/*
 * Copyright (c) 2010, 2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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.glassfish.grizzly.http.util;

import java.io.CharConversionException;
import java.io.IOException;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;
import java.util.Arrays;

import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.utils.Charsets;

Utilities to manipulate char chunks. While String is the easiest way to manipulate chars ( search, substrings, etc),
it is known to not be the most efficient solution - Strings are designed as immutable and secure objects.
Author:
dac@sun.com, James Todd [gonzo@sun.com], Costin Manolache, Remy Maucherat/**
 * Utilities to manipulate char chunks. While String is the easiest way to manipulate chars ( search, substrings, etc),
 * it is known to not be the most efficient solution - Strings are designed as immutable and secure objects.
 *
 * @author dac@sun.com
 * @author James Todd [gonzo@sun.com]
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public final class CharChunk implements Chunk, Cloneable, Serializable {

    
Default encoding used to convert to strings. It should be UTF8, as most standards seem to converge, but the servlet
API requires 8859_1, and this object is used mostly for servlets.
/**
     * Default encoding used to convert to strings. It should be UTF8, as most standards seem to converge, but the servlet
     * API requires 8859_1, and this object is used mostly for servlets.
     */
    public static final Charset DEFAULT_HTTP_CHARSET = Constants.DEFAULT_HTTP_CHARSET;

    private static final long serialVersionUID = -1L;

    // Input interface, used when the buffer is emptied.
    public interface CharInputChannel {
        
Read new bytes ( usually the internal conversion buffer ). The implementation is allowed to ignore the parameters,
and mutate the chunk if it wishes to implement its own buffering.
/**
         * Read new bytes ( usually the internal conversion buffer ). The implementation is allowed to ignore the parameters,
         * and mutate the chunk if it wishes to implement its own buffering.
         */
        int realReadChars(char cbuf[], int off, int len) throws IOException;
    }

    
When we need more space we'll either grow the buffer ( up to the limit ) or send it to a channel.
/**
     * When we need more space we'll either grow the buffer ( up to the limit ) or send it to a channel.
     */
    public interface CharOutputChannel {
        
Send the bytes ( usually the internal conversion buffer ). Expect 8k output if the buffer is full.
/**
         * Send the bytes ( usually the internal conversion buffer ). Expect 8k output if the buffer is full.
         */
        void realWriteChars(char cbuf[], int off, int len) throws IOException;
    }

    // --------------------
    // char[]
    private char buff[];

    private int start;
    private int end;

    private boolean isSet = false; // XXX

    // -1: grow undefinitely
    // maximum amount to be cached
    private int limit = -1;

    private transient CharInputChannel in = null;
    private transient CharOutputChannel out = null;

    private boolean optimizedWrite = true;

    private String cachedString;

    
Creates a new, uninitialized CharChunk object.
/**
     * Creates a new, uninitialized CharChunk object.
     */
    public CharChunk() {
    }

    public CharChunk(int size) {
        allocate(size, -1);
    }

    // --------------------

    public CharChunk getClone() {
        try {
            return (CharChunk) this.clone();
        } catch (Exception ex) {
            return null;
        }
    }

    public boolean isNull() {
        return end <= 0 && !isSet;
    }

    
Resets the message bytes to an uninitialized state.
/**
     * Resets the message bytes to an uninitialized state.
     */
    public void recycle() {
        // buff=null;
        isSet = false; // XXX
        start = 0;
        end = 0;
    }

    public void reset() {
        buff = null;
        cachedString = null;
    }

    // -------------------- Setup --------------------

    public void allocate(int initial, int limit) {
        if (buff == null || buff.length < initial) {
            buff = new char[initial];
        }
        this.limit = limit;
        start = 0;
        end = 0;
        isSet = true;
        resetStringCache();
    }

    public void ensureCapacity(final int size) {
        resetStringCache();

        if (buff == null || buff.length < size) {
            buff = new char[size];
            limit = -1;
        }

        start = 0;
        end = 0;
    }

    public void setOptimizedWrite(boolean optimizedWrite) {
        this.optimizedWrite = optimizedWrite;
    }

    public void setChars(char[] c, int off, int len) {
        buff = c;
        start = off;
        end = start + len;
        isSet = true;
        resetStringCache();
    }

    
Maximum amount of data in this buffer.
If -1 or not set, the buffer will grow indefinitely. Can be smaller than the current buffer size ( which will not
shrink ). When the limit is reached, the buffer will be flushed ( if out is set ) or throw exception.
/**
     * Maximum amount of data in this buffer.
     *
     * If -1 or not set, the buffer will grow indefinitely. Can be smaller than the current buffer size ( which will not
     * shrink ). When the limit is reached, the buffer will be flushed ( if out is set ) or throw exception.
     */
    public void setLimit(int limit) {
        this.limit = limit;
        resetStringCache();
    }

    public int getLimit() {
        return limit;
    }

    
When the buffer is empty, read the data from the input channel.
/**
     * When the buffer is empty, read the data from the input channel.
     */
    public void setCharInputChannel(CharInputChannel in) {
        this.in = in;
    }

    
When the buffer is full, write the data to the output channel. Also used when large amount of data is appended.
If not set, the buffer will grow to the limit.
/**
     * When the buffer is full, write the data to the output channel. Also used when large amount of data is appended.
     *
     * If not set, the buffer will grow to the limit.
     */
    public void setCharOutputChannel(CharOutputChannel out) {
        this.out = out;
    }

    // compat
    public char[] getChars() {
        return getBuffer();
    }

    public char[] getBuffer() {
        return buff;
    }

    
Returns the start offset of the bytes. For output this is the end of the buffer.
/**
     * Returns the start offset of the bytes. For output this is the end of the buffer.
     */
    @Override
    public int getStart() {
        return start;
    }

    
Returns the start offset of the bytes.
/**
     * Returns the start offset of the bytes.
     */
    @Override
    public void setStart(int start) {
        this.start = start;
        resetStringCache();
    }

    
Returns the length of the bytes.
/**
     * Returns the length of the bytes.
     */
    @Override
    public int getLength() {
        return end - start;
    }

    @Override
    public int getEnd() {
        return end;
    }

    @Override
    public void setEnd(int i) {
        end = i;
        resetStringCache();
    }

    // -------------------- Adding data --------------------

    public void append(char b) throws IOException {
        makeSpace(1);

        // couldn't make space
        if (limit > 0 && end >= limit) {
            flushBuffer();
        }
        buff[end++] = b;
        resetStringCache();
    }

    public void append(CharChunk src) throws IOException {
        append(src.getBuffer(), src.getStart(), src.getLength());
    }

    
Add data to the buffer
/**
     * Add data to the buffer
     */
    public void append(char src[], int off, int len) throws IOException {
        // will grow, up to limit
        resetStringCache();
        makeSpace(len);

        // if we don't have limit: makeSpace can grow as it wants
        if (limit < 0) {
            // assert: makeSpace made enough space
            System.arraycopy(src, off, buff, end, len);
            end += len;
            return;
        }

        // Optimize on a common case.
        // If the source is going to fill up all the space in buffer, may
        // as well write it directly to the output, and avoid an extra copy
        if (optimizedWrite && len == limit && end == start) {
            out.realWriteChars(src, off, len);
            return;
        }

        // if we have limit and we're below
        if (len <= limit - end) {
            // makeSpace will grow the buffer to the limit,
            // so we have space
            System.arraycopy(src, off, buff, end, len);

            end += len;
            return;
        }

        // need more space than we can afford, need to flush
        // buffer

        // the buffer is already at ( or bigger than ) limit

        // Optimization:
        // If len-avail < length ( i.e. after we fill the buffer with
        // what we can, the remaining will fit in the buffer ) we'll just
        // copy the first part, flush, then copy the second part - 1 write
        // and still have some space for more. We'll still have 2 writes, but
        // we write more on the first.

        if (len + end < 2 * limit) {
            /*
             * If the request length exceeds the size of the output buffer, flush the output buffer and then write the data
             * directly. We can't avoid 2 writes, but we can write more on the second
             */
            int avail = limit - end;
            System.arraycopy(src, off, buff, end, avail);
            end += avail;

            flushBuffer();

            System.arraycopy(src, off + avail, buff, end, len - avail);
            end += len - avail;

        } else { // len > buf.length + avail
            // long write - flush the buffer and write the rest
            // directly from source
            flushBuffer();

            out.realWriteChars(src, off, len);
        }
    }

    
Add data to the buffer
/**
     * Add data to the buffer
     */
    public void append(StringBuffer sb) throws IOException {
        resetStringCache();
        int len = sb.length();

        // will grow, up to limit
        makeSpace(len);

        // if we don't have limit: makeSpace can grow as it wants
        if (limit < 0) {
            // assert: makeSpace made enough space
            sb.getChars(0, len, buff, end);
            end += len;
            return;
        }

        int off = 0;
        int sbOff = off;
        int sbEnd = off + len;
        while (sbOff < sbEnd) {
            int d = min(limit - end, sbEnd - sbOff);
            sb.getChars(sbOff, sbOff + d, buff, end);
            sbOff += d;
            end += d;
            if (end >= limit) {
                flushBuffer();
            }
        }
    }

    
Append a string to the buffer
/**
     * Append a string to the buffer
     */
    public void append(String s) throws IOException {
        if (s != null) {
            append(s, 0, s.length());
        }
    }

    
Append a string to the buffer
/**
     * Append a string to the buffer
     */
    public void append(String s, int off, int len) throws IOException {
        if (s == null) {
            return;
        }

        resetStringCache();
        // will grow, up to limit
        makeSpace(len);

        // if we don't have limit: makeSpace can grow as it wants
        if (limit < 0) {
            // assert: makeSpace made enough space
            s.getChars(off, off + len, buff, end);
            end += len;
            return;
        }

        int sOff = off;
        int sEnd = off + len;
        while (sOff < sEnd) {
            int d = min(limit - end, sEnd - sOff);
            s.getChars(sOff, sOff + d, buff, end);
            sOff += d;
            end += d;
            if (end >= limit) {
                flushBuffer();
            }
        }
    }

    // -------------------- Removing data from the buffer --------------------
    @Override
    public void delete(final int start, final int end) {
        resetStringCache();
        final int diff = this.end - end;
        if (diff == 0) {
            this.end = start;
        } else {
            System.arraycopy(buff, end, buff, start, diff);
            this.end = start + diff;
        }
    }

    public int substract() throws IOException {

        resetStringCache();
        if (end - start == 0) {
            if (in == null) {
                return -1;
            }
            int n = in.realReadChars(buff, end, buff.length - end);
            if (n < 0) {
                return -1;
            }
        }

        return buff[start++];

    }

    public int substract(CharChunk src) throws IOException {

        resetStringCache();
        if (end - start == 0) {
            if (in == null) {
                return -1;
            }
            int n = in.realReadChars(buff, end, buff.length - end);
            if (n < 0) {
                return -1;
            }
        }

        int len = getLength();
        src.append(buff, start, len);
        start = end;
        return len;

    }

    public int substract(char src[], int off, int len) throws IOException {

        resetStringCache();
        if (end - start == 0) {
            if (in == null) {
                return -1;
            }
            int n = in.realReadChars(buff, end, buff.length - end);
            if (n < 0) {
                return -1;
            }
        }

        int n = len;
        if (len > getLength()) {
            n = getLength();
        }
        System.arraycopy(buff, start, src, off, n);
        start += n;
        return n;

    }

    public void flushBuffer() throws IOException {
        // assert out!=null
        if (out == null) {
            throw new IOException("Buffer overflow, no sink " + limit + ' ' + buff.length);
        }
        out.realWriteChars(buff, start, end - start);
        end = start;
        resetStringCache();
    }

    
Make space for len chars. If len is small, allocate a reserve space too. Never grow bigger than limit.
/**
     * Make space for len chars. If len is small, allocate a reserve space too. Never grow bigger than limit.
     */
    void makeSpace(int count) {
        char[] tmp;

        int newSize;
        int desiredSize = end + count;

        // Can't grow above the limit
        if (limit > 0 && desiredSize > limit) {
            desiredSize = limit;
        }

        if (buff == null) {
            if (desiredSize < 256) {
                desiredSize = 256; // take a minimum
            }
            buff = new char[desiredSize];
        }

        // limit < buf.length ( the buffer is already big )
        // or we already have space XXX
        if (desiredSize <= buff.length) {
            return;
        }
        // grow in larger chunks
        if (desiredSize < 2 * buff.length) {
            newSize = buff.length * 2;
            if (limit > 0 && newSize > limit) {
                newSize = limit;
            }
            tmp = new char[newSize];
        } else {
            newSize = buff.length * 2 + count;
            if (limit > 0 && newSize > limit) {
                newSize = limit;
            }
            tmp = new char[newSize];
        }

        System.arraycopy(buff, start, tmp, start, end - start);
        buff = tmp;
        tmp = null;
    }

    
Notify the Chunk that its content is going to be changed directly
/**
     * Notify the Chunk that its content is going to be changed directly
     */
    protected void notifyDirectUpdate() {
    }

    protected void resetStringCache() {
        cachedString = null;
    }

    // -------------------- Conversion and getters --------------------

    @Override
    public String toString() {
        if (null == buff || end - start == 0) {
            return "";
        } else if (cachedString != null) {
            return cachedString;
        }
//        return StringCache.toString(this);
        cachedString = toStringInternal();
        return cachedString;
    }

    @Override
    public String toString(int start, int end) {
        if (start == this.start && end == this.end) {
            return toString();
        } else if (null == buff) {
            return null;
        } else if (end - start == 0) {
            return "";
        }

        return new String(buff, this.start + start, end - start);
    }

    public String toStringInternal() {
        return new String(buff, start, end - start);
    }

    public int getInt() {
        return Ascii.parseInt(buff, start, end - start);
    }

    
Set ByteChunk content to CharChunk using given Charset. 
Throws:
CharConversionException – /**
     * Set {@link ByteChunk} content to CharChunk using given {@link Charset}.
     * 
     * @throws CharConversionException
     */
    public void set(final ByteChunk byteChunk, final Charset encoding) throws CharConversionException {

        final int bufferStart = byteChunk.getStart();
        final int bufferLength = byteChunk.getLength();
        allocate(bufferLength, -1);

        final byte[] buffer = byteChunk.getBuffer();

        if (!DEFAULT_HTTP_CHARSET.equals(encoding)) {
            final ByteBuffer bb = ByteBuffer.wrap(buffer, bufferStart, bufferLength);
            final CharBuffer cb = CharBuffer.wrap(buff, start, buff.length - start);

            final CharsetDecoder decoder = Charsets.getCharsetDecoder(encoding);
            final CoderResult cr = decoder.decode(bb, cb, true);

            if (cr != CoderResult.UNDERFLOW) {
                throw new CharConversionException("Decoding error");
            }

            end = start + cb.position();

            return;
        }

        // Default encoding: fast conversion
        for (int i = 0; i < bufferLength; i++) {
            buff[i] = (char) (buffer[i + bufferStart] & 0xff);
        }
        end = bufferLength;

    }

    
Set BufferChunk content to CharChunk using given Charset. 
Throws:
CharConversionException – /**
     * Set {@link BufferChunk} content to CharChunk using given {@link Charset}.
     * 
     * @throws CharConversionException
     */
    public void set(final BufferChunk bufferChunk, final Charset encoding) throws CharConversionException {

        final int bufferStart = bufferChunk.getStart();
        final int bufferLength = bufferChunk.getLength();
        allocate(bufferLength, -1);

        final Buffer buffer = bufferChunk.getBuffer();

        if (!DEFAULT_HTTP_CHARSET.equals(encoding)) {
            final ByteBuffer bb = buffer.toByteBuffer(bufferStart, bufferStart + bufferLength);
            final CharBuffer cb = CharBuffer.wrap(buff, start, buff.length - start);

            final CharsetDecoder decoder = Charsets.getCharsetDecoder(encoding);
            final CoderResult cr = decoder.decode(bb, cb, true);

            if (cr != CoderResult.UNDERFLOW) {
                throw new CharConversionException("Decoding error");
            }

            end = start + cb.position();

            return;
        }

        // Default encoding: fast conversion
        for (int i = 0; i < bufferLength; i++) {
            buff[i] = (char) (buffer.get(i + bufferStart) & 0xff);
        }
        end = bufferLength;

//        return cc;
//        uri.setChars(cbuf, 0, bc.getLength());
    }

    // -------------------- equals --------------------

    @Override
    public int hashCode() {
        int result = Arrays.hashCode(buff);
        result = 31 * result + start;
        result = 31 * result + end;
        result = 31 * result + (isSet ? 1 : 0);
        result = 31 * result + limit;
        result = 31 * result + in.hashCode();
        result = 31 * result + out.hashCode();
        result = 31 * result + (optimizedWrite ? 1 : 0);
        return result;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        CharChunk charChunk = (CharChunk) o;

        if (end != charChunk.end) {
            return false;
        }
        if (isSet != charChunk.isSet) {
            return false;
        }
        if (limit != charChunk.limit) {
            return false;
        }
        if (optimizedWrite != charChunk.optimizedWrite) {
            return false;
        }
        if (start != charChunk.start) {
            return false;
        }
        if (!Arrays.equals(buff, charChunk.buff)) {
            return false;
        }
        if (in != null ? !in.equals(charChunk.in) : charChunk.in != null) {
            return false;
        }
        if (out != null ? !out.equals(charChunk.out) : charChunk.out != null) {
            return false;
        }

        return true;
    }

    
Compares the message bytes to the specified String object.
Params:
s – the String to compare
Returns:
true if the comparison succeeded, false otherwise/**
     * Compares the message bytes to the specified String object.
     * 
     * @param s the String to compare
     * @return true if the comparison succeeded, false otherwise
     */
    public boolean equals(CharSequence s) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    
Compares the message bytes to the specified byte array representing ASCII characters.
Params:
b – the byte[] to compare
Returns:
true if the comparison succeeded, false otherwise
Since:
2.3/**
     * Compares the message bytes to the specified byte array representing ASCII characters.
     * 
     * @param b the <code>byte[]</code> to compare
     *
     * @return true if the comparison succeeded, false otherwise
     *
     * @since 2.3
     */
    public boolean equals(byte[] b) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != b.length) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (c[off++] != b[i]) {
                return false;
            }
        }
        return true;
    }

    
Compares the message bytes to the specified String object.
Params:
s – the String to compare
Returns:
true if the comparison succeeded, false otherwise/**
     * Compares the message bytes to the specified String object.
     * 
     * @param s the String to compare
     * @return true if the comparison succeeded, false otherwise
     */
    public boolean equalsIgnoreCase(CharSequence s) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    
Compares the message bytes to the specified byte array representing ASCII characters.
Params:
b – the byte[] to compare
Returns:
true if the comparison succeeded, false otherwise
Since:
2.1.2/**
     * Compares the message bytes to the specified byte array representing ASCII characters.
     * 
     * @param b the <code>byte[]</code> to compare
     *
     * @return true if the comparison succeeded, false otherwise
     *
     * @since 2.1.2
     */
    public boolean equalsIgnoreCase(final byte[] b) {
        return equalsIgnoreCase(b, 0, b.length);
    }

    
Compares the message bytes to the specified byte array representing ASCII characters.
Params:
b – the byte[] to compare
Returns:
true if the comparison succeeded, false otherwise
Since:
2.3/**
     * Compares the message bytes to the specified byte array representing ASCII characters.
     * 
     * @param b the <code>byte[]</code> to compare
     *
     * @return true if the comparison succeeded, false otherwise
     *
     * @since 2.3
     */
    public boolean equalsIgnoreCase(final byte[] b, final int offset, final int len) {
        char[] c = buff;
        if (c == null || getLength() != len) {
            return false;
        }
        int offs1 = start;
        int offs2 = offset;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[offs1++]) != Ascii.toLower(b[offs2++])) {
                return false;
            }
        }
        return true;
    }

    
Compares the message bytes to the specified char array representing ASCII characters.
Params:
b – the char[] to compare
Returns:
true if the comparison succeeded, false otherwise
Since:
2.3/**
     * Compares the message bytes to the specified char array representing ASCII characters.
     * 
     * @param b the <code>char[]</code> to compare
     *
     * @return true if the comparison succeeded, false otherwise
     *
     * @since 2.3
     */
    public boolean equalsIgnoreCase(final char[] b, final int offset, final int len) {
        char[] c = buff;
        if (c == null || getLength() != len) {
            return false;
        }
        int offs1 = start;
        int offs2 = offset;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[offs1++]) != Ascii.toLower(b[offs2++])) {
                return false;
            }
        }
        return true;
    }

    
Compares the char chunk to the specified byte array representing lower-case ASCII characters.
Params:
b – the byte[] to compare
Returns:
true if the comparison succeeded, false otherwise
Since:
2.1.2/**
     * Compares the char chunk to the specified byte array representing lower-case ASCII characters.
     *
     * @param b the <code>byte[]</code> to compare
     *
     * @return true if the comparison succeeded, false otherwise
     *
     * @since 2.1.2
     */
    public boolean equalsIgnoreCaseLowerCase(final byte[] b) {
        char[] c = buff;
        int len = end - start;
        if (c == null || len != b.length) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[off++]) != b[i]) {
                return false;
            }
        }
        return true;
    }

    public boolean equals(CharChunk cc) {
        return equals(cc.getChars(), cc.getStart(), cc.getLength());
    }

    public boolean equals(char b2[], int off2, int len2) {
        char b1[] = buff;
        if (b1 == null && b2 == null) {
            return true;
        }

        if (b1 == null || b2 == null || end - start != len2) {
            return false;
        }
        int off1 = start;
        int len = end - start;
        while (len-- > 0) {
            if (b1[off1++] != b2[off2++]) {
                return false;
            }
        }
        return true;
    }

    public boolean equals(byte b2[], int off2, int len2) {
        char b1[] = buff;
        if (b2 == null && b1 == null) {
            return true;
        }

        if (b1 == null || b2 == null || end - start != len2) {
            return false;
        }
        int off1 = start;
        int len = end - start;

        while (len-- > 0) {
            if (b1[off1++] != (char) b2[off2++]) {
                return false;
            }
        }
        return true;
    }

    
Returns true if the message bytes starts with the specified string.
Params:
s – the string/**
     * Returns true if the message bytes starts with the specified string.
     * 
     * @param s the string
     */
    public boolean startsWith(String s) {
        return startsWith(s, 0);
    }

    boolean startsWith(final String s, final int pos) {
        char[] c = buff;
        int len = s.length();
//        if (c == null || len + pos > end) {
        if (c == null || len + pos > end - start) {
            return false;
        }
        int off = start + pos;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    
Returns true if the message bytes starts with the specified string.
Params:
s – the string/**
     * Returns true if the message bytes starts with the specified string.
     * 
     * @param s the string
     */
    public boolean startsWithIgnoreCase(final String s, final int pos) {
        char[] c = buff;
        int len = s.length();
        if (c == null || len + pos > end - start) {
            return false;
        }
        int off = start + pos;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(c[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    public boolean endsWith(String s) {
        char[] c = buff;
        int len = s.length();
        if (c == null || len > end - start) {
            return false;
        }
        int off = end - len;
        for (int i = 0; i < len; i++) {
            if (c[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    // -------------------- Hash code --------------------

    // normal hash.
    public int hash() {
        int code = 0;
        for (int i = start; i < end; i++) {
            code = code * 31 + buff[i];
        }
        return code;
    }

    // hash ignoring case
    public int hashIgnoreCase() {
        int code = 0;
        for (int i = start; i < end; i++) {
            code = code * 31 + Ascii.toLower(buff[i]);
        }
        return code;
    }

    public int indexOf(char c) {
        return indexOf(c, start);
    }

    
Returns true if the message bytes starts with the specified string.
Params:
c – the character/**
     * Returns true if the message bytes starts with the specified string.
     * 
     * @param c the character
     */
    @Override
    public int indexOf(char c, int starting) {
        int ret = indexOf(buff, start + starting, end, c);
        return ret >= start ? ret - start : -1;
    }

    public static int indexOf(char chars[], int off, int cend, char qq) {
        while (off < cend) {
            if (chars[off] == qq) {
                return off;
            }
            off++;
        }
        return -1;
    }

    @Override
    public int indexOf(String s, int fromIndex) {
        return indexOf(s, 0, s.length(), fromIndex);
    }

    public int indexOf(String src, int srcOff, int srcLen, int myOff) {
        char first = src.charAt(srcOff);

        // Look for first char
        int srcEnd = srcOff + srcLen;

        for (int i = myOff + start; i <= end - srcLen; i++) {
            if (buff[i] != first) {
                continue;
            }
            // found first char, now look for a match
            int myPos = i + 1;
            for (int srcPos = srcOff + 1; srcPos < srcEnd;) {
                if (buff[myPos++] != src.charAt(srcPos++)) {
                    break;
                }
                if (srcPos == srcEnd) {
                    return i - start; // found it
                }
            }
        }

        return -1;
    }

    public void trimLeft() {
        boolean modified = false;
        while (buff[start] <= 0x20) {
            modified = true;
            start++;
        }
        if (modified) {
            resetStringCache();
        }
    }

    // -------------------- utils
    private int min(int a, int b) {
        if (a < b) {
            return a;
        }
        return b;
    }

}