/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project 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 io.netty.util;

import io.netty.util.ByteProcessor.IndexOfProcessor;
import io.netty.util.internal.EmptyArrays;
import io.netty.util.internal.PlatformDependent;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import static io.netty.util.internal.ObjectUtil.checkNotNull;

/**
 * A string which has been encoded into a character encoding whose character always takes a single byte, similarly to
 * ASCII. It internally keeps its content in a byte array unlike {@link String}, which uses a character array, for
 * reduced memory footprint and faster data transfer from/to byte-based data structures such as a byte array and
 * {@link ByteBuffer}. It is often used in conjunction with {@link TextHeaders}.
 */
public final class AsciiString extends ByteString implements CharSequence, Comparable<CharSequence> {

    private static final char MAX_CHAR_VALUE = 255;
    public static final AsciiString EMPTY_STRING = new AsciiString("");

    public static final HashingStrategy<CharSequence> CASE_INSENSITIVE_HASHER =
            new HashingStrategy<CharSequence>() {
        @Override
        public int hashCode(CharSequence o) {
            return AsciiString.caseInsensitiveHashCode(o);
        }

        @Override
        public boolean equals(CharSequence a, CharSequence b) {
            return AsciiString.contentEqualsIgnoreCase(a, b);
        }
    };
    public static final HashingStrategy<CharSequence> CASE_SENSITIVE_HASHER =
            new HashingStrategy<CharSequence>() {
        @Override
        public int hashCode(CharSequence o) {
            return AsciiString.hashCode(o);
        }

        @Override
        public boolean equals(CharSequence a, CharSequence b) {
            return AsciiString.contentEquals(a, b);
        }
    };

    /**
     * Factory which uses the {@link #AsciiString(byte[], int, int, boolean)} constructor.
     */
    private static final ByteStringFactory DEFAULT_FACTORY = new ByteStringFactory() {
        @Override
        public ByteString newInstance(byte[] value, int start, int length, boolean copy) {
            return new AsciiString(value, start, length, copy);
        }
    };

    private String string;
    private int caseInsensitiveHash;

    /**
     * Returns an {@link AsciiString} containing the given character sequence. If the given string is already a
     * {@link AsciiString}, just returns the same instance.
     */
    public static AsciiString of(CharSequence string) {
        return string instanceof AsciiString ? (AsciiString) string : new AsciiString(string);
    }

    public AsciiString(byte[] value) {
        super(value);
    }

    public AsciiString(byte[] value, boolean copy) {
        super(value, copy);
    }

    public AsciiString(byte[] value, int start, int length, boolean copy) {
        super(value, start, length, copy);
    }

    public AsciiString(ByteString value, boolean copy) {
        super(value, copy);
    }

    public AsciiString(ByteBuffer value) {
        super(value);
    }

    public AsciiString(ByteBuffer value, int start, int length, boolean copy) {
        super(value, start, length, copy);
    }

    public AsciiString(char[] value) {
        this(checkNotNull(value, "value"), 0, value.length);
    }

    public AsciiString(char[] value, int start, int length) {
        super(length);
        if (start < 0 || start > checkNotNull(value, "value").length - length) {
            throw new IndexOutOfBoundsException("expected: " + "0 <= start(" + start + ") <= start + length(" + length
                            + ") <= " + "value.length(" + value.length + ')');
        }

        for (int i = 0, j = start; i < length; i++, j++) {
            this.value[i] = c2b(value[j]);
        }
    }

    public AsciiString(CharSequence value) {
        this(checkNotNull(value, "value"), 0, value.length());
    }

    public AsciiString(CharSequence value, int start, int length) {
        super(length);
        if (start < 0 || length < 0 || length > checkNotNull(value, "value").length() - start) {
            throw new IndexOutOfBoundsException("expected: " + "0 <= start(" + start + ") <= start + length(" + length
                            + ") <= " + "value.length(" + value.length() + ')');
        }

        for (int i = 0, j = start; i < length; i++, j++) {
            this.value[i] = c2b(value.charAt(j));
        }
    }

    @Override
    public char charAt(int index) {
        return (char) (byteAt(index) & 0xFF);
    }

    @Override
    public void arrayChanged() {
        string = null;
        caseInsensitiveHash = 0;
        super.arrayChanged();
    }

    @Override
    public String toString(Charset charset, int start, int end) {
        if (start == 0 && end == length()) {
            if (string == null) {
                string = super.toString(charset, start, end);
            }
            return string;
        }

        return super.toString(charset, start, end);
    }

    /**
     * Compares the specified string to this string using the ASCII values of the characters. Returns 0 if the strings
     * contain the same characters in the same order. Returns a negative integer if the first non-equal character in
     * this string has an ASCII value which is less than the ASCII value of the character at the same position in the
     * specified string, or if this string is a prefix of the specified string. Returns a positive integer if the first
     * non-equal character in this string has a ASCII value which is greater than the ASCII value of the character at
     * the same position in the specified string, or if the specified string is a prefix of this string.
     *
     * @param string the string to compare.
     * @return 0 if the strings are equal, a negative integer if this string is before the specified string, or a
     *         positive integer if this string is after the specified string.
     * @throws NullPointerException if {@code string} is {@code null}.
     */
    @Override
    public int compareTo(CharSequence string) {
        if (this == string) {
            return 0;
        }

        int result;
        int length1 = length();
        int length2 = string.length();
        int minLength = Math.min(length1, length2);
        for (int i = 0, j = arrayOffset(); i < minLength; i++, j++) {
            result = (char) (value[j] & 0xFF) - string.charAt(i);
            if (result != 0) {
                return result;
            }
        }

        return length1 - length2;
    }

    /**
     * Concatenates this string and the specified string.
     *
     * @param string the string to concatenate
     * @return a new string which is the concatenation of this string and the specified string.
     */
    public AsciiString concat(CharSequence string) {
        int thisLen = length();
        int thatLen = string.length();
        if (thatLen == 0) {
            return this;
        }

        if (string instanceof AsciiString) {
            AsciiString that = (AsciiString) string;
            if (isEmpty()) {
                return that;
            }

            byte[] newValue = new byte[thisLen + thatLen];
            System.arraycopy(value, arrayOffset(), newValue, 0, thisLen);
            System.arraycopy(that.value, that.arrayOffset(), newValue, thisLen, thatLen);
            return new AsciiString(newValue, false);
        }

        if (isEmpty()) {
            return new AsciiString(string);
        }

        byte[] newValue = new byte[thisLen + thatLen];
        System.arraycopy(value, arrayOffset(), newValue, 0, thisLen);
        for (int i = thisLen, j = 0; i < newValue.length; i++, j++) {
            newValue[i] = c2b(string.charAt(j));
        }

        return new AsciiString(newValue, false);
    }

    /**
     * Compares the specified string to this string to determine if the specified string is a suffix.
     *
     * @param suffix the suffix to look for.
     * @return {@code true} if the specified string is a suffix of this string, {@code false} otherwise.
     * @throws NullPointerException if {@code suffix} is {@code null}.
     */
    public boolean endsWith(CharSequence suffix) {
        int suffixLen = suffix.length();
        return regionMatches(length() - suffixLen, suffix, 0, suffixLen);
    }

    /**
     * Compares the specified string to this string ignoring the case of the characters and returns true if they are
     * equal.
     *
     * @param string the string to compare.
     * @return {@code true} if the specified string is equal to this string, {@code false} otherwise.
     */
    public boolean contentEqualsIgnoreCase(CharSequence string) {
        if (string == null || string.length() != length()) {
            return false;
        }

        if (string.getClass() == AsciiString.class) {
            AsciiString rhs = (AsciiString) string;
            for (int i = arrayOffset(), j = rhs.arrayOffset(); i < length(); ++i, ++j) {
                byte c1 = value[i];
                byte c2 = value[j];
                if (c1 != c2 && toLowerCase(c1) != toLowerCase(c2)) {
                    return false;
                }
            }
            return true;
        }

        for (int i = arrayOffset(), j = 0; i < length(); ++i, ++j) {
            char c1 = (char) (value[i] & 0xFF);
            char c2 = string.charAt(j);
            if (c1 != c2 && toLowerCase(c1) != toLowerCase(c2)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Copies the characters in this string to a character array.
     *
     * @return a character array containing the characters of this string.
     */
    public char[] toCharArray() {
        return toCharArray(0, length());
    }

    /**
     * Copies the characters in this string to a character array.
     *
     * @return a character array containing the characters of this string.
     */
    public char[] toCharArray(int start, int end) {
        int length = end - start;
        if (length == 0) {
            return EmptyArrays.EMPTY_CHARS;
        }

        if (start < 0 || length > length() - start) {
            throw new IndexOutOfBoundsException("expected: " + "0 <= start(" + start + ") <= srcIdx + length("
                            + length + ") <= srcLen(" + length() + ')');
        }

        final char[] buffer = new char[length];
        for (int i = 0, j = start + arrayOffset(); i < length; i++, j++) {
            buffer[i] = (char) (value[j] & 0xFF);
        }
        return buffer;
    }

    /**
     * Copied the content of this string to a character array.
     *
     * @param srcIdx the starting offset of characters to copy.
     * @param dst the destination character array.
     * @param dstIdx the starting offset in the destination byte array.
     * @param length the number of characters to copy.
     */
    public void copy(int srcIdx, char[] dst, int dstIdx, int length) {
        if (dst == null) {
            throw new NullPointerException("dst");
        }

        if (srcIdx < 0 || length > length() - srcIdx) {
            throw new IndexOutOfBoundsException("expected: " + "0 <= srcIdx(" + srcIdx + ") <= srcIdx + length("
                            + length + ") <= srcLen(" + length() + ')');
        }

        final int dstEnd = dstIdx + length;
        for (int i = dstIdx, j = srcIdx + arrayOffset(); i < dstEnd; i++, j++) {
            dst[i] = (char) (value[j] & 0xFF);
        }
    }

    @Override
    public AsciiString subSequence(int start) {
        return subSequence(start, length());
    }

    @Override
    public AsciiString subSequence(int start, int end) {
       return subSequence(start, end, true);
    }

    @Override
    public AsciiString subSequence(int start, int end, boolean copy) {
        return (AsciiString) super.subSequence(start, end, copy, DEFAULT_FACTORY);
    }

    /**
     * Searches in this string for the first index of the specified string. The search for the string starts at the
     * beginning and moves towards the end of this string.
     *
     * @param string the string to find.
     * @return the index of the first character of the specified string in this string, -1 if the specified string is
     *         not a substring.
     * @throws NullPointerException if {@code string} is {@code null}.
     */
    public int indexOf(CharSequence string) {
        return indexOf(string, 0);
    }

    /**
     * Searches in this string for the index of the specified string. The search for the string starts at the specified
     * offset and moves towards the end of this string.
     *
     * @param subString the string to find.
     * @param start the starting offset.
     * @return the index of the first character of the specified string in this string, -1 if the specified string is
     *         not a substring.
     * @throws NullPointerException if {@code subString} is {@code null}.
     */
    public int indexOf(CharSequence subString, int start) {
        if (start < 0) {
            start = 0;
        }

        final int thisLen = length();

        int subCount = subString.length();
        if (subCount <= 0) {
            return start < thisLen ? start : thisLen;
        }
        if (subCount > thisLen - start) {
            return -1;
        }

        final char firstChar = subString.charAt(0);
        if (firstChar > MAX_CHAR_VALUE) {
            return -1;
        }
        ByteProcessor IndexOfVisitor = new IndexOfProcessor((byte) firstChar);
        try {
            for (;;) {
                int i = forEachByte(start, thisLen - start, IndexOfVisitor);
                if (i == -1 || subCount + i > thisLen) {
                    return -1; // handles subCount > count || start >= count
                }
                int o1 = i, o2 = 0;
                while (++o2 < subCount && (char) (value[++o1 + arrayOffset()] & 0xFF) == subString.charAt(o2)) {
                    // Intentionally empty
                }
                if (o2 == subCount) {
                    return i;
                }
                start = i + 1;
            }
        } catch (Exception e) {
            PlatformDependent.throwException(e);
            return -1;
        }
    }

    /**
     * Searches in this string for the last index of the specified string. The search for the string starts at the end
     * and moves towards the beginning of this string.
     *
     * @param string the string to find.
     * @return the index of the first character of the specified string in this string, -1 if the specified string is
     *         not a substring.
     * @throws NullPointerException if {@code string} is {@code null}.
     */
    public int lastIndexOf(CharSequence string) {
        // Use count instead of count - 1 so lastIndexOf("") answers count
        return lastIndexOf(string, length());
    }

    /**
     * Searches in this string for the index of the specified string. The search for the string starts at the specified
     * offset and moves towards the beginning of this string.
     *
     * @param subString the string to find.
     * @param start the starting offset.
     * @return the index of the first character of the specified string in this string , -1 if the specified string is
     *         not a substring.
     * @throws NullPointerException if {@code subString} is {@code null}.
     */
    public int lastIndexOf(CharSequence subString, int start) {
        final int thisLen = length();
        final int subCount = subString.length();

        if (subCount > thisLen || start < 0) {
            return -1;
        }

        if (subCount <= 0) {
            return start < thisLen ? start : thisLen;
        }

        start = Math.min(start, thisLen - subCount);

        // count and subCount are both >= 1
        final char firstChar = subString.charAt(0);
        if (firstChar > MAX_CHAR_VALUE) {
            return -1;
        }
        ByteProcessor IndexOfVisitor = new IndexOfProcessor((byte) firstChar);
        try {
            for (;;) {
                int i = forEachByteDesc(start, thisLen - start, IndexOfVisitor);
                if (i == -1) {
                    return -1;
                }
                int o1 = i, o2 = 0;
                while (++o2 < subCount && (char) (value[++o1 + arrayOffset()] & 0xFF) == subString.charAt(o2)) {
                    // Intentionally empty
                }
                if (o2 == subCount) {
                    return i;
                }
                start = i - 1;
            }
        } catch (Exception e) {
            PlatformDependent.throwException(e);
            return -1;
        }
    }

    /**
     * Compares the specified string to this string and compares the specified range of characters to determine if they
     * are the same.
     *
     * @param thisStart the starting offset in this string.
     * @param string the string to compare.
     * @param start the starting offset in the specified string.
     * @param length the number of characters to compare.
     * @return {@code true} if the ranges of characters are equal, {@code false} otherwise
     * @throws NullPointerException if {@code string} is {@code null}.
     */
    public boolean regionMatches(int thisStart, CharSequence string, int start, int length) {
        if (string == null) {
            throw new NullPointerException("string");
        }

        if (start < 0 || string.length() - start < length) {
            return false;
        }

        final int thisLen = length();
        if (thisStart < 0 || thisLen - thisStart < length) {
            return false;
        }

        if (length <= 0) {
            return true;
        }

        final int thatEnd = start + length;
        for (int i = start, j = thisStart + arrayOffset(); i < thatEnd; i++, j++) {
            if ((char) (value[j] & 0xFF) != string.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Compares the specified string to this string and compares the specified range of characters to determine if they
     * are the same. When ignoreCase is true, the case of the characters is ignored during the comparison.
     *
     * @param ignoreCase specifies if case should be ignored.
     * @param thisStart the starting offset in this string.
     * @param string the string to compare.
     * @param start the starting offset in the specified string.
     * @param length the number of characters to compare.
     * @return {@code true} if the ranges of characters are equal, {@code false} otherwise.
     * @throws NullPointerException if {@code string} is {@code null}.
     */
    public boolean regionMatches(boolean ignoreCase, int thisStart, CharSequence string, int start, int length) {
        if (!ignoreCase) {
            return regionMatches(thisStart, string, start, length);
        }

        if (string == null) {
            throw new NullPointerException("string");
        }

        final int thisLen = length();
        if (thisStart < 0 || length > thisLen - thisStart) {
            return false;
        }
        if (start < 0 || length > string.length() - start) {
            return false;
        }

        thisStart += arrayOffset();
        final int thisEnd = thisStart + length;
        while (thisStart < thisEnd) {
            char c1 = (char) (value[thisStart++] & 0xFF);
            char c2 = string.charAt(start++);
            if (c1 != c2 && toLowerCase(c1) != toLowerCase(c2)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Copies this string replacing occurrences of the specified character with another character.
     *
     * @param oldChar the character to replace.
     * @param newChar the replacement character.
     * @return a new string with occurrences of oldChar replaced by newChar.
     */
    public AsciiString replace(char oldChar, char newChar) {
        if (oldChar > MAX_CHAR_VALUE) {
            return this;
        }

        final int index;
        final byte oldCharByte = c2b(oldChar);
        try {
            index = forEachByte(new IndexOfProcessor(oldCharByte));
        } catch (Exception e) {
            PlatformDependent.throwException(e);
            return this;
        }
        if (index == -1) {
            return this;
        }

        final byte newCharByte = c2b(newChar);
        byte[] buffer = new byte[length()];
        for (int i = 0, j = arrayOffset(); i < buffer.length; i++, j++) {
            byte b = value[j];
            if (b == oldCharByte) {
                b = newCharByte;
            }
            buffer[i] = b;
        }

        return new AsciiString(buffer, false);
    }

    /**
     * Compares the specified string to this string to determine if the specified string is a prefix.
     *
     * @param prefix the string to look for.
     * @return {@code true} if the specified string is a prefix of this string, {@code false} otherwise
     * @throws NullPointerException if {@code prefix} is {@code null}.
     */
    public boolean startsWith(CharSequence prefix) {
        return startsWith(prefix, 0);
    }

    /**
     * Compares the specified string to this string, starting at the specified offset, to determine if the specified
     * string is a prefix.
     *
     * @param prefix the string to look for.
     * @param start the starting offset.
     * @return {@code true} if the specified string occurs in this string at the specified offset, {@code false}
     *         otherwise.
     * @throws NullPointerException if {@code prefix} is {@code null}.
     */
    public boolean startsWith(CharSequence prefix, int start) {
        return regionMatches(start, prefix, 0, prefix.length());
    }

    /**
     * Converts the characters in this string to lowercase, using the default Locale.
     *
     * @return a new string containing the lowercase characters equivalent to the characters in this string.
     */
    public AsciiString toLowerCase() {
        boolean lowercased = true;
        int i, j;
        final int len = length() + arrayOffset();
        for (i = arrayOffset(); i < len; ++i) {
            byte b = value[i];
            if (b >= 'A' && b <= 'Z') {
                lowercased = false;
                break;
            }
        }

        // Check if this string does not contain any uppercase characters.
        if (lowercased) {
            return this;
        }

        final byte[] newValue = new byte[length()];
        for (i = 0, j = arrayOffset(); i < newValue.length; ++i, ++j) {
            newValue[i] = toLowerCase(value[j]);
        }

        return new AsciiString(newValue, false);
    }

    /**
     * Converts the characters in this string to uppercase, using the default Locale.
     *
     * @return a new string containing the uppercase characters equivalent to the characters in this string.
     */
    public AsciiString toUpperCase() {
        boolean uppercased = true;
        int i, j;
        final int len = length() + arrayOffset();
        for (i = arrayOffset(); i < len; ++i) {
            byte b = value[i];
            if (b >= 'a' && b <= 'z') {
                uppercased = false;
                break;
            }
        }

        // Check if this string does not contain any lowercase characters.
        if (uppercased) {
            return this;
        }

        final byte[] newValue = new byte[length()];
        for (i = 0, j = arrayOffset(); i < newValue.length; ++i, ++j) {
            newValue[i] = toUpperCase(value[j]);
        }

        return new AsciiString(newValue, false);
    }

    /**
     * Copies this string removing white space characters from the beginning and end of the string.
     *
     * @return a new string with characters {@code <= \\u0020} removed from the beginning and the end.
     */
    public AsciiString trim() {
        int start = arrayOffset(), last = arrayOffset() + length();
        int end = last;
        while (start <= end && value[start] <= ' ') {
            start++;
        }
        while (end >= start && value[end] <= ' ') {
            end--;
        }
        if (start == 0 && end == last) {
            return this;
        }
        return new AsciiString(value, start, end - start + 1, false);
    }

    /**
     * Compares a {@code CharSequence} to this {@code String} to determine if their contents are equal.
     *
     * @param a the character sequence to compare to.
     * @return {@code true} if equal, otherwise {@code false}
     */
    public boolean contentEquals(CharSequence a) {
        if (this == a) {
            return true;
        }
        if (a instanceof AsciiString) {
            return equals(a);
        }

        if (a.length() != length()) {
            return false;
        }
        for (int i = arrayOffset(), j = 0; j < a.length(); ++i, ++j) {
            if ((char) (value[i] & 0xFF) != a.charAt(j)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Determines whether this string matches a given regular expression.
     *
     * @param expr the regular expression to be matched.
     * @return {@code true} if the expression matches, otherwise {@code false}.
     * @throws PatternSyntaxException if the syntax of the supplied regular expression is not valid.
     * @throws NullPointerException if {@code expr} is {@code null}.
     */
    public boolean matches(String expr) {
        return Pattern.matches(expr, this);
    }

    /**
     * Splits this string using the supplied regular expression {@code expr}. The parameter {@code max} controls the
     * behavior how many times the pattern is applied to the string.
     *
     * @param expr the regular expression used to divide the string.
     * @param max the number of entries in the resulting array.
     * @return an array of Strings created by separating the string along matches of the regular expression.
     * @throws NullPointerException if {@code expr} is {@code null}.
     * @throws PatternSyntaxException if the syntax of the supplied regular expression is not valid.
     * @see Pattern#split(CharSequence, int)
     */
    public AsciiString[] split(String expr, int max) {
        return toAsciiStringArray(Pattern.compile(expr).split(this, max));
    }

    private static byte c2b(char c) {
        if (c > MAX_CHAR_VALUE) {
            return '?';
        }
        return (byte) c;
    }

    /**
     * Splits the specified {@link String} with the specified delimiter..
     */
    public AsciiString[] split(char delim) {
        final List<AsciiString> res = new ArrayList<AsciiString>();

        int start = 0;
        final int length = length();
        for (int i = start; i < length; i++) {
            if (charAt(i) == delim) {
                if (start == i) {
                    res.add(EMPTY_STRING);
                } else {
                    res.add(new AsciiString(value, start + arrayOffset(), i - start, false));
                }
                start = i + 1;
            }
        }

        if (start == 0) { // If no delimiter was found in the value
            res.add(this);
        } else {
            if (start != length) {
                // Add the last element if it's not empty.
                res.add(new AsciiString(value, start + arrayOffset(), length - start, false));
            } else {
                // Truncate trailing empty elements.
                for (int i = res.size() - 1; i >= 0; i--) {
                    if (res.get(i).isEmpty()) {
                        res.remove(i);
                    } else {
                        break;
                    }
                }
            }
        }

        return res.toArray(new AsciiString[res.size()]);
    }

    /**
     * Generate a hash code that will be consistent regardless of ASCII character casing.
     * <p>
     * NOTE: This must be compatible with {@link #caseInsensitiveHashCode(CharSequence)}.
     */
    public int hashCodeCaseInsensitive() {
        int h = caseInsensitiveHash;
        if (h == 0) {
            final int end = arrayOffset() + length();
            for (int i = arrayOffset(); i < end; ++i) {
                h = h * HASH_CODE_PRIME + toLowerCase((char) (value[i] & 0xFF));
            }

            caseInsensitiveHash = h;
        }
        return caseInsensitiveHash;
    }

    /**
     * Returns the case-insensitive hash code of the specified string. Note that this method uses the same hashing
     * algorithm with {@link #hashCode()} so that you can put both {@link AsciiString}s and arbitrary
     * {@link CharSequence}s into the same {@link TextHeaders}.
     */
    public static int caseInsensitiveHashCode(CharSequence value) {
        if (value.getClass() == AsciiString.class) {
            return ((AsciiString) value).hashCodeCaseInsensitive();
        }

        int hash = 0;
        for (int i = 0; i < value.length(); ++i) {
            hash = hash * HASH_CODE_PRIME + toLowerCase(value.charAt(i));
        }
        return hash;
    }

    /**
     * A case-sensitive version of {@link caseInsensitiveHashCode(CharSequence)}.
     * @param value
     * @return
     */
    public static int hashCode(CharSequence value) {
        if (value.getClass() == AsciiString.class) {
            return ((AsciiString) value).hashCode();
        }

        int hash = 0;
        for (int i = 0; i < value.length(); ++i) {
            hash = hash * HASH_CODE_PRIME + value.charAt(i);
        }
        return hash;
    }

    /**
     * Returns {@code true} if both {@link CharSequence}'s are equals when ignore the case. This only supports 8-bit
     * ASCII.
     */
    public static boolean contentEqualsIgnoreCase(CharSequence a, CharSequence b) {
        if (a == b) {
            return true;
        }

        if (a == null || b == null) {
            return false;
        }

        if (a.getClass() == AsciiString.class) {
            return ((AsciiString) a).contentEqualsIgnoreCase(b);
        }
        if (b.getClass() == AsciiString.class) {
            return ((AsciiString) b).contentEqualsIgnoreCase(a);
        }

        if (a.length() != b.length()) {
            return false;
        }
        for (int i = 0, j = 0; i < a.length(); ++i, ++j) {
            char c1 = a.charAt(i);
            char c2 = b.charAt(j);
            if (c1 != c2 && toLowerCase(c1) != toLowerCase(c2)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Returns {@code true} if the content of both {@link CharSequence}'s are equals. This only supports 8-bit ASCII.
     */
    public static boolean contentEquals(CharSequence a, CharSequence b) {
        if (a == b) {
            return true;
        }

        if (a == null || b == null) {
            return false;
        }

        if (a.getClass() == AsciiString.class) {
            return ((AsciiString) a).contentEquals(b);
        }

        if (b.getClass() == AsciiString.class) {
            return ((AsciiString) b).contentEquals(a);
        }

        if (a.length() != b.length()) {
            return false;
        }
        for (int i = 0; i <  a.length(); ++i) {
            if (a.charAt(i) != b.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    private static AsciiString[] toAsciiStringArray(String[] jdkResult) {
        AsciiString[] res = new AsciiString[jdkResult.length];
        for (int i = 0; i < jdkResult.length; i++) {
            res[i] = new AsciiString(jdkResult[i]);
        }
        return res;
    }

    /**
     * Determines if this {@code String} contains the sequence of characters in the {@code CharSequence} passed.
     *
     * @param cs the character sequence to search for.
     * @return {@code true} if the sequence of characters are contained in this string, otherwise {@code false}.
     */
    public boolean contains(CharSequence cs) {
        if (cs == null) {
            throw new NullPointerException();
        }
        return indexOf(cs) >= 0;
    }

    private static byte toLowerCase(byte b) {
        if ('A' <= b && b <= 'Z') {
            return (byte) (b + 32);
        }
        return b;
    }

    private static char toLowerCase(char c) {
        if ('A' <= c && c <= 'Z') {
            return (char) (c + 32);
        }
        return c;
    }

    private static byte toUpperCase(byte b) {
        if ('a' <= b && b <= 'z') {
            return (byte) (b - 32);
        }
        return b;
    }
}