package baf.sci;

import java.io.*;

public class InternalResourceIndex extends ResourceIndex {
  int resfilenum, loc;

  /** Creates a new InternalResourceIndex from the given data
   */
  public InternalResourceIndex(int restype, int resnum,
			       int resfilenum, int loc) {
    super(restype, resnum);
    this.resfilenum = resfilenum;
    this.loc = loc;
  }

  /** Crates a new InternalResourceIndex, reading all necessary
   *  data off the input strap as it is stored in an SCI
   *  resource.map file.
   */
  public InternalResourceIndex(InputStream in) throws IOException {
    // Unfortunately, DataInputStream is big-endian and the stream
    // we're reading is little-endian.  We must convert to ints
    // by hand.
    int id = in.read();
    id |= in.read() << 0x08;
    if (id == 0xffff) throw new EOFException();

    restype = Resource.getType(id);
    resnum = Resource.getNum(id);

    loc = in.read();
    loc |= in.read() << 0x08;
    loc |= in.read() << 0x10;
    loc |= in.read() << 0x18;

    resfilenum = loc >> 26;
    loc &= 0x3ffffff;
  }

  public byte[] getArray() throws ResourceNotFoundException {
    try {
      String filename = ""+resfilenum;
      while (filename.length() < 3) filename = '0'+filename;
      filename = "resource."+filename;
      File f = new File(parent.parent.parent.file, filename);
			
      FileInputStream fin = new FileInputStream(f);
      fin.skip(loc);

      BufferedInputStream in = new BufferedInputStream(fin);

      // Read the header
      int readID = readWord(in);
      if (readID != Resource.getID(restype, resnum)) {
	throw new ResourceNotFoundException
	  (restype, resnum, "Index mismatch - "+
	   Resource.getID(restype, resnum) + " != "+readID);
      }
      int compressedsize = readWord(in) - 4;
      int size = readWord(in);
      int algorithm = readWord(in);

      // Read the content
      byte b[] = new byte[size];
      switch (algorithm) {
	case 0: // no compression
	  in.read(b, 0, size);
	  return b;
      default:
	throw new ResourceNotFoundException(restype, resnum,
					    "Unknown compression type "+
					    algorithm );
      }

    } catch (IOException e) {
      throw new ResourceNotFoundException(restype, resnum, e.toString());
    }
  }

  int readWord(InputStream in) throws IOException {
    int word = in.read();
    word |= in.read() << 8;
    return word;
  }

}