/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.coyote.http11;

import java.io.EOFException;
import java.io.IOException;
import java.nio.channels.Selector;
import java.nio.charset.Charset;

import org.apache.coyote.InputBuffer;
import org.apache.coyote.Request;
import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.net.AbstractEndpoint;
import org.apache.tomcat.util.net.NioChannel;
import org.apache.tomcat.util.net.NioEndpoint;
import org.apache.tomcat.util.net.NioSelectorPool;
import org.apache.tomcat.util.net.SocketWrapper;

/**
 * Implementation of InputBuffer which provides HTTP request header parsing as
 * well as transfer decoding.
 *
 * @author <a href="mailto:remm@apache.org">Remy Maucherat</a>
 * @author Filip Hanik
 */
public class InternalNioInputBuffer extends AbstractInputBuffer<NioChannel> {

    /**
     * Parse the HTTP headers.
     */
    @Override
    public boolean parseHeaders() throws IOException {
        HeaderParseStatus status = HeaderParseStatus.HAVE_MORE_HEADERS;
        do {
            status = parseHeader();
        } while ( status == HeaderParseStatus.HAVE_MORE_HEADERS );
        if (status == HeaderParseStatus.DONE) {
            parsingHeader = false;
            end = pos;
            if (end - skipBlankLinesBytes > headerBufferSize || buf.length - end < socketReadBufferSize) {
                throw new IllegalArgumentException(sm.getString("iib.requestheadertoolarge.error"));
            }
        }
	}


    /**
     * Parse an HTTP header.
     * 
     * @return false after reading a blank line (which indicates that the
     * HTTP header parsing is done
     */
    private HeaderParseStatus parseHeader() throws IOException {
        //
        // Check for blank line
        //
        byte chr = 0;
        while (headerParsePos == HeaderParsePosition.HEADER_START) {

            // Read new bytes if needed
            if (pos >= lastValid) {
                if (!fill(true,false)) {//parse header 
                    headerParsePos = HeaderParsePosition.HEADER_START;
                    return HeaderParseStatus.NEED_MORE_DATA;
                }
            }

            chr = buf[pos];

            if (chr == Constants.CR) {
                // Skip
            } else if (chr == Constants.LF) {
                pos++;
                return HeaderParseStatus.DONE;
            } else {
                break;
            }

            pos++;

        }

        if ( headerParsePos == HeaderParsePosition.HEADER_START ) {
            // Mark the current buffer position
            headerData.start = pos;
            headerParsePos = HeaderParsePosition.HEADER_NAME;
        }

        //
        // Reading the header name
        // Header name is always US-ASCII
        //

        while (headerParsePos == HeaderParsePosition.HEADER_NAME) {

            // Read new bytes if needed
            if (pos >= lastValid) {
                if (!fill(true,false)) { //parse header 
                    return HeaderParseStatus.NEED_MORE_DATA;
                }
            }

            chr = buf[pos];
            if (chr == Constants.COLON) {
                headerParsePos = HeaderParsePosition.HEADER_VALUE_START;
                headerData.headerValue = headers.addValue(buf, headerData.start, pos - headerData.start);
                pos++;
                // Mark the current buffer position
                headerData.start = pos;
                headerData.realPos = pos;
                headerData.lastSignificantChar = pos;
                break;
            } else if (!HTTP_TOKEN_CHAR[chr]) {
                // If a non-token header is detected, skip the line and
                // ignore the header
                headerData.lastSignificantChar = pos;
                return skipLine();
            }

            // chr is next byte of header name. Convert to lowercase.
            if ((chr >= Constants.A) && (chr <= Constants.Z)) {
                buf[pos] = (byte) (chr - Constants.LC_OFFSET);
            }
            pos++;
        }

        // Skip the line and ignore the header
        if (headerParsePos == HeaderParsePosition.HEADER_SKIPLINE) {
            return skipLine();
        }

        //
        // Reading the header value (which can be spanned over multiple lines)
        //

        while (headerParsePos == HeaderParsePosition.HEADER_VALUE_START || headerParsePos == HeaderParsePosition.HEADER_VALUE || headerParsePos == HeaderParsePosition.HEADER_MULTI_LINE) {

            if ( headerParsePos == HeaderParsePosition.HEADER_VALUE_START ) {
                // Skipping spaces
                while (true) {
                    // Read new bytes if needed
                    if (pos >= lastValid) {
                        if (!fill(true,false)) {//parse header 
                            //HEADER_VALUE_START
                            return HeaderParseStatus.NEED_MORE_DATA;
                        }
                    }

                    chr = buf[pos];
                    if (chr == Constants.SP || chr == Constants.HT) {
                        pos++;
                    } else {
                        headerParsePos = HeaderParsePosition.HEADER_VALUE;
                        break;
                    }
                }
            }
            if ( headerParsePos == HeaderParsePosition.HEADER_VALUE ) {

                // Reading bytes until the end of the line
                boolean eol = false;
                while (!eol) {

                    // Read new bytes if needed
                    if (pos >= lastValid) {
                        if (!fill(true,false)) {//parse header 
                            //HEADER_VALUE
                            return HeaderParseStatus.NEED_MORE_DATA;
                        }
                    }

                    chr = buf[pos];
                    if (chr == Constants.CR) {
                        // Skip
                    } else if (chr == Constants.LF) {
                        eol = true;
                    } else if (chr == Constants.SP || chr == Constants.HT) {
                        buf[headerData.realPos] = chr;
                        headerData.realPos++;
                    } else {
                        buf[headerData.realPos] = chr;
                        headerData.realPos++;
                        headerData.lastSignificantChar = headerData.realPos;
                    }

                    pos++;
                }

                // Ignore whitespaces at the end of the line
                headerData.realPos = headerData.lastSignificantChar;

                // Checking the first character of the new line. If the character
                // is a LWS, then it's a multiline header
                headerParsePos = HeaderParsePosition.HEADER_MULTI_LINE;
            }
            // Read new bytes if needed
            if (pos >= lastValid) {
                if (!fill(true,false)) {//parse header
                    
                    //HEADER_MULTI_LINE
                    return HeaderParseStatus.NEED_MORE_DATA;
                }
            }

            chr = buf[pos];
            if ( headerParsePos == HeaderParsePosition.HEADER_MULTI_LINE ) {
                if ( (chr != Constants.SP) && (chr != Constants.HT)) {
                    headerParsePos = HeaderParsePosition.HEADER_START;
                    break;
                } else {
                    // Copying one extra space in the buffer (since there must
                    // be at least one space inserted between the lines)
                    buf[headerData.realPos] = chr;
                    headerData.realPos++;
                    headerParsePos = HeaderParsePosition.HEADER_VALUE_START;
                }
            }
        }
        // Set the header value
        headerData.headerValue.setBytes(buf, headerData.start, headerData.lastSignificantChar - headerData.start);
        headerData.recycle();
        return HeaderParseStatus.HAVE_MORE_HEADERS;
    }
}