/*
 * ============================================================================
 * GNU General Public License
 * ============================================================================
 *
 * Copyright (C) 2006-2011 Serotonin Software Technologies Inc. http://serotoninsoftware.com
 * @author Matthew Lohbihler
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * When signing a commercial license with Serotonin Software Technologies Inc.,
 * the following extension to GPL is made. A special exception to the GPL is 
 * included to allow you to distribute a combined work that includes BAcnet4J 
 * without being obliged to provide the source code for any proprietary components.
 */
package com.serotonin.bacnet4j.obj;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.math.BigInteger;

import com.serotonin.bacnet4j.LocalDevice;
import com.serotonin.bacnet4j.exception.BACnetRuntimeException;
import com.serotonin.bacnet4j.exception.BACnetServiceException;
import com.serotonin.bacnet4j.type.constructed.DateTime;
import com.serotonin.bacnet4j.type.enumerated.FileAccessMethod;
import com.serotonin.bacnet4j.type.enumerated.PropertyIdentifier;
import com.serotonin.bacnet4j.type.primitive.Boolean;
import com.serotonin.bacnet4j.type.primitive.ObjectIdentifier;
import com.serotonin.bacnet4j.type.primitive.OctetString;
import com.serotonin.bacnet4j.type.primitive.UnsignedInteger;
import org.free.bacnet4j.util.StreamUtils;

/**
 * @author Matthew Lohbihler
 */
public class FileObject extends BACnetObject {
    private static final long serialVersionUID = 1089963077847602732L;

    /**
     * The actual file that this object represents.
     */
    private final File file;

    public FileObject(LocalDevice localDevice, ObjectIdentifier oid, File file, FileAccessMethod fileAccessMethod) {
        super(localDevice, oid);
        this.file = file;

        if (file.isDirectory())
            throw new BACnetRuntimeException("File is a directory");

        updateProperties();

        try {
            setProperty(PropertyIdentifier.fileAccessMethod, fileAccessMethod);
        }
        catch (BACnetServiceException e) {
            // Should never happen, but wrap in an unchecked just in case.
            throw new BACnetRuntimeException(e);
        }
    }

    public void updateProperties() {
        try {
            // TODO this is only a snapshot. Property read methods need to be overridden to report real time values.
            setProperty(PropertyIdentifier.fileSize, new UnsignedInteger(new BigInteger(Long.toString(length()))));
            setProperty(PropertyIdentifier.modificationDate, new DateTime(file.lastModified()));
            setProperty(PropertyIdentifier.readOnly, new Boolean(!file.canWrite()));
        }
        catch (BACnetServiceException e) {
            // Should never happen, but wrap in an unchecked just in case.
            throw new BACnetRuntimeException(e);
        }
    }

    public long length() {
        return file.length();
    }

    public OctetString readData(long start, long length) throws IOException {
        FileInputStream in = new FileInputStream(file);
        try {
            while (start > 0) {
                long result = in.skip(start);
                if (result == -1)
                    // EOF
                    break;
                start -= result;
            }
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            StreamUtils.transfer(in, out, length);
            return new OctetString(out.toByteArray());
        }
        finally {
            in.close();
        }
    }

    public void writeData(long start, OctetString fileData) throws IOException {
        RandomAccessFile raf = new RandomAccessFile(file, "rw");
        try {
            byte data[] = fileData.getBytes();
            long newLength = start + data.length;
            raf.seek(start);
            raf.write(data);
            raf.setLength(newLength);
        }
        finally {
            raf.close();
        }

        updateProperties();
    }

    //    
    // public SequenceOf<OctetString> readRecords(int start, int length) throws IOException {
    //        
    // }
}