package io.github.lonamiwebs.overgram.utils;


import io.github.lonamiwebs.overgram.tl.TLObject;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.charset.StandardCharsets;
import java.util.List;

public class BinaryWriter {
    private final ByteBuffer buffer;

    public BinaryWriter() {
        buffer = ByteBuffer.allocate(128);
        buffer.order(ByteOrder.LITTLE_ENDIAN);
    }

    public void write(final int value) {
        buffer.putInt(value);
    }

    public void write(final long value) {
        buffer.putLong(value);
    }

    public void write(final double value) {
        buffer.putDouble(value);
    }

    public void write(final boolean value) {
        buffer.putInt(value ? 0x997275b5 : 0xbc799737);
    }

    public void write(final byte[] bytes) {
        int padding;
        if (bytes.length < 0xfe) {
            padding = (bytes.length + 1) % 4;
            buffer.put((byte) bytes.length);
            buffer.put(bytes);
        } else {
            padding = bytes.length % 4;
            buffer.putInt(bytes.length << 8 | 0xfe);
            buffer.put(bytes);
        }
        if (padding != 0) {
            for (padding = 4 - padding; padding-- != 0; ) {
                buffer.put((byte) 0);
            }
        }
    }

    public void write(final String string) {
        buffer.put(StandardCharsets.UTF_8.encode(string));
    }

    // TODO Handle boxed vs unboxed types (and vector<>)
    public void write(final TLObject object) {
        object.serialize(this);
    }

    @SuppressWarnings("unchecked")
    public void write(final List<?> objects) {
        write(0x1cb5c415);
        write(objects.size());
        if (objects.isEmpty()) {
            return;
        }

        final Object first = objects.get(0);
        if (first instanceof TLObject) {
            for (final TLObject obj : (List<TLObject>) objects) {
                write(obj);
            }
        } else if (first instanceof Integer) {
            for (final Integer obj : (List<Integer>) objects) {
                write(obj);
            }
        } else if (first instanceof Long) {
            for (final Long obj : (List<Long>) objects) {
                write(obj);
            }
        } else if (first instanceof byte[]) {
            for (final byte[] obj : (List<byte[]>) objects) {
                write(obj);
            }
        } else {
            throw new UnsupportedOperationException();
        }
    }
}