/*
 * @(#)ConditionalSpecialCasing.java	1.3 03/12/19
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.lang;

import java.text.BreakIterator;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Locale;
import sun.text.Normalizer;


/**
 * This is a utility class for <code>String.toLowerCase()</code> and
 * <code>String.toUpperCase()</code>, that handles special casing with
 * conditions.  In other words, it handles the mappings with conditions
 * that are defined in 
 * <a href="http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt">Special
 * Casing Properties</a> file.  
 * <p>
 * Note that the unconditional case mappings (including 1:M mappings)
 * are handled in <code>Character.toLower/UpperCase()</code>.
 */
final class ConditionalSpecialCasing {

    // context conditions.
    final static int FINAL_CASED =		1;
    final static int AFTER_SOFT_DOTTED =	2;
    final static int MORE_ABOVE =		3;
    final static int AFTER_I = 			4;
    final static int NOT_BEFORE_DOT = 		5;

    // combining class definitions
    final static int COMBINING_CLASS_ABOVE = 230;

    // Special case mapping entries
    static Entry[] entry = {
	//# ================================================================================
	//# Conditional mappings
	//# ================================================================================
	new Entry(0x03A3, new char[]{0x03C2}, new char[]{0x03A3}, null, FINAL_CASED), // # GREEK CAPITAL LETTER SIGMA

	//# ================================================================================
	//# Locale-sensitive mappings
	//# ================================================================================
	//# Lithuanian
	new Entry(0x0307, new char[]{0x0307}, new char[]{}, "lt",  AFTER_SOFT_DOTTED), // # COMBINING DOT ABOVE
	new Entry(0x0049, new char[]{0x0069, 0x0307}, new char[]{0x0049}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER I
	new Entry(0x004A, new char[]{0x006A, 0x0307}, new char[]{0x004A}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER J
	new Entry(0x012E, new char[]{0x012F, 0x0307}, new char[]{0x012E}, "lt", MORE_ABOVE), // # LATIN CAPITAL LETTER I WITH OGONEK
	new Entry(0x00CC, new char[]{0x0069, 0x0307, 0x0300}, new char[]{0x00CC}, "lt", 0), // # LATIN CAPITAL LETTER I WITH GRAVE
	new Entry(0x00CD, new char[]{0x0069, 0x0307, 0x0301}, new char[]{0x00CD}, "lt", 0), // # LATIN CAPITAL LETTER I WITH ACUTE
	new Entry(0x0128, new char[]{0x0069, 0x0307, 0x0303}, new char[]{0x0128}, "lt", 0), // # LATIN CAPITAL LETTER I WITH TILDE

	//# ================================================================================
	//# Turkish and Azeri
//	new Entry(0x0130, new char[]{0x0069}, new char[]{0x0130}, "tr", 0), // # LATIN CAPITAL LETTER I WITH DOT ABOVE
//	new Entry(0x0130, new char[]{0x0069}, new char[]{0x0130}, "az", 0), // # LATIN CAPITAL LETTER I WITH DOT ABOVE
	new Entry(0x0307, new char[]{}, new char[]{0x0307}, "tr", AFTER_I), // # COMBINING DOT ABOVE
	new Entry(0x0307, new char[]{}, new char[]{0x0307}, "az", AFTER_I), // # COMBINING DOT ABOVE
	new Entry(0x0049, new char[]{0x0131}, new char[]{0x0049}, "tr", NOT_BEFORE_DOT), // # LATIN CAPITAL LETTER I
	new Entry(0x0049, new char[]{0x0131}, new char[]{0x0049}, "az", NOT_BEFORE_DOT), // # LATIN CAPITAL LETTER I
	new Entry(0x0069, new char[]{0x0069}, new char[]{0x0130}, "tr", 0), // # LATIN SMALL LETTER I
	new Entry(0x0069, new char[]{0x0069}, new char[]{0x0130}, "az", 0)  // # LATIN SMALL LETTER I
    };

    // A hash table that contains the above entries
    static Hashtable entryTable = new Hashtable();
    static {
	// create hashtable from the entry
	for (int i = 0; i < entry.length; i ++) {
	    Entry cur = entry[i];
	    Integer cp = new Integer(cur.getCodePoint());
	    HashSet set = (HashSet)entryTable.get(cp);
	    if (set == null) {
		set = new HashSet();
	    }
	    set.add(cur);
	    entryTable.put(cp, set);
	}
    }
	
    static int toLowerCaseEx(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, true);

	if (result != null) {
	    if (result.length == 1) {
		return result[0];
	    } else {
		return Character.CHAR_ERROR;
	    }
	} else {
	    // default to Character class' one
	    return Character.toLowerCase(src.codePointAt(index));
	}
    }

    static int toUpperCaseEx(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, false);

	if (result != null) {
	    if (result.length == 1) {
		return result[0];
	    } else {
		return Character.CHAR_ERROR;
	    }
	} else {
	    // default to Character class' one
	    return Character.toUpperCaseEx(src.codePointAt(index));
	}
    }

    static char[] toLowerCaseCharArray(String src, int index, Locale locale) {
        return lookUpTable(src, index, locale, true);
    }

    static char[] toUpperCaseCharArray(String src, int index, Locale locale) {
        char[] result = lookUpTable(src, index, locale, false);
	if (result != null) {
	    return result;
	} else {
	    return Character.toUpperCaseCharArray(src.codePointAt(index));
	}
    }

    private static char[] lookUpTable(String src, int index, Locale locale, boolean bLowerCasing) {
	HashSet set = (HashSet)entryTable.get(new Integer(src.codePointAt(index)));

	if (set != null) {
	    Iterator iter = set.iterator();
	    String currentLang = locale.getLanguage();
	    while (iter.hasNext()) {
		Entry entry = (Entry)iter.next();
		String conditionLang= entry.getLanguage();
		if (((conditionLang == null) || (conditionLang.equals(currentLang))) &&
			isConditionMet(src, index, locale, entry.getCondition())) {
		    return (bLowerCasing ? entry.getLowerCase() : entry.getUpperCase());
		}
	    }
	}

	return null;
    }

    private static boolean isConditionMet(String src, int index, Locale locale, int condition) {
	switch (condition) {
	case FINAL_CASED:
	    return isFinalCased(src, index, locale);

	case AFTER_SOFT_DOTTED:
	    return isAfterSoftDotted(src, index);

	case MORE_ABOVE:
	    return isMoreAbove(src, index);

	case AFTER_I:
	    return isAfterI(src, index);

	case NOT_BEFORE_DOT:
	    return !isBeforeDot(src, index);

	default:
	    return true;
	}
    }

    /**
     * Implements the "Final_Cased" condition
     *
     * Specification: Within the closest word boundaries containing C, there is a cased
     * letter before C, and there is no cased letter after C.
     *
     * Regular Expression: 
     *   Before C: [{cased==true}][{wordBoundary!=true}]*
     *   After C: !([{wordBoundary!=true}]*[{cased}])
     */
    private static boolean isFinalCased(String src, int index, Locale locale) {
	BreakIterator wordBoundary = BreakIterator.getWordInstance(locale);
	wordBoundary.setText(src);
	int ch;

	// Look for a preceding 'cased' letter
	for (int i = index; (i >= 0) && !wordBoundary.isBoundary(i);
		i -= Character.charCount(ch)) {

	    ch = src.codePointBefore(i);
	    if (isCased(ch)) {

		int len = src.length();
		// Check that there is no 'cased' letter after the index
		for (i = index + Character.charCount(src.codePointAt(index));
			(i < len) && !wordBoundary.isBoundary(i);
			i += Character.charCount(ch)) {

		    ch = src.codePointAt(i);
		    if (isCased(ch)) {
			return false;
		    }
		}

		return true;
	    }
	}

	return false;
    }

    /**
     * Implements the "After_I" condition
     *
     * Specification: The last preceding base character was an uppercase I,
     * and there is no intervening combining character class 230 (ABOVE).
     *
     * Regular Expression: 
     *   Before C: [I]([{cc!=230}&{cc!=0}])*
     */
    private static boolean isAfterI(String src, int index) {
	int ch;
	int cc;

	// Look for the last preceding base character
	for (int i = index; i > 0; i -= Character.charCount(ch)) {

	    ch = src.codePointBefore(i);

	    if (ch == 'I') {
		return true;
	    } else {
		cc = Normalizer.getClass(ch);
		if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
		    return false;
		}
	    }
	}

	return false;
    }

    /**
     * Implements the "After_Soft_Dotted" condition
     *
     * Specification: The last preceding character with combining class
     * of zero before C was Soft_Dotted, and there is no intervening
     * combining character class 230 (ABOVE).
     *
     * Regular Expression: 
     *   Before C: [{Soft_Dotted==true}]([{cc!=230}&{cc!=0}])*
     */
    private static boolean isAfterSoftDotted(String src, int index) {
	int ch;
	int cc;

	// Look for the last preceding character
	for (int i = index; i > 0; i -= Character.charCount(ch)) {

	    ch = src.codePointBefore(i);

	    if (isSoftDotted(ch)) {
		return true;
	    } else {
		cc = Normalizer.getClass(ch);
		if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
		    return false;
		}
	    }
	}

	return false;
    }

    /**
     * Implements the "More_Above" condition
     *
     * Specification: C is followed by one or more characters of combining
     * class 230 (ABOVE) in the combining character sequence.
     *
     * Regular Expression: 
     *   After C: [{cc!=0}]*[{cc==230}]
     */
    private static boolean isMoreAbove(String src, int index) {
	int ch;
	int cc;
	int len = src.length();

	// Look for a following ABOVE combining class character
	for (int i = index + Character.charCount(src.codePointAt(index));
		i < len; i += Character.charCount(ch)) {
	    
	    ch = src.codePointAt(i);
	    cc = Normalizer.getClass(ch);

	    if (cc == COMBINING_CLASS_ABOVE) {
		return true;
	    } else if (cc == 0) {
		return false;
	    }
	}

	return false;
    }

    /**
     * Implements the "Before_Dot" condition
     *
     * Specification: C is followed by <code>U+0307 COMBINING DOT ABOVE</code>.
     * Any sequence of characters with a combining class that is
     * neither 0 nor 230 may intervene between the current character
     * and the combining dot above.
     *
     * Regular Expression: 
     *   After C: ([{cc!=230}&{cc!=0}])*[\u0307]
     */
    private static boolean isBeforeDot(String src, int index) {
	int ch;
	int cc;
	int len = src.length();

	// Look for a following COMBINING DOT ABOVE
	for (int i = index + Character.charCount(src.codePointAt(index));
		i < len; i += Character.charCount(ch)) {
	    
	    ch = src.codePointAt(i);

	    if (ch == '\u0307') {
		return true;
	    } else {
		cc = Normalizer.getClass(ch);
		if ((cc == 0) || (cc == COMBINING_CLASS_ABOVE)) {
		    return false;
		}
	    }
	}

	return false;
    }

    /**
     * Examines whether a character is 'cased'.
     *
     * A character C is defined to be 'cased' if and only if at least one of
     * following are true for C: uppercase==true, or lowercase==true, or 
     * general_category==titlecase_letter.
     * 
     * The uppercase and lowercase property values are specified in the data
     * file DerivedCoreProperties.txt in the Unicode Character Database.
     */
    private static boolean isCased(int ch) {
	int type = Character.getType(ch);
	if (type == Character.LOWERCASE_LETTER ||
		type == Character.UPPERCASE_LETTER ||
		type == Character.TITLECASE_LETTER) {
	    return true;
	} else {
	    // Check for Other_Lowercase and Other_Uppercase
	    //
            if ((ch >= 0x02B0) && (ch <= 0x02B8)) {
		// MODIFIER LETTER SMALL H..MODIFIER LETTER SMALL Y
		return true;
	    } else if ((ch >= 0x02C0) && (ch <= 0x02C1)) {
		// MODIFIER LETTER GLOTTAL STOP..MODIFIER LETTER REVERSED GLOTTAL STOP
		return true;
	    } else if ((ch >= 0x02E0) && (ch <= 0x02E4)) {
		// MODIFIER LETTER SMALL GAMMA..MODIFIER LETTER SMALL REVERSED GLOTTAL STOP
		return true;
	    } else if (ch == 0x0345) {
		// COMBINING GREEK YPOGEGRAMMENI
		return true;
	    } else if (ch == 0x037A) {
		// GREEK YPOGEGRAMMENI
		return true;
	    } else if ((ch >= 0x1D2C) && (ch <= 0x1D61)) {
		// MODIFIER LETTER CAPITAL A..MODIFIER LETTER SMALL CHI
		return true;
	    } else if ((ch >= 0x2160) && (ch <= 0x217F)) {
		// ROMAN NUMERAL ONE..ROMAN NUMERAL ONE THOUSAND
		// SMALL ROMAN NUMERAL ONE..SMALL ROMAN NUMERAL ONE THOUSAND
		return true;
	    } else if ((ch >= 0x24B6) && (ch <= 0x24E9)) {
		// CIRCLED LATIN CAPITAL LETTER A..CIRCLED LATIN CAPITAL LETTER Z
		// CIRCLED LATIN SMALL LETTER A..CIRCLED LATIN SMALL LETTER Z
		return true;
	    } else {
		return false;
	    }
	}
    }

    private static boolean isSoftDotted(int ch) {
	switch (ch) {
	case 0x0069: // Soft_Dotted # L&       LATIN SMALL LETTER I
	case 0x006A: // Soft_Dotted # L&       LATIN SMALL LETTER J
	case 0x012F: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH OGONEK
	case 0x0268: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH STROKE
	case 0x0456: // Soft_Dotted # L&       CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I
	case 0x0458: // Soft_Dotted # L&       CYRILLIC SMALL LETTER JE
	case 0x1D62: // Soft_Dotted # L&       LATIN SUBSCRIPT SMALL LETTER I
	case 0x1E2D: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH TILDE BELOW
	case 0x1ECB: // Soft_Dotted # L&       LATIN SMALL LETTER I WITH DOT BELOW
	case 0x2071: // Soft_Dotted # L&       SUPERSCRIPT LATIN SMALL LETTER I
	    return true;
	default:
	    return false;
	}
    }

    /**
     * An internal class that represents an entry in the Special Casing Properties. 
     */
    static class Entry {
	int ch;
	char [] lower;
	char [] upper;
	String lang;
	int condition;

	Entry(int ch, char[] lower, char[] upper, String lang, int condition) {
	    this.ch = ch;
	    this.lower = lower;
	    this.upper = upper;
	    this.lang = lang;
	    this.condition = condition;
	}

	int getCodePoint() {
	    return ch;
	}

	char[] getLowerCase() {
	    return lower;
	}

	char[] getUpperCase() {
	    return upper;
	}

	String getLanguage() {
	    return lang;
	}
	
	int getCondition() {
	    return condition;
	}
    }
}