/**

 * 以Byte数的方式来实现的LengthFilter

 * @author bvin

 */

public class OneByteInputFilter implements InputFilter{

    private final int mMax;

    public OneByteInputFilter(int mMax) {

        super();

        this.mMax = mMax;

    }

    @Override

    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart,

                    int dend) {

        //int remainLength = dest.length()-(dend-dstart);

        CharSequence placeStart = dest.subSequence(0, dstart);

        CharSequence placeEnd = dest.subSequence(dend, dest.length());

        int placeStartLength = Util.computeLenthByByte(placeStart.toString());

        int placeEndLength = Util.computeLenthByByte(placeEnd.toString());

        int canReplaceSize = mMax-placeStartLength-placeEndLength;

        if (canReplaceSize>0) {

            CharSequence sourceSpan = source.subSequence(start, end);

            int sourceSpanLength = Util.computeLenthByByte(sourceSpan.toString());

            if (sourceSpanLength>=canReplaceSize) {//替换内容长度大于可容纳长度

                String result = fixSplit(sourceSpan.toString(), canReplaceSize, false);

                if (!TextUtils.isEmpty(result)) {

                    return result;

                }else {

                    return "";

                }

            }else {

                return null;

            }

        }else {

            return "";

        }

    }

    private static String fixSplit(String s,int sum,boolean debug){

        int counter = 0;

        String fixString = null;

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

            if (counter>=sum) {

                break;

            }

            int length = (s.charAt(i)+"").getBytes().length;

            if(length>1){

                counter += 2;

                if (counter<=sum) {

                    fixString = s.substring(0, i+1);

                }

            } else if (length==1){

                if (counter<=sum) {

                    fixString = s.substring(0, i+1);

                }

                ++counter;

            }else {//小于1

                continue;

            }

            /*if (counter>=sum) {

                System.out.println("break；"+counter);

                break;

            }else {

                fixString = s.substring(0, i+1);

            }*/

        }

        return fixString;

    }

}