// Filename: bamFile.cxx
// Created by:  drose (02Jul00)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) 2001 - 2004, Disney Enterprises, Inc.  All rights reserved
//
// All use of this software is subject to the terms of the Panda 3d
// Software license.  You should have received a copy of this license
// along with this source code; you will also find a current copy of
// the license at http://etc.cmu.edu/panda3d/docs/license/ .
//
// To contact the maintainers of this program write to
// panda3d-general@lists.sourceforge.net .
//
////////////////////////////////////////////////////////////////////

#include "bamFile.h"
#include "config_pgraph.h"

#include "bam.h"
#include "bamCacheRecord.h"
#include "config_util.h"
#include "bamReader.h"
#include "bamWriter.h"
#include "filename.h"
#include "config_express.h"
#include "virtualFileSystem.h"
#include "dcast.h"

////////////////////////////////////////////////////////////////////
//     Function: BamFile::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
BamFile::
BamFile() {
  _reader = NULL;
  _writer = NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::Destructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
BamFile::
~BamFile() {
  close();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::open_read
//       Access: Public
//  Description: Attempts to open the indicated filename for reading.
//               Returns true if successful, false on error.
////////////////////////////////////////////////////////////////////
bool BamFile::
open_read(const Filename &bam_filename, bool report_errors) {
  close();

  if (!_din.open(bam_filename)) {
    return false;
  }

  loader_cat.info()
    << "Reading " << bam_filename << "\n";

  return continue_open_read(bam_filename, report_errors);
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::open_read
//       Access: Public
//  Description: Attempts to open the indicated stream for reading.
//               The filename is just for information purposes only.
//               Returns true if successful, false on error.
////////////////////////////////////////////////////////////////////
bool BamFile::
open_read(istream &in, const string &bam_filename, bool report_errors) {
  close();

  if (!_din.open(in)) {
    return false;
  }

  return continue_open_read(bam_filename, report_errors);
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::read_object
//       Access: Public
//  Description: Reads and returns the next object from the Bam file,
//               or NULL if the end of the file has been reached, or
//               if there is an error condition.  Use is_eof() to
//               differentiate these two cases.
//
//               The pointers returned by this method will not be
//               valid for use until resolve() is subsequently called.
////////////////////////////////////////////////////////////////////
TypedWritable *BamFile::
read_object() {
  if (_reader == (BamReader *)NULL) {
    return NULL;
  }

  return _reader->read_object();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::is_eof
//       Access: Public
//  Description: Returns true if the reader has reached end-of-file,
//               false otherwise.  This call is only valid after a
//               call to read_object().
////////////////////////////////////////////////////////////////////
bool BamFile::
is_eof() const {
  return _reader != (BamReader *)NULL && _reader->is_eof();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::resolve
//       Access: Public
//  Description: This must be called after one or more objects have
//               been read via calls to read_object() in order to
//               resolve all internal pointer references in the
//               objects read and make all the pointers valid.  It
//               returns true if all objects are successfully
//               resolved, or false if some have not been (in which
//               case you must call resolve() again later).
////////////////////////////////////////////////////////////////////
bool BamFile::
resolve() {
  if (_reader == (BamReader *)NULL) {
    return false;
  }

  return _reader->resolve();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::read_node
//       Access: Public
//  Description: Although the bam file format is general enough to
//               store a list of objects of arbitrary type, bam files
//               on disk usually contain just one object, a PandaNode
//               that is the root of a scene graph.  (Bam files that
//               store other kinds of things are usually given the
//               extension "boo", for "binary other objects", to
//               differentiate them from the normal scene graph type
//               file.)
//
//               This is a convenience method for when you believe you
//               are reading a scene graph bam file.  It reads the one
//               PandaNode and returns it.  It also calls resolve() to
//               fully resolve the object, since we expect this will
//               be the only object in the file.
//
//               If the bam file contains something other than a
//               PandaNode, an error is printed and NULL is returned.
////////////////////////////////////////////////////////////////////
PT(PandaNode) BamFile::
read_node(bool report_errors) {
  PT(PandaNode) result;

  TypedWritable *object = read_object();

  if (object != (TypedWritable *)NULL && 
      object->is_exact_type(BamCacheRecord::get_class_type())) {
    // Here's a special case: if the first object in the file is a
    // BamCacheRecord, it's really a cache data file and not a true
    // bam file; but skip over the cache data record and let the user
    // treat it like an ordinary bam file.
    object = read_object();
  }

  if (object == TypedWritable::Null) {
    if (report_errors) {
      loader_cat.error() << "Bam file " << _bam_filename << " is empty.\n";
    }

  } else if (!object->is_of_type(PandaNode::get_class_type())) {
    if (report_errors) {
      loader_cat.error()
        << "Bam file " << _bam_filename
        << " contains a " << object->get_type() << ", not a PandaNode.\n";
    }

  } else {
    result = DCAST(PandaNode, object);

    if (report_errors) {
      read_object();
      if (!is_eof()) {
        loader_cat.warning()
          << "Ignoring extra objects in " << _bam_filename << "\n";
      }
    }
  }

  if (!resolve()) {
    if (report_errors) {
      loader_cat.error()
        << "Unable to resolve Bam file.\n";
      result = (PandaNode *)NULL;
    }
  }

  return result;
}


////////////////////////////////////////////////////////////////////
//     Function: BamFile::open_write
//       Access: Public
//  Description: Attempts to open the indicated file for writing.  If
//               another file by the same name already exists, it will
//               be silently removed.  Returns true if successful,
//               false otherwise.
////////////////////////////////////////////////////////////////////
bool BamFile::
open_write(const Filename &bam_filename, bool report_errors) {
  close();

  loader_cat.info() << "Writing " << bam_filename << "\n";

  bam_filename.unlink();
  if (!_dout.open(bam_filename)) {
    if (report_errors) {
      loader_cat.error() << "Unable to open " << bam_filename << "\n";
    }
    return false;
  }

  return continue_open_write(bam_filename, report_errors);
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::open_write
//       Access: Public
//  Description: Attempts to open the indicated stream for writing.
//               The filename is just for information purposes only.
//               Returns true if successful, false on error.
////////////////////////////////////////////////////////////////////
bool BamFile::
open_write(ostream &out, const string &bam_filename, bool report_errors) {
  close();

  if (!_dout.open(out)) {
    loader_cat.error() << "Could not write bam: " << bam_filename << "\n";
    return false;
  }

  return continue_open_write(bam_filename, report_errors);
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::write_object
//       Access: Public
//  Description: Writes the indicated object to the Bam file.  Returns
//               true if successful, false on error.
////////////////////////////////////////////////////////////////////
bool BamFile::
write_object(const TypedWritable *object) {
  if (_writer == (BamWriter *)NULL) {
    return false;
  }

  if (!_writer->write_object(object)) {
    close();
    return false;
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::close
//       Access: Public
//  Description: Closes the input or output stream.
////////////////////////////////////////////////////////////////////
void BamFile::
close() {
  if (_reader != (BamReader *)NULL) {
    resolve();
    delete _reader;
    _reader = NULL;
  }
  if (_writer != (BamWriter *)NULL) {
    delete _writer;
    _writer = NULL;
  }
  _din.close();
  _dout.close();
}


////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_file_major_ver
//       Access: Public
//  Description: Returns the major version number of the file
//               currently being read, or the system current major
//               version number if no file is currently open for
//               reading.
////////////////////////////////////////////////////////////////////
int BamFile::
get_file_major_ver() {
  if (_reader == (BamReader *)NULL) {
    return _bam_major_ver;
  }
  return _reader->get_file_major_ver();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_file_minor_ver
//       Access: Public
//  Description: Returns the minor version number of the file
//               currently being read, or the system current minor
//               version number if no file is currently open for
//               reading.
////////////////////////////////////////////////////////////////////
int BamFile::
get_file_minor_ver() {
  if (_reader == (BamReader *)NULL) {
    return _bam_minor_ver;
  }
  return _reader->get_file_minor_ver();
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_file_endian
//       Access: Public
//  Description: Returns the endian preference indicated by the Bam
//               file currently being read or written.
////////////////////////////////////////////////////////////////////
BamEndian BamFile::
get_file_endian() const {
  if (_writer != (BamWriter *)NULL) {
    return _writer->get_file_endian();
  }
  if (_reader != (BamReader *)NULL) {
    return _reader->get_file_endian();
  }

  return bam_endian;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_current_major_ver
//       Access: Public
//  Description: Returns the system current major version number.
//               This is the version number that will be assigned to
//               any generated Bam files.
////////////////////////////////////////////////////////////////////
int BamFile::
get_current_major_ver() {
  return _bam_major_ver;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_current_minor_ver
//       Access: Public
//  Description: Returns the system current minor version number.
//               This is the version number that will be assigned to
//               any generated Bam files.
////////////////////////////////////////////////////////////////////
int BamFile::
get_current_minor_ver() {
  return _bam_minor_ver;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_reader
//       Access: Public
//  Description: Returns the BamReader in charge of performing the
//               read operations.  This will return NULL unless
//               open_read() was called.
////////////////////////////////////////////////////////////////////
BamReader *BamFile::
get_reader() {
  return _reader;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::get_writer
//       Access: Public
//  Description: Returns the BamWriter in charge of performing the
//               write operations.  This will return NULL unless
//               open_write() was called.
////////////////////////////////////////////////////////////////////
BamWriter *BamFile::
get_writer() {
  return _writer;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::continue_open_read
//       Access: Private
//  Description: Reads the header of the recently-opened bam stream
//               and prepares to read the contents of the file.
//               Returns true if successful, false otherwise.
////////////////////////////////////////////////////////////////////
bool BamFile::
continue_open_read(const string &bam_filename, bool report_errors) {
  _bam_filename = bam_filename;

  string head;
  if (!_din.read_header(head, _bam_header.size())) {
    if (report_errors) {
      loader_cat.error() << _bam_filename << " is not a valid BAM file.\n";
    }
    return false;
  }

  if (head != _bam_header) {
    if (report_errors) {
      loader_cat.error() << _bam_filename << " is not a valid BAM file.\n";
    }
    return false;
  }

  _reader = new BamReader(&_din, _bam_filename);
  if (!_reader->init()) {
    close();
    return false;
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: BamFile::continue_open_write
//       Access: Private
//  Description: Writers the header of the recently-opened bam stream
//               and prepares to write the contents of the file.
//               Returns true if successful, false otherwise.
////////////////////////////////////////////////////////////////////
bool BamFile::
continue_open_write(const string &bam_filename, bool report_errors) {
  _bam_filename = bam_filename;

  if (!_dout.write_header(_bam_header)) {
    if (report_errors) {
      loader_cat.error() << "Unable to write to " << _bam_filename << "\n";
    }
    return false;
  }

  _writer = new BamWriter(&_dout, _bam_filename);

  if (!_writer->init()) {
    close();
    return false;
  }

  return true;
}
