content: /*
   *  Copyright (C) 2010 Ryszard Wiśniewski <brut.alll@gmail.com>
   *  Copyright (C) 2010 Connor Tumbleson <connor.tumbleson@gmail.com>
   *
   *  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
   *
   *       https://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 brut.androlib.res.decoder;
  
  import brut.androlib.res.xml.ResXmlEncoders;
  import brut.util.ExtDataInput;
  import com.google.common.annotations.VisibleForTesting;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.charset.*;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.logging.Logger;
  
  public class StringBlock {
  
      /**
       * Reads whole (including chunk type) string block from stream. Stream must
       * be at the chunk type.
       * @param reader ExtDataInput
       * @return StringBlock
       *
       * @throws IOException Parsing resources.arsc error
       */
      public static StringBlock read(ExtDataInput reader) throws IOException {
          reader.skipCheckChunkTypeInt(CHUNK_STRINGPOOL_TYPE, CHUNK_NULL_TYPE);
          int chunkSize = reader.readInt();
  
          // ResStringPool_header
          int stringCount = reader.readInt();
          int styleCount = reader.readInt();
          int flags = reader.readInt();
          int stringsOffset = reader.readInt();
          int stylesOffset = reader.readInt();
  
          StringBlock block = new StringBlock();
          block.m_isUTF8 = (flags & UTF8_FLAG) != 0;
          block.m_stringOffsets = reader.readIntArray(stringCount);
  
          if (styleCount != 0) {
              block.m_styleOffsets = reader.readIntArray(styleCount);
          }
  
          int size = ((stylesOffset == 0) ? chunkSize : stylesOffset) - stringsOffset;
          block.m_strings = new byte[size];
          reader.readFully(block.m_strings);
  
          if (stylesOffset != 0) {
              size = (chunkSize - stylesOffset);
              block.m_styles = reader.readIntArray(size / 4);
  
              // read remaining bytes
              int remaining = size % 4;
              if (remaining >= 1) {
                  while (remaining-- > 0) {
                      reader.readByte();
                  }
              }
          }
  
          return block;
      }
  
      /**
       * Returns raw string (without any styling information) at specified index.
       * @param index int
       * @return String
       */
      public String getString(int index) {
          if (index < 0 || m_stringOffsets == null || index >= m_stringOffsets.length) {
              return null;
          }
          int offset = m_stringOffsets[index];
          int length;
  
          int[] val;
          if (m_isUTF8) {
              val = getUtf8(m_strings, offset);
              offset = val[0];
          } else {
              val = getUtf16(m_strings, offset);
              offset += val[0];
          }
          length = val[1];
          return decodeString(offset, length);
      }
  
      /**
       * @param index Location (index) of string to process to HTML
       * @return String Returns string with style tags (html-like).
       */
      public String getHTML(int index) {
          String text = getString(index);
          if (text == null) {
              return null;
          }
          int[] style = getStyle(index);
          if (style == null) {
              return ResXmlEncoders.escapeXmlChars(text);
          }
  
          // If the returned style is further in string, than string length. Lets skip it.
          if (style[1] > text.length()) {
              return ResXmlEncoders.escapeXmlChars(text);
          }
  
          // Convert styles to spans
          List<StyledString.Span> spans = new ArrayList<>(style.length / 3);
          for (int i = 0; i < style.length; i += 3) {
              spans.add(new StyledString.Span(getString(style[i]), style[i + 1], style[i + 2]));
          }
          Collections.sort(spans);
  
          StyledString styledString = new StyledString(text, spans);
          return styledString.toString();
      }
  
      /**
       * Finds index of the string. Returns -1 if the string was not found.
       *
       * @param string String to index location of
       * @return int (Returns -1 if not found)
       */
      public int find(String string) {
          if (string == null) {
              return -1;
          }
          for (int i = 0; i != m_stringOffsets.length; ++i) {
              int offset = m_stringOffsets[i];
              int length = getShort(m_strings, offset);
              if (length != string.length()) {
                  continue;
              }
              int j = 0;
              for (; j != length; ++j) {
                  offset += 2;
                  if (string.charAt(j) != getShort(m_strings, offset)) {
                      break;
                  }
              }
              if (j == length) {
                  return i;
              }
          }
          return -1;
      }
  
      private StringBlock() {
      }
  
      @VisibleForTesting
      StringBlock(byte[] strings, boolean isUTF8) {
          m_strings = strings;
          m_isUTF8 = isUTF8;
      }
  
      /**
       * Returns style information - array of int triplets, where in each triplet:
       * * first int is index of tag name ('b','i', etc.) * second int is tag
       * start index in string * third int is tag end index in string
       */
      private int[] getStyle(int index) {
          if (m_styleOffsets == null || m_styles == null|| index >= m_styleOffsets.length) {
              return null;
          }
          int offset = m_styleOffsets[index] / 4;
          int count = 0;
          int[] style;
  
          for (int i = offset; i < m_styles.length; ++i) {
              if (m_styles[i] == -1) {
                  break;
              }
              count += 1;
          }
  
          if (count == 0 || (count % 3) != 0) {
              return null;
          }
          style = new int[count];
  
          for (int i = offset, j = 0; i < m_styles.length;) {
              if (m_styles[i] == -1) {
                  break;
              }
              style[j++] = m_styles[i++];
          }
          return style;
      }
  
      @VisibleForTesting
      String decodeString(int offset, int length) {
          try {
              final ByteBuffer wrappedBuffer = ByteBuffer.wrap(m_strings, offset, length);
              return (m_isUTF8 ? UTF8_DECODER : UTF16LE_DECODER).decode(wrappedBuffer).toString();
          } catch (CharacterCodingException ex) {
              if (!m_isUTF8) {
                  LOGGER.warning("Failed to decode a string at offset " + offset + " of length " + length);
                  return null;
              }
          }
  
          try {
              final ByteBuffer wrappedBufferRetry = ByteBuffer.wrap(m_strings, offset, length);
              // in some places, Android uses 3-byte UTF-8 sequences instead of 4-bytes.
              // If decoding failed, we try to use CESU-8 decoder, which is closer to what Android actually uses.
              return CESU8_DECODER.decode(wrappedBufferRetry).toString();
          } catch (CharacterCodingException e) {
              LOGGER.warning("Failed to decode a string with CESU-8 decoder.");
              return null;
          }
      }
  
      private static int getShort(byte[] array, int offset) {
          return (array[offset + 1] & 0xff) << 8 | array[offset] & 0xff;
      }
  
      private static int[] getUtf8(byte[] array, int offset) {
          int val = array[offset];
          int length;
          // We skip the utf16 length of the string
          if ((val & 0x80) != 0) {
              offset += 2;
          } else {
              offset += 1;
          }
          // And we read only the utf-8 encoded length of the string
          val = array[offset];
          offset += 1;
          if ((val & 0x80) != 0) {
          	int low = (array[offset] & 0xFF);
          	length = ((val & 0x7F) << 8) + low;
              offset += 1;
          } else {
              length = val;
          }
          return new int[] { offset, length};
      }
  
      private static int[] getUtf16(byte[] array, int offset) {
          int val = ((array[offset + 1] & 0xFF) << 8 | array[offset] & 0xFF);
  
          if ((val & 0x8000) != 0) {
              int high = (array[offset + 3] & 0xFF) << 8;
              int low = (array[offset + 2] & 0xFF);
              int len_value =  ((val & 0x7FFF) << 16) + (high + low);
              return new int[] {4, len_value * 2};
  
          }
          return new int[] {2, val * 2};
      }
  
      private int[] m_stringOffsets;
      private byte[] m_strings;
      private int[] m_styleOffsets;
      private int[] m_styles;
      private boolean m_isUTF8;
  
      private final CharsetDecoder UTF16LE_DECODER = StandardCharsets.UTF_16LE.newDecoder();
      private final CharsetDecoder UTF8_DECODER = StandardCharsets.UTF_8.newDecoder();
      private final CharsetDecoder CESU8_DECODER = Charset.forName("CESU8").newDecoder();
      private static final Logger LOGGER = Logger.getLogger(StringBlock.class.getName());
  
      // ResChunk_header = header.type (0x0001) + header.headerSize (0x001C)
      private static final int CHUNK_STRINGPOOL_TYPE = 0x001C0001;
      private static final int CHUNK_NULL_TYPE = 0x00000000;
      private static final int UTF8_FLAG = 0x00000100;
  }
  