// Copyright (C) 2010, Guy Barrand. All rights reserved.
// See the file tools.license for terms.

#ifndef tools_rroot_file
#define tools_rroot_file

#include "ifile"

#include "directory"

#include "../platform"

#include <string>
#include <fcntl.h>
#include <errno.h>

#ifdef _MSC_VER
#include <io.h>
#include <sys/stat.h>
// disable the warning about the usage of "this" in the constructor.
#pragma warning(disable:4355)
#else
#include <unistd.h>
#endif

namespace tools {
namespace rroot {

class file : public virtual ifile {
  static int not_open() {return -1;}
public:
  static const std::string& s_class() {
    static const std::string s_v("tools::rroot::file");
    return s_v;
  }
  virtual const std::string& s_cls() const {return s_class();}
public: //ifile
  virtual const std::string& path() const {return m_path;}

  virtual bool verbose() const {return m_verbose;}
  virtual std::ostream& out() const {return m_out;}

  virtual bool byte_swap() const {return is_little_endian();}
  virtual bool set_pos(seek a_offset = 0,from a_from = begin){
    int whence = 0;
    switch(a_from) {
    case begin:
      whence = SEEK_SET;
      break;
    case current:
      whence = SEEK_CUR;
      break;
    case end:
      whence = SEEK_END;
      break;
    }

#if defined(__linux__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 2)
    if (::lseek64(m_file, a_offset, whence) < 0) {
#elif defined(_MSC_VER)
    if (::_lseeki64(m_file, a_offset, whence) < 0) {
#else
    if (::lseek(m_file, a_offset, whence) < 0) {
#endif
      m_out << "tools::rroot::file::set_pos :"
            << " cannot set position " << a_offset 
            << " in file " << sout(m_path) << "."
            << std::endl;
      return false;
    }
    return true;
  }
  virtual bool read_buffer(char* a_buffer,uint32 a_length) {
    // Read a buffer from the file.
    // This is the basic low level read operation.
#ifdef _MSC_VER
    typedef int ssize_t;
#endif
    ssize_t siz;
    while ((siz = ::read(m_file,a_buffer,a_length)) < 0 && 
           error_number() == EINTR) reset_error_number();
    if (siz < 0) {
      m_out << "tools::rroot::file::read_buffer :"
            << " error reading from file " << sout(m_path) << "."
            << std::endl;
      return false;
    }
    if (siz != ssize_t(a_length)) {
      m_out << "tools::rroot::file::read_buffer :"
            << " error reading all requested bytes from file " 
            << sout(m_path) << ", got " << long_out(siz)
            << " of " << a_length
            << std::endl;
      return false;
    }
    m_bytes_read += siz;
    return true;
  }
  virtual bool unziper(char a_key,decompress_func& a_func) const {
    std::map<char,decompress_func>::const_iterator it = m_unzipers.find(a_key);
    if(it==m_unzipers.end()) {
      a_func = 0;
      return false;
    }
    a_func = (*it).second;
    return true;
  }

  virtual key& sinfos_key() {return m_streamer_info_key;}

public:
  file(std::ostream& a_out,const std::string& a_path,bool a_verbose = false)
  :m_out(a_out)
  ,m_path(a_path)
  ,m_verbose(a_verbose)
  ,m_file(not_open())
  ,m_bytes_read(0)
  ,m_root_directory(*this)
  ,m_streamer_info_key(a_out)
  // begin of record :
  ,m_version(0)
  ,m_BEGIN(0)
  ,m_END(0)
  ,m_seek_free(0)
  ,m_seek_info(0)
  ,m_nbytes_free(0)
  ,m_nbytes_info(0)
  ,m_nbytes_name(0)
  {
#ifdef TOOLS_MEM
    mem::increment(s_class().c_str());
#endif

    m_file = _open(a_path.c_str(),
#ifdef _MSC_VER
                               O_RDONLY | O_BINARY,S_IREAD | S_IWRITE
#else
                               O_RDONLY,0644
#endif
    );
    if(m_file==not_open()) {
      m_out << "tools::rroot::file::file :"
            << " can't open " << sout(a_path) << "."
            << std::endl;
      return;
    }
    initialize();
  }
  virtual ~file() {
    close();
#ifdef TOOLS_MEM
    mem::decrement(s_class().c_str());
#endif
  }
protected:
  file(const file& a_from)
  :ifile(a_from)
  ,m_out(a_from.m_out)
  ,m_root_directory(*this)
  ,m_streamer_info_key(a_from.m_out)
  { 
#ifdef TOOLS_MEM
    mem::increment(s_class().c_str());
#endif
  }
  file& operator=(const file&){return *this;}
public:
  uint32 version() const {return m_version;}

  bool is_open() const {
    return (m_file==not_open()?false:true);
  }

  void close() {
    if(m_file!=not_open()) ::close(m_file);
    m_file = not_open();
    m_root_directory.clear_keys();
  }

  directory& dir() {return m_root_directory;}
  const directory& dir() const {return m_root_directory;}

  bool add_unziper(char a_key,decompress_func a_func){
    std::map<char,decompress_func>::const_iterator it = m_unzipers.find(a_key);
    if(it!=m_unzipers.end()) {
      //(*it).second = a_func; //override ?
      return false;
    } else {
      m_unzipers[a_key] = a_func;
      return true;
    }
  }

protected:
  static int _open(const char* a_name,int a_flags,uint32 a_mode) {
#if defined(__linux__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 2)
     return ::open64(a_name,a_flags,a_mode);
#else
     return ::open(a_name,a_flags,a_mode);
#endif
  }
  static std::string sout(const std::string& a_string) {return "\""+a_string+"\"";}
  bool initialize() {
    if(!read_header()) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read header."
            << std::endl;
      return false;
    }
/*
    fRootDirectory->setSeekDirectory(fBEGIN);
    // Read Free segments structure if file is writable :
    if (fWritable) {
      if (fSeekFree > fBEGIN) {
        if(!readFreeSegments()) {
          m_out << "tools::rroot::file::initialize : Cannot read free segments." 
               << std::endl;
          return false;
        }
      } else {
        m_out << "tools::rroot::file::initialize : file \"" << fName 
             << "\" probably not closed, cannot read free segments" << std::endl;
      }
    }
*/
    // Read Directory info :
    uint32 nbytes = m_nbytes_name + m_root_directory.record_size(m_version);
    char* header = new char[nbytes];
    char* buffer = header;
    if(!set_pos(m_BEGIN)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't set position."
            << std::endl;
      delete [] header;
      return false;
    }
    if(!read_buffer(buffer,nbytes)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read buffer."
            << std::endl;
      delete [] header;
      return false;
    }
    buffer = header+m_nbytes_name;
    const char* eob = header+nbytes;
    if(!m_root_directory.from_buffer(eob,buffer)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read buffer (2)."
            << std::endl;
      delete [] header;
      return false;
    }
    uint32 nk =          //size of Key
      sizeof(int) +      //Key::fNumberOfBytes
      sizeof(short) +    //Key::fVersion
      2*sizeof(int) +    //Key::fObjectSize, Date
      2*sizeof(short) +  //Key::fKeyLength,fCycle
      2*sizeof(seek32);  //Key::fSeekKey,fSeekParentDirectory
                        //WARNING : the upper is seek32 since at begin of file.
    buffer = header+nk;
    std::string cname;
    rbuf rb(m_out,byte_swap(),eob,buffer);
    // Should be "TFile".
    if(!rb.read(cname)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read buffer (3)."
            << std::endl;
      delete [] header;
      return false;
    }
    if(cname!="TFile") {
      m_out << "tools::rroot::file::initialize : TFile expected." << std::endl;
      delete [] header;
      return false;
    }
    if(m_verbose) {
      m_out << "tools::rroot::file::initialize :"
            << " " << sout("TFile") << " found."
            << std::endl;
    }
    if(!rb.read(cname)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read buffer (4)."
            << std::endl;
      delete [] header;
      return false;
    }
    if(m_verbose) {
      m_out << "tools::rroot::file::initialize :"
            << " found file name " << sout(cname)
            << std::endl;
    }
    if(!rb.read(m_title)) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read buffer (5)."
            << std::endl;
      delete [] header;
      return false;
    }
    delete [] header;
    if(m_verbose) {
      m_out << "tools::rroot::file::initialize :"
            << " found title " << sout(m_title)
            << std::endl;
    }
    uint32 dirNbytesName = m_root_directory.nbytes_name();
    if (dirNbytesName < 10 || dirNbytesName > 1000) {
      m_out << "tools::rroot::file::initialize :"
            << " can't read directory info."
            << std::endl;
      return false;
    }
    // Read keys of the top directory :
    if(m_root_directory.seek_keys() > m_BEGIN) {
      uint32 n;
      if(!m_root_directory.read_keys(n)) {
        m_out << "tools::rroot::file::initialize :"
              << " can't read keys."
              << std::endl;
        return false;
      }
    } else {
      m_out << "tools::rroot::file::initialize :"
            << " file " << sout(m_path)
            << " probably not closed."
            << std::endl;
      return false;
    }

    // Create StreamerInfo index
    if(m_seek_info > m_BEGIN) {
      if(!read_streamer_infos()) {
        m_out << "tools::rroot::file::initialize :"
              << " read_streamer_infos() failed."
              << std::endl;
        return false;
      }
    } else {
      m_out << "tools::rroot::file::initialize :"
            << " file " << sout(m_path)
            << " probably not closed."
            << std::endl;
      return false;
    }

    return true;
  }
  bool read_header() {
    static const uint32 kBegin = 64;
    char header[kBegin];
    if(!set_pos()) return false;
    if(!read_buffer(header,kBegin)) return false;
    // make sure this is a root file
    if(::strncmp(header, "root", 4)) {
      m_out << "tools::rroot::file::read_header :"
            << " " << sout(m_path) << " not a file at the CERN-ROOT format."
            << std::endl;
      return false;
    }
    if(m_verbose) {
      m_out << "tools::rroot::file::read_header :"
            << " file signature is " << sout("root")
            << std::endl;
    }
    char* buffer = header + 4;    // skip the "root" file identifier
    const char* eob = header + kBegin;
    rbuf rb(m_out,byte_swap(),eob,buffer);
   {int v;
    if(!rb.read(v)) return false;
    m_version = v;}
   {seek32 i;
    if(!rb.read(i)) return false;
    m_BEGIN = i;}
    if(m_version>1000000) {
      if(!rb.read(m_END)) return false;
      if(!rb.read(m_seek_free)) return false;
    } else {
     {seek32 i;
      if(!rb.read(i)) return false;
      m_END = i;}
     {seek32 i;
      if(!rb.read(i)) return false;
      m_seek_free = i;}
    }
    if(m_verbose) {
      m_out << "tools::rroot::file::read_header :"
            << " begin " << m_BEGIN
            << " end " << m_END
            << std::endl;
    }
   {int v;
    if(!rb.read(v)) return false;
    m_nbytes_free = v;}
    int nfree = 0;
    if(!rb.read(nfree)) return false;
   {int v;
    if(!rb.read(v)) return false;
    m_nbytes_name = v;}
    //m_out << "debug : 1002 " << m_nbytes_name << std::endl;
   {char fUnits;
    if(!rb.read(fUnits)) return false;}
   {int fCompress;
    if(!rb.read(fCompress)) return false;}
    if(m_version>1000000) {
      if(!rb.read(m_seek_info)) return false;
    } else {
     {seek32 i;
      if(!rb.read(i)) return false;
      m_seek_info = i;}
    }
    if(!rb.read(m_nbytes_info)) return false;
    //m_out << "debug : seek_info " << m_seek_info << " nbytes_info " << m_nbytes_info << std::endl;
    return true;
  }

  bool read_streamer_infos() {
    // Read the list of StreamerInfo from this file
    // The key with name holding the list of TStreamerInfo objects is read.
    // The corresponding TClass objects are updated.
    if(m_seek_info<=0) return false;
    if(m_seek_info>=m_END) return false;
    if(!set_pos(m_seek_info)) return false;
    char* buffer = new char[m_nbytes_info+1];
    if(!read_buffer(buffer,m_nbytes_info)) {delete [] buffer;return false;}
    char* buf = buffer;
    if(!m_streamer_info_key.from_buffer(byte_swap(),buffer+m_nbytes_info,buf,m_verbose)) {
      delete [] buffer;
      return false;
    }
    delete [] buffer;
    return true;
  }


#if defined(__sun) && !defined(__linux__) && (__SUNPRO_CC > 0x420)
  int error_number() {return ::errno;}
  void reset_error_number() {::errno = 0;}
#else
  int error_number() {return errno;}
  void reset_error_number() {errno = 0;}
#endif

protected:
  std::ostream& m_out;
  std::string m_path;
  bool m_verbose;
  int m_file;
  tools::uint64 m_bytes_read; //Number of bytes read from this file
  directory m_root_directory;
  key m_streamer_info_key;
  std::map<char,decompress_func> m_unzipers;
  std::string m_title;
  // begin of record :
  uint32 m_version;       //File format version
  seek m_BEGIN;           //First used byte in file
  seek m_END;             //Last used byte in file
  seek m_seek_free;       //Location on disk of free segments structure
  seek m_seek_info;       //Location on disk of StreamerInfo record
  uint32 m_nbytes_free;   //Number of bytes for free segments structure
  uint32 m_nbytes_info;   //Number of bytes for StreamerInfo record
  //int nfree
  uint32 m_nbytes_name;   //Number of bytes in TNamed at creation time
};


}}

#endif

//doc
//
//  A ROOT file is a suite of consecutive data records with the following
//    format (see also the TKey class);
// TKey ---------------------
//      byte 1->4  Nbytes    = Length of compressed object (in bytes)
//           5->6  Version   = TKey version identifier
//           7->10 ObjLen    = Length of uncompressed object
//          11->14 Datime    = Date and time when object was written to file
//          15->16 KeyLen    = Length of the key structure (in bytes)
//          17->18 Cycle     = Cycle of key
//          19->22 SeekKey   = Pointer to record itself (consistency check)
//          23->26 SeekPdir  = Pointer to directory header
//          27->27 lname     = Number of bytes in the class name
//          28->.. ClassName = Object Class Name
//          ..->.. lname     = Number of bytes in the object name
//          ..->.. Name      = lName bytes with the name of the object
//          ..->.. lTitle    = Number of bytes in the object title
//          ..->.. Title     = Title of the object
//          -----> DATA      = Data bytes associated to the object
//
//  The first data record starts at byte fBEGIN (currently set to kBegin)
//  Bytes 1->kBegin contain the file description:
//       byte  1->4  "root"      = Root file identifier
//             5->8  fVersion    = File format version
//             9->12 fBEGIN      = Pointer to first data record
//            13->16 fEND        = Pointer to first free word at the EOF
//            17->20 fSeekFree   = Pointer to FREE data record
//            21->24 fNbytesFree = Number of bytes in FREE data record
//            25->28 nfree       = Number of free data records
//            29->32 fNbytesName = Number of bytes in TNamed at creation time
//            33->33 fUnits      = Number of bytes for file pointers
//            34->37 fCompress   = Zip compression level
//