/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2000 Sun
 * Microsystems, Inc. All Rights Reserved.
 */


package org.netbeans.editor.ext;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;


/**
 *   DataAccessor for Code Completion DB files via RandomAccessFile implementation
 *
 *   @author  Martin Roskanin
 */
public class FileAccessor implements DataAccessor{
    
    private File f;
    private RandomAccessFile file;


    /** Creates a new instance of FileAccessor */
    public FileAccessor(File file) {
        f = file;
    }
    
    /** Appends exactly len bytes, starting at off of the buffer pointer
     * to the end of file resource.
     * @param  buffer the buffer from which the data is appended.
     * @param  off    the start offset of the data in the buffer.
     * @param  len    the number of bytes to append.
     * @return        the actual file offset before appending.
     */
    public void append(byte[] buffer, int off, int len) throws IOException {
        file.write(buffer, off, len);
    }
    
    /** Reads up to len bytes of data from this file resource into an array of bytes.
     * @param buffer the buffer into which the data is read.
     * @param off the start offset of the data.
     * @param len the maximum number of bytes read.
     */
    
    public void read(byte[] buffer, int off, int len) throws IOException {
        file.readFully(buffer, off, len);
    }
    
    /** Opens DataAccessor file resource 
     *  @param requestWrite if true, file is opened for read/write operation.
     */
    public void open(boolean requestWrite) throws IOException {
        file = new RandomAccessFile(f, requestWrite ? "rw" : "r"); //NOI18N
        if (!f.exists()){
            f.createNewFile();
        }
    }
    
    /** Closes DataAccessor file resource  */
    public void close() throws IOException {
        if (file!=null){
            file.close();
        }
    }
    
    /**
     * Returns the current offset in this file.
     *
     * @return     the offset from the beginning of the file, in bytes,
     *             at which the next read or write occurs.
     */
    public long getFilePointer() throws IOException {
        return file.getFilePointer();
    }

    /** Clears the file and sets the offset to 0 */    
    public void resetFile() throws IOException {
        file.setLength(0);
    }
    
    public void seek(long pos) throws IOException {
        file.seek(pos);
    }

    public int getFileLength() {
        return (int)f.length();
    }
    
    public String toString() {
        return f.getAbsolutePath();
    }
    
}