/*

   Derby - Class org.apache.derby.impl.drda.AppRequester

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You 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.apache.derby.impl.drda;
import org.apache.derby.shared.common.reference.DRDAConstants;
import org.apache.derby.shared.common.error.MessageUtils;
import org.apache.derby.shared.common.sanity.SanityManager;

/**
    AppRequester stores information about the application requester.
    It is used so that multiple sessions can share information when they are
    started from the same version of the application requester.
*/
class AppRequester
{

    protected static final int MGR_LEVEL_UNKNOWN = -1;

    protected static final int UNKNOWN_CLIENT = 0;

    protected static final int DNC_CLIENT = 3;      // derby net client

    private static final int [] MIN_MGR_LEVELS = {
                                            3, // AGENT - JCC comes in at 3
                                            4, // CCSIDMGR
                                            3, // CMNAPPC, 
                                            4, // CMNSYNCPT
                                            5, // CMNTCPIP
                                            1, // DICTIONARY
                                            3, // RDB
                                            4, // RSYNCMGR
                                            1, // SECMGR    
                                            6, // SQLAM
                                            1, // SUPERVISOR    
                                            5, // SYNCPTMGR
                                            1208, // UNICODEMGR
                                            0  // XAMGR
                                            };
    
    // Application requester information
    protected String    extnam;         // External Name - EXCSAT
    protected String    srvnam;         // Server Name - EXCSAT
    protected String    srvrlslv;       // Server Product Release Level - EXCSAT
    protected String    srvclsnm;       // Server Class Name - EXCSAT
    protected String    spvnam;         // Supervisor Name - EXCSAT
    protected String    prdid;          // Product specific identifier - ACCRDB protected
    private int[]       managerLevels = new int[CodePoint.MGR_CODEPOINTS.length];
    private int         clientType;
    protected int       versionLevel;
    protected int       releaseLevel;
    protected int       modifyLevel;
    

    // constructor 
    /** 
     * AppRequester constructor
     * 
     * @exception throws IOException
     */
    AppRequester () 
    {
        for (int i = 0; i < CodePoint.MGR_CODEPOINTS.length; i++)
            managerLevels[i] = MGR_LEVEL_UNKNOWN;
    }

    /**
     * get the Application requester manager level
     *
     * @param manager   codepoint for manager we are looking for
     *
     * @return manager level for that manager
     */
    protected int getManagerLevel(int manager)
    {
        int mindex = CodePoint.getManagerIndex(manager);
        if (SanityManager.DEBUG)
        {
            if (mindex < 0 || mindex > managerLevels.length)
                SanityManager.THROWASSERT("Unknown manager "+ manager + " mindex = "+
                    mindex);
        }
        return managerLevels[mindex];
    }

    protected void setClientVersion(String productId)
    {
        prdid = productId;

        versionLevel = Integer.parseInt(prdid.substring (3, 5));
        releaseLevel = Integer.parseInt(prdid.substring (5, 7));
        modifyLevel = Integer.parseInt(prdid.substring (7, 8));
        if ((prdid.indexOf(DRDAConstants.DERBY_DRDA_CLIENT_ID) != -1)) {
            clientType = DNC_CLIENT;
        } else {
            clientType = UNKNOWN_CLIENT;
        }
    }

    /**
     * Returns true if Derby's client driver supports SECMEC_USRSSBPWD 
     * DRDA security mechanism.
     */
    protected boolean supportsSecMecUSRSSBPWD()
    {
        return
            (
                ( clientType == DNC_CLIENT ) &&
                ( greaterThanOrEqualTo( 10, 2, 0 ) )
            );
    }

    /**
     * Check if the client expects QRYCLSIMP to be supported when the
     * protocol is LMTBLKPRC.
     *
     * @return <code>true</code> if QRYCLSIMP is supported for
     * LMTBLKPRC
     */
    protected final boolean supportsQryclsimpForLmtblkprc() {
        return clientType == DNC_CLIENT;
    }

    /**
     * Check if provided JCC version level is greaterThanOrEqualTo current level
     *
     * @param vLevel    Version level
     * @param rLevel    Release level
     * @param mLevel    Modification level
     */
     
    protected boolean greaterThanOrEqualTo(int vLevel, int rLevel, int mLevel)
    {
        if (versionLevel > vLevel)
                return true;
        else if (versionLevel == vLevel) {
                if (releaseLevel > rLevel)
                        return true;
                else if (releaseLevel == rLevel)
                        if (modifyLevel >= mLevel)
                                return true;
        }
        return false;
    }

    /** 
     * set Application requester manager level
     * if the manager level is less than the minimum manager level,
     * set the manager level to zero (saying we can't handle this
     * level), this will be returned
     * to the application requester and he can decide whether or not to
     * proceed
     * For CCSIDMGR, if the target server supports the CCSID manager but
     * not the CCSID requested, the value returned is FFFF
     * For now, we won't support the CCSIDMGR since JCC doesn't request it.
     *
     * @param manager   codepoint of the manager
     * @param managerLevel  level for that manager
     *
     */
    protected void setManagerLevel(int manager, int managerLevel)
    {
        int i = CodePoint.getManagerIndex(manager);
        if (SanityManager.DEBUG)
        {
            if (i < 0 || i > managerLevels.length)
                SanityManager.THROWASSERT("Unknown manager "+ manager + " i = " + i);
        }
        if (managerLevel >= MIN_MGR_LEVELS[i])
            managerLevels[i] = managerLevel;    
        else
            managerLevels[i] = 0;
    }
    
    /**
     * Check if the application requester is the same as this one
     *
     * @param a application requester to compare to
     * @return true if same false otherwise
     */
    protected boolean equals(AppRequester a)
    {
        // check prdid - this should be different if they are different
        if (!prdid.equals(a.prdid))
            return false;

        // check server product release level
        if (notEquals(srvrlslv, a.srvrlslv))
            return false;

        // check server names
        if (notEquals(extnam, a.extnam))
            return false;

        if (notEquals(srvnam, a.srvnam))
            return false;

        if (notEquals(srvclsnm, a.srvclsnm))
            return false;

        if (notEquals(spvnam, a.spvnam))
            return false;

        // check manager levels
        for (int i = 0; i < managerLevels.length; i++)
            if (managerLevels[i] != a.managerLevels[i])
                return false;

        // O.K. looks good
        return true;
    }
    /**
     * Check whether two objects are not equal when 1 of the objects could
     * be null
     *
     * @param a first object
     * @param b second object
     * @return true if not equals false otherwise
     */
    private boolean notEquals(Object a, Object b)
    {
        if (a != null && b == null)
            return true;
        if (a == null && b != null)
            return true;
        if (a != null && !a.equals(b))
            return true;
        return false;
    }

    /**
     * Get the maximum length supported for an exception's message
     * parameter string.
     */

    protected int supportedMessageParamLength() {
        return MessageUtils.DB2_JCC_MAX_EXCEPTION_PARAM_LENGTH;
    }

    /**
     * Get the type of the client.
     */

    protected int getClientType() {

        return clientType;

    }

    /**
     * Is this an AppRequester that supports XA 
     *
     * return true if XAMGR &gt;= 7, false otherwise
     **/

    protected  boolean isXARequester()
    {
        return (getManagerLevel(CodePoint.XAMGR) >= 7);
        
    }

    /**
     * Tells whether the client sends a trailing Derby-specific status byte
     * when transferring EXTDTA objects.
     *
     * @return {@code true} if the status byte is sent, {@code false} if not
     */
    protected boolean supportsEXTDTAAbort() {
        return (clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 6, 0));
    }
    
    /**
     * Returns whether our AppRequester's UNICODEMGR supports UTF8 (CCSID 1208)
     * @return {@code true} if the AppRequester supports CCSID 1208, {@code false} if not
     */
    protected boolean supportsUtf8Ccsid() {
        return (getManagerLevel(CodePoint.UNICODEMGR) == CcsidManager.UTF8_CCSID);
    }

    protected boolean supportsSessionDataCaching() {
        return (clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 4, 0));
    }

    protected boolean supportsUDTs() {
        return (clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 6, 0));
    }

    protected boolean supportsTimestampNanoseconds() {
        return (clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 6, 0));
    }

    protected boolean supportsBooleanValues() {
        return (clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 7, 0));
    }

    /**
     * Return true if the client contains the fix for DERBY-5236, which allows
     * DDMWriter.writeLDString() to write strings that need up to 64K-1 bytes
     * when represented in UTF-8. Otherwise, writeLDString() should use the
     * old maximum length, which is 32700 bytes.
     */
    protected boolean supportsLongerLDStrings() {
        // The fix for DERBY-5236 went into the 10.8 branch after the first
        // release off that branch. The DRDA maintenance version was bumped
        // to 1 when the fix went in (the third argument in the call to
        // greaterThanOrEqualTo() refers to that maintenance version, not to
        // the third digit of the product's version number).
        return clientType == DNC_CLIENT && greaterThanOrEqualTo(10, 8, 1);
    }

    /**
     * The timestamp length may be truncated for old versions of Derby.
     * See DERBY-2602.
     */
    protected int getTimestampLength()
    {
        return supportsTimestampNanoseconds() ?
            DRDAConstants.JDBC_TIMESTAMP_LENGTH : DRDAConstants.DRDA_OLD_TIMESTAMP_LENGTH;
    }

}
