package net.lax1dude.eaglercraft.sp;

import com.jcraft.jzlib.CRC32;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.util.Date;

public class EPK2Compiler {

    private final ByteArrayOutputStream os;
    private final CRC32 checkSum = new CRC32();
    private int lengthIntegerOffset = 0;
    private int totalFileCount = 0;

    public EPK2Compiler(String name, String owner, String type) {
        os = new ByteArrayOutputStream(0x200000);
        try {

            os.write(new byte[]{(byte) 69, (byte) 65, (byte) 71, (byte) 80, (byte) 75, (byte) 71, (byte) 36, (byte) 36}); // EAGPKG$$
            os.write(new byte[]{(byte) 6, (byte) 118, (byte) 101, (byte) 114, (byte) 50, (byte) 46, (byte) 48}); // 6 + ver2.0
            Date d = new Date();

            byte[] filename = (name + ".epk").getBytes(StandardCharsets.UTF_8);
            os.write(filename.length);
            os.write(filename);

            byte[] comment = ("\n\n #  Eagler EPK v2.0 (c) " + (new SimpleDateFormat("yyyy")).format(d) + " " +
                    owner + "\n #  export: on " + (new SimpleDateFormat("MM/dd/yyyy")).format(d) + " at " +
                    (new SimpleDateFormat("hh:mm:ss aa")).format(d) + "\n\n #  world name: " + name + "\n\n")
                    .getBytes(StandardCharsets.UTF_8);

            os.write((comment.length >> 8) & 255);
            os.write(comment.length & 255);
            os.write(comment);

            writeLong(d.getTime(), os);

            lengthIntegerOffset = os.size();
            os.write(new byte[]{(byte) 255, (byte) 255, (byte) 255, (byte) 255}); // this will be replaced with the file count

            os.write('0'); // compression type: none

            os.write(new byte[]{(byte) 72, (byte) 69, (byte) 65, (byte) 68}); // HEAD
            os.write(new byte[]{(byte) 9, (byte) 102, (byte) 105, (byte) 108, (byte) 101, (byte) 45, (byte) 116, (byte) 121,
                    (byte) 112, (byte) 101}); // 9 + file-type

            byte[] typeBytes = type.getBytes(StandardCharsets.UTF_8);
            writeInt(typeBytes.length, os);
            os.write(typeBytes); // write type
            os.write('>');

            ++totalFileCount;

            os.write(new byte[]{(byte) 72, (byte) 69, (byte) 65, (byte) 68}); // HEAD
            os.write(new byte[]{(byte) 10, (byte) 119, (byte) 111, (byte) 114, (byte) 108, (byte) 100, (byte) 45, (byte) 110,
                    (byte) 97, (byte) 109, (byte) 101}); // 10 + world-name

            byte[] nameBytes = name.getBytes(StandardCharsets.UTF_8);
            writeInt(nameBytes.length, os);
            os.write(nameBytes); // write name
            os.write('>');

            ++totalFileCount;

            os.write(new byte[]{(byte) 72, (byte) 69, (byte) 65, (byte) 68}); // HEAD
            os.write(new byte[]{(byte) 11, (byte) 119, (byte) 111, (byte) 114, (byte) 108, (byte) 100, (byte) 45, (byte) 111,
                    (byte) 119, (byte) 110, (byte) 101, (byte) 114}); // 11 + world-owner

            byte[] ownerBytes = owner.getBytes(StandardCharsets.UTF_8);
            writeInt(ownerBytes.length, os);
            os.write(ownerBytes); // write owner
            os.write('>');

            ++totalFileCount;

        } catch (IOException ex) {
            throw new RuntimeException("This happened somehow", ex);
        }
    }

    public void append(String name, byte[] dat) {
        try {

            checkSum.reset();
            checkSum.update(dat, 0, dat.length);
            long sum = checkSum.getValue();

            os.write(new byte[]{(byte) 70, (byte) 73, (byte) 76, (byte) 69}); // FILE

            byte[] nameBytes = name.getBytes(StandardCharsets.UTF_8);
            os.write(nameBytes.length);
            os.write(nameBytes);

            writeInt(dat.length + 5, os);
            writeInt((int) sum, os);

            os.write(dat);

            os.write(':');
            os.write('>');

            ++totalFileCount;

        } catch (IOException ex) {
            throw new RuntimeException("This happened somehow", ex);
        }
    }

    public byte[] complete() {
        try {

            os.write(new byte[]{(byte) 69, (byte) 78, (byte) 68, (byte) 36}); // END$
            os.write(new byte[]{(byte) 58, (byte) 58, (byte) 58, (byte) 89, (byte) 69, (byte) 69, (byte) 58, (byte) 62}); // :::YEE:>

            byte[] ret = os.toByteArray();

            ret[lengthIntegerOffset] = (byte) ((totalFileCount >> 24) & 0xFF);
            ret[lengthIntegerOffset + 1] = (byte) ((totalFileCount >> 16) & 0xFF);
            ret[lengthIntegerOffset + 2] = (byte) ((totalFileCount >> 8) & 0xFF);
            ret[lengthIntegerOffset + 3] = (byte) (totalFileCount & 0xFF);

            return ret;

        } catch (IOException ex) {
            throw new RuntimeException("This happened somehow", ex);
        }
    }

    public static void writeInt(int i, OutputStream os) throws IOException {
        os.write((i >> 24) & 0xFF);
        os.write((i >> 16) & 0xFF);
        os.write((i >> 8) & 0xFF);
        os.write(i & 0xFF);
    }

    public static void writeLong(long i, OutputStream os) throws IOException {
        os.write((int) ((i >> 56) & 0xFF));
        os.write((int) ((i >> 48) & 0xFF));
        os.write((int) ((i >> 40) & 0xFF));
        os.write((int) ((i >> 32) & 0xFF));
        os.write((int) ((i >> 24) & 0xFF));
        os.write((int) ((i >> 16) & 0xFF));
        os.write((int) ((i >> 8) & 0xFF));
        os.write((int) (i & 0xFF));
    }

}