/*

 * 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.  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

 */

package java.net.http;

import java.io.IOException;

import java.net.URI;

import java.nio.ByteBuffer;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.function.LongConsumer;

import static java.net.http.HttpClient.Version.HTTP_1_1;

/**

 * Handles a HTTP/1.1 response in two blocking calls. readHeaders() and

 * readBody(). There can be more than one of these per Http exchange.

 */

class Http1Response {

    private ResponseContent content;

    private final HttpRequestImpl request;

    HttpResponseImpl response;

    private final HttpConnection connection;

    private ResponseHeaders headers;

    private int responseCode;

    private ByteBuffer buffer; // same buffer used for reading status line and headers

    private final Http1Exchange exchange;

    private final boolean redirecting; // redirecting

    private boolean return2Cache; // return connection to cache when finished

    Http1Response(HttpConnection conn, Http1Exchange exchange) {

        this.request = exchange.request();

        this.exchange = exchange;

        this.connection = conn;

        this.redirecting = false;

        buffer = connection.getRemaining();

    }

    // called when the initial read should come from a buffer left

    // over from a previous response.

    void setBuffer(ByteBuffer buffer) {

        this.buffer = buffer;

    }

    @SuppressWarnings("unchecked")

    public void readHeaders() throws IOException {

        String statusline = readStatusLine();

        if (statusline == null) {

            if (Log.errors()) {

                Log.logError("Connection closed. Retry");

            }

            connection.close();

            // connection was closed

            throw new IOException("Connection closed");

        }

        if (!statusline.startsWith("HTTP/1.")) {

            throw new IOException("Invalid status line: " + statusline);

        }

        char c = statusline.charAt(7);

        responseCode = Integer.parseInt(statusline.substring(9, 12));

        headers = new ResponseHeaders(connection, buffer);

        headers.initHeaders();

        if (Log.headers()) {

            logHeaders(headers);

        }

        response = new HttpResponseImpl(responseCode,

                                        exchange.exchange,

                                        headers,

                                        null,

                                        connection.sslParameters(),

                                        HTTP_1_1,

                                        connection);

    }

    private boolean finished;

    synchronized void completed() {

        finished = true;

    }

    synchronized boolean finished() {

        return finished;

    }

    // Blocking flow controller implementation. Only works when a

    // thread is dedicated to reading response body

    static class FlowController implements LongConsumer {

        long window ;

        @Override

        public synchronized void accept(long value) {

            window += value;

            notifyAll();

        }

        public synchronized void request(long value) throws InterruptedException {

            while (window < value) {

                wait();

            }

            window -= value;

        }

    }

    FlowController flowController;

    int fixupContentLen(int clen) {

        if (request.method().equalsIgnoreCase("HEAD")) {

            return 0;

        }

        if (clen == -1) {

            if (headers.firstValue("Transfer-encoding").orElse("")

                       .equalsIgnoreCase("chunked")) {

                return -1;

            }

            return 0;

        }

        return clen;

    }

    private void returnBuffer(ByteBuffer buf) {

        // not currently used, but will be when we change SSL to use fixed

        // sized buffers and a single buffer pool for HttpClientImpl

    }

    @SuppressWarnings("unchecked")

    public <T> T readBody(java.net.http.HttpResponse.BodyProcessor<T> p,

                          boolean return2Cache)

        throws IOException

    {

        T body = null; // TODO: check null case below

        this.return2Cache = return2Cache;

        final java.net.http.HttpResponse.BodyProcessor<T> pusher = p;

        int clen0 = headers.getContentLength();

        final int clen = fixupContentLen(clen0);

        flowController = new FlowController();

        body = pusher.onResponseBodyStart(clen, headers, flowController);

        ExecutorWrapper executor;

        if (body == null) {

            executor = ExecutorWrapper.callingThread();

        } else {

            executor = request.client().executorWrapper();

        }

        final ResponseHeaders h = headers;

        if (body == null) {

            content = new ResponseContent(connection,

                                          clen,

                                          h,

                                          pusher,

                                          flowController);

            content.pushBody(headers.getResidue());

            body = pusher.onResponseComplete();

            completed();

            onFinished();

            return body;

        } else {

            executor.execute(() -> {

                    try {

                        content = new ResponseContent(connection,

                                                      clen,

                                                      h,

                                                      pusher,

                                                      flowController);

                        content.pushBody(headers.getResidue());

                        pusher.onResponseComplete();

                        completed();

                        onFinished();

                    } catch (Throwable e) {

                        pusher.onResponseError(e);

                    }

                },

                () -> response.getAccessControlContext());

        }

        return body;

    }

    private void onFinished() {

        connection.buffer = content.getResidue();

        if (return2Cache) {

            connection.returnToCache(headers);

        }

    }

    private void logHeaders(ResponseHeaders headers) {

        Map<String, List<String>> h = headers.mapInternal();

        Set<String> keys = h.keySet();

        Set<Map.Entry<String, List<String>>> entries = h.entrySet();

        for (Map.Entry<String, List<String>> entry : entries) {

            String key = entry.getKey();

            StringBuilder sb = new StringBuilder();

            sb.append(key).append(": ");

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

            if (values != null) {

                for (String value : values) {

                    sb.append(value).append(' ');

                }

            }

            Log.logHeaders(sb.toString());

        }

    }

    HttpResponseImpl response() {

        return response;

    }

    boolean redirecting() {

        return redirecting;

    }

    HttpHeaders responseHeaders() {

        return headers;

    }

    int responseCode() {

        return responseCode;

    }

    static final char CR = '\r';

    static final char LF = '\n';

    private ByteBuffer getBuffer() throws IOException {

        if (buffer == null || !buffer.hasRemaining()) {

            buffer = connection.read();

        }

        return buffer;

    }

    ByteBuffer buffer() {

        return buffer;

    }

    String readStatusLine() throws IOException {

        boolean cr = false;

        StringBuilder statusLine = new StringBuilder(128);

        ByteBuffer b;

        while ((b = getBuffer()) != null) {

            byte[] buf = b.array();

            int offset = b.position();

            int len = b.limit() - offset;

            for (int i = 0; i < len; i++) {

                char c = (char) buf[i+offset];

                if (cr) {

                    if (c == LF) {

                        b.position(i + 1 + offset);

                        return statusLine.toString();

                    } else {

                        throw new IOException("invalid status line");

                    }

                }

                if (c == CR) {

                    cr = true;

                } else {

                    statusLine.append(c);

                }

            }

            // unlikely, but possible, that multiple reads required

            b.position(b.limit());

        }

        return null;

    }

}