/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.javac.util;

/** Utility class for static conversion methods between numbers

 *  and strings in various formats.

 *

 *  <p>Note regarding UTF-8.

 *  The JVMS defines its own version of the UTF-8 format so that it

 *  contains no zero bytes (modified UTF-8). This is not actually the same

 *  as Charset.forName("UTF-8").

 *

 *  <p>

 *  See also:

 *  <ul>

 *  <li><a href="http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.4.7">

 *    JVMS 4.4.7 </a></li>

 *  <li><a href="http://docs.oracle.com/javase/7/docs/api/java/io/DataInput.html#modified-utf-8">

      java.io.DataInput: Modified UTF-8 </a></li>

    <li><a href="https://en.wikipedia.org/wiki/UTF-8#Modified_UTF-8">

      Modified UTF-8 (wikipedia) </a></li>

 *  </ul>

 *

 *  The methods here support modified UTF-8.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class Convert {

    /** Convert string to integer.

     */

    public static int string2int(String s, int radix)

        throws NumberFormatException {

        if (radix == 10) {

            return Integer.parseInt(s, radix);

        } else {

            char[] cs = s.toCharArray();

            int limit = Integer.MAX_VALUE / (radix/2);

            int n = 0;

            for (char c : cs) {

                int d = Character.digit(c, radix);

                if (n < 0 ||

                    n > limit ||

                    n * radix > Integer.MAX_VALUE - d)

                    throw new NumberFormatException();

                n = n * radix + d;

            }

            return n;

        }

    }

    /** Convert string to long integer.

     */

    public static long string2long(String s, int radix)

        throws NumberFormatException {

        if (radix == 10) {

            return Long.parseLong(s, radix);

        } else {

            char[] cs = s.toCharArray();

            long limit = Long.MAX_VALUE / (radix/2);

            long n = 0;

            for (char c : cs) {

                int d = Character.digit(c, radix);

                if (n < 0 ||

                    n > limit ||

                    n * radix > Long.MAX_VALUE - d)

                    throw new NumberFormatException();

                n = n * radix + d;

            }

            return n;

        }

    }

/* Conversion routines between names, strings, and byte arrays in Utf8 format

 */

    /** Convert `len' bytes from utf8 to characters.

     *  Parameters are as in System.arraycopy

     *  Return first index in `dst' past the last copied char.

     *  @param src        The array holding the bytes to convert.

     *  @param sindex     The start index from which bytes are converted.

     *  @param dst        The array holding the converted characters..

     *  @param dindex     The start index from which converted characters

     *                    are written.

     *  @param len        The maximum number of bytes to convert.

     */

    public static int utf2chars(byte[] src, int sindex,

                                char[] dst, int dindex,

                                int len) {

        int i = sindex;

        int j = dindex;

        int limit = sindex + len;

        while (i < limit) {

            int b = src[i++] & 0xFF;

            if (b >= 0xE0) {

                b = (b & 0x0F) << 12;

                b = b | (src[i++] & 0x3F) << 6;

                b = b | (src[i++] & 0x3F);

            } else if (b >= 0xC0) {

                b = (b & 0x1F) << 6;

                b = b | (src[i++] & 0x3F);

            }

            dst[j++] = (char)b;

        }

        return j;

    }

    /** Return bytes in Utf8 representation as an array of characters.

     *  @param src        The array holding the bytes.

     *  @param sindex     The start index from which bytes are converted.

     *  @param len        The maximum number of bytes to convert.

     */

    public static char[] utf2chars(byte[] src, int sindex, int len) {

        char[] dst = new char[len];

        int len1 = utf2chars(src, sindex, dst, 0, len);

        char[] result = new char[len1];

        System.arraycopy(dst, 0, result, 0, len1);

        return result;

    }

    /** Return all bytes of a given array in Utf8 representation

     *  as an array of characters.

     *  @param src        The array holding the bytes.

     */

    public static char[] utf2chars(byte[] src) {

        return utf2chars(src, 0, src.length);

    }

    /** Return bytes in Utf8 representation as a string.

     *  @param src        The array holding the bytes.

     *  @param sindex     The start index from which bytes are converted.

     *  @param len        The maximum number of bytes to convert.

     */

    public static String utf2string(byte[] src, int sindex, int len) {

        char dst[] = new char[len];

        int len1 = utf2chars(src, sindex, dst, 0, len);

        return new String(dst, 0, len1);

    }

    /** Return all bytes of a given array in Utf8 representation

     *  as a string.

     *  @param src        The array holding the bytes.

     */

    public static String utf2string(byte[] src) {

        return utf2string(src, 0, src.length);

    }

    /** Copy characters in source array to bytes in target array,

     *  converting them to Utf8 representation.

     *  The target array must be large enough to hold the result.

     *  returns first index in `dst' past the last copied byte.

     *  @param src        The array holding the characters to convert.

     *  @param sindex     The start index from which characters are converted.

     *  @param dst        The array holding the converted characters..

     *  @param dindex     The start index from which converted bytes

     *                    are written.

     *  @param len        The maximum number of characters to convert.

     */

    public static int chars2utf(char[] src, int sindex,

                                byte[] dst, int dindex,

                                int len) {

        int j = dindex;

        int limit = sindex + len;

        for (int i = sindex; i < limit; i++) {

            char ch = src[i];

            if (1 <= ch && ch <= 0x7F) {

                dst[j++] = (byte)ch;

            } else if (ch <= 0x7FF) {

                dst[j++] = (byte)(0xC0 | (ch >> 6));

                dst[j++] = (byte)(0x80 | (ch & 0x3F));

            } else {

                dst[j++] = (byte)(0xE0 | (ch >> 12));

                dst[j++] = (byte)(0x80 | ((ch >> 6) & 0x3F));

                dst[j++] = (byte)(0x80 | (ch & 0x3F));

            }

        }

        return j;

    }

    /** Return characters as an array of bytes in Utf8 representation.

     *  @param src        The array holding the characters.

     *  @param sindex     The start index from which characters are converted.

     *  @param len        The maximum number of characters to convert.

     */

    public static byte[] chars2utf(char[] src, int sindex, int len) {

        byte[] dst = new byte[len * 3];

        int len1 = chars2utf(src, sindex, dst, 0, len);

        byte[] result = new byte[len1];

        System.arraycopy(dst, 0, result, 0, len1);

        return result;

    }

    /** Return all characters in given array as an array of bytes

     *  in Utf8 representation.

     *  @param src        The array holding the characters.

     */

    public static byte[] chars2utf(char[] src) {

        return chars2utf(src, 0, src.length);

    }

    /** Return string as an array of bytes in in Utf8 representation.

     */

    public static byte[] string2utf(String s) {

        return chars2utf(s.toCharArray());

    }

    /**

     * Escapes each character in a string that has an escape sequence or

     * is non-printable ASCII.  Leaves non-ASCII characters alone.

     */

    public static String quote(String s) {

        StringBuilder buf = new StringBuilder();

        for (int i = 0; i < s.length(); i++) {

            buf.append(quote(s.charAt(i)));

        }

        return buf.toString();

    }

    /**

     * Escapes a character if it has an escape sequence or is

     * non-printable ASCII.  Leaves non-ASCII characters alone.

     */

    public static String quote(char ch) {

        switch (ch) {

        case '\b':  return "\\b";

        case '\f':  return "\\f";

        case '\n':  return "\\n";

        case '\r':  return "\\r";

        case '\t':  return "\\t";

        case '\'':  return "\\'";

        case '\"':  return "\\\"";

        case '\\':  return "\\\\";

        default:

            return (isPrintableAscii(ch))

                ? String.valueOf(ch)

                : String.format("\\u%04x", (int) ch);

        }

    }

    /**

     * Is a character printable ASCII?

     */

    private static boolean isPrintableAscii(char ch) {

        return ch >= ' ' && ch <= '~';

    }

    /** Escape all unicode characters in string.

     */

    public static String escapeUnicode(String s) {

        int len = s.length();

        int i = 0;

        while (i < len) {

            char ch = s.charAt(i);

            if (ch > 255) {

                StringBuilder buf = new StringBuilder();

                buf.append(s.substring(0, i));

                while (i < len) {

                    ch = s.charAt(i);

                    if (ch > 255) {

                        buf.append("\\u");

                        buf.append(Character.forDigit((ch >> 12) % 16, 16));

                        buf.append(Character.forDigit((ch >>  8) % 16, 16));

                        buf.append(Character.forDigit((ch >>  4) % 16, 16));

                        buf.append(Character.forDigit((ch      ) % 16, 16));

                    } else {

                        buf.append(ch);

                    }

                    i++;

                }

                s = buf.toString();

            } else {

                i++;

            }

        }

        return s;

    }

/* Conversion routines for qualified name splitting

 */

    /** Return the last part of a class name.

     */

    public static Name shortName(Name classname) {

        return classname.subName(

            classname.lastIndexOf((byte)'.') + 1, classname.getByteLength());

    }

    public static String shortName(String classname) {

        return classname.substring(classname.lastIndexOf('.') + 1);

    }

    /** Return the package name of a class name, excluding the trailing '.',

     *  "" if not existent.

     */

    public static Name packagePart(Name classname) {

        return classname.subName(0, classname.lastIndexOf((byte)'.'));

    }

    public static String packagePart(String classname) {

        int lastDot = classname.lastIndexOf('.');

        return (lastDot < 0 ? "" : classname.substring(0, lastDot));

    }

    public static List<Name> enclosingCandidates(Name name) {

        List<Name> names = List.nil();

        int index;

        while ((index = name.lastIndexOf((byte)'$')) > 0) {

            name = name.subName(0, index);

            names = names.prepend(name);

        }

        return names;

    }

}