package org.aion.ledger;

import org.aion.ledger.exceptions.LedgerWriteException;

import org.hid4java.HidDevice;

import org.hid4java.HidManager;

import org.hid4java.HidServices;

import javax.annotation.Nonnull;

import javax.annotation.Nullable;

import java.io.IOException;

import static org.aion.ledger.Constants.PACKET_SIZE;

public class LedgerHIDAPI extends LedgerDevice {

private HidDevice device;

public LedgerHIDAPI(@Nonnull final HidDevice device) {

this.device = device;

}

// TODO: what if this is called twice?

@Override

public void close() {

if (this.device.isOpen()) {

this.device.close();

}

}

/**

* Writes a chunk of 64-byte data out to the Ledger device.

* As best as I can tell this should be always formatted in 64 byte

* chunks.

*

* @implNote Note that there is no guarantee the data is actually written

* to the device, or when this data is written to the device.

*

* @param arg 64-byte chunk of data to be written to device.

*/

@Override

protected void write(@Nonnull final byte[] arg) throws LedgerWriteException {

this.device.write(arg, arg.length, (byte) 0x00);

}

/**

* Retrieves a 64-byte chunk of data from the device

* Note: this method should only be called from one thread

*

* @param waitPeriod how long to wait, <= 0 for indefinite blocking

* @return {@code 64-byte} chunk of data, returns {@code null} on any conditions failing

*/

@Nullable

@Override

protected byte[] read(final int waitPeriod) {

byte[] data = new byte[PACKET_SIZE];

int resp = this.device.read(data);

if (resp < 0) {

// TODO: should distinguish this state

return null;

}

return data;

}

@Override

protected void resetLedger() {

this.device.close();

HidServices services = HidManager.getHidServices();

services.scan();

try {

// TODO: violates abstraction

this.device = ((LedgerHIDAPI) LedgerUtilities.findLedgerDevice()).device;

} catch (IOException e) {

throw new RuntimeException(e);

}

}

@Override

protected void setNonBlocking(boolean condition) {

this.device.setNonBlocking(condition);

}

@Override

public String toString() {

return this.device.toString();

}

}