/**
 * cache for a single square
 *
 * @author ab
 */
package btools.mapaccess;

import java.io.IOException;
import java.io.RandomAccessFile;

import btools.codec.DataBuffers;
import btools.codec.MicroCache;
import btools.codec.MicroCache2;
import btools.codec.TagValueValidator;
import btools.codec.WaypointMatcher;
import btools.util.ByteDataReader;
import btools.util.Crc32;

final class OsmFile
{
  private RandomAccessFile is = null;
  private long fileOffset;

  private int[] posIdx;
  private MicroCache[] microCaches;

  public int lonDegree;
  public int latDegree;

  public String filename;

  private int divisor;
  private int cellsize;
  private int ncaches;
  private int indexsize;

  public OsmFile( PhysicalFile rafile, int lonDegree, int latDegree, DataBuffers dataBuffers ) throws Exception
  {
    this.lonDegree = lonDegree;
    this.latDegree = latDegree;
    int lonMod5 = lonDegree % 5;
    int latMod5 = latDegree % 5;
    int tileIndex = lonMod5 * 5 + latMod5;

    if ( rafile != null )
    {
      divisor = rafile.divisor;

      cellsize = 1000000 / divisor;
      ncaches = divisor * divisor;
      indexsize = ncaches * 4;

      byte[] iobuffer = dataBuffers.iobuffer;
      filename = rafile.fileName;

      long[] index = rafile.fileIndex;
      fileOffset = tileIndex > 0 ? index[tileIndex - 1] : 200L;
      if ( fileOffset == index[tileIndex] )
        return; // empty

      is = rafile.ra;
      posIdx = new int[ncaches];
      microCaches = new MicroCache[ncaches];
      is.seek( fileOffset );
      is.readFully( iobuffer, 0, indexsize );

      if ( rafile.fileHeaderCrcs != null )
      {
        int headerCrc = Crc32.crc( iobuffer, 0, indexsize );
        if ( rafile.fileHeaderCrcs[tileIndex] != headerCrc )
        {
          throw new IOException( "sub index checksum error" );
        }
      }

      ByteDataReader dis = new ByteDataReader( iobuffer );
      for ( int i = 0; i < ncaches; i++ )
      {
        posIdx[i] = dis.readInt();
      }
    }
  }

  public boolean hasData()
  {
    return microCaches != null;
  }

  public MicroCache getMicroCache( int ilon, int ilat )
  {
    int lonIdx = ilon / cellsize;
    int latIdx = ilat / cellsize;
    int subIdx = ( latIdx - divisor * latDegree ) * divisor + ( lonIdx - divisor * lonDegree );
    return microCaches[subIdx];
  }

  public MicroCache createMicroCache( int ilon, int ilat, DataBuffers dataBuffers, TagValueValidator wayValidator, WaypointMatcher waypointMatcher )
      throws Exception
  {
    int lonIdx = ilon / cellsize;
    int latIdx = ilat / cellsize;
    MicroCache segment = createMicroCache( lonIdx, latIdx, dataBuffers, wayValidator, waypointMatcher, true );
    int subIdx = ( latIdx - divisor * latDegree ) * divisor + ( lonIdx - divisor * lonDegree );
    microCaches[subIdx] = segment;
    return segment;
  }

  private int getPosIdx( int idx )
  {
    return idx == -1 ? indexsize : posIdx[idx];
  }

  public int getDataInputForSubIdx( int subIdx, byte[] iobuffer ) throws Exception
  {
    int startPos = getPosIdx( subIdx - 1 );
    int endPos = getPosIdx( subIdx );
    int size = endPos - startPos;
    if ( size > 0 )
    {
      is.seek( fileOffset + startPos );
      if ( size <= iobuffer.length )
      {
        is.readFully( iobuffer, 0, size );
      }
    }
    return size;
  }

  public MicroCache createMicroCache( int lonIdx, int latIdx, DataBuffers dataBuffers, TagValueValidator wayValidator,
      WaypointMatcher waypointMatcher, boolean reallyDecode ) throws Exception
  {
    int subIdx = ( latIdx - divisor * latDegree ) * divisor + ( lonIdx - divisor * lonDegree );

    byte[] ab = dataBuffers.iobuffer;
    int asize = getDataInputForSubIdx( subIdx, ab );

    if ( asize == 0 )
    {
      return MicroCache.emptyCache();
    }
    if ( asize > ab.length )
    {
      ab = new byte[asize];
      asize = getDataInputForSubIdx( subIdx, ab );
      dataBuffers = new DataBuffers( ab );
    }
    // hack: the checksum contains the information
    // which type of microcache we have

    int crcData = Crc32.crc( ab, 0, asize - 4 );
    int crcFooter = new ByteDataReader( ab, asize - 4 ).readInt();
    if ( crcData == crcFooter )
    {
      throw new IOException( "old, unsupported data-format" );
    }
    else if ( ( crcData ^ 2 ) == crcFooter )
    {
      return reallyDecode ? new MicroCache2( dataBuffers, lonIdx, latIdx, divisor, wayValidator, waypointMatcher ) : null;
    }
    throw new IOException( "checkum error" );
  }

  // set this OsmFile to ghost-state:
  long setGhostState()
  {
    long sum = 0;
    int nc = microCaches == null ? 0 : microCaches.length;
    for ( int i = 0; i < nc; i++ )
    {
      MicroCache mc = microCaches[i];
      if ( mc == null )
        continue;
      if ( mc.virgin )
      {
        mc.ghost = true;
        sum += mc.getDataSize();
      }
      else
      {
        microCaches[i] = null;
      }
    }
    return sum;
  }

  long collectAll()
  {
    long deleted = 0;
    int nc = microCaches == null ? 0 : microCaches.length;
    for ( int i = 0; i < nc; i++ )
    {
      MicroCache mc = microCaches[i];
      if ( mc == null )
        continue;
      if ( !mc.ghost )
      {
        deleted += mc.collect( 0 );
      }
    }
    return deleted;
  }

  long cleanGhosts()
  {
    long deleted = 0;
    int nc = microCaches == null ? 0 : microCaches.length;
    for ( int i = 0; i < nc; i++ )
    {
      MicroCache mc = microCaches[i];
      if ( mc == null )
        continue;
      if ( mc.ghost )
      {
        microCaches[i] = null;
      }
    }
    return deleted;
  }

  void cleanNonVirgin()
  {
    int nc = microCaches == null ? 0 : microCaches.length;
    for ( int i = 0; i < nc; i++ )
    {
      MicroCache mc = microCaches[i];
      if ( mc == null )
        continue;
      if ( !mc.virgin )
      {
        microCaches[i] = null;
      }
    }
  }
}