/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.channel.embedded;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelId;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOutboundInvoker;
import io.netty.channel.ChannelPipeline;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.Promise;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.Timeout;

import java.nio.channels.ClosedChannelException;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

public class EmbeddedChannelTest {

    @Test
    public void testParent() {
        EmbeddedChannel parent = new EmbeddedChannel();
        EmbeddedChannel channel = new EmbeddedChannel(parent, EmbeddedChannelId.INSTANCE, true, false);
        assertSame(parent, channel.parent());
        assertNull(parent.parent());

        assertFalse(channel.finish());
        assertFalse(parent.finish());
    }

    @Test
    public void testNotRegistered() throws Exception {
        EmbeddedChannel channel = new EmbeddedChannel(false, false);
        assertFalse(channel.isRegistered());
        channel.register();
        assertTrue(channel.isRegistered());
        assertFalse(channel.finish());
    }

    @Test
    public void testRegistered() throws Exception {
        EmbeddedChannel channel = new EmbeddedChannel(true, false);
        assertTrue(channel.isRegistered());
        try {
            channel.register();
            fail();
        } catch (IllegalStateException expected) {
            // This is expected the channel is registered already on an EventLoop.
        }
        assertFalse(channel.finish());
    }

    @Test
    @Timeout(value = 2000, unit = TimeUnit.MILLISECONDS)
    public void promiseDoesNotInfiniteLoop() throws InterruptedException {
        EmbeddedChannel channel = new EmbeddedChannel();
        channel.closeFuture().addListener(channel, (c, f) -> c.close());

        channel.close().syncUninterruptibly();
    }

    @Test
    public void testConstructWithChannelInitializer() {
        final Integer first = 1;
        final Integer second = 2;

        final ChannelHandler handler = new ChannelHandler() {
            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                ctx.fireChannelRead(first);
                ctx.fireChannelRead(second);
            }
        };
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelInitializer<Channel>() {
            @Override
            protected void initChannel(Channel ch) throws Exception {
                ch.pipeline().addLast(handler);
            }
        });
        ChannelPipeline pipeline = channel.pipeline();
        assertSame(handler, pipeline.firstContext().handler());
        assertTrue(channel.writeInbound(3));
        assertTrue(channel.finish());
        assertSame(first, channel.readInbound());
        assertSame(second, channel.readInbound());
        assertNull(channel.readInbound());
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Test
    public void testScheduling() throws Exception {
        EmbeddedChannel ch = new EmbeddedChannel(new ChannelHandler() { });
        final CountDownLatch latch = new CountDownLatch(2);
        Future future = ch.executor().schedule(latch::countDown, 1, TimeUnit.SECONDS);
        future.addListener(future1 -> latch.countDown());
        long next = ch.runScheduledPendingTasks();
        assertTrue(next > 0);
        // Sleep for the nanoseconds but also give extra 50ms as the clock my not be very precise and so fail the test
        // otherwise.
        Thread.sleep(TimeUnit.NANOSECONDS.toMillis(next) + 50);
        assertEquals(-1, ch.runScheduledPendingTasks());
        latch.await();
    }

    @Test
    public void testScheduledCancelled() throws Exception {
        EmbeddedChannel ch = new EmbeddedChannel(new ChannelHandler() { });
        Future<?> future = ch.executor().schedule(() -> { }, 1, TimeUnit.DAYS);
        ch.finish();
        assertTrue(future.isCancelled());
    }

    @Test
    @Timeout(value = 3000, unit = TimeUnit.MILLISECONDS)
    public void testHandlerAddedExecutedInEventLoop() throws Throwable {
        final CountDownLatch latch = new CountDownLatch(1);
        final AtomicReference<Throwable> error = new AtomicReference<>();
        final ChannelHandler handler = new ChannelHandler() {
            @Override
            public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
                try {
                    assertTrue(ctx.executor().inEventLoop());
                } catch (Throwable cause) {
                    error.set(cause);
                } finally {
                    latch.countDown();
                }
            }
        };
        EmbeddedChannel channel = new EmbeddedChannel(handler);
        assertFalse(channel.finish());
        latch.await();
        Throwable cause = error.get();
        if (cause != null) {
            throw cause;
        }
    }

    @Test
    public void testConstructWithOutHandler() {
        EmbeddedChannel channel = new EmbeddedChannel();
        assertTrue(channel.writeInbound(1));
        assertTrue(channel.writeOutbound(2));
        assertTrue(channel.finish());
        assertSame(1, channel.readInbound());
        assertNull(channel.readInbound());
        assertSame(2, channel.readOutbound());
        assertNull(channel.readOutbound());
    }

    @Test
    public void testConstructWithChannelId() {
        ChannelId channelId = new CustomChannelId(1);
        EmbeddedChannel channel = new EmbeddedChannel(channelId);
        assertSame(channelId, channel.id());
    }

    // See https://github.com/netty/netty/issues/4316.
    @Test
    @Timeout(value = 2000, unit = TimeUnit.MILLISECONDS)
    public void testFireChannelInactiveAndUnregisteredOnClose() throws InterruptedException {
        testFireChannelInactiveAndUnregistered(ChannelOutboundInvoker::close);
    }

    @Test
    @Timeout(value = 2000, unit = TimeUnit.MILLISECONDS)
    public void testFireChannelInactiveAndUnregisteredOnDisconnect() throws InterruptedException {
        testFireChannelInactiveAndUnregistered(ChannelOutboundInvoker::disconnect);
    }

    private static void testFireChannelInactiveAndUnregistered(Action action) throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(3);
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                latch.countDown();
                // Should be executed.
                ctx.executor().execute(latch::countDown);
            }

            @Override
            public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
                latch.countDown();
            }
        });
        action.doRun(channel).syncUninterruptibly();
        latch.await();
    }

    private interface Action {
        Future<Void> doRun(Channel channel);
    }

    @Test
    public void testHasDisconnect() {
        EventOutboundHandler handler = new EventOutboundHandler();
        EmbeddedChannel channel = new EmbeddedChannel(true, handler);
        assertTrue(channel.disconnect().isSuccess());
        assertTrue(channel.close().isSuccess());
        assertEquals(EventOutboundHandler.DISCONNECT, handler.pollEvent());
        assertEquals(EventOutboundHandler.CLOSE, handler.pollEvent());
        assertNull(handler.pollEvent());
    }

    @Test
    public void testHasNoDisconnect() {
        EventOutboundHandler handler = new EventOutboundHandler();
        EmbeddedChannel channel = new EmbeddedChannel(false, handler);
        assertTrue(channel.disconnect().isSuccess());
        assertTrue(channel.close().isSuccess());
        assertEquals(EventOutboundHandler.CLOSE, handler.pollEvent());
        assertEquals(EventOutboundHandler.CLOSE, handler.pollEvent());
        assertNull(handler.pollEvent());
    }

    @Test
    public void testHasNoDisconnectSkipDisconnect() {
        EmbeddedChannel channel = new EmbeddedChannel(false, new ChannelHandler() {
            @Override
            public Future<Void> close(ChannelHandlerContext ctx) {
                return ctx.newFailedFuture(new Throwable());
            }
        });
        assertFalse(channel.disconnect().isSuccess());
    }

    @Test
    public void testFinishAndReleaseAll() {
        ByteBuf in = Unpooled.buffer();
        ByteBuf out = Unpooled.buffer();
        try {
            EmbeddedChannel channel = new EmbeddedChannel();
            assertTrue(channel.writeInbound(in));
            assertEquals(1, in.refCnt());

            assertTrue(channel.writeOutbound(out));
            assertEquals(1, out.refCnt());

            assertTrue(channel.finishAndReleaseAll());
            assertEquals(0, in.refCnt());
            assertEquals(0, out.refCnt());

            assertNull(channel.readInbound());
            assertNull(channel.readOutbound());
        } finally {
            release(in, out);
        }
    }

    @Test
    public void testReleaseInbound() {
        ByteBuf in = Unpooled.buffer();
        ByteBuf out = Unpooled.buffer();
        try {
            EmbeddedChannel channel = new EmbeddedChannel();
            assertTrue(channel.writeInbound(in));
            assertEquals(1, in.refCnt());

            assertTrue(channel.writeOutbound(out));
            assertEquals(1, out.refCnt());

            assertTrue(channel.releaseInbound());
            assertEquals(0, in.refCnt());
            assertEquals(1, out.refCnt());

            assertTrue(channel.finish());
            assertNull(channel.readInbound());

            ByteBuf buffer = channel.readOutbound();
            assertSame(out, buffer);
            buffer.release();

            assertNull(channel.readOutbound());
        } finally {
            release(in, out);
        }
    }

    @Test
    public void testReleaseOutbound() {
        ByteBuf in = Unpooled.buffer();
        ByteBuf out = Unpooled.buffer();
        try {
            EmbeddedChannel channel = new EmbeddedChannel();
            assertTrue(channel.writeInbound(in));
            assertEquals(1, in.refCnt());

            assertTrue(channel.writeOutbound(out));
            assertEquals(1, out.refCnt());

            assertTrue(channel.releaseOutbound());
            assertEquals(1, in.refCnt());
            assertEquals(0, out.refCnt());

            assertTrue(channel.finish());
            assertNull(channel.readOutbound());

            ByteBuf buffer = channel.readInbound();
            assertSame(in, buffer);
            buffer.release();

            assertNull(channel.readInbound());
        } finally {
            release(in, out);
        }
    }

    @Test
    public void testWriteLater() {
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public Future<Void> write(final ChannelHandlerContext ctx, final Object msg) {
                Promise<Void> promise = ctx.newPromise();
                ctx.executor().execute(() -> ctx.write(msg).cascadeTo(promise));
                return promise;
            }
        });
        Object msg = new Object();

        assertTrue(channel.writeOutbound(msg));
        assertTrue(channel.finish());
        assertSame(msg, channel.readOutbound());
        assertNull(channel.readOutbound());
    }

    @Test
    public void testWriteScheduled() throws InterruptedException  {
        final int delay = 500;
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public Future<Void> write(final ChannelHandlerContext ctx, final Object msg) {
                Promise<Void> promise = ctx.newPromise();
                ctx.executor().schedule(() -> {
                    ctx.writeAndFlush(msg).cascadeTo(promise);
                }, delay, TimeUnit.MILLISECONDS);
                return promise;
            }
        });
        Object msg = new Object();

        assertFalse(channel.writeOutbound(msg));
        Thread.sleep(delay  * 2);
        assertTrue(channel.finish());
        assertSame(msg, channel.readOutbound());
        assertNull(channel.readOutbound());
    }

    @Test
    public void testFlushInbound() throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
              latch.countDown();
            }
        });

        channel.flushInbound();

        if (!latch.await(1L, TimeUnit.SECONDS)) {
            fail("Nobody called #channelReadComplete() in time.");
        }
    }

    @Test
    public void testWriteOneInbound() throws InterruptedException {
      final CountDownLatch latch = new CountDownLatch(1);
      final AtomicInteger flushCount = new AtomicInteger(0);

      EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
          @Override
          public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
              ReferenceCountUtil.release(msg);
              latch.countDown();
          }

          @Override
          public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
              flushCount.incrementAndGet();
          }
      });

      channel.writeOneInbound("Hello, Netty!");

      if (!latch.await(1L, TimeUnit.SECONDS)) {
          fail("Nobody called #channelRead() in time.");
      }

      channel.close().syncUninterruptibly();

      // There was no #flushInbound() call so nobody should have called
      // #channelReadComplete()
      assertEquals(0, flushCount.get());
    }

    @Test
    public void testFlushOutbound() throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public void flush(ChannelHandlerContext ctx) {
                latch.countDown();
            }
        });

        channel.flushOutbound();

        if (!latch.await(1L, TimeUnit.SECONDS)) {
            fail("Nobody called #flush() in time.");
        }
    }

    @Test
    public void testWriteOneOutbound() throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);
        final AtomicInteger flushCount = new AtomicInteger(0);

        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public Future<Void> write(ChannelHandlerContext ctx, Object msg) {
                Future<Void> future = ctx.write(msg);
                latch.countDown();
                return future;
            }

            @Override
            public void flush(ChannelHandlerContext ctx) {
                flushCount.incrementAndGet();
            }
        });

        // This shouldn't trigger a #flush()
        channel.writeOneOutbound("Hello, Netty!");

        if (!latch.await(1L, TimeUnit.SECONDS)) {
            fail("Nobody called #write() in time.");
        }

        channel.close().syncUninterruptibly();

        // There was no #flushOutbound() call so nobody should have called #flush()
        assertEquals(0, flushCount.get());
    }

    @Test
    public void testEnsureOpen() throws InterruptedException {
        EmbeddedChannel channel = new EmbeddedChannel();
        channel.close().syncUninterruptibly();

        try {
            channel.writeOutbound("Hello, Netty!");
            fail("This should have failed with a ClosedChannelException");
        } catch (Exception expected) {
            assertTrue(expected instanceof ClosedChannelException);
        }

        try {
            channel.writeInbound("Hello, Netty!");
            fail("This should have failed with a ClosedChannelException");
        } catch (Exception expected) {
            assertTrue(expected instanceof ClosedChannelException);
        }
    }

    @Test
    public void testHandleInboundMessage() throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);

        EmbeddedChannel channel = new EmbeddedChannel() {
            @Override
            protected void handleInboundMessage(Object msg) {
                latch.countDown();
            }
        };

        channel.writeOneInbound("Hello, Netty!");

        if (!latch.await(1L, TimeUnit.SECONDS)) {
            fail("Nobody called #handleInboundMessage() in time.");
        }
    }

    @Test
    public void testHandleOutboundMessage() throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);

        EmbeddedChannel channel = new EmbeddedChannel() {
            @Override
            protected void handleOutboundMessage(Object msg) {
                latch.countDown();
            }
        };

        channel.writeOneOutbound("Hello, Netty!");
        if (latch.await(50L, TimeUnit.MILLISECONDS)) {
            fail("Somebody called unexpectedly #flush()");
        }

        channel.flushOutbound();
        if (!latch.await(1L, TimeUnit.SECONDS)) {
            fail("Nobody called #handleOutboundMessage() in time.");
        }
    }

    @Test
    @Timeout(value = 5000, unit = TimeUnit.MILLISECONDS)
    public void testChannelInactiveFired() throws InterruptedException {
        final AtomicBoolean inactive = new AtomicBoolean();
        EmbeddedChannel channel = new EmbeddedChannel(new ChannelHandler() {
            @Override
            public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
                ctx.close();
            }

            @Override
            public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                inactive.set(true);
            }
        });
        channel.pipeline().fireExceptionCaught(new IllegalStateException());

        assertTrue(inactive.get());
    }

    private static void release(ByteBuf... buffers) {
        for (ByteBuf buffer : buffers) {
            if (buffer.refCnt() > 0) {
                buffer.release();
            }
        }
    }

    private static final class EventOutboundHandler implements ChannelHandler {
        static final Integer DISCONNECT = 0;
        static final Integer CLOSE = 1;

        private final Queue<Integer> queue = new ArrayDeque<>();

        @Override
        public Future<Void> disconnect(ChannelHandlerContext ctx) {
            queue.add(DISCONNECT);
            return ctx.newSucceededFuture();
        }

        @Override
        public Future<Void> close(ChannelHandlerContext ctx) {
            queue.add(CLOSE);
            return ctx.newSucceededFuture();
        }

        Integer pollEvent() {
            return queue.poll();
        }
    }
}