content: /*
   * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program 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 for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program. If not, see <http://www.gnu.org/licenses/>.
   */
  
  package net.nullsum.audinaut.util.tags;
  
  import java.io.IOException;
  import java.io.RandomAccessFile;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Locale;
  
  
  class ID3v2File extends Common {
  
      public ID3v2File() {
      }
  
      public HashMap getTags(RandomAccessFile s) throws IOException {
          HashMap tags;
  
          final int v2hdr_len = 10;
          byte[] v2hdr = new byte[v2hdr_len];
  
          // read the whole 10 byte header into memory
          s.seek(0);
          s.read(v2hdr);
  
          int v3len = ((b2be32(v2hdr, 6)));          // total size EXCLUDING the this 10 byte header
          v3len = ((v3len & 0x7f000000) >> 3) | // for some funky reason, this is encoded as 7*4 bits
                  ((v3len & 0x007f0000) >> 2) |
                  ((v3len & 0x00007f00) >> 1) |
                  ((v3len & 0x0000007f));
  
          // debug(">> tag version ID3v2."+id3v);
          // debug(">> LEN= "+v3len+" // "+v3len);
  
          // we should already be at the first frame
          // so we can start the parsing right now
          tags = parse_v3_frames(s, v3len);
          tags.put("_hdrlen", v3len + v2hdr_len);
          return tags;
      }
  
      /* Parses all ID3v2 frames at the current position up until payload_len
       ** bytes were read
       */
      private HashMap parse_v3_frames(RandomAccessFile s, long payload_len) throws IOException {
          HashMap tags = new HashMap();
          byte[] frame = new byte[10]; // a frame header is always 10 bytes
          long bread = 0;            // total amount of read bytes
  
          while (bread < payload_len) {
              bread += s.read(frame);
              String framename = new String(frame, 0, 4);
              int slen = b2be32(frame, 4);
  
              /* Abort on silly sizes */
              if (slen < 1 || slen > 524288)
                  break;
  
              byte[] xpl = new byte[slen];
              bread += s.read(xpl);
  
              if (framename.substring(0, 1).equals("T")) {
                  String[] nmzInfo = normalizeTaginfo(framename, xpl);
  
                  for (int i = 0; i < nmzInfo.length; i += 2) {
                      String oggKey = nmzInfo[i];
                      String decPld = nmzInfo[i + 1];
  
                      if (oggKey.length() > 0 && !tags.containsKey(oggKey)) {
                          addTagEntry(tags, oggKey, decPld);
                      }
                  }
              }
          }
          return tags;
      }
  
      /* Converts ID3v2 sillyframes to OggNames */
      private String[] normalizeTaginfo(String k, byte[] v) {
          String[] rv = new String[]{"", ""};
          HashMap lu = new HashMap<String, String>();
          lu.put("TIT2", "TITLE");
          lu.put("TALB", "ALBUM");
          lu.put("TPE1", "ARTIST");
  
          if (lu.containsKey(k)) {
              /* A normal, known key: translate into Ogg-Frame name */
              rv[0] = (String) lu.get(k);
              rv[1] = getDecodedString(v);
          } else if (k.equals("TXXX")) {
              /* A freestyle field, ieks! */
              String[] txData = getDecodedString(v).split(Character.toString('\0'), 2);
              /* Check if we got replaygain info in key\0value style */
              if (txData.length == 2) {
                  if (txData[0].matches("^(?i)REPLAYGAIN_(ALBUM|TRACK)_GAIN$")) {
                      rv[0] = txData[0].toUpperCase(); /* some tagwriters use lowercase for this */
                      rv[1] = txData[1];
                  } else {
                      // Check for replaygain tags just thrown randomly in field
                      int nextStartIndex;
                      int startName = txData[1].toLowerCase(Locale.US).indexOf("replaygain_");
                      ArrayList<String> parts = new ArrayList<>();
                      while (startName != -1) {
                          int endName = txData[1].indexOf((char) 0, startName);
                          if (endName != -1) {
                              parts.add(txData[1].substring(startName, endName).toUpperCase());
                              int endValue = txData[1].indexOf((char) 0, endName + 1);
                              if (endValue != -1) {
                                  parts.add(txData[1].substring(endName + 1, endValue));
                                  nextStartIndex = endValue + 1;
                              } else {
                                  break;
                              }
                          } else {
                              break;
                          }
  
                          startName = txData[1].toLowerCase(Locale.US).indexOf("replaygain_", nextStartIndex);
                      }
  
                      if (parts.size() > 0) {
                          rv = new String[parts.size()];
                          rv = parts.toArray(rv);
                      }
                  }
              }
          }
  
          return rv;
      }
  
      /* Converts a raw byte-stream text into a java String */
      private String getDecodedString(byte[] raw) {
          int encid = raw[0] & 0xFF;
          int len = raw.length;
          String v = "";
          try {
              int ID3_ENC_LATIN = 0x00;
              int ID3_ENC_UTF8 = 0x03;
              int ID3_ENC_UTF16BE = 0x02;
              int ID3_ENC_UTF16LE = 0x01;
              if (encid == ID3_ENC_LATIN) {
                  v = new String(raw, 1, len - 1, StandardCharsets.ISO_8859_1);
              } else if (encid == ID3_ENC_UTF8) {
                  v = new String(raw, 1, len - 1, StandardCharsets.UTF_8);
              } else if (encid == ID3_ENC_UTF16LE) {
                  v = new String(raw, 3, len - 3, StandardCharsets.UTF_16LE);
              } else if (encid == ID3_ENC_UTF16BE) {
                  v = new String(raw, 3, len - 3, StandardCharsets.UTF_16BE);
              }
          } catch (Exception ignored) {
          }
          return v;
      }
  
  }
  