package org.jaghax.server.protocol;

import org.jaghax.Client;
import org.jaghax.server.rs.net.ByteArrayPool;
import org.jaghax.server.rs.net.ByteBufferPool;
import org.jaghax.server.util.CacheFile;
import org.jaghax.server.util.Global;

import java.nio.ByteBuffer;
import java.util.zip.CRC32;

/**
 * {@code JaggrabProtocolHandler}
 *
 * @author James Lawrence
 * @version 1
 */
public class JaggrabProtocolHandler implements ProtocolHandler {
    private static JaggrabProtocolHandler instance;
    private static int[] cache_crc;
    private static int cache_hash;

    /**
     * Returns the singleton of this ProtocolHandler
     *
     * @return the only instance of this protocol handler
     */
    public static JaggrabProtocolHandler getInstance() {
        return instance;
    }

    static {
        instance = new JaggrabProtocolHandler();

        // Initialise cache CRCs
        cache_crc = new int[9];
        CRC32 crc = new CRC32();
        for (int i = 0; i < 9; i++) {
            byte[] data = CacheFile.cache[0].readEntry(i);
            if (data == null) {
                System.err.println("cache[0][" + i + "] is null :S");
                continue;
            }

            crc.update(data, 0, data.length);
            cache_crc[i] = (int) crc.getValue();
            crc.reset();
            data = null;
        }
        crc = null;

        cache_hash = 1234;
        for (int i = 0; i < 9; i++)
            cache_hash = (cache_hash << 1) + cache_crc[i];
    }

    private JaggrabProtocolHandler() {
    }

    public int handleInput(Client c) {
        ByteBuffer input = c.getInputBuffer();

        // See if we have a whole request (peek for '\n\n')
        boolean gotN = false;
        int length = -1;
        for (int i = 0; i < input.limit(); i++) {
            byte b = input.get(i);
            if (b == '\n') {
                if (gotN) {
                    length = i + 1;
                    break;
                }
                gotN = true;
            } else
                gotN = false;
        }

        if (length != -1)
            return 0;

        //J A G G R A B ' '
        if (input.getLong() != 0x4a41474752414220L) {
            System.err.println("Invalid request received on JAGGRAB server (doesn't start with JAGGRAB)");
            c.close();
            return 0;
        }

        // Read the request
        byte[] str_data = ByteArrayPool.acquire(length - 10);
        input.get(str_data, 0, length - 10);
        String s = new String(str_data);
        System.out.println("JAGGRAB REQUEST: " + s);

        // Find the request string
        if(s.startsWith("crc")) { // CRC request...
            if(!s.endsWith(String.valueOf(Global.CLIENT_VERSION))) {
                System.err.println("CRC request from non-317 client, dropped.");
                c.close();
                return 0;
            }

            // Send the CRCs
            ByteBuffer b = ByteBufferPool.acquire(40);
            for(int i = 0; i < 9; i++)
                b.putInt(cache_crc[i]);
            b.putInt(cache_hash);
            c.write(b);
            return length;
        } else { // Find the archive from the cache...
            int id = -1;
            if(s.startsWith("title"))
                id = 1;
            else if(s.startsWith("config"))
                id = 2;
            else if(s.startsWith("interface"))
                id = 3;
            else if(s.startsWith("media"))
                id = 4;
            else if(s.startsWith("versionlist"))
                id = 5;
            else if(s.startsWith("textures"))
                id = 6;
            else if(s.startsWith("wordenc"))
                id = 7;
            else if(s.startsWith("sounds"))
                id = 8;
            else {
                System.err.println("Invalid JAGGRAB request: " + s + ", connection dropped.");
                c.close();
                return 0;
            }

            // Check the client requested with the correct CRC
            if(!s.endsWith(String.valueOf(cache_crc[id]))) {
                System.err.println("Valid request, but CRC for request was inconsistent, connection dropped.");
                c.close();
                return 0;
            }

            byte[] data = CacheFile.cache[0].readEntry(id);
            if(data == null)
                throw new RuntimeException("Error in JAGGRAB server, failed to serve request '" + s + "' (not found in cache!)");
            ByteBuffer b = ByteBufferPool.acquire(data.length);
            c.write(b);
            data = null;

            return length;
        }
    }
}