/*

 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.Closeable;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.Socket;

import java.net.URI;

import javax.net.ssl.SSLSession;

import javax.net.ssl.SSLSocket;

import java.net.URISyntaxException;

import java.nio.ByteBuffer;

import java.nio.charset.StandardCharsets;

import java.util.*;

import java.util.concurrent.ExecutorService;

import java.util.function.Consumer;

import jdk.incubator.http.internal.common.ByteBufferReference;

import jdk.incubator.http.internal.frame.FramesDecoder;

import jdk.incubator.http.internal.common.BufferHandler;

import jdk.incubator.http.internal.common.HttpHeadersImpl;

import jdk.incubator.http.internal.common.Queue;

import jdk.incubator.http.internal.frame.*;

import jdk.incubator.http.internal.hpack.Decoder;

import jdk.incubator.http.internal.hpack.DecodingCallback;

import jdk.incubator.http.internal.hpack.Encoder;

import static jdk.incubator.http.internal.frame.SettingsFrame.HEADER_TABLE_SIZE;

/**

 * Represents one HTTP2 connection, either plaintext upgraded from HTTP/1.1

 * or HTTPS opened using "h2" ALPN.

 */

public class Http2TestServerConnection {

    final Http2TestServer server;

    @SuppressWarnings({"rawtypes","unchecked"})

    final Map<Integer, Queue> streams; // input q per stream

    final HashSet<Integer> pushStreams;

    final Queue<Http2Frame> outputQ;

    volatile int nextstream;

    final Socket socket;

    final InputStream is;

    final OutputStream os;

    volatile Encoder hpackOut;

    volatile Decoder hpackIn;

    volatile SettingsFrame clientSettings;

    final SettingsFrame serverSettings;

    final ExecutorService exec;

    final boolean secure;

    volatile boolean stopping;

    volatile int nextPushStreamId = 2;

    final static ByteBuffer EMPTY_BUFFER = ByteBuffer.allocate(0);

    final static byte[] EMPTY_BARRAY = new byte[0];

    final static byte[] clientPreface = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".getBytes();

    Http2TestServerConnection(Http2TestServer server, Socket socket) throws IOException {

        System.err.println("TestServer: New connection from " + socket);

        this.server = server;

        this.streams = Collections.synchronizedMap(new HashMap<>());

        this.outputQ = new Queue<>();

        this.socket = socket;

        this.serverSettings = SettingsFrame.getDefaultSettings();

        this.exec = server.exec;

        this.secure = server.secure;

        this.pushStreams = new HashSet<>();

        is = new BufferedInputStream(socket.getInputStream());

        os = new BufferedOutputStream(socket.getOutputStream());

    }

    void close() {

        streams.forEach((i, q) -> {

            q.close();

        });

        stopping = true;

        try {

            socket.close();

            // TODO: put a reset on each stream

        } catch (IOException e) {

        }

    }

    private void readPreface() throws IOException {

        int len = clientPreface.length;

        byte[] bytes = new byte[len];

        is.readNBytes(bytes, 0, len);

        if (Arrays.compare(clientPreface, bytes) != 0) {

            throw new IOException("Invalid preface: " + new String(bytes, 0, len));

        }

    }

    String doUpgrade() throws IOException {

        String upgrade = readHttp1Request();

        String h2c = getHeader(upgrade, "Upgrade");

        if (h2c == null || !h2c.equals("h2c")) {

            System.err.println("Server:HEADERS: " + upgrade);

            throw new IOException("Bad upgrade 1 " + h2c);

        }

        sendHttp1Response(101, "Switching Protocols", "Connection", "Upgrade",

                "Upgrade", "h2c");

        sendSettingsFrame();

        readPreface();

        String clientSettingsString = getHeader(upgrade, "HTTP2-Settings");

        clientSettings = getSettingsFromString(clientSettingsString);

        return upgrade;

    }

    /**

     * Decodes the given, Client, settings payload provided in base64 HTTP1

     * header value.

     */

    private SettingsFrame getSettingsFromString(String s) throws IOException {

        Base64.Decoder decoder = Base64.getUrlDecoder();

        byte[] payload = decoder.decode(s);

        ByteBuffer bb1 = ByteBuffer.wrap(payload);

        // simulate header of Settings Frame

        ByteBuffer bb0 = ByteBuffer.wrap(

                new byte[] {0, 0, (byte)payload.length, 4, 0, 0, 0, 0, 0});

        List<Http2Frame> frames = new ArrayList<>();

        FramesDecoder reader = new FramesDecoder(frames::add);

        reader.decode(ByteBufferReference.of(bb0));

        reader.decode(ByteBufferReference.of(bb1));

        if (frames.size()!=1)

            throw new IOException("Expected 1 frame got "+frames.size()) ;

        Http2Frame frame = frames.get(0);

        if (!(frame instanceof SettingsFrame))

            throw new IOException("Expected SettingsFrame");

        return (SettingsFrame)frame;

    }

    void run() throws Exception {

        String upgrade = null;

        if (!secure) {

            upgrade = doUpgrade();

        } else {

            readPreface();

            sendSettingsFrame(true);

            clientSettings = (SettingsFrame) readFrame();

            if (clientSettings.getFlag(SettingsFrame.ACK)) {

                // we received the ack to our frame first

                clientSettings = (SettingsFrame) readFrame();

            }

            nextstream = 1;

        }

        System.out.println("ServerSettings: " + serverSettings);

        System.out.println("ClientSettings: " + clientSettings);

        hpackOut = new Encoder(serverSettings.getParameter(HEADER_TABLE_SIZE));

        hpackIn = new Decoder(clientSettings.getParameter(HEADER_TABLE_SIZE));

        if (!secure) {

            createPrimordialStream(upgrade);

            nextstream = 3;

        }

        exec.submit(this::readLoop);

        exec.submit(this::writeLoop);

    }

    static class BufferPool implements BufferHandler {

        public void setMinBufferSize(int size) {

        }

        @Override

        public ByteBuffer getBuffer() {

            int size = 32 * 1024;

            return ByteBuffer.allocate(size);

        }

        @Override

        public void returnBuffer(ByteBuffer buffer) {

        }

    }

    private void writeFrame(Http2Frame frame) throws IOException {

        ByteBufferReference[] refs = new FramesEncoder().encodeFrame(frame);

        //System.err.println("TestServer: Writing frame " + frame.toString());

        int c = 0;

        for (ByteBufferReference ref : refs) {

            ByteBuffer buf = ref.get();

            byte[] ba = buf.array();

            int start = buf.arrayOffset() + buf.position();

            c += buf.remaining();

            os.write(ba, start, buf.remaining());

        }

        os.flush();

        //System.err.printf("TestServer: wrote %d bytes\n", c);

    }

    void handleStreamReset(ResetFrame resetFrame) throws IOException {

        // TODO: cleanup

        throw new IOException("Stream reset");

    }

    private void handleCommonFrame(Http2Frame f) throws IOException {

        if (f instanceof SettingsFrame) {

            SettingsFrame sf = (SettingsFrame) f;

            if (sf.getFlag(SettingsFrame.ACK)) // ignore

            {

                return;

            }

            // otherwise acknowledge it

            clientSettings = sf;

            SettingsFrame frame = new SettingsFrame();

            frame.setFlag(SettingsFrame.ACK);

            frame.streamid(0);

            outputQ.put(frame);

            return;

        }

        //System.err.println("TestServer: Received ---> " + f.toString());

        throw new UnsupportedOperationException("Not supported yet.");

    }

    void sendWindowUpdates(int len, int streamid) throws IOException {

        if (len == 0)

            return;

        WindowUpdateFrame wup = new WindowUpdateFrame(streamid, len);

        outputQ.put(wup);

        wup = new WindowUpdateFrame(0 , len);

        outputQ.put(wup);

    }

    HttpHeadersImpl decodeHeaders(List<HeaderFrame> frames) {

        HttpHeadersImpl headers = new HttpHeadersImpl();

        DecodingCallback cb = (name, value) -> {

            headers.addHeader(name.toString(), value.toString());

        };

        for (HeaderFrame frame : frames) {

            ByteBufferReference[] buffers = frame.getHeaderBlock();

            for (ByteBufferReference buffer : buffers) {

                hpackIn.decode(buffer.get(), false, cb);

            }

        }

        hpackIn.decode(EMPTY_BUFFER, true, cb);

        return headers;

    }

    String getRequestLine(String request) {

        int eol = request.indexOf(CRLF);

        return request.substring(0, eol);

    }

    String getHeaders(String request) {

        int start = request.indexOf(CRLF);

        int end = request.indexOf(CRLFCRLF);

        if (start == -1 || end == -1) {

            throw new RuntimeException("Malformed request");

        }

        return request.substring(start,end);

    }

    void addHeaders(String headers, HttpHeadersImpl hdrs) {

        String[] hh = headers.split(CRLF);

        for (String header : hh) {

            int colon = header.indexOf(':');

            if (colon == -1)

                continue;

            String name = header.substring(0, colon);

            String value = header.substring(colon+1);

            while (value.startsWith(" "))

                value = value.substring(1);

            hdrs.addHeader(name, value);

        }

    }

    // First stream (1) comes from a plaintext HTTP/1.1 request

    @SuppressWarnings({"rawtypes","unchecked"})

    void createPrimordialStream(String request) throws IOException {

        HttpHeadersImpl headers = new HttpHeadersImpl();

        String requestLine = getRequestLine(request);

        String[] tokens = requestLine.split(" ");

        if (!tokens[2].equals("HTTP/1.1")) {

            throw new IOException("bad request line");

        }

        URI uri = null;

        try {

            uri = new URI(tokens[1]);

        } catch (URISyntaxException e) {

            throw new IOException(e);

        }

        String host = getHeader(request, "Host");

        if (host == null) {

            throw new IOException("missing Host");

        }

        headers.setHeader(":method", tokens[0]);

        headers.setHeader(":scheme", "http"); // always in this case

        headers.setHeader(":authority", host);

        headers.setHeader(":path", uri.getPath());

        Queue q = new Queue();

        String body = getRequestBody(request);

        addHeaders(getHeaders(request), headers);

        headers.setHeader("Content-length", Integer.toString(body.length()));

        addRequestBodyToQueue(body, q);

        streams.put(1, q);

        exec.submit(() -> {

            handleRequest(headers, q, 1, true /*complete request has been read*/);

        });

    }

    // all other streams created here

    @SuppressWarnings({"rawtypes","unchecked"})

    void createStream(HeaderFrame frame) throws IOException {

        List<HeaderFrame> frames = new LinkedList<>();

        frames.add(frame);

        int streamid = frame.streamid();

        if (streamid != nextstream) {

            throw new IOException("unexpected stream id");

        }

        nextstream += 2;

        boolean endStream = false;

        if (frame.getFlag(HeaderFrame.END_STREAM)) {

            endStream = true;

        }

        while (!frame.getFlag(HeaderFrame.END_HEADERS)) {

            Http2Frame f = readFrame();

            if (!(f instanceof HeaderFrame)) {

                handleCommonFrame(f); // should only be error frames

            } else {

                frame = (HeaderFrame) f;

                if (frame.getFlag(HeaderFrame.END_STREAM)) {

                    endStream = true;

                }

                frames.add(frame);

            }

        }

        boolean endStreamReceived = endStream;

        HttpHeadersImpl headers = decodeHeaders(frames);

        Queue q = new Queue();

        streams.put(streamid, q);

        exec.submit(() -> {

            handleRequest(headers, q, streamid, endStreamReceived);

        });

    }

    // runs in own thread. Handles request from start to finish. Incoming frames

    // for this stream/request delivered on Q

    @SuppressWarnings({"rawtypes","unchecked"})

    void handleRequest(HttpHeadersImpl headers,

                       Queue queue,

                       int streamid,

                       boolean endStreamReceived)

    {

        String method = headers.firstValue(":method").orElse("");

        //System.out.println("method = " + method);

        String path = headers.firstValue(":path").orElse("");

        //System.out.println("path = " + path);

        String scheme = headers.firstValue(":scheme").orElse("");

        //System.out.println("scheme = " + scheme);

        String authority = headers.firstValue(":authority").orElse("");

        //System.out.println("authority = " + authority);

        System.err.printf("TestServer: %s %s\n", method, path);

        HttpHeadersImpl rspheaders = new HttpHeadersImpl();

        int winsize = clientSettings.getParameter(

                        SettingsFrame.INITIAL_WINDOW_SIZE);

        //System.err.println ("Stream window size = " + winsize);

        final InputStream bis;

            bis = NullInputStream.INSTANCE;

        } else {

            bis = new BodyInputStream(queue, streamid, this);

        }

        try (bis;

             BodyOutputStream bos = new BodyOutputStream(streamid, winsize, this))

        {

            String us = scheme + "://" + authority + path;

            URI uri = new URI(us);

            boolean pushAllowed = clientSettings.getParameter(SettingsFrame.ENABLE_PUSH) == 1;

            Http2TestExchange exchange = new Http2TestExchange(streamid, method,

                    headers, rspheaders, uri, bis, getSSLSession(),

                    bos, this, pushAllowed);

            // give to user

            Http2Handler handler = server.getHandlerFor(uri.getPath());

            handler.handle(exchange);

            // everything happens in the exchange from here. Hopefully will

            // return though.

        } catch (Throwable e) {

            System.err.println("TestServer: handleRequest exception: " + e);

            e.printStackTrace();

        }

    }

    private SSLSession getSSLSession() {

        if (! (socket instanceof SSLSocket))

            return null;

        SSLSocket ssl = (SSLSocket)socket;

        return ssl.getSession();

    }

    // Runs in own thread

    @SuppressWarnings({"rawtypes","unchecked"})

    void readLoop() {

        try {

            while (!stopping) {

                Http2Frame frame = readFrame();

                //System.err.printf("TestServer: received frame %s\n", frame);

                int stream = frame.streamid();

                if (stream == 0) {

                    if (frame.type() == WindowUpdateFrame.TYPE) {

                        WindowUpdateFrame wup = (WindowUpdateFrame) frame;

                        updateConnectionWindow(wup.getUpdate());

                    } else {

                        // other common frame types

                        handleCommonFrame(frame);

                    }

                } else {

                    Queue q = streams.get(stream);

                    if (frame.type() == HeadersFrame.TYPE) {

                        if (q != null) {

                            System.err.println("HEADERS frame for existing stream! Error.");

                            // TODO: close connection

                            continue;

                        } else {

                            createStream((HeadersFrame) frame);

                        }

                    } else {

                        if (q == null && !pushStreams.contains(stream)) {

                            System.err.printf("Non Headers frame received with"+

                                " non existing stream (%d) ", frame.streamid());

                            System.err.println(frame);

                            continue;

                        }

                        if (frame.type() == WindowUpdateFrame.TYPE) {

                            WindowUpdateFrame wup = (WindowUpdateFrame) frame;

                            synchronized (updaters) {

                                Consumer<Integer> r = updaters.get(stream);

                                r.accept(wup.getUpdate());

                            }

                        } else {

                            q.put(frame);

                        }

                    }

                }

            }

        } catch (Throwable e) {

            if (!stopping) {

                System.err.println("Http server reader thread shutdown");

                e.printStackTrace();

            }

            close();

        }

    }

    ByteBufferReference[] encodeHeaders(HttpHeadersImpl headers) {

        List<ByteBuffer> buffers = new LinkedList<>();

        ByteBuffer buf = getBuffer();

        boolean encoded;

        for (Map.Entry<String, List<String>> entry : headers.map().entrySet()) {

            List<String> values = entry.getValue();

            String key = entry.getKey().toLowerCase();

            for (String value : values) {

                do {

                    hpackOut.header(key, value);

                    encoded = hpackOut.encode(buf);

                    if (!encoded) {

                        buf.flip();

                        buffers.add(buf);

                        buf = getBuffer();

                    }

                } while (!encoded);

            }

        }

        buf.flip();

        buffers.add(buf);

        return ByteBufferReference.toReferences(buffers.toArray(bbarray));

    }

    static void closeIgnore(Closeable c) {

        try {

            c.close();

        } catch (IOException e) {}

    }

    // Runs in own thread

    void writeLoop() {

        try {

            while (!stopping) {

                Http2Frame frame = outputQ.take();

                if (frame instanceof ResponseHeaders) {

                    ResponseHeaders rh = (ResponseHeaders)frame;

                    HeadersFrame hf = new HeadersFrame(rh.streamid(), rh.getFlags(), encodeHeaders(rh.headers));

                    writeFrame(hf);

                } else if (frame instanceof OutgoingPushPromise) {

                    handlePush((OutgoingPushPromise)frame);

                } else

                    writeFrame(frame);