package hello;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.module.afterburner.AfterburnerModule;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.AsciiString;
import io.netty.util.CharsetUtil;
import io.netty.util.concurrent.FastThreadLocal;

public class HelloServerHandler extends SimpleChannelInboundHandler<HttpRequest> {

	private static final FastThreadLocal<DateFormat> FORMAT = new FastThreadLocal<DateFormat>() {
		@Override
		protected DateFormat initialValue() {
			return new SimpleDateFormat("E, dd MMM yyyy HH:mm:ss z");
		}
	};

	private static final ObjectMapper newMapper() {
		ObjectMapper m = new ObjectMapper();
		m.registerModule(new AfterburnerModule());
		return m;
	}

	private static final Message newMsg() {
		return new Message("Hello, World!");
	}

	private static final int jsonLen() {
		try {
			return newMapper().writeValueAsBytes(newMsg()).length;
		} catch (JsonProcessingException e) {
			throw new RuntimeException(e);
		}
	}

	private static final byte[] STATIC_PLAINTEXT = "Hello, World!".getBytes(CharsetUtil.UTF_8);
	private static final int STATIC_PLAINTEXT_LEN = STATIC_PLAINTEXT.length;
	private static final ByteBuf PLAINTEXT_CONTENT_BUFFER = Unpooled.unreleasableBuffer(Unpooled.directBuffer().writeBytes(STATIC_PLAINTEXT));
	private static final CharSequence PLAINTEXT_CLHEADER_VALUE = new AsciiString(String.valueOf(STATIC_PLAINTEXT_LEN));
	private static final CharSequence JSON_CLHEADER_VALUE = new AsciiString(String.valueOf(jsonLen()));

	private static final CharSequence TYPE_PLAIN = new AsciiString("text/plain");
	private static final CharSequence TYPE_JSON = new AsciiString("application/json");
	private static final CharSequence SERVER_NAME = new AsciiString("Netty");
	private static final CharSequence CONTENT_TYPE_ENTITY = HttpHeaderNames.CONTENT_TYPE;
	private static final CharSequence DATE_ENTITY = HttpHeaderNames.DATE;
	private static final CharSequence CONTENT_LENGTH_ENTITY = HttpHeaderNames.CONTENT_LENGTH;
	private static final CharSequence SERVER_ENTITY = HttpHeaderNames.SERVER;
	private static final ObjectMapper MAPPER = newMapper();

	private volatile CharSequence date = new AsciiString(FORMAT.get().format(new Date()));

	HelloServerHandler(ScheduledExecutorService service) {
		service.scheduleWithFixedDelay(new Runnable() {
			private final DateFormat format = FORMAT.get();

			@Override
			public void run() {
				date = new AsciiString(format.format(new Date()));
			}
		}, 1000, 1000, TimeUnit.MILLISECONDS);

	}

	@Override
	public void channelRead0(ChannelHandlerContext ctx, HttpRequest msg) throws Exception {
		HttpRequest request = (HttpRequest) msg;
		String uri = request.uri();
		switch (uri) {
		case "/plaintext":
			writeResponse(ctx, request, PLAINTEXT_CONTENT_BUFFER.duplicate(), TYPE_PLAIN, PLAINTEXT_CLHEADER_VALUE);
			return;
		case "/json":
			byte[] json = MAPPER.writeValueAsBytes(newMsg());
			writeResponse(ctx, request, Unpooled.wrappedBuffer(json), TYPE_JSON, JSON_CLHEADER_VALUE);
			return;
		}
		FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.NOT_FOUND, Unpooled.EMPTY_BUFFER, false);
		ctx.write(response).addListener(ChannelFutureListener.CLOSE);
	}

	private void writeResponse(ChannelHandlerContext ctx, HttpRequest request, ByteBuf buf, CharSequence contentType, CharSequence contentLength) {

		// Build the response object.
		FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, buf, false);
		HttpHeaders headers = response.headers();
		headers.set(CONTENT_TYPE_ENTITY, contentType);
		headers.set(SERVER_ENTITY, SERVER_NAME);
		headers.set(DATE_ENTITY, date);
		headers.set(CONTENT_LENGTH_ENTITY, contentLength);

		// Close the non-keep-alive connection after the write operation is done.
		ctx.write(response, ctx.voidPromise());
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		ctx.close();
	}

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