/*
 * For work developed by the HSQL Development Group:
 *
 * Copyright (c) 2001-2019, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 *
 * For work originally developed by the Hypersonic SQL Group:
 *
 * Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Hypersonic SQL Group.
 */


package org.hsqldb.server;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.hsqldb.DatabaseManager;
import org.hsqldb.DatabaseURL;
import org.hsqldb.HsqlException;
import org.hsqldb.Session;
import org.hsqldb.lib.DataOutputStream;
import org.hsqldb.lib.HsqlByteArrayOutputStream;
import org.hsqldb.persist.HsqlProperties;
import org.hsqldb.result.Result;
import org.hsqldb.result.ResultConstants;
import org.hsqldb.rowio.RowInputBinary;
import org.hsqldb.rowio.RowOutputBinary;

// fredt@users 20020130 - patch 475586 by wreissen@users
// fredt@users 20020328 - patch 1.7.0 by fredt - error trapping
// fredt@users 20030630 - patch 1.7.2 - new protocol, persistent sessions
// fredt@users 20041112 - patch by William Crick - use web_inf directory

Servlet can act as an interface between the client and the database for the
the client / server mode of HSQL Database Engine. It uses the HTTP protocol
for communication. This class is not required if the included HSQLDB
Weberver is used on the server host. But if the host is running a J2EE
application server or a servlet container such as Tomcat, the Servlet class
can be hosted on this server / container to serve external requests from
external hosts.

The remote applet / application should
use the normal JDBC interfaces to connect to the URL of this servlet. An
example URL is:
jdbc:hsqldb:http://myhost.com:8080/servlet/org.hsqldb.server.Servlet

The database path/name is taken from the servlet engine property:
hsqldb.server.database


If the database is deployed in the WEB-INF directory of the servlet container,
the property:
 hsqldb.server.use_web-inf_path

should be set "true" in the web.xml file of the servlet container.
In this case, the database path should begin with a "/".
JDBC connections via the HTTP protocol are persistent
in the JDBC sense. The JDBC Connection that is established can support
transactions spanning several Statement calls and real PreparedStatement
calls are supported.

Author:
Fred Toussi (fredt@users dot sourceforge.net)
Version:
2.3.4
Since:
1.6.2/**
 * Servlet can act as an interface between the client and the database for the
 * the client / server mode of HSQL Database Engine. It uses the HTTP protocol
 * for communication. This class is not required if the included HSQLDB
 * Weberver is used on the server host. But if the host is running a J2EE
 * application server or a servlet container such as Tomcat, the Servlet class
 * can be hosted on this server / container to serve external requests from
 * external hosts.<p>
 * The remote applet / application should
 * use the normal JDBC interfaces to connect to the URL of this servlet. An
 * example URL is:
 * <pre>
 * jdbc:hsqldb:http://myhost.com:8080/servlet/org.hsqldb.server.Servlet
 * </pre>
 * The database path/name is taken from the servlet engine property:
 * <pre>
 * hsqldb.server.database
 * </pre>
 * <p>
 * If the database is deployed in the WEB-INF directory of the servlet container,
 * the property:
 * <pre>
 *  hsqldb.server.use_web-inf_path
 * </pre>
 * should be set "true" in the web.xml file of the servlet container.
 * In this case, the database path should begin with a "/".
 *
 * JDBC connections via the HTTP protocol are persistent
 * in the JDBC sense. The JDBC Connection that is established can support
 * transactions spanning several Statement calls and real PreparedStatement
 * calls are supported.<p>
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 2.3.4
 * @since 1.6.2
 */
public class Servlet extends HttpServlet {

    private static final int BUFFER_SIZE = 256;
    private String           dbType;
    private String           dbPath;
    private String           initError;

    public void init(ServletConfig config) {

        try {
            super.init(config);
        } catch (ServletException e) {
            log(e.toString());
        }

        String dbStr = getInitParameter("hsqldb.server.database");

        if (dbStr == null) {
            dbStr = ".";
        }

// begin WEB-INF patch */
        String useWebInfStr =
            getInitParameter("hsqldb.server.use_web-inf_path");

        if (!dbStr.equals(".") && "true".equalsIgnoreCase(useWebInfStr)) {
            dbStr = getServletContext().getRealPath("/") + "WEB-INF/" + dbStr;
        }

// end WEB-INF patch
        HsqlProperties dbURL = DatabaseURL.parseURL(dbStr, false, false);

        log("Database filename = " + dbStr);

        if (dbURL == null) {
            initError = "Bad Database name";
        } else {
            dbPath = dbURL.getProperty("database");
            dbType = dbURL.getProperty("connection_type");

            try {
                DatabaseManager.getDatabase(dbType, dbPath, dbURL);
            } catch (HsqlException e) {
                initError = e.getMessage();
            }
        }

        if (initError == null) {
            log("Initialization completed.");
        } else {
            log("Database could not be initialised.");
            log(initError);
        }
    }

    private static long lModified = 0;

    protected long getLastModified(HttpServletRequest req) {

        // this is made so that the cache of the http server is not used
        // maybe there is some other way
        return lModified++;
    }

    public void doGet(HttpServletRequest request,
                      HttpServletResponse response)
                      throws IOException, ServletException {

        String query = request.getQueryString();

        if ((query == null) || (query.length() == 0)) {
            response.setContentType("text/html");

            // fredt@users 20020130 - patch 1.7.0 by fredt
            // to avoid caching on the browser
            response.setHeader("Pragma", "no-cache");

            PrintWriter out = response.getWriter();

            out.println(
                "<html><head><title>HSQL Database Engine Servlet</title>");
            out.println("</head><body><h1>HSQL Database Engine Servlet</h1>");
            out.println("The servlet is running.<p>");

            if (initError == null) {
                out.println("Connected to the database.<p>");
                out.println("Database name: " + dbType + dbPath + "<p>");
            } else {
                out.println("<h2>The database is not available.</h2>");
                out.println("The error message is:<p>");
                out.println(initError);
            }

            out.println("</body></html>");
        }
    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response)
                       throws IOException, ServletException {

        DataInputStream  inStream = null;
        DataOutputStream dataOut  = null;

        try {
            inStream = new DataInputStream(request.getInputStream());

            int            databaseID = inStream.readInt();
            long           sessionID  = inStream.readLong();
            int            mode       = inStream.readByte();
            RowInputBinary rowIn      = new RowInputBinary(BUFFER_SIZE);
            Session session = DatabaseManager.getSession(databaseID,
                sessionID);
            Result resultIn = Result.newResult(session, mode, inStream, rowIn);

            resultIn.setDatabaseId(databaseID);
            resultIn.setSessionId(sessionID);

            Result resultOut;
            int    type = resultIn.getType();

            if (type == ResultConstants.CONNECT) {
                try {
                    session =
                        DatabaseManager.newSession(dbType, dbPath,
                                                   resultIn.getMainString(),
                                                   resultIn.getSubString(),
                                                   new HsqlProperties(),
                                                   resultIn.getZoneString(),
                                                   resultIn.getUpdateCount());
                    resultOut =
                        Result.newConnectionAcknowledgeResponse(session);
                } catch (HsqlException e) {
                    resultOut = Result.newErrorResult(e);
                }
            } else if (type == ResultConstants.DISCONNECT
                       || type == ResultConstants.RESETSESSION) {

                // Upon DISCONNECT 6 bytes are read by the ClientConnectionHTTP": mode (1 byte), a length (int), and an 'additional results (1 byte)
                response.setHeader("Cache-Control", "no-cache");    // DB-traffic should not be cached by proxies
                response.setContentType("application/octet-stream");
                response.setContentLength(6);

                // Only acquire output-stream after headers are set
                dataOut = new DataOutputStream(response.getOutputStream());

                dataOut.writeByte(ResultConstants.DISCONNECT);      // Mode
                dataOut.writeInt(4);                                // Length Int of first result is always read! Minvalue is 4: It is the number of bytes of the current result (it includes the length of this Int itself)
                dataOut.writeByte(ResultConstants.NONE);            // No Additional results
                dataOut.close();

                return;
            } else if (type == ResultConstants.SQLCANCEL) {
                int  dbId      = resultIn.getDatabaseId();
                long sessionId = resultIn.getSessionId();

                session   = DatabaseManager.getSession(dbId, sessionId);
                resultOut = session.cancel(resultIn);
            } else {
                int  dbId      = resultIn.getDatabaseId();
                long sessionId = resultIn.getSessionId();

                session = DatabaseManager.getSession(dbId, sessionId);

                resultIn.readLobResults(session, inStream, rowIn);

                resultOut = session.execute(resultIn);
            }

            HsqlByteArrayOutputStream memStream =
                new HsqlByteArrayOutputStream();
            DataOutputStream tempOutput = new DataOutputStream(memStream);
            RowOutputBinary  rowOut     = new RowOutputBinary(BUFFER_SIZE, 1);

            resultOut.write(session, tempOutput, rowOut);
            response.setHeader("Cache-Control", "no-cache");        // DB-traffic should not be cached by proxies
            response.setContentType("application/octet-stream");
            response.setContentLength(memStream.size());

            // Only acquire output-stream after headers are set
            dataOut = new DataOutputStream(response.getOutputStream());

            memStream.writeTo(dataOut);
        } catch (HsqlException e) {}
        finally {
            if (dataOut != null) {
                dataOut.close();
            }

            if (inStream != null) {
                inStream.close();
            }
        }
    }
}