/*
 *******************************************************************************
 * Copyright (C) 1996-2005, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 */
package com.ibm.icu.text;

import java.io.IOException;

import com.ibm.icu.impl.UCaseProps;

import com.ibm.icu.util.ULocale;

import com.ibm.icu.text.ReplaceableContextIterator;

/**
 * A transliterator that performs locale-sensitive toUpper()
 * case mapping.
 */
class UppercaseTransliterator extends Transliterator {

    /**
     * Package accessible ID.
     */
    static final String _ID = "Any-Upper";
    // TODO: Add variants for tr, az, lt, default = default locale

    /**
     * System registration hook.
     */
    static void register() {
        Transliterator.registerFactory(_ID, new Transliterator.Factory() {
            public Transliterator getInstance(String ID) {
                return new UppercaseTransliterator(ULocale.US);
            }
        });
    }

    private ULocale locale;

    private UCaseProps csp;
    private ReplaceableContextIterator iter;
    private StringBuffer result;
    private int[] locCache;

    /**
     * Constructs a transliterator.
     */
    public UppercaseTransliterator(ULocale loc) {
        super(_ID, null);
        locale = loc;
        try {
            csp=UCaseProps.getSingleton();
        } catch (IOException e) {
            csp=null;
        }
        iter=new ReplaceableContextIterator();
        result = new StringBuffer();
        int[] locCache = new int[1];
        locCache[0]=0;
    }

    /**
     * Implements {@link Transliterator#handleTransliterate}.
     */
    protected void handleTransliterate(Replaceable text,
                                       Position offsets, boolean isIncremental) {
    if(csp==null) {
        return;
    }

    if(offsets.start >= offsets.limit) {
        return;
    } 

    iter.setText(text);
    result.setLength(0);
    int c, delta;

    // Walk through original string
    // If there is a case change, modify corresponding position in replaceable

    iter.setIndex(offsets.start);
    iter.setLimit(offsets.limit);
    iter.setContextLimits(offsets.contextStart, offsets.contextLimit);
    while((c=iter.nextCaseMapCP())>=0) {
        c=csp.toFullUpper(c, iter, result, locale, locCache);

        if(iter.didReachLimit() && isIncremental) {
            // the case mapping function tried to look beyond the context limit
            // wait for more input
            offsets.start=iter.getCaseMapCPStart();
            return;
        }

        /* decode the result */
        if(c<0) {
            /* c mapped to itself, no change */
            continue;
        } else if(c<=UCaseProps.MAX_STRING_LENGTH) {
            /* replace by the mapping string */
            delta=iter.replace(result.toString());
            result.setLength(0);
        } else {
            /* replace by single-code point mapping */
                delta=iter.replace(UTF16.valueOf(c));
            }

            if(delta!=0) {
                offsets.limit += delta;
                offsets.contextLimit += delta;
            }
        }
        offsets.start = offsets.limit;
    }
}