/*
 * Copyright (c) 2009 The openGion Project.
 *
 * Licensed 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 org.opengion.fukurou.mail;

import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;

import org.opengion.fukurou.system.OgRuntimeException ;         // 6.4.2.0 (2016/01/29)

/**
 * 文字関係のｺﾝﾊﾞｰﾀです。
 *
 * @version     4.0
 * @author      Kazuhiko Hasegawa
 * @since       JDK5.0,
 */
final class CharCodeConverter {
        private static final byte[] SJIS_KANA;  // 5.1.9.0 (2010/09/01) public ⇒ private へ変更

        /**
         * ﾃﾞﾌｫﾙﾄｺﾝｽﾄﾗｸﾀｰをprivateにして、
         * ｵﾌﾞｼﾞｪｸﾄの生成をさせないようにする。
         */
        private CharCodeConverter() {
                // 何もありません。(PMD エラー回避)
        }

        static {
                try {
                        // 全角への変換ﾃｰﾌﾞﾙ
                        SJIS_KANA = "。「」、・ヲァィゥェォャュョッーアイウエオカキクケコサシスセソタチツテトナニヌネノハヒフヘホマミムメモヤユヨラリルレロワン゛゜".getBytes("Shift_JIS");
                } catch( final UnsupportedEncodingException ex ) {
                        throw new OgRuntimeException( "CANT HAPPEN",ex );
                }
        }

        /**
         * Shift_JIS ｴﾝｺｰﾃﾞｨﾝｸﾞｽｷｰﾑに基づくﾊﾞｲﾄ列を
         * ISO-2022-JP ｴﾝｺｰﾃﾞｨﾝｸﾞｽｷｰﾑに変換します。
         * ｢半角ｶﾅ｣は対応する全角文字に変換します。
         *
         * @param sjisBytes ｴﾝｺｰﾄﾞするShift_JISﾊﾞｲﾄ配列
         *
         * @return      変換後のISO-2022-JP(JIS)ﾊﾞｲﾄ配列(not null)
         * @og.rtnNotNull
         */
        public static byte[] sjisToJis( final byte[] sjisBytes ) {
                final ByteArrayOutputStream out = new ByteArrayOutputStream();
                boolean nonAscii = false;
                final int len = sjisBytes.length;
                // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
//              for( int i=0; i<len; i++ ) {
                int idx = 0;
                while( idx < len ) {
                        final byte sbt = sjisBytes[idx];
//                      if( sjisBytes[i] >= 0 ) {
                        if( sbt >= 0 ) {                                                        // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                                if( nonAscii ) {
                                        nonAscii = false;
                                        out.write(0x1b);
                                        out.write('(');
                                        out.write('B');
                                }
//                              out.write(sjisBytes[i]);
                                out.write(sbt);                                                 // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                        } else {
                                if( !nonAscii ) {
                                        nonAscii = true;
                                        out.write(0x1b);
                                        out.write('$');
                                        out.write('B');
                                }
//                              final int bt = sjisBytes[i] & 0xff;
                                final int bt = sbt & 0xff;                              // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                                if( bt>=0xa1 && bt<=0xdf ) {
                                        // 半角カナは全角に変換
                                        final int kanaIndex = (bt - 0xA1) * 2;
                                        sjisToJis( out, SJIS_KANA[kanaIndex], SJIS_KANA[kanaIndex+1] );
                                } else {
//                                      i++;
//                                      if( i==len ) { break; }
//                                      sjisToJis( out, sjisBytes[i-1], sjisBytes[i] );
                                        idx++;                                                                  // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                                        if( idx == len ) { break; }                             // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                                        sjisToJis( out, sbt, sjisBytes[idx] );  // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                                }
                        }
                        idx++ ;                 // 8.5.4.2 (2024/01/12) PMD 7.0.0 AvoidReassigningLoopVariables
                }
                if( nonAscii ) {
                        out.write(0x1b);
                        out.write('(');
                        out.write('B');
                }
                return out.toByteArray();
        }

        /**
         * 1文字の2ﾊﾞｲﾄ Shift_JIS ｺｰﾄﾞを JIS ｺｰﾄﾞに変換して書き出します。
         *
         * @param       outStrm 出力するByteArrayOutputStream
         * @param       bhi             変換する上位ﾊﾞｲﾄ
         * @param       blo             変換する下位ﾊﾞｲﾄ
         */
        private static void sjisToJis( final ByteArrayOutputStream outStrm, final byte bhi, final byte blo ) {
                int hi = (bhi << 1) & 0xFF;
                int lo = blo & 0xFF;
                if( lo < 0x9F ) {
                        if( hi<0x3F) { hi += 0x1F; } else { hi -= 0x61; }
                        if( lo>0x7E) { lo -= 0x20; } else { lo -= 0x1F; }
                } else {
                        if( hi<0x3F) { hi += 0x20; } else { hi -= 0x60; }
                        lo -= 0x7E;
                }
                outStrm.write(hi);
                outStrm.write(lo);
        }
}