source: greenstone3/branches/customizingGreenstone3/src/java/org/greenstone/gsdl3/util/GDBMWrapper.java@ 15191

package org.greenstone.gsdl3.util;

import au.com.pharos.gdbm.GdbmFile;
import au.com.pharos.packing.*;
import au.com.pharos.gdbm.GdbmException;

import org.apache.log4j.*;

/** java wrapper class for gdbm - uses Java-GDBM written by Martin Pool
 * replaces gdbmclass in the old version
 */

public class GDBMWrapper {

      static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.GDBMWrapper.class.getName());


    // Values must match those from gdbm.h - uses the definitions from GdbmFile !
    /** Indicates that the caller will just read the database.  Many
     * readers may share a database. */
    public final static int READER = GdbmFile.READER;
 
    /** The caller wants read/write access to an existing database and
     * requires exclusive access. */
    public final static int WRITER = GdbmFile.WRITER;
 
    /** The caller wants exclusive read/write access, and the database
     * should be created if it does not already exist. */
    public final static int WRCREAT = GdbmFile.WRCREAT;
 
    /** The caller wants exclusive read/write access, and the database
     * should be replaced if it already exists. */
    public final static int NEWDB = GdbmFile.NEWDB;

    protected GdbmFile db_=null;

    /** open the database filename, with mode mode - uses the constants
    above, eg GdbmFile.WRITER */
    public boolean openDatabase(String filename, int mode){
    try {
        if (db_!=null) {
        db_.close();
        }
        db_ = new GdbmFile(filename, mode);
    } catch ( GdbmException e) { // the database wasn't opened or created
        logger.error("couldn't open database "+filename);
        return false;
    } 
    db_.setKeyPacking(new StringPacking());
    db_.setValuePacking(new StringPacking());
    return true;
    }

    /** close the database associated with this wrapper */
    public void closeDatabase() {
    try {
        if (db_ != null) {
        db_.close();
        db_ = null;
        }
    } catch (GdbmException e) {
        // should never get here - close never actually throws an exception
        logger.error("error on close()");
    }
    }

    /** returns a DBInfo object containing all the name-value pairs for 
     * main_key 
     * @see DBInfo
     */
    public DBInfo getInfo(String main_key) {
    if (db_==null) {
        return null;
    }
    String s_info;
    try {
        s_info = (String)db_.fetch(main_key);
    } catch (GdbmException e) {
        logger.error("couldn't get record");
        return null;
    }
    if (s_info==null) {
        // record not present
        logger.error("key "+main_key+" not present in db");
        return null;
    }
    DBInfo info = new DBInfo();

    String [] lines = s_info.split("\n");
    String key;
    String value;
    for (int i=0; i<lines.length; i++) {
        logger.debug("line:"+lines[i]);
        int a = lines[i].indexOf('<');
        int b= lines[i].indexOf('>');
        if (a==-1 || b==-1) {
        logger.error("bad format in db");
        }
        else {
        key=lines[i].substring(a+1, b);
        value=lines[i].substring(b+1);
        logger.debug("key="+key+", val="+value);
        info.addInfo(key, value);

        }
    }
    return info;
    }

    /** sets all the name-value pairs in info as the content for key key 
     * TODO - not implemented yet */
    public boolean setInfo(String key, DBInfo info) {
    if (db_==null) {
        return false;
    }
    return true;
    }
    /** sets the key value as info 
     * TODO - not implemented yet */
    public boolean setInfo (String key, String info) {
    if (db_==null) {
        return false;
    }
    return true;
    }
    /** deletes the entry for key 
     * TODO - not implemented yet */
    public boolean deleteKey(String key) {
    if (db_==null) {
        return false;
    }
    return true;
    }

    // greenstone convenience methods - should these go into a separate class?
    // yes I think so.
    /** converts a greenstone OID to internal docnum */
    public long OID2Docnum(String OID) {
    DBInfo info = getInfo(OID);
    if (info != null) {
        long real_num = Long.parseLong(info.getInfo("docnum"));
        return real_num;
    }
    return -1;
    }
    /** converts a docnum to greenstone OID */
    public String docnum2OID(long docnum) {
    return docnum2OID(Long.toString(docnum));
    }
    
    /** converts a docnum to greenstone OID */
    public String docnum2OID(String docnum) {
    DBInfo info = getInfo(docnum);
    if (info!=null){
        String oid = info.getInfo("section");
        return oid;
    }else{
        return null;
    }
    }

    /** converts an external id to greenstone OID */
    public String externalId2OID(String extid) {
    DBInfo info = getInfo(extid);
    if (info != null) {
        String oid = info.getInfo("section");
        return oid;
    }
    return null;
    }
    /** translates relative oids into proper oids:
     * .pr (parent), .rt (root) .fc (first child), .lc (last child),
     * .ns (next sibling), .ps (previous sibling) 
     * .np (next page), .pp (previous page) : links sections in the order that you'd read the document
     * a suffix is expected to be present so test before using 
     */
    public String translateOID(String oid) {

    int p = oid.lastIndexOf('.');
    if (p != oid.length()-3) {
        logger.info("translateoid error: '.' is not the third to last char!!");
        return oid;
    }
    
    String top = oid.substring(0, p);
    String suff = oid.substring(p+1);
    // just in case we have multiple extensions, we must translate
    // we process inner ones first
    if (OID.needsTranslating(top)) {
        top = translateOID(top);
    }
    if (suff.equals("pr")) {
        return OID.getParent(top);
    } 
    if (suff.equals("rt")) {
        return OID.getTop(top);
    } 
    if (suff.equals("np")) {
        // try first child
        String node_id = translateOID(top+".fc");
        if (!node_id.equals(top)) {
        return node_id;
        }
        // try next sibling
        node_id = translateOID(top+".ns");
        if (!node_id.equals(top)) {
        return node_id;
        }
        // otherwise we keep trying parents sibling
        String child_id = top;
        String parent_id = OID.getParent(child_id);
        while(!parent_id.equals(child_id)) {
        node_id = translateOID(parent_id+".ns");
        if (!node_id.equals(parent_id)) {
            return node_id;
        }
        child_id = parent_id;
        parent_id = OID.getParent(child_id);
        }
        return top; // we couldn't get a next page, so just return the original
    } 
    if (suff.equals("pp")) {
        String prev_sib = translateOID(top+".ps");
        if (prev_sib.equals(top)) {
        // no previous sibling, so return the parent
        return OID.getParent(top);
        }
        // there is a previous sibling, so its either this section, or the last child of the last child..
        String last_child = translateOID(prev_sib+".lc");
        while (!last_child.equals(prev_sib)) {
        prev_sib = last_child;
        last_child = translateOID(prev_sib+".lc");
        }
        return last_child;
    } 
    
    int sibling_num = 0;
    if (suff.equals("ss")) {
        // we have to remove the sib num before we get top
        p = top.lastIndexOf('.');
        sibling_num = Integer.parseInt(top.substring(p+1));
        top = top.substring(0, p);
    }
    
    // need to get info out of gdbm db -
    String doc_id = top;
    if (suff.endsWith("s")) {
        doc_id = OID.getParent(top);
        if (doc_id.equals(top)) {
        // i.e. we are already at the top
        return top;
        }
    }
    DBInfo info = getInfo(doc_id);
    if (info==null) {
        logger.info("info is null!!");
        return top;
    }
    
    String contains = info.getInfo("contains");
    if (contains.equals("")) {
        // something is wrong
        return top;
    }
    contains = contains.replaceAll("\"", doc_id);
    String [] children = contains.split(";");
    if (suff.equals("fc")) {
        return children[0];
    } else if (suff.equals("lc")) {
        return children[children.length-1];
    } else {
        if (suff.equals("ss")) {
        return children[sibling_num-1];
        }
        // find the position that we are at.
        int i=0;
        while (i<children.length) {
        if (children[i].equals(top)) {
            break;
        }
        i++;
        }
        
        if (suff.equals("ns")) {
        if (i==children.length-1) {
            return children[i];
        }
        return children[i+1];
        } else if (suff.equals("ps")) {
        if (i==0) {
            return children[i];
        }
        return children[i-1];
        }
    }
    
    return top;
    }
}