/*
 * Copyright (c) 2005, 2020, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.
 */

package sun.net.httpserver;

import java.io.*;
import java.net.*;
import javax.net.ssl.*;
import java.util.*;
import java.lang.System.Logger;
import java.lang.System.Logger.Level;
import java.text.*;
import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.stream.Stream;
import com.sun.net.httpserver.*;

class ExchangeImpl {

    Headers reqHdrs, rspHdrs;
    Request req;
    String method;
    boolean writefinished;
    URI uri;
    HttpConnection connection;
    long reqContentLen;
    long rspContentLen;
    /* raw streams which access the socket directly */
    InputStream ris;
    OutputStream ros;
    Thread thread;
    /* close the underlying connection when this exchange finished */
    boolean close;
    boolean closed;
    boolean http10 = false;

    /* for formatting the Date: header */
    private static final DateTimeFormatter FORMATTER;
    static {
        String pattern = "EEE, dd MMM yyyy HH:mm:ss zzz";
        FORMATTER = DateTimeFormatter.ofPattern(pattern, Locale.US)
                                     .withZone(ZoneId.of("GMT"));
    }

    private static final String HEAD = "HEAD";

    /* streams which take care of the HTTP protocol framing
     * and are passed up to higher layers
     */
    InputStream uis;
    OutputStream uos;
    LeftOverInputStream uis_orig; // uis may have be a user supplied wrapper
    PlaceholderOutputStream uos_orig;

    boolean sentHeaders; /* true after response headers sent */
    Map<String,Object> attributes;
    int rcode = -1;
    HttpPrincipal principal;
    ServerImpl server;

    ExchangeImpl (
        String m, URI u, Request req, long len, HttpConnection connection
    ) throws IOException {
        this.req = req;
        this.reqHdrs = req.headers();
        this.rspHdrs = new Headers();
        this.method = m;
        this.uri = u;
        this.connection = connection;
        this.reqContentLen = len;
        /* ros only used for headers, body written directly to stream */
        this.ros = req.outputStream();
        this.ris = req.inputStream();
        server = getServerImpl();
        server.startExchange();
    }

    public Headers getRequestHeaders () {
        return new UnmodifiableHeaders (reqHdrs);
    }

    public Headers getResponseHeaders () {
        return rspHdrs;
    }

    public URI getRequestURI () {
        return uri;
    }

    public String getRequestMethod (){
        return method;
    }

    public HttpContextImpl getHttpContext (){
        return connection.getHttpContext();
    }

    private boolean isHeadRequest() {
        return HEAD.equals(getRequestMethod());
    }

    public void close () {
        if (closed) {
            return;
        }
        closed = true;

        /* close the underlying connection if,
         * a) the streams not set up yet, no response can be sent, or
         * b) if the wrapper output stream is not set up, or
         * c) if the close of the input/outpu stream fails
         */
        try {
            if (uis_orig == null || uos == null) {
                connection.close();
                return;
            }
            if (!uos_orig.isWrapped()) {
                connection.close();
                return;
            }
            if (!uis_orig.isClosed()) {
                uis_orig.close();
            }
            uos.close();
        } catch (IOException e) {
            connection.close();
        }
    }

    public InputStream getRequestBody () {
        if (uis != null) {
            return uis;
        }
        if (reqContentLen == -1L) {
            uis_orig = new ChunkedInputStream (this, ris);
            uis = uis_orig;
        } else {
            uis_orig = new FixedLengthInputStream (this, ris, reqContentLen);
            uis = uis_orig;
        }
        return uis;
    }

    LeftOverInputStream getOriginalInputStream () {
        return uis_orig;
    }

    public int getResponseCode () {
        return rcode;
    }

    public OutputStream getResponseBody () {
        /* TODO. Change spec to remove restriction below. Filters
         * cannot work with this restriction
         *
         * if (!sentHeaders) {
         *    throw new IllegalStateException ("headers not sent");
         * }
         */
        if (uos == null) {
            uos_orig = new PlaceholderOutputStream (null);
            uos = uos_orig;
        }
        return uos;
    }


    /* returns the place holder stream, which is the stream
     * returned from the 1st call to getResponseBody()
     * The "real" ouputstream is then placed inside this
     */
    PlaceholderOutputStream getPlaceholderResponseBody () {
        getResponseBody();
        return uos_orig;
    }

    public void sendResponseHeaders (int rCode, long contentLen)
    throws IOException
    {
        if (sentHeaders) {
            throw new IOException ("headers already sent");
        }
        this.rcode = rCode;
        String statusLine = "HTTP/1.1 "+rCode+Code.msg(rCode)+"\r\n";
        OutputStream tmpout = new BufferedOutputStream (ros);
        PlaceholderOutputStream o = getPlaceholderResponseBody();
        tmpout.write (bytes(statusLine, 0), 0, statusLine.length());
        boolean noContentToSend = false; // assume there is content
        boolean noContentLengthHeader = false; // must not send Content-length is set
        rspHdrs.set("Date", FORMATTER.format(Instant.now()));

        /* check for response type that is not allowed to send a body */

        if ((rCode>=100 && rCode <200) /* informational */
            ||(rCode == 204)           /* no content */
            ||(rCode == 304))          /* not modified */
        {
            if (contentLen != -1) {
                Logger logger = server.getLogger();
                String msg = "sendResponseHeaders: rCode = "+ rCode
                    + ": forcing contentLen = -1";
                logger.log (Level.WARNING, msg);
            }
            contentLen = -1;
            noContentLengthHeader = (rCode != 304);
        }

        if (isHeadRequest() || rCode == 304) {
            /* HEAD requests or 304 responses should not set a content length by passing it
             * through this API, but should instead manually set the required
             * headers.*/
            if (contentLen >= 0) {
                final Logger logger = server.getLogger();
                String msg =
                    "sendResponseHeaders: being invoked with a content length for a HEAD request";
                logger.log (Level.WARNING, msg);
            }
            noContentToSend = true;
            contentLen = 0;
        } else { /* not a HEAD request or 304 response */
            if (contentLen == 0) {
                if (http10) {
                    o.setWrappedStream (new UndefLengthOutputStream (this, ros));
                    close = true;
                } else {
                    rspHdrs.set ("Transfer-encoding", "chunked");
                    o.setWrappedStream (new ChunkedOutputStream (this, ros));
                }
            } else {
                if (contentLen == -1) {
                    noContentToSend = true;
                    contentLen = 0;
                }
                if (!noContentLengthHeader) {
                    rspHdrs.set("Content-length", Long.toString(contentLen));
                }
                o.setWrappedStream (new FixedLengthOutputStream (this, ros, contentLen));
            }
        }

        // A custom handler can request that the connection be
        // closed after the exchange by supplying Connection: close
        // to the response header. Nothing to do if the exchange is
        // already set up to be closed.
        if (!close) {
            Stream<String> conheader =
                    Optional.ofNullable(rspHdrs.get("Connection"))
                    .map(List::stream).orElse(Stream.empty());
            if (conheader.anyMatch("close"::equalsIgnoreCase)) {
                Logger logger = server.getLogger();
                logger.log (Level.DEBUG, "Connection: close requested by handler");
                close = true;
            }
        }

        write (rspHdrs, tmpout);
        this.rspContentLen = contentLen;
        tmpout.flush() ;
        tmpout = null;
        sentHeaders = true;
        if (noContentToSend) {
            WriteFinishedEvent e = new WriteFinishedEvent (this);
            server.addEvent (e);
            closed = true;
        }
        server.logReply (rCode, req.requestLine(), null);
    }

    void write (Headers map, OutputStream os) throws IOException {
        Set<Map.Entry<String,List<String>>> entries = map.entrySet();
        for (Map.Entry<String,List<String>> entry : entries) {
            String key = entry.getKey();
            byte[] buf;
            List<String> values = entry.getValue();
            for (String val : values) {
                int i = key.length();
                buf = bytes (key, 2);
                buf[i++] = ':';
                buf[i++] = ' ';
                os.write (buf, 0, i);
                buf = bytes (val, 2);
                i = val.length();
                buf[i++] = '\r';
                buf[i++] = '\n';
                os.write (buf, 0, i);
            }
        }
        os.write ('\r');
        os.write ('\n');
    }

    private byte[] rspbuf = new byte [128]; // used by bytes()

    
convert string to byte[], using rspbuf
Make sure that at least "extra" bytes are free at end
of rspbuf. Reallocate rspbuf if not big enough.
caller must check return value to see if rspbuf moved
/**
     * convert string to byte[], using rspbuf
     * Make sure that at least "extra" bytes are free at end
     * of rspbuf. Reallocate rspbuf if not big enough.
     * caller must check return value to see if rspbuf moved
     */
    private byte[] bytes (String s, int extra) {
        int slen = s.length();
        if (slen+extra > rspbuf.length) {
            int diff = slen + extra - rspbuf.length;
            rspbuf = new byte [2* (rspbuf.length + diff)];
        }
        char c[] = s.toCharArray();
        for (int i=0; i<c.length; i++) {
            rspbuf[i] = (byte)c[i];
        }
        return rspbuf;
    }

    public InetSocketAddress getRemoteAddress (){
        Socket s = connection.getChannel().socket();
        InetAddress ia = s.getInetAddress();
        int port = s.getPort();
        return new InetSocketAddress (ia, port);
    }

    public InetSocketAddress getLocalAddress (){
        Socket s = connection.getChannel().socket();
        InetAddress ia = s.getLocalAddress();
        int port = s.getLocalPort();
        return new InetSocketAddress (ia, port);
    }

    public String getProtocol (){
        String reqline = req.requestLine();
        int index = reqline.lastIndexOf (' ');
        return reqline.substring (index+1);
    }

    public SSLSession getSSLSession () {
        SSLEngine e = connection.getSSLEngine();
        if (e == null) {
            return null;
        }
        return e.getSession();
    }

    public Object getAttribute (String name) {
        if (name == null) {
            throw new NullPointerException ("null name parameter");
        }
        if (attributes == null) {
            attributes = getHttpContext().getAttributes();
        }
        return attributes.get (name);
    }

    public void setAttribute (String name, Object value) {
        if (name == null) {
            throw new NullPointerException ("null name parameter");
        }
        if (attributes == null) {
            attributes = getHttpContext().getAttributes();
        }
        attributes.put (name, value);
    }

    public void setStreams (InputStream i, OutputStream o) {
        assert uis != null;
        if (i != null) {
            uis = i;
        }
        if (o != null) {
            uos = o;
        }
    }

    
PP
/**
     * PP
     */
    HttpConnection getConnection () {
        return connection;
    }

    ServerImpl getServerImpl () {
        return getHttpContext().getServerImpl();
    }

    public HttpPrincipal getPrincipal () {
        return principal;
    }

    void setPrincipal (HttpPrincipal principal) {
        this.principal = principal;
    }

    static ExchangeImpl get (HttpExchange t) {
        if (t instanceof HttpExchangeImpl) {
            return ((HttpExchangeImpl)t).getExchangeImpl();
        } else {
            assert t instanceof HttpsExchangeImpl;
            return ((HttpsExchangeImpl)t).getExchangeImpl();
        }
    }
}

An OutputStream which wraps another stream
which is supplied either at creation time, or sometime later.
If a caller/user tries to write to this stream before
the wrapped stream has been provided, then an IOException will
be thrown.
/**
 * An OutputStream which wraps another stream
 * which is supplied either at creation time, or sometime later.
 * If a caller/user tries to write to this stream before
 * the wrapped stream has been provided, then an IOException will
 * be thrown.
 */
class PlaceholderOutputStream extends java.io.OutputStream {

    OutputStream wrapped;

    PlaceholderOutputStream (OutputStream os) {
        wrapped = os;
    }

    void setWrappedStream (OutputStream os) {
        wrapped = os;
    }

    boolean isWrapped () {
        return wrapped != null;
    }

    private void checkWrap () throws IOException {
        if (wrapped == null) {
            throw new IOException ("response headers not sent yet");
        }
    }

    public void write(int b) throws IOException {
        checkWrap();
        wrapped.write (b);
    }

    public void write(byte b[]) throws IOException {
        checkWrap();
        wrapped.write (b);
    }

    public void write(byte b[], int off, int len) throws IOException {
        checkWrap();
        wrapped.write (b, off, len);
    }

    public void flush() throws IOException {
        checkWrap();
        wrapped.flush();
    }

    public void close() throws IOException {
        checkWrap();
        wrapped.close();
    }
}