build.gradle

import java.nio.ByteBuffer
import java.nio.channels.DatagramChannel
import java.util.concurrent.ExecutorService
import java.util.function.BiConsumer
import java.util.function.BiFunction
import java.util.function.Consumer
import java.util.function.Function

import static java.lang.String.*
import static java.nio.ByteBuffer.allocateDirect
import static java.nio.channels.DatagramChannel.*
import static java.util.concurrent.Executors.newSingleThreadExecutor

group 'me.exerosis.debugging'
version '1.0.0'

apply plugin: 'java'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
    maven {
        url = 'https://hub.spigotmc.org/nexus/content/repositories/snapshots/'
    }
}

dependencies {
    compile 'org.spigotmc:spigot:1.12.2-R0.1-SNAPSHOT'
    compile 'org.apache.commons:commons-lang3:3.3.2'
    compile files("/libs/tools.jar")
}


task test(type: TestTask) {
    doFirst {


    }
}

class DebugConnection {
    private final byte OP_TOGGLE = 0
    private final byte OP_LIST = 1
    private final byte OP_CHECK = 2
    private final DebugServer server

    DebugConnection(Number port) {
        server = new DebugServer(port, 512)
    }

    private static String ERROR_CHECK = "\tPlugin check failed.\n\tPlugin: %s\n\tCode: %s"

    private final Map<String, Plugin> plugins = new HashMap<>();

    Plugin getPlugin(SocketAddress address, String name) {
        return plugins.computeIfAbsent(name, { plugin ->
            Plugin pl = new Plugin(name) {
                @Override
                boolean setEnabled(boolean enabled, Number delay) {
                    return false
                }

                @Override
                boolean isEnabled(boolean refresh) {
                    if (refresh) {
                        server.request(OP_CHECK, address, { request ->
                            putString(request, name);
                            return { response ->
                                byte error = response.get();
                                if (error != -1)
                                    throw new RuntimeException(format(ERROR_CHECK, name, error))
                                enabled = response.get() == 1;
                            }
                        })

                    }
                    return enabled
                }
            }
            pl.isEnabled(true)
            return pl;
        })
    }


    void toggle(SocketAddress address, Consumer<Boolean> callback, PluginAction... actions) {
        server.request(OP_TOGGLE, address, { request ->
            request.put((byte) actions.length)
            actions.each { action ->
                putString(request, action.name)
                request.putLong(action.delay)
                request.put((byte) (action.enable ? 1 : 0))
            }
            return { response ->
                byte[] errors = new byte[actions.length]
                response.get(errors)
                errors.each { code ->
                    if (code != -1) {
                        callback.accept(false)
                        return;
                    }
                }
                callback.accept(true)
            }
        })
    }

    void list(SocketAddress address, String filter, Consumer<List<Plugin>> callback) {
        server.request(OP_LIST, address, { request ->
            putString(request, filter)
            return { response ->
                List<Plugin> plugins = new ArrayList<>()
                byte length;
                while ((length = response.get()) != 0) {
                    byte[] bytes = new byte[length]
                    response.get(bytes)
                    plugins.add(getPlugin(address, new String(bytes)))
                }
                callback.accept(plugins)
            }
        })
    }

    static abstract class Plugin {
        private final String name
        private boolean enabled = false

        private Plugin(String name) {
            this.name = name
        }

        abstract boolean setEnabled(boolean enabled, Number delay = 5_000)

        abstract boolean isEnabled(boolean refresh = true)

        String name() {
            return name
        }

        void enable(Number delay = 5_000) {
            if (!enabled && setEnabled(true, delay))
                enabled = true
        }

        void disable(Number delay = 5_000) {
            if (enabled && setEnabled(false, delay))
                enabled = false
        }

        void toggle(Number delay = 5_000) {
            if (setEnabled(!enabled, delay))
                enabled = !enabled
        }
    }

    static class PluginAction {
        private final boolean enable
        private final long delay
        private final String name

        private PluginAction(String name, boolean enable, Number delay) {
            this.name = name
            this.delay = delay.longValue()
            this.enable = enable
        }
    }

    static void putString(ByteBuffer buffer, String string, Consumer<Number> length = { buffer.put(it.byteValue()) }) {
        length.accept(string.length())
        buffer.put(string.bytes)
    }
}

class DebugServer implements Closeable {
    private final Map<Number, BiConsumer<ByteBuffer, SocketAddress>> handlers = new HashMap<>()
    private final ExecutorService executor = newSingleThreadExecutor()
    private final DatagramChannel channel
    private final ByteBuffer buffer

    DebugServer(Number port, Number length) throws IOException {
        this(port, length, { buffer ->
            buffer.put(length.byteValue())
        })
    }

    DebugServer(Number port, Number length, Function<ByteBuffer, Number> opcodes) throws IOException {
        buffer = allocateDirect(length.intValue())
        channel = open()
        channel.configureBlocking(true)
        channel.bind(new InetSocketAddress(port.intValue()))
        executor.submit({
            while (channel.isOpen()) {
                SocketAddress address = channel.receive(buffer)
                buffer.flip()
                handlers.get(opcodes.apply(buffer)).accept(buffer, address)
                buffer.clear()
            }
            return null
        })
    }

    void send(SocketAddress address, Number opcode, Consumer<ByteBuffer> packet) {
        try {
            synchronized (buffer) {
                buffer.clear()
                buffer.put(opcode.byteValue())
                packet.accept(buffer)
                channel.send(buffer, address)
            }
        } catch (IOException e) {
            throw new RuntimeException(e)
        }
    }

    void receive(Number opcode, BiConsumer<ByteBuffer, SocketAddress> handler) {
        handlers.put(opcode, handler)
    }

    void request(Number opcode, SocketAddress address, Function<ByteBuffer, Consumer<ByteBuffer>> handler) {
        send(address, opcode, { request ->
            receive(opcode, { response, ignored ->
                handler.apply(response)
                handlers.remove(opcode)
            })
        } as Consumer)
    }

    void respond(Number opcode, Function<ByteBuffer, Consumer<ByteBuffer>> handler) {
        respond(opcode, { request, address -> handler.apply(request) } as BiFunction)
    }

    void respond(Number opcode, BiFunction<ByteBuffer, SocketAddress, Consumer<ByteBuffer>> handler) {
        receive(opcode, { request, address ->
            Consumer<ByteBuffer> response = handler.apply(request, address)
            buffer.clear()
            buffer.put(opcode.byteValue())
            response.accept(request)
            channel.send(buffer, address)
        } as BiConsumer)
    }

    @Override
    void close() throws IOException {
        channel.close()
        executor.shutdown()
    }
}

class TestTask extends DefaultTask {
    @TaskAction
    def tryConnect() {
        println 'hello from GreetingTask'
    }
}