/*
 * Copyright (c) 2005, 2017, 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 com.sun.net.httpserver.*;
import com.sun.net.httpserver.spi.*;

class ChunkedInputStream extends LeftOverInputStream {
    ChunkedInputStream (ExchangeImpl t, InputStream src) {
        super (t, src);
    }

    private int remaining;

    /* true when a chunk header needs to be read */

    private boolean needToReadHeader = true;

    final static char CR = '\r';
    final static char LF = '\n';
    /*
     * Maximum chunk header size of 2KB + 2 bytes for CRLF
     */
    private final static int MAX_CHUNK_HEADER_SIZE = 2050;

    private int numeric (char[] arr, int nchars) throws IOException {
        assert arr.length >= nchars;
        int len = 0;
        for (int i=0; i<nchars; i++) {
            char c = arr[i];
            int val=0;
            if (c>='0' && c <='9') {
                val = c - '0';
            } else if (c>='a' && c<= 'f') {
                val = c - 'a' + 10;
            } else if (c>='A' && c<= 'F') {
                val = c - 'A' + 10;
            } else {
                throw new IOException ("invalid chunk length");
            }
            len = len * 16 + val;
        }
        return len;
    }

    /* read the chunk header line and return the chunk length
     * any chunk extensions are ignored
     */
    private int readChunkHeader () throws IOException {
        boolean gotCR = false;
        int c;
        char[] len_arr = new char [16];
        int len_size = 0;
        boolean end_of_len = false;
        int read = 0;

        while ((c=in.read())!= -1) {
            char ch = (char) c;
            read++;
            if ((len_size == len_arr.length -1) ||
                (read > MAX_CHUNK_HEADER_SIZE))
            {
                throw new IOException ("invalid chunk header");
            }
            if (gotCR) {
                if (ch == LF) {
                    int l = numeric (len_arr, len_size);
                    return l;
                } else {
                    gotCR = false;
                }
                if (!end_of_len) {
                    len_arr[len_size++] = ch;
                }
            } else {
                if (ch == CR) {
                    gotCR = true;
                } else if (ch == ';') {
                    end_of_len = true;
                } else if (!end_of_len) {
                    len_arr[len_size++] = ch;
                }
            }
        }
        throw new IOException ("end of stream reading chunk header");
    }

    protected int readImpl (byte[]b, int off, int len) throws IOException {
        if (eof) {
            return -1;
        }
        if (needToReadHeader) {
            remaining = readChunkHeader();
            if (remaining == 0) {
                eof = true;
                consumeCRLF();
                t.getServerImpl().requestCompleted (t.getConnection());
                return -1;
            }
            needToReadHeader = false;
        }
        if (len > remaining) {
            len = remaining;
        }
        int n = in.read(b, off, len);
        if (n > -1) {
            remaining -= n;
        }
        if (remaining == 0) {
            needToReadHeader = true;
            consumeCRLF();
        }
        if (n < 0 && !eof)
            throw new IOException("connection closed before all data received");
        return n;
    }

    private void consumeCRLF () throws IOException {
        char c;
        c = (char)in.read(); /* CR */
        if (c != CR) {
            throw new IOException ("invalid chunk end");
        }
        c = (char)in.read(); /* LF */
        if (c != LF) {
            throw new IOException ("invalid chunk end");
        }
    }

    
returns the number of bytes available to read in the current chunk
which may be less than the real amount, but we'll live with that
limitation for the moment. It only affects potential efficiency
rather than correctness.
/**
     * returns the number of bytes available to read in the current chunk
     * which may be less than the real amount, but we'll live with that
     * limitation for the moment. It only affects potential efficiency
     * rather than correctness.
     */
    public int available () throws IOException {
        if (eof || closed) {
            return 0;
        }
        int n = in.available();
        return n > remaining? remaining: n;
    }

    /* called after the stream is closed to see if bytes
     * have been read from the underlying channel
     * and buffered internally
     */
    public boolean isDataBuffered () throws IOException {
        assert eof;
        return in.available() > 0;
    }

    public boolean markSupported () {return false;}

    public void mark (int l) {
    }

    public void reset () throws IOException {
        throw new IOException ("mark/reset not supported");
    }
}