// hepTupleFileType.cc

#include "HepTuple/hepTupleFileType.h"

#include "HepTuple/HepFileManager.h"
#include "HepTuple/Exceptions.h"
#include "Exceptions/ZMthrow.h"
#include "ZMutility/fstream"


ZM_BEGIN_NAMESPACE( zmht )	/*  namespace zmht  {  */

// -------------------------
// Ways of identifying files:
// --------------------------

bool fileByKey ( std::ifstream & infile , const std::string & key) {
    int keylen = key.length();
    char * c = new char[keylen+1];
    infile.get ( c, keylen+1 );
    return ( std::string (c) == key );
}

bool fileIsRoot ( std::ifstream & infile ) {
    return fileByKey ( infile , "root" );
}

bool fileIsHistoscope ( std::ifstream & infile ) {
    return fileByKey ( infile , "HISTOSCOPE" );
}

bool fileIsHbook ( std::ifstream & infile ) {
    // Not knowing how to identify an Hbook file, we place the test last,
    // and just assume any file that is neither root nor histoscope and
    // that passes our Hbook plausibility test is Hbook.
    char c[17];
    infile.get ( c, 17 );
    for (int i=0;i<16;i++) {
      if ( (c[i] != 0) && ( (i != 7) || (c[i] != 4) ) ) return false;
    }
    return true;
}
  

// -------------------------
// hepTupleFileType 
// --------------------------

HepTupleFileFormat hepTupleFileType (const std::string & name) {

  { 
    std::ifstream in(name.c_str(),std::ios::in );
    if ( (!in) || (!in.good()) ) {
      ZMthrow ( ZMxHepCantOpenFile(name) ); 
      return HEPTUPLE_CANTOPEN;
    }
  }

  // 
  // Detect the file format.  
  //			Since the ifstream goes out of scope after each
  //			instantiation, the file closes after each open.
  //

  { 
    std::ifstream in(name.c_str() );
    if ( fileIsRoot ( in ) ) {
      return HEPTUPLE_ROOT;
    }
  }

  { 
    std::ifstream in(name.c_str() );
    if ( fileIsHistoscope ( in ) ) {
      return HEPTUPLE_HISTOSCOPE;
    }
  }

  
  { // Place test for HBOOK last since we have no positive identification
    std::ifstream in(name.c_str() );
    if ( fileIsHbook ( in ) ) {
      return HEPTUPLE_HBOOK;
    }
  }

  return HEPTUPLE_UNRECOGNIZED;

}

// -------------------------
// hepTupleFileType (manager)
// --------------------------

HepTupleFileFormat hepTupleFileType (const HepFileManager * manager) {
  return manager->hepFileFormat();
}

HepTupleFileFormat hepTupleFileType (const HepFileManager & manager) {
  return manager.hepFileFormat();
}
  
ZM_END_NAMESPACE( zmht )	/*  }  // namespace zmht  */