAILED: Please input both a relation name and a condition.";
     }

     StringBuffer sb = new StringBuffer();
     sb.append("DELETE FROM " +relName+ " WHERE " +condition);
     executeUpdate(sb.toString());

     //Execute it
     String temp = in.readLine();
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Send a query to the data server
   *
   * @param queryStr the query string
   * @param isXML set the format of the query result. true will return
   * XML, otherwise HTML
   */
  public String query(String queryStr, boolean isXML)
			throws IOException {
     if (queryStr == null) {
        success = false;
        return "FAILED: Please input a query string.";
     }

     StringBuffer sb = new StringBuffer();
     if (isXML)
	sb.append("QUERY XML " +queryStr);
     else
     	sb.append("QUERY HTML " +queryStr);

     //Execute it
     String temp = executeQuery(sb.toString());
     if (temp.startsWith("FAILED:")) {
        success = false;
     }
     else {
        success = true;
     }

     return temp;
  }

  /**
   * Get the respond from the data server
   */
  private String getRespond() throws IOException{
    String inputLine = null;
    StringBuffer sb = new StringBuffer();
    while ((inputLine = in.readLine()) != null && inputLine.length() > 0) {
	sb.append(inputLine+ "\n");
    }

    return (sb.toString()).trim();
  }

  /**
   * Execute the update command
   *
   * @param update the update string
   */
  private void executeUpdate(String update) {
     out.println(update);
  }

  /**
   * Execute the query command
   *
   * @param query the query string
   */
  private String executeQuery(String query) throws IOException {
     out.println(query);

     //Get the XML data from the server
     StringBuffer sb = new StringBuffer();
     String aLine = null;
     int blankLineCount = 0;  //Count of continuous blank lines
     while ((aLine = in.readLine()) != null) {
        if (aLine.equals("null")) break;
        if (aLine.length() == 0) {
           blankLineCount++;
        }
        else {
           blankLineCount = 0;
        }

        sb.append(aLine+ "\n");

        if (blankLineCount == 2) break;	//Check if the end of message
     }

     return (sb.toString()).trim();
  }

  // Return the status
  public boolean getSuccess() {
     return success;
  }
}