package org.openslx.dnbd3;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.util.List;

import org.openslx.dnbd3.xml.Client;
import org.openslx.dnbd3.xml.Image;
import org.openslx.dnbd3.xml.Info;
import org.simpleframework.xml.core.Persister;

public class DNBD3Server {

    private static final int CMDSTOP = 0;
    private static final int CMDRELOAD = 1;
    private static final int CMDINFO = 2;
    private static final int CMDADDIMG = 3;
    private static final int CMDDELIMG = 4;

    private static final String HOST = "127.0.0.1";
    private static final int PORT = 5004;

    public void doReload() throws IOException, DNBD3Exception {
        sndCommand(CMDRELOAD);
    }

    public void doShutdown() throws IOException, DNBD3Exception {
        sndCommand(CMDSTOP);
    }

    public void addImage(Image image) throws Exception {
        Info info = new Info();
        info.getImages().add(image);
        sndData(CMDADDIMG, info);
        doReload();
    }
    
    public void delImage(Image image) throws Exception {
        Info info = new Info();
        info.getImages().add(image);
        sndData(CMDDELIMG, info);
        doReload();
    }

    public List<Image> getImages() throws Exception {
        return rcvData().getImages();
    }

    public List<Client> getClients() throws Exception {
        return rcvData().getClients();
    }

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    private void sndCommand(int cmd) throws IOException, DNBD3Exception {
        Socket sock = new Socket(HOST, PORT);
        sndHeader(sock, new DNBD3Header(cmd, 0, 0));
        rcvHeader(sock);
        sock.close();
    }
    
    private void sndData(int cmd, Info info) throws Exception {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        new Persister().write(info, os);
        Socket sock = new Socket(HOST, PORT);
        sndHeader(sock, new DNBD3Header(cmd, os.size(), 0));
        sock.getOutputStream().write(os.toByteArray());
        rcvHeader(sock);
        sock.close();
    }
    
    private Info rcvData() throws Exception {
        Socket sock = new Socket(HOST, PORT);
        sndHeader(sock, new DNBD3Header(CMDINFO, 0, 0));
        rcvHeader(sock);
        Info info = new Persister().read(Info.class, sock.getInputStream());
        sock.close();
        return info;
    }
    
    private void sndHeader(Socket sock, DNBD3Header header) throws IOException {
        OutputStream os = sock.getOutputStream();
        os.write(header.toByteArray());
    }

    private DNBD3Header rcvHeader(Socket sock) throws IOException, DNBD3Exception {
        DNBD3Header header = new DNBD3Header();
        InputStream is = sock.getInputStream();
        byte[] bytes = ByteBuffer.allocate(12).array();
        is.read(bytes, 0, 12);
        header.fromByteArray(bytes);

        switch (header.getError()) {

        case 0:
            return header;

        case DNBD3Header.ERROR_FILE_NOT_FOUND:
            throw new DNBD3Exception(DNBD3Header.ERROR_FILE_NOT_FOUND,
                    "Image file does not exist or is not readable");

        case DNBD3Header.ERROR_IMAGE_ALREADY_EXISTS:
            throw new DNBD3Exception(DNBD3Header.ERROR_IMAGE_ALREADY_EXISTS,
                    "Image with given vid and rid already exists");

        case DNBD3Header.ERROR_CONFIG_FILE_PERMISSIONS:
            throw new DNBD3Exception(DNBD3Header.ERROR_CONFIG_FILE_PERMISSIONS,
                    "Config file is not writable");
            
        case DNBD3Header.ERROR_IMAGE_NOT_FOUND:
            throw new DNBD3Exception(DNBD3Header.ERROR_IMAGE_NOT_FOUND,
                    "Image does not exist");
            
        case DNBD3Header.ERROR_RID:
            throw new DNBD3Exception(DNBD3Header.ERROR_RID,
                    "Delete with rid=0 is not allowed");
            
        case DNBD3Header.ERROR_IMAGE_IN_USE:
            throw new DNBD3Exception(DNBD3Header.ERROR_IMAGE_IN_USE,
                    "Image is in use");

        default:
            throw new DNBD3Exception(DNBD3Header.ERROR_UNKNOWN,
                    "Unknown error, something went horribly wrong...");
        }
    }

}