/*
 * Copyright (c) 2010, 2017 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 org.glassfish.grizzly.Buffer;

This class implements some basic ASCII character handling functions.
Author:
dac@eng.sun.com, James Todd [gonzo@eng.sun.com]/**
 * This class implements some basic ASCII character handling functions.
 *
 * @author dac@eng.sun.com
 * @author James Todd [gonzo@eng.sun.com]
 */
public final class Ascii {
    private static final long INT_OVERFLOW_LIMIT = Integer.MAX_VALUE / 10;
    private static final long LONG_OVERFLOW_LIMIT = Long.MAX_VALUE / 10;
    
    
All possible chars for representing a number as a String
/**
     * All possible chars for representing a number as a String
     */
    final static char[] digits = {
	'0' , '1' , '2' , '3' , '4' , '5' ,
	'6' , '7' , '8' , '9' , 'a' , 'b' ,
	'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
	'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
	'o' , 'p' , 'q' , 'r' , 's' , 't' ,
	'u' , 'v' , 'w' , 'x' , 'y' , 'z'
    };
    
    
Returns the upper case equivalent of the specified ASCII character.
/**
     * Returns the upper case equivalent of the specified ASCII character.
     */
    public static int toUpper(int c) {
        return (c >= 'a' && c <= 'z') ? (c + 'A' - 'a') : (c & 0xff);
    }

    
Converts passed bytes (representing ASCII characters) to the upper case
equivalent.
/**
     * Converts passed bytes (representing ASCII characters) to the upper case
     * equivalent.
     */
    public static void toUpper(final byte[] bytes) {
        for (int i = 0; i < bytes.length; i++) {
            byte b = bytes[i];
            bytes[i] = (byte)((b >= 'a' && b <= 'z') ? (b + 'A' - 'a') : b);
        }
    }

    
Returns the lower case equivalent of the specified ASCII character.
/**
     * Returns the lower case equivalent of the specified ASCII character.
     */
    public static int toLower(int c) {
        return (c >= 'A' && c <= 'Z') ? (c - 'A' + 'a') : (c & 0xff);
    }

    
Converts passed bytes (representing ASCII characters) to the lower case
equivalent.
/**
     * Converts passed bytes (representing ASCII characters) to the lower case
     * equivalent.
     */
    public static void toLower(final byte[] bytes) {
        for (int i = 0; i < bytes.length; i++) {
            byte b = bytes[i];
            bytes[i] = (byte)((b >= 'A' && b <= 'Z') ? (b - 'A' + 'a') : b);
        }
    }

    
Returns true if the specified ASCII character is upper or lower case.
/**
     * Returns true if the specified ASCII character is upper or lower case.
     */
    public static boolean isAlpha(int c) {
        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
    }

    
Returns true if the specified ASCII character is upper case.
/**
     * Returns true if the specified ASCII character is upper case.
     */
    public static boolean isUpper(int c) {
        return (c >= 'A' && c <= 'Z');
    }

    
Returns true if the specified ASCII character is lower case.
/**
     * Returns true if the specified ASCII character is lower case.
     */
    public static boolean isLower(int c) {
        return (c >= 'a' && c <= 'z');
    }

    
Returns true if the specified ASCII character is white space.
/**
     * Returns true if the specified ASCII character is white space.
     */
    public static boolean isWhite(int c) {
        return (c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '\f' || c == '\b');
    }

    
Returns true if the specified ASCII character is a digit.
/**
     * Returns true if the specified ASCII character is a digit.
     */
    public static boolean isDigit(int c) {
        return (c >= '0' && c <= '9');
    }

    
Parses an unsigned integer from the specified DataChunk. 
Params:
dataChunk – the DataChunk
Throws:
NumberFormatException – if the integer format was invalid/**
     * Parses an unsigned integer from the specified {@link DataChunk}.
     * @param dataChunk the {@link DataChunk}
     * @exception NumberFormatException if the integer format was invalid
     */    
    public static int parseInt(final DataChunk dataChunk) {
        switch(dataChunk.getType()) {
            case Buffer:
                final BufferChunk bc = dataChunk.getBufferChunk();

                return parseInt(bc.getBuffer(),
                        bc.getStart(),
                        bc.getLength());
            case String:
                return Integer.parseInt(dataChunk.toString());
            case Chars:
                final CharChunk cc = dataChunk.getCharChunk();

                return parseInt(cc.getBuffer(),
                        cc.getStart(),
                        cc.getLength());

            default: throw new NullPointerException();
        }
    }
    
    
Parses an unsigned integer from the specified part of DataChunk. 
Params:
dataChunk – the DataChunk
offset – the start offset
length – the length
Throws:
NumberFormatException – if the integer format was invalid/**
     * Parses an unsigned integer from the specified part of {@link DataChunk}.
     * @param dataChunk the {@link DataChunk}
     * @param offset the start offset
     * @param length the length
     * @exception NumberFormatException if the integer format was invalid
     */
    public static int parseInt(final DataChunk dataChunk, final int offset,
            final int length) {
        
        switch(dataChunk.getType()) {
            case Buffer:
                final BufferChunk bc = dataChunk.getBufferChunk();

                return parseInt(bc.getBuffer(),
                        bc.getStart() + offset,
                        length);
            case String:
                return parseInt(dataChunk.toString(), offset, length);
            case Chars:
                final CharChunk cc = dataChunk.getCharChunk();

                return parseInt(cc.getBuffer(),
                        cc.getStart() + offset,
                        cc.getLength());

            default: throw new NullPointerException();
        }
    }
    
    
Parses an unsigned integer from the specified sub-array of bytes.
Params:
b – the bytes to parse
off – the start offset of the bytes
len – the length of the bytes
Throws:
NumberFormatException – if the integer format was invalid/**
     * Parses an unsigned integer from the specified sub-array of bytes.
     * @param b the bytes to parse
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     * @exception NumberFormatException if the integer format was invalid
     */
    public static int parseInt(byte[] b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b[off++])) {
            throw new NumberFormatException();
        }

        int n = c - '0';

        while (--len > 0) {
            if (!isDigit(c = b[off++])) {
                throw new NumberFormatException();
            }
            n = n * 10 + c - '0';
        }

        return n;
    }

    public static int parseInt(char[] b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b[off++])) {
            throw new NumberFormatException();
        }

        int n = c - '0';

        while (--len > 0) {
            if (!isDigit(c = b[off++])) {
                throw new NumberFormatException();
            }
            n = n * 10 + c - '0';
        }

        return n;
    }

    
Parses an unsigned int from the specified sub-array of bytes.
Params:
b – the Buffer to parse
off – the start offset of the bytes
len – the length of the bytes
Throws:
NumberFormatException – if the long format was invalid/**
     * Parses an unsigned int from the specified sub-array of bytes.
     * @param b the Buffer to parse
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     * @exception NumberFormatException if the long format was invalid
     */
    public static int parseInt(Buffer b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b.get(off++))) {
            throw new NumberFormatException();
        }

        int n = c - '0';

        while (--len > 0) {
            if (!isDigit(c = b.get(off++))) {
                throw new NumberFormatException();
            }
            n = n * 10 + c - '0';
        }

        return n;
    }
    
    public static int parseInt(String s, int off, int len)
            throws NumberFormatException {
        int c;

        if (s == null || len <= 0 || !isDigit(c = s.charAt(off++))) {
            throw new NumberFormatException();
        }

        int n = c - '0';
        while (--len > 0) {
            if (isDigit(c = s.charAt(off++))
                    && (n < INT_OVERFLOW_LIMIT || (n == INT_OVERFLOW_LIMIT && (c - '0') < 8))) {
                n = n * 10 + c - '0';
            } else {
                throw new NumberFormatException();
            }
        }

        return n;
    }
    
    
Parses an unsigned long from the specified sub-array of bytes.
Params:
b – the bytes to parse
off – the start offset of the bytes
len – the length of the bytes
Throws:
NumberFormatException – if the long format was invalid/**
     * Parses an unsigned long from the specified sub-array of bytes.
     * @param b the bytes to parse
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     * @exception NumberFormatException if the long format was invalid
     */
    public static long parseLong(byte[] b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b[off++])) {
            throw new NumberFormatException();
        }

        long n = c - '0';
        while (--len > 0) {
            if (isDigit(c = b[off++])
                    && (n < LONG_OVERFLOW_LIMIT || (n == LONG_OVERFLOW_LIMIT && (c - '0') < 8))) {
                n = n * 10 + c - '0';
            } else {
                throw new NumberFormatException();
            }
        }

        return n;
    }
    
    public static long parseLong(char[] b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b[off++])) {
            throw new NumberFormatException();
        }

        long n = c - '0';
        while (--len > 0) {
            if (isDigit(c = b[off++])
                    && (n < LONG_OVERFLOW_LIMIT || (n == LONG_OVERFLOW_LIMIT && (c - '0') < 8))) {
                n = n * 10 + c - '0';
            } else {
                throw new NumberFormatException();
            }
        }

        return n;
    }

    public static long parseLong(String s, int off, int len)
            throws NumberFormatException {
        int c;

        if (s == null || len <= 0 || !isDigit(c = s.charAt(off++))) {
            throw new NumberFormatException();
        }

        long n = c - '0';
        while (--len > 0) {
            if (isDigit(c = s.charAt(off++))
                    && (n < LONG_OVERFLOW_LIMIT || (n == LONG_OVERFLOW_LIMIT && (c - '0') < 8))) {
                n = n * 10 + c - '0';
            } else {
                throw new NumberFormatException();
            }
        }

        return n;
    }

    
Parses an unsigned long from the specified sub-array of bytes.
Params:
b – the Buffer to parse
off – the start offset of the bytes
len – the length of the bytes
Throws:
NumberFormatException – if the long format was invalid/**
     * Parses an unsigned long from the specified sub-array of bytes.
     * @param b the Buffer to parse
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     * @exception NumberFormatException if the long format was invalid
     */
    public static long parseLong(Buffer b, int off, int len)
            throws NumberFormatException {
        int c;

        if (b == null || len <= 0 || !isDigit(c = b.get(off++))) {
            throw new NumberFormatException();
        }

        long n = c - '0';
        while (--len > 0) {
            if (isDigit(c = b.get(off++))
                    && (n < LONG_OVERFLOW_LIMIT || (n == LONG_OVERFLOW_LIMIT && (c - '0') < 8))) {
                n = n * 10 + c - '0';
            } else {
                throw new NumberFormatException();
            }
        }

        return n;        
    }

    public static long parseLong(final DataChunk dataChunk) {
        switch(dataChunk.getType()) {
            case Buffer:
                final BufferChunk bc = dataChunk.getBufferChunk();

                return parseLong(bc.getBuffer(),
                        bc.getStart(),
                        bc.getLength());
            case String:
                return Long.parseLong(dataChunk.toString());
            case Chars:
                final CharChunk cc = dataChunk.getCharChunk();

                return parseLong(cc.getBuffer(),
                        cc.getStart(),
                        cc.getLength());

            default: throw new NullPointerException();
        }
    }

    public static long parseLong(final DataChunk dataChunk, final int offset,
            final int length) {
        
        switch(dataChunk.getType()) {
            case Buffer:
                final BufferChunk bc = dataChunk.getBufferChunk();

                return parseLong(bc.getBuffer(),
                        bc.getStart() + offset,
                        length);
            case String:
                return parseLong(dataChunk.toString(), offset, length);
            case Chars:
                final CharChunk cc = dataChunk.getCharChunk();

                return parseLong(cc.getBuffer(),
                        cc.getStart() + offset,
                        cc.getLength());

            default: throw new NullPointerException();
        }
    }

    
    public static void intToHexString(Buffer buffer, int i) {
	intToUnsignedString(buffer, i, 4);
    }

    
Convert the integer to an unsigned number.
/**
     * Convert the integer to an unsigned number.
     */
    public static void intToUnsignedString(Buffer buffer, int value, int shift) {
        if (value == 0) {
            buffer.put((byte) '0');
            return;
        }

        int currentShift = 32 - shift;

        int radix = 1 << shift;
	int mask = (radix - 1) << currentShift;

        boolean initialZeros = true;
        
        while (mask != 0) {
            final int digit = (value & mask) >>> currentShift;
            if (digit != 0 || !initialZeros) {
                buffer.put((byte) digits[digit]);
                initialZeros = false;
            }
            
            mask >>>= shift;
            currentShift -= shift;
        }
    }
}