package digital.cabin.ezipc;


import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.platform.linux.ErrNo;


public abstract class EzIPC
{
    protected interface LibraryNamedFIFO extends Library
    {
        static LibraryNamedFIFO INSTANCE =
            Native.load("c", LibraryNamedFIFO.class);

        public int mkfifo(String pathname, int mode);
    }


    protected LibraryNamedFIFO lib;

    protected String connPath;

    protected FileInputStream  in_pipe;
    protected FileOutputStream out_pipe;


    public EzIPC(String connPath) throws IOException
    {
        this.lib = LibraryNamedFIFO.INSTANCE;
        this.connPath = connPath;

        if(lib.mkfifo(connPath+"_c2s", 0660) != 0)
            if(Native.getLastError() != ErrNo.EEXIST)
                throw new IOException("Could not create client->server pipe");

        if(lib.mkfifo(connPath+"_s2c", 0660) != 0)
            if(Native.getLastError() != ErrNo.EEXIST)
                throw new IOException("Could not create server->client pipe");

        this.in_pipe  = null;
        this.out_pipe = null;
    }

    public abstract void open() throws IOException;

    public void close() throws IOException
    {
        if(in_pipe  != null)  in_pipe.close();
        if(out_pipe != null) out_pipe.close();
    }


    // FIXME: check write() return val
    public boolean send(byte[] data) throws IOException
    {
        if(out_pipe == null) return false;
        if(data.length == 0) return true;

        // FIXME: JAVA DOES NOT HAVE FUCKING UNSIGNED BRO
        ByteBuffer bb = ByteBuffer.allocate(8);
        bb.order(ByteOrder.nativeOrder()); // Imagine not being native by def.
        bb.putLong(data.length);

        out_pipe.write(bb.array());
        out_pipe.write(data);

        return true;
    }

    // FIXME: check write() return val
    public boolean receive(byte[] data) throws IOException
    {
        if(in_pipe == null)  return false;
        if(data.length == 0) return true;

        byte[] bytes = new byte[8];

        // FIXME: yikes
        while(in_pipe.available() < 8);
        in_pipe.read(bytes);

        ByteBuffer bb = ByteBuffer.wrap(bytes);
        bb.order(ByteOrder.nativeOrder()); // Imagine not being native by def.

        // FIXME: JAVA DOES NOT HAVE FUCKING UNSIGNED BRO
        long in_size   = bb.getLong();
        long read_size = in_size > data.length ? data.length : in_size;

        // FIXME: yikes
        while(in_pipe.available() < read_size);
        long read = in_pipe.read(data);

        // truncate
        for(long i = 0; i < (in_size - read_size); i++) in_pipe.read();

        return true;
    }
}