Format

package ltd.genuinesounds.game.SaveFormat;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;
import java.util.Map.Entry;
import java.util.zip.GZIPOutputStream;

@SuppressWarnings("unchecked")
public class Format {

    // Error keys
    public static final byte ERROR_DEFINITION = 0;

    // Setting Flags
    public static final byte FLAG_READ = 1;
    public static final byte FLAG_WRITE = 2;
    public static final byte FLAG_DEFUALT = (byte) (FLAG_READ | FLAG_WRITE);

    // Format System Bits
    public static final byte SYS_SIZE_IN_BYTES = 2;
    public static final byte SYS_START_NAME = 4;
    public static final byte SYS_END_NAME = 8;
    public static final byte SYS_START_CONTENT = 16;
    public static final byte SYS_END_CONTENT = 32;

    // Type Tags
    public static final byte TAG_BOOLEAN = 0;
    public static final byte TAG_BYTE = 1;
    public static final byte TAG_SHORT = 2;
    public static final byte TAG_CHAR = 3;
    public static final byte TAG_INT = 4;
    public static final byte TAG_FLOAT = 5;
    public static final byte TAG_DOUBLE = 6;
    public static final byte TAG_LONG = 7;
    public static final byte TAG_STRING = 8;

    public static void saveAsReadble(byte caser, ISetting<?> setting) throws SaveException {
        saveAs(true, caser, setting);
    }

    public static void saveAsCompact(byte caser, ISetting<?> setting) throws SaveException {
        saveAs(false, caser, setting);
    }

    private static void saveAs(boolean readable, byte tagType, ISetting<?> setting) throws SaveException {
        // init ByteBuffer
        ByteBuffer bb = ByteBuffer.allocate(0xFFFFFF).order(ByteOrder.nativeOrder());

        byte[] name = setting.name().getBytes();
        // state which kind of information is carried in file.
        bb.put(tagType);

        // mark next byte as size in bytes, byte after that is settings name.
        bb.put((byte) (SYS_SIZE_IN_BYTES | SYS_START_NAME));
        bb.put((byte) name.length);
        bb.put(name);

        // type of settings list.
        switch (tagType) {
            case TAG_BOOLEAN:
                createByteArrayForBoolean(bb, (ISetting<Boolean>) setting);
                break;

            // TODO: add other cases
            default: throw new SaveException(setting);
        }

        // end all settings
        bb.put(SYS_END_CONTENT);

        // zero byte (not used)
        bb.put((byte) 0);

        // reduce buffer size to end bit (0)
        bb.limit(bb.position());

        // rewind for correct order
        bb.rewind();

        // write buffer
        try {
            File file = new File("D:/" + setting.name() + ".dat");
            file.createNewFile();
            writeBuffer(readable, bb, file);
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void createByteArrayForBoolean(ByteBuffer bb, ISetting<Boolean> setting) {
        boolean first = true;
        for (Entry<String, Boolean> entry : setting.set()) {
            byte[] name = entry.getKey().getBytes();

            // on first run to save space end name from header else end privious content here for space saving
            // state size and begin name
            bb.put((byte) ((first ? SYS_END_NAME : SYS_END_CONTENT) | SYS_SIZE_IN_BYTES | SYS_START_NAME));
            bb.put((byte) name.length);
            bb.put(name);

            // end name and begin content, no size flag needed, booleans are assumed to be one bit
            bb.put((byte) (SYS_END_NAME | SYS_START_CONTENT));
            bb.put((byte) (entry.getValue() ? 1 : 0));

            // set not first run
            first = false;
        }
    }

    private static void writeBuffer(boolean readable, ByteBuffer buffer, File file) throws IOException {
        WritableByteChannel channel;
        if (!readable)
            channel = Channels.newChannel(new GZIPOutputStream(new FileOutputStream(file)));
        else
            channel = Channels.newChannel(new FileOutputStream(file));
        channel.write(buffer);
        channel.close();
    }

}