package betsy.bpel.virtual.common.messages.deploy;

import java.io.IOException;
import java.io.Serializable;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Objects;

import org.apache.commons.lang.StringUtils;

/**
 * A {@link FileMessage} contains the binary data and the name (with extension)
 * of a file. Additionally a Checksum is created to verify the integrity of the
 * data after sending this {@link FileMessage} over a network.
 *
 * @author Cedric Roeck
 * @version 1.0
 */
public class FileMessage implements Serializable {

    /**
     * SerialVersionUID.
     */
    private static final long serialVersionUID = 1L;

    private final byte[] data;
    private final String filename;
    private final Checksum checksum;

    public FileMessage(final String filename, final byte... data) {
        if (StringUtils.isBlank(filename)) {
            throw new IllegalArgumentException(
                    "fileName must not be null or empty");
        }

        this.filename = filename;
        this.data = Objects.requireNonNull(data);
        this.checksum = Checksum.createChecksum(data);
    }

    public static FileMessage build(Path path) throws IOException {
        byte[] data = Files.readAllBytes(path);
        return new FileMessage(path.getFileName().toString(), data);
    }

    public byte[] getData() {
        return data;
    }

    public String getFilename() {
        return filename;
    }

    public Checksum getChecksum() {
        return checksum;
    }

    /**
     * Check whether the data is still equal to the time it was read.
     *
     * @return true if data is valid, false if parts have been lost/changed
     */
    public boolean isInvalid() {
        return !Checksum.isValid(getData(), getChecksum());
    }

    @Override
    public String toString() {
        return "FileMessage for '" + filename + "'";
    }
}