//
//  ========================================================================
//  Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;

/**
 * ReadLineInputStream
 *
 * Read from an input stream, accepting CR/LF, LF or just CR.
 */
public class ReadLineInputStream extends BufferedInputStream
{
    boolean _seenCRLF;
    boolean _skipLF;
    
    public ReadLineInputStream(InputStream in)
    {
        super(in);
    }

    public ReadLineInputStream(InputStream in, int size)
    {
        super(in,size);
    }
    
    public String readLine() throws IOException
    {
        mark(buf.length);
                
        while (true)
        {
            int b=super.read();
            
            if (markpos < 0)
                throw new IOException("Buffer size exceeded: no line terminator");
            
            if (b==-1)
            {
                int m=markpos;
                markpos=-1;
                if (pos>m)
                    return new String(buf,m,pos-m, StandardCharsets.UTF_8);

                return null;
            }
            
            if (b=='\r')
            {
                int p=pos;
                
                // if we have seen CRLF before, hungrily consume LF
                if (_seenCRLF && pos<count)
                {
                    if (buf[pos]=='\n')
                        pos+=1;
                }
                else
                    _skipLF=true;
                int m=markpos;
                markpos=-1;
                return new String(buf,m,p-m-1,StandardCharsets.UTF_8);
            }
            
            if (b=='\n')
            {
                if (_skipLF)
                {
                    _skipLF=false;
                    _seenCRLF=true;
                    markpos++;
                    continue;
                }
                int m=markpos;
                markpos=-1;
                return new String(buf,m,pos-m-1,StandardCharsets.UTF_8);
            }
        }
    }

    @Override
    public synchronized int read() throws IOException
    {
        int b = super.read();
        if (_skipLF)
        {
            _skipLF=false;
            if (_seenCRLF && b=='\n')
                b=super.read();
        }
        return b;
    }

    @Override
    public synchronized int read(byte[] buf, int off, int len) throws IOException
    {
        if (_skipLF && len>0)
        {
            _skipLF=false;
            if (_seenCRLF)
            {
                int b = super.read();
                if (b==-1)
                    return -1;
                
                if (b!='\n')
                {
                    buf[off]=(byte)(0xff&b);
                    return 1+super.read(buf,off+1,len-1);
                }
            }
        }
        
        return super.read(buf,off,len);
    }
    
    
}
