// Streams.cc is a part of the PYTHIA event generator.
// Copyright (C) 2017 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.

// Internal classes to implement gzstream. See header file for user classes.
// Adapted for Sherpa by Frank Siegert from:
// gzstream, C++ iostream classes wrapping the zlib compression library.
// Copyright (C) 2001  Deepak Bandyopadhyay, Lutz Kettner
// (http://www.cs.unc.edu/Research/compgeom/gzstream).
// Further adapted to PYTHIA by Stefan Prestel.

#include "Pythia8/Streams.h"

namespace Pythia8 {

#ifdef GZIPSUPPORT
//==========================================================================

// The gzstreambuf class.

//--------------------------------------------------------------------------

gzstreambuf* gzstreambuf::open( const char* name, int open_mode) {
    if ( is_open())
        return (gzstreambuf*)0;
    mode = open_mode;
    // no append nor read/write mode
    if ((mode & std::ios::ate) || (mode & std::ios::app)
        || ((mode & std::ios::in) && (mode & std::ios::out)))
        return (gzstreambuf*)0;
    char  fmode[10];
    char* fmodeptr = fmode;
    if ( mode & std::ios::in)
        *fmodeptr++ = 'r';
    else if ( mode & std::ios::out)
        *fmodeptr++ = 'w';
    *fmodeptr++ = 'b';
    *fmodeptr = '\0';
    file = gzopen( name, fmode);
    if (file == Z_NULL)
        return (gzstreambuf*)0;
    opened = 1;
    return this;
}

//--------------------------------------------------------------------------

gzstreambuf * gzstreambuf::close() {
    if ( is_open()) {
        sync();
        opened = 0;
        if ( gzclose( file) == Z_OK)
            return this;
    }
    return (gzstreambuf*)0;
}

//--------------------------------------------------------------------------

int gzstreambuf::underflow() { // used for input buffer only
    if ( gptr() && ( gptr() < egptr()))
        return * reinterpret_cast<unsigned char *>( gptr());

    if ( ! (mode & std::ios::in) || ! opened)
        return EOF;
    // Josuttis' implementation of inbuf
    int n_putback = gptr() - eback();
    if ( n_putback > 4)
        n_putback = 4;
    memcpy( buffer + (4 - n_putback), gptr() - n_putback, n_putback);

    int num = gzread( file, buffer+4, bufferSize-4);
    if (num <= 0) // ERROR or EOF
        return EOF;

    // reset buffer pointers
    setg( buffer + (4 - n_putback),   // beginning of putback area
          buffer + 4,                 // read position
          buffer + 4 + num);          // end of buffer

    // return next character
    return * reinterpret_cast<unsigned char *>( gptr());
}

//--------------------------------------------------------------------------

int gzstreambuf::flush_buffer() {
    // Separate the writing of the buffer from overflow() and
    // sync() operation.
    int w = pptr() - pbase();
    if ( gzwrite( file, pbase(), w) != w)
        return EOF;
    pbump( -w);
    return w;
}

//--------------------------------------------------------------------------

int gzstreambuf::overflow( int c) { // used for output buffer only
    if ( ! ( mode & std::ios::out) || ! opened)
        return EOF;
    if (c != EOF) {
        *pptr() = c;
        pbump(1);
    }
    if ( flush_buffer() == EOF)
        return EOF;
    return c;
}

//--------------------------------------------------------------------------

int gzstreambuf::sync() {
    // Changed to use flush_buffer() instead of overflow( EOF)
    // which caused improper behavior with std::endl and flush(),
    // bug reported by Vincent Ricard.
    if ( pptr() && pptr() > pbase()) {
        if ( flush_buffer() == EOF)
            return -1;
    }
    return 0;
}

//==========================================================================

// The gzstreambase class.

//--------------------------------------------------------------------------

gzstreambase::gzstreambase( const char* name, int mode) {
    init( &buf);
    open( name, mode);
}

//--------------------------------------------------------------------------

gzstreambase::~gzstreambase() {
    buf.close();
}

//--------------------------------------------------------------------------

void gzstreambase::open( const char* name, int mode) {
    if ( ! buf.open( name, mode))
        clear( rdstate() | std::ios::badbit);
}

//--------------------------------------------------------------------------

void gzstreambase::close() {
    if ( buf.is_open())
        if ( ! buf.close())
            clear( rdstate() | std::ios::badbit);
}
#endif

//==========================================================================

} // end namespace Pythia8