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package org.openoffice.xmerge.converter.palm;

import java.io.OutputStream;
import java.io.InputStream;
import java.io.DataOutputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

/**
 *  <p>This class contains data for a single Palm database for use during
 *  a conversion process.</p>
 *
 *  <p>It contains zero or more <code>Record</code> objects stored in an
 *  array.  The index of the <code>Record</code> object in the array is
 *  the <code>Record</code> id or number for that specific <code>Record</code> object.
 *  Note that this class does not check for maximum number of Records
 *  allowable in an actual PDB.</p>
 *
 *  <p>This class also contains the PDB name associated with the Palm
 *  database it represents.  A PDB name consists of 32 bytes of a
 *  certain encoding (extended ASCII in this case).</p>
 *
 *  <p>The non default constructors take in a name parameter which may not
 *  be the exact PDB name to be used.  The name parameter in
 *  <code>String</code> or <code>byte</code> array are converted to an exact
 *  <code>NAME_LENGTH</code> byte array.  If the length of the name is less
 *  than <code>NAME_LENGTH</code>, it is padded with '\0' characters.  If it
 *  is more, it gets truncated.  The last character in the resulting byte
 *  array is always a '\0' character.  The resulting byte array is stored in
 *  <code>bName</code>, and a corresponding String object <code>sName</code>
 *  that contains characters without the '\0' characters.</p>
 *
 *  <p>The {@link #write write} method is called within the
 *  {@link org.openoffice.xmerge.converter.palm.PalmDocument#write
 *  PalmDocument.write} method for writing out its data to the <code>OutputStream</code>
 *  object.</p>
 *
 *  <p>The {@link #read read} method is called within the
 *  {@link org.openoffice.xmerge.converter.palm.PalmDocument#read
 *  PalmDocument.read} method for reading in its data from the <code>InputStream</code>
 *  object.</p>
 *
 *  @author  Akhil Arora, Herbie Ong
 *  @see     PalmDocument
 *  @see     Record
 */

public final class PalmDB {

   /* Backup attribute for a PDB.  This corresponds to dmHdrAttrBackup.  */
    public final static short PDB_HEADER_ATTR_BACKUP = 0x0008;

    /**  Number of bytes for the name field in the PDB. */
    public final static int NAME_LENGTH = 32;

    /**  List of <code>Record</code> objects. */
    private Record[] records;

    /**  PDB name in bytes. */
    private byte[] bName = null;

    /**  PDB name in String. */
    private String sName = null;

    /**  Creator ID. */
    private int creatorID = 0;

    /**  Type ID */
    private int typeID = 0;

    /**
     *  PDB version. Palm UInt16.
     *  It is treated as a number here, since there is no unsigned 16 bit
     *  in Java, int is used instead, but only 2 bytes are written out or
     *  read in.
     */
    private int version = 0;

    /**
     *  PDB attribute - flags for the database.
     *  Palm UInt16. Unsignedness should be irrelevant.
     */
    private short attribute = 0;


    /**
     *  Default constructor.
     *
     *  @param  creatorID  The PDB Creator ID.
     *  @param  typeID     The PDB Type ID.
     *  @param  version    The PDB header version.
     *  @param  attribute  The PDB header attribute.
     */
    public PalmDB(int creatorID, int typeID, int version, short attribute) {

        records = new Record[0];
        setAttributes(creatorID, typeID, version, attribute);
    }


    /**
     *  Constructor to create <code>PalmDB</code> object with
     *  <code>Record</code> objects.  <code>recs.length</code>
     * can be zero for an empty PDB.
     *
     *  @param  name       Suggested PDB name in a <code>String</code>.
     *  @param  creatorID  The PDB Creator ID.
     *  @param  typeID     The PDB Type ID.
     *  @param  version    The PDB header version.
     *  @param  attribute  The PDB header attribute.
     *  @param  recs       Array of <code>Record</code> objects.
     *
     *  @throws  UnsupportedEncodingException  If <code>name</code> is
     *                                         not properly encoded.
     *  @throws  NullPointerException          If <code>recs</code> is null.
     */
    public PalmDB(String name, int creatorID, int typeID, int version,
        short attribute, Record[] recs)
        throws UnsupportedEncodingException {

        this(name.getBytes(PdbUtil.ENCODING), creatorID, typeID, version,
            attribute, recs);
    }


    /**
     *  Constructor to create object with <code>Record</code>
     *  objects.  <code>recs.length</code> can be zero for an
     *  empty PDB.
     *
     *  @param   name      Suggested PDB name in a <code>byte</code>
     *                     array.
     *  @param  creatorID  The PDB Creator ID.
     *  @param  typeID     The PDB Type ID.
     *  @param  version    The PDB header version.
     *  @param  attribute  The PDB header attribute.
     *  @param   recs      Array of <code>Record</code> objects.
     *
     *  @throws  UnsupportedEncodingException  If <code>name</code> is
     *                                         not properly encoded.
     *  @throws  NullPointerException          If recs is null.
     */
    public PalmDB(byte[] name, int creatorID, int typeID, int version,
        short attribute, Record[] recs) throws UnsupportedEncodingException {

        store(name);

        records = new Record[recs.length];
        System.arraycopy(recs, 0, records, 0, recs.length);
        setAttributes(creatorID, typeID, version, attribute);
    }


    /**
     *  Set the attributes for the <code>PalmDB</code> object.
     *
     *  @param  creatorID  The PDB Creator ID.
     *  @param  typeID     The PDB Type ID.
     *  @param  version    The PDB header version.
     *  @param  attribute  The PDB header attribute.
     */
    public void setAttributes (int creatorID, int typeID, int version, short attribute) {
        this.creatorID = creatorID;
        this.typeID = typeID;
        this.version = version;
        this.attribute = attribute;
    }


    /**
     *  This private method is mainly used by the constructors above.
     *  to store bytes into name and also create a <code>String</code>
     *  representation. and also by the <code>read</code> method.
     *
     *  TODO: Note that this method assumes that the <code>byte</code>
     *  array parameter contains one character per <code>byte</code>,
     *  else it would truncate improperly.
     *
     *  @param  bytes  PDB name in <code>byte</code> array.
     *
     *  @throws  UnsupportedEncodingException  If ENCODING is
     *           not supported.
     */
    private void store(byte[] bytes) throws UnsupportedEncodingException {

        // note that this will initialize all bytes in name to 0.
        bName = new byte[NAME_LENGTH];

        // determine minimum length to copy over from bytes to bName.
        // Note that the last byte in bName has to be '\0'.

        int lastIndex = NAME_LENGTH - 1;

        int len = (bytes.length < lastIndex)? bytes.length: lastIndex;

        int i;

        for (i = 0; i < len; i++) {

            if (bytes[i] == 0) {
                break;
            }

            bName[i] = bytes[i];
        }

        // set sName, no need to include the '\0' character.
        sName = new String(bName, 0, i, PdbUtil.ENCODING);
    }


    /**
     *  Returns creator ID.
     *
     *  @return  The creator ID.
     */
    public int getCreatorID() {

        return creatorID;
    }


    /**
     *  Returns type ID.
     *
     *  @return  The type ID.
     */
    public int getTypeID() {

        return typeID;
    }


    /**
     *  Returns attribute flag.
     *
     *  @return  The attribute flag.
     */
    public short getAttribute() {

        return attribute;
    }


    /**
     *  Returns version.
     *
     *  @return  The version.
     */
    public int getVersion() {

        return version;
    }


    /**
     *  Return the number of Records contained in this
     *  PDB <code>PalmDB</code> object.
     *
     *  @return  Number of <code>Record</code> objects.
     */
    public int getRecordCount() {

        return records.length;
    }


    /**
     *  Return the specific <code>Record</code> object associated
     *  with the <code>Record</code> number.
     *
     *  @param  index  <code>Record</code> index number.
     *
     *  @return  The <code>Record</code> object in the specified index
     *
     *  @throws  ArrayIndexOutOfBoundsException  If index is out of bounds.
     */
    public Record getRecord(int index) {

        return records[index];
    }


    /**
     *  Return the list of <code>Record</code> objects.
     *
     *  @return  The array of <code>Record</code> objects.
     */
    public Record[] getRecords() {

        return records;
    }

    /**
     *  Return the PDB name associated with this object.
     *
     *  @return  The PDB name.
     */
    public String getPDBNameString() {

        return sName;
    }


    /**
     *  Return the PDB name associated with this object in
     *  <code>byte</code> array of exact length of 32 bytes.
     *
     *  @return  The PDB name in <code>byte</code> array of
     *           length 32.
     */
    public byte[] getPDBNameBytes() {

        return bName;
    }


    /**
     *  Write out the number of Records followed by what
     *  will be written out by each <code>Record</code> object.
     *
     *  @param  os  The <code>OutputStream</code> to write the
     *              object.
     *
     *  @throws  IOException  If any I/O error occurs.
     */
    public void write(OutputStream os) throws IOException {

        DataOutputStream out = new DataOutputStream(os);

        // write out PDB name
        out.write(bName);

        // write out 2 bytes for number of records
        out.writeShort(records.length);

        // let each Record object write out its own info.
        for (int i = 0; i < records.length; i++)
            records[i].write(out);
    }

    /**
     *  Read the necessary data to create a PDB from
     *  the <code>InputStream</code>.
     *
     *  @param  is  The <code>InputStream</code> to read data
     *              in order to restore the object.
     *
     *  @throws  IOException  If any I/O error occurs.
     */
    public void read(InputStream is) throws IOException {

        DataInputStream in = new DataInputStream(is);

        // read in the PDB name.
        byte[] bytes = new byte[NAME_LENGTH];
        in.readFully(bytes);
        store(bytes);

        // read in number of records
        int nrec = in.readUnsignedShort();
        records = new Record[nrec];

        // read in the Record infos
        for (int i = 0; i < nrec; i++) {

            records[i] = new Record();
            records[i].read(in);
        }
    }

    /**
     *  Override equals method of <code>Object</code>.
     *
     *  Two <code>PalmDB</code> objects are equal if they contain
     *  the same information, i.e. PDB name and Records.
     *
     *  This is used primarily for testing purposes only for now.
     *
     *  @param  obj  A <code>PalmDB</code> <code>Object</code> to
     *               compare.
     *
     *  @return  true if <code>obj</code> is equal to this, otherwise
     *           false.
     */
    public boolean equals(Object obj) {

        boolean bool = false;

        if (obj instanceof PalmDB) {

            PalmDB pdb = (PalmDB) obj;

            checkLabel: {

                // compare sName

                if (!sName.equals(pdb.sName)) {

                    break checkLabel;
                }

                // compare bName

                if (bName.length != pdb.bName.length) {

                    break checkLabel;
                }

                for (int i = 0; i < bName.length; i++) {

                    if (bName[i] != pdb.bName[i]) {

                        break checkLabel;
                    }
                }

                // compare each Record

                if (records.length != pdb.records.length) {

                    break checkLabel;
                }

                for (int i = 0; i < records.length; i++) {

                    if (!records[i].equals(pdb.records[i])) {

                        break checkLabel;
                    }
                }

                // all checks done
                bool = true;
            }
        }

        return bool;
    }
}