package org.apache.velocity.runtime.parser;

/*
 * 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.    
 */

/**
 *  NOTE : This class was originally an ASCII_CharStream autogenerated
 *  by Javacc.  It was then modified via changing class name with appropriate
 *  fixes for CTORS, and mods to readChar().
 *
 *  This is safe because we *always* use Reader with this class, and never a
 *  InputStream.  This guarantees that we have a correct stream of 16-bit
 *  chars - all encoding transformations have been done elsewhere, so we
 *  believe that there is no risk in doing this.  Time will tell :)
 */

/**
 * An implementation of interface CharStream, where the stream is assumed to
 * contain only ASCII characters (without unicode processing).
 */

public final class VelocityCharStream
implements CharStream
{
    public static final boolean staticFlag = false;
    int bufsize;
    private int nextBufExpand;
    int available;
    int tokenBegin;

    public int bufpos = -1;
    private int bufline[];
    private int bufcolumn[];

    private int column = 0;
    private int line = 1;

    private boolean prevCharIsCR = false;
    private boolean prevCharIsLF = false;

    private java.io.Reader inputStream;

    private char[] buffer;
    private int maxNextCharInd = 0;
    private int inBuf = 0;

    private final void ExpandBuff(boolean wrapAround)
    {
        char[] newbuffer = new char[bufsize + nextBufExpand];
        int newbufline[] = new int[bufsize + nextBufExpand];
        int newbufcolumn[] = new int[bufsize + nextBufExpand];

        try
        {
            if (wrapAround)
            {
                System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
                System.arraycopy(buffer, 0, newbuffer,
                        bufsize - tokenBegin, bufpos);
                buffer = newbuffer;

                System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
                System.arraycopy(bufline, 0, newbufline, bufsize - tokenBegin, bufpos);
                bufline = newbufline;

                System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
                System.arraycopy(bufcolumn, 0, newbufcolumn, bufsize - tokenBegin, bufpos);
                bufcolumn = newbufcolumn;

                maxNextCharInd = (bufpos += (bufsize - tokenBegin));
            }
            else
            {
                System.arraycopy(buffer, tokenBegin, newbuffer, 0, bufsize - tokenBegin);
                buffer = newbuffer;

                System.arraycopy(bufline, tokenBegin, newbufline, 0, bufsize - tokenBegin);
                bufline = newbufline;

                System.arraycopy(bufcolumn, tokenBegin, newbufcolumn, 0, bufsize - tokenBegin);
                bufcolumn = newbufcolumn;

                maxNextCharInd = (bufpos -= tokenBegin);
            }
        }
        catch (Throwable t)
        {
            throw new Error(t.getMessage());
        }


        bufsize += nextBufExpand;
        nextBufExpand = bufsize;
        available = bufsize;
        tokenBegin = 0;
    }

    private final void FillBuff() throws java.io.IOException
    {
        if (maxNextCharInd == available)
        {
            if (available == bufsize)
            {
                if (tokenBegin > nextBufExpand)
                {
                    bufpos = maxNextCharInd = 0;
                    available = tokenBegin;
                }
                else if (tokenBegin < 0)
                {
                    bufpos = maxNextCharInd = 0;
                }
                else
                {
                    ExpandBuff(false);
                }
            }
            else if (available > tokenBegin)
            {
                available = bufsize;
            }
            else if ((tokenBegin - available) < nextBufExpand)
            {
                ExpandBuff(true);
            }
            else
            {
                available = tokenBegin;
            }
        }

        int i;
        try 
        {
            if ((i = inputStream.read(buffer, maxNextCharInd,
                    available - maxNextCharInd)) == -1)
            {
                inputStream.close();
                throw new java.io.IOException();
            }
            else
            {
                maxNextCharInd += i;
            }
            return;
        }
        catch(java.io.IOException e) 
        {
            --bufpos;
            backup(0);
            if (tokenBegin == -1)
            {
                tokenBegin = bufpos;
            }
            throw e;
        }
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#BeginToken()
     */
    public final char BeginToken() throws java.io.IOException
    {
        tokenBegin = -1;
        char c = readChar();
        tokenBegin = bufpos;

        return c;
    }

    private final void UpdateLineColumn(char c)
    {
        column++;

        if (prevCharIsLF)
        {
            prevCharIsLF = false;
            line += (column = 1);
        }
        else if (prevCharIsCR)
        {
            prevCharIsCR = false;
            if (c == '\n')
            {
                prevCharIsLF = true;
            }
            else
            {
                line += (column = 1);
            }
        }

        switch (c)
        {
        case '\r' :
            prevCharIsCR = true;
            break;
        case '\n' :
            prevCharIsLF = true;
            break;
        case '\t' :
            column--;
            column += (8 - (column & 07));
            break;
        default :
            break;
        }

        bufline[bufpos] = line;
        bufcolumn[bufpos] = column;
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#readChar()
     */
    public final char readChar() throws java.io.IOException
    {
        if (inBuf > 0)
        {
            --inBuf;

            /*
             *  was : return (char)((char)0xff & buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos]);
             */
            return  buffer[(bufpos == bufsize - 1) ? (bufpos = 0) : ++bufpos];
        }

        if (++bufpos >= maxNextCharInd)
        {
            FillBuff();
        }

        /*
         *  was : char c = (char)((char)0xff & buffer[bufpos]);
         */
        char c = buffer[bufpos];

        UpdateLineColumn(c);
        return (c);
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getColumn()
     * @deprecated
     */
    public final int getColumn() 
    {
        return bufcolumn[bufpos];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getLine()
     * @deprecated
     */
    public final int getLine() 
    {
        return bufline[bufpos];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getEndColumn()
     */
    public final int getEndColumn() 
    {
        return bufcolumn[bufpos];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getEndLine()
     */
    public final int getEndLine() 
    {
        return bufline[bufpos];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getBeginColumn()
     */
    public final int getBeginColumn() 
    {
        return bufcolumn[tokenBegin];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#getBeginLine()
     */
    public final int getBeginLine() 
    {
        return bufline[tokenBegin];
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#backup(int)
     */
    public final void backup(int amount) 
    {

        inBuf += amount;
        if ((bufpos -= amount) < 0)
            bufpos += bufsize;
    }

    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     * @param buffersize
     */
    public VelocityCharStream(java.io.Reader dstream, int startline,
            int startcolumn, int buffersize)
    {
        inputStream = dstream;
        line = startline;
        column = startcolumn - 1;

        available = bufsize = nextBufExpand = buffersize;
        buffer = new char[buffersize];
        bufline = new int[buffersize];
        bufcolumn = new int[buffersize];
    }

    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     */
    public VelocityCharStream(java.io.Reader dstream, int startline,
            int startcolumn)
    {
        this(dstream, startline, startcolumn, 4096);
    }
    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     * @param buffersize
     */
    public void ReInit(java.io.Reader dstream, int startline,
            int startcolumn, int buffersize)
    {
        inputStream = dstream;
        line = startline;
        column = startcolumn - 1;

        if (buffer == null || buffersize != buffer.length)
        {
            available = bufsize = nextBufExpand = buffersize;
            buffer = new char[buffersize];
            bufline = new int[buffersize];
            bufcolumn = new int[buffersize];
        }
        prevCharIsLF = prevCharIsCR = false;
        tokenBegin = inBuf = maxNextCharInd = 0;
        bufpos = -1;
    }

    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     */
    public void ReInit(java.io.Reader dstream, int startline,
            int startcolumn)
    {
        ReInit(dstream, startline, startcolumn, 4096);
    }
    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     * @param buffersize
     */
    public VelocityCharStream(java.io.InputStream dstream, int startline,
            int startcolumn, int buffersize)
    {
        this(new java.io.InputStreamReader(dstream), startline, startcolumn, buffersize);
    }

    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     */
    public VelocityCharStream(java.io.InputStream dstream, int startline,
            int startcolumn)
    {
        this(dstream, startline, startcolumn, 4096);
    }

    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     * @param buffersize
     */
    public void ReInit(java.io.InputStream dstream, int startline,
            int startcolumn, int buffersize)
    {
        ReInit(new java.io.InputStreamReader(dstream), startline, startcolumn, buffersize);
    }
    /**
     * @param dstream
     * @param startline
     * @param startcolumn
     */
    public void ReInit(java.io.InputStream dstream, int startline,
            int startcolumn)
    {
        ReInit(dstream, startline, startcolumn, 4096);
    }
    /**
     * @see org.apache.velocity.runtime.parser.CharStream#GetImage()
     */
    public final String GetImage()
    {
        if (bufpos >= tokenBegin)
        {
            return new String(buffer, tokenBegin, bufpos - tokenBegin + 1);
        }
        else
        {
            return new String(buffer, tokenBegin, bufsize - tokenBegin) +
            new String(buffer, 0, bufpos + 1);
        }
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#GetSuffix(int)
     */
    public final char[] GetSuffix(int len)
    {
        char[] ret = new char[len];

        if ((bufpos + 1) >= len)
        {
            System.arraycopy(buffer, bufpos - len + 1, ret, 0, len);
        }
        else
        {
            System.arraycopy(buffer, bufsize - (len - bufpos - 1), ret, 0,
                    len - bufpos - 1);
            System.arraycopy(buffer, 0, ret, len - bufpos - 1, bufpos + 1);
        }

        return ret;
    }

    /**
     * @see org.apache.velocity.runtime.parser.CharStream#Done()
     */
    public void Done()
    {
        buffer = null;
        bufline = null;
        bufcolumn = null;
    }

    /**
     * Method to adjust line and column numbers for the start of a token.<BR>
     * @param newLine
     * @param newCol
     */
    public void adjustBeginLineColumn(int newLine, int newCol)
    {
        int start = tokenBegin;
        int len;

        if (bufpos >= tokenBegin)
        {
            len = bufpos - tokenBegin + inBuf + 1;
        }
        else
        {
            len = bufsize - tokenBegin + bufpos + 1 + inBuf;
        }

        int i = 0, j = 0, k = 0;
        int nextColDiff = 0, columnDiff = 0;

        while (i < len &&
                bufline[j = start % bufsize] == bufline[k = ++start % bufsize])
        {
            bufline[j] = newLine;
            nextColDiff = columnDiff + bufcolumn[k] - bufcolumn[j];
            bufcolumn[j] = newCol + columnDiff;
            columnDiff = nextColDiff;
            i++;
        }

        if (i < len)
        {
            bufline[j] = newLine++;
            bufcolumn[j] = newCol + columnDiff;

            while (i++ < len)
            {
                if (bufline[j = start % bufsize] != bufline[++start % bufsize])
                    bufline[j] = newLine++;
                else
                    bufline[j] = newLine;
            }
        }

        line = bufline[j];
        column = bufcolumn[j];
    }

}
