package kjd.reactnative.bluetooth.conn;

import android.bluetooth.BluetoothSocket;
import android.util.Base64;
import android.util.Log;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.Properties;

/**
 * Implements {@link DeviceConnection} providing direct write and reading of byte[] data.   When
 * writing data to the device, the byte[] is transferred as is with no extra encoding or
 * manipulation.
 * <p>
 * When data is received, it's written to the input buffer or transferred as is.  At this point
 * there is no concept of a deliminator, if required we can add one in later where we just look
 * for matching bytes.
 *
 * @author kendavidson
 *
 */
public class ByteArrayDeviceConnectionImpl extends AbstractDeviceConnection {

    /**
     * The buffer in which data is stored.
     */
    private final ByteBuffer mBuffer;

    /**
     * Creates a new {@link AbstractDeviceConnection} to the provided NativeDevice, using the provided
     * Properties.
     *
     * @param socket
     * @param properties
     */
    public ByteArrayDeviceConnectionImpl(BluetoothSocket socket, Properties properties) throws IOException {
        super(socket, properties);

        int bufferSize = StandardOption.READ_SIZE.get(mProperties);
        this.mBuffer = ByteBuffer.allocate(bufferSize);
    }

    @Override
    protected void receivedData(byte[] bytes) {
        Log.d(this.getClass().getSimpleName(),
                String.format("Received %d bytes from device %s", bytes.length, getDevice().getAddress()));
        mBuffer.put(bytes);

        if (mOnDataReceived != null) {
            Log.d(this.getClass().getSimpleName(),
                    "BluetoothEvent.READ listener is registered, providing data");
            mOnDataReceived.accept(getDevice(), read());
        } else {
            Log.d(this.getClass().getSimpleName(),
                    "No BluetoothEvent.READ listeners are registered, storing in buffer");
        }
    }

    /**
     * Provides the number of full messages (delimiters) available within the buffer.
     *
     * @return the number of messages available
     */
    @Override
    public int available() {
        return mBuffer.array().length;
    }

    @Override
    public synchronized boolean clear() {
        mBuffer.clear();
        return true;
    }

    /**
     * Reads the full ByteBuffer into a Base64 encoded String for transfer back to React Native
     * bridge.
     *
     * @return the next message from the buffer
     * @throws IOException if an error occurs during reading
     */
    @Override
    public String read() {
        byte[] arr = new byte[mBuffer.position()];
        mBuffer.flip();
        mBuffer.get(arr);
        String message = Base64.encodeToString(arr, Base64.DEFAULT);
        clear();

        return message;
    }

}