// Filename: loader.cxx
// Created by:  mike (09Jan97)
//
////////////////////////////////////////////////////////////////////
//
// 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 "loader.h"
#include "loaderFileType.h"
#include "loaderFileTypeRegistry.h"
#include "config_pgraph.h"
#include "modelPool.h"
#include "config_express.h"
#include "config_util.h"
#include "virtualFileSystem.h"
#include "filename.h"
#include "load_dso.h"
#include "string_utils.h"
#include "bamCache.h"
#include "bamCacheRecord.h"
#include "sceneGraphReducer.h"
#include "renderState.h"
#include "bamFile.h"

bool Loader::_file_types_loaded = false;
TypeHandle Loader::_type_handle;

////////////////////////////////////////////////////////////////////
//     Function: Loader::Constructor
//       Access: Published
//  Description:
////////////////////////////////////////////////////////////////////
Loader::
Loader(const string &name, int num_threads) :
  AsyncTaskManager(name, num_threads)
{
  if (_num_threads < 0) {
    // -1 means the default number of threads.

    ConfigVariableInt loader_num_threads
      ("loader-num-threads", 1,
       PRC_DESC("The number of threads that will be started by the Loader class "
                "to load models asynchronously.  These threads will only be "
                "started if the asynchronous interface is used, and if threading "
                "support is compiled into Panda.  The default is one thread, "
                "which allows models to be loaded one at a time in a single "
                "asychronous thread.  You can set this higher, particularly if "
                "you have many CPU's available, to allow loading multiple models "
                "simultaneously."));

    _num_threads = loader_num_threads;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: Loader::load_bam_stream
//       Access: Published
//  Description: Attempts to read a bam file from the indicated stream
//               and return the scene graph defined there.
////////////////////////////////////////////////////////////////////
PT(PandaNode) Loader::
load_bam_stream(istream &in) {
  BamFile bam_file;
  if (!bam_file.open_read(in)) {
    return NULL;
  }

  return bam_file.read_node();
}

////////////////////////////////////////////////////////////////////
//     Function: Loader::output
//       Access: Published, Virtual
//  Description: 
////////////////////////////////////////////////////////////////////
void Loader::
output(ostream &out) const {
  out << get_type() << " " << get_name();

  if (!_threads.empty()) {
    out << " (" << get_num_tasks() << " models pending)";
  }
}

////////////////////////////////////////////////////////////////////
//     Function: Loader::load_file
//       Access: Private
//  Description: Loads a single scene graph file, if possible.
//               Returns the Node that is the root of the file, or
//               NULL if the file cannot be loaded.
//
//               If search is true, the file is searched for along the
//               model path; otherwise, only the exact filename is
//               loaded.
////////////////////////////////////////////////////////////////////
PT(PandaNode) Loader::
load_file(const Filename &filename, const LoaderOptions &options) const {
  Filename this_filename(filename);
  LoaderOptions this_options(options);

  bool report_errors = (this_options.get_flags() & LoaderOptions::LF_report_errors) != 0;

  string extension = this_filename.get_extension();
  if (extension.empty()) {
    // If the filename has no filename extension, append the default
    // extension specified in the Config file.
    this_filename = this_filename.get_fullpath() + default_model_extension.get_value();
    extension = this_filename.get_extension();
  }

  bool pz_file = false;
#ifdef HAVE_ZLIB
  if (extension == "pz") {
    pz_file = true;
    extension = Filename(this_filename.get_basename_wo_extension()).get_extension();
  }
#endif  // HAVE_ZLIB

  if (extension.empty()) {
    if (report_errors) {
      loader_cat.error()
        << "Cannot load " << this_filename
        << " without filename extension.  Loading of model filenames with an "
        "implicit extension is deprecated in Panda3D.  Please "
        "correct the filename reference.  If necessary, you may put the "
        "line \"default-model-extension .bam\" or \"default-model-extension .egg\" "
        "in your Config.prc to globally assume a particular model "
        "filename extension.\n";
    }
    return NULL;
  }

  LoaderFileTypeRegistry *reg = LoaderFileTypeRegistry::get_global_ptr();
  LoaderFileType *requested_type =
    reg->get_type_from_extension(extension);
  if (requested_type == (LoaderFileType *)NULL) {
    if (report_errors) {
      loader_cat.error()
        << "Extension of file " << this_filename
        << " is unrecognized; cannot load.\n";
      loader_cat.error(false)
        << "Currently known scene file types are:\n";
      reg->write(loader_cat.error(false), 2);
    }
    return NULL;
  } else if (pz_file && !requested_type->supports_compressed()) {
    if (report_errors) {
      loader_cat.error()
        << requested_type->get_name() << " file type (."
        << extension << ") does not support in-line compression.\n";
    }
    return NULL;
  }

  bool search = (this_options.get_flags() & LoaderOptions::LF_search) != 0;
  if (!filename.is_local()) {
    // If we have a global filename, we don't search the model path.
    search = false;
  }

  // Now that we've decided whether to search for the file, don't try
  // to search again.
  this_options.set_flags(this_options.get_flags() & ~LoaderOptions::LF_search);

  VirtualFileSystem *vfs = VirtualFileSystem::get_global_ptr();

  if (search) {
    // Look for the file along the model path.
    int num_dirs = model_path.get_num_directories();
    for (int i = 0; i < num_dirs; ++i) {
      Filename pathname(model_path.get_directory(i), this_filename);
      PT(PandaNode) result = try_load_file(pathname, this_options, 
                                           requested_type);
      if (result != (PandaNode *)NULL) {
        return result;
      }
    }

    if (report_errors) {
      bool any_exist = false;
      for (int i = 0; i < num_dirs; ++i) {
        Filename pathname(model_path.get_directory(i), this_filename);
        if (vfs->exists(pathname)) {
          any_exist = true;
          break;
        }
      }

      if (any_exist) {
        loader_cat.error()
          << "Couldn't load file " << this_filename
          << ": all matching files on model path invalid "
          << "(the model path is currently: \"" << get_model_path() << "\")\n";
      } else {
        loader_cat.error()
          << "Couldn't load file " << this_filename
          << ": not found on model path "
          << "(currently: \"" << get_model_path() << "\")\n";
      }
    }

  } else {
    // Look for the file only where it is.
    VirtualFileSystem *vfs = VirtualFileSystem::get_global_ptr();
    PT(PandaNode) result = try_load_file(this_filename, this_options, requested_type);
    if (result != (PandaNode *)NULL) {
      return result;
    }
    if (report_errors) {
      if (vfs->exists(this_filename)) {
        loader_cat.error()
          << "Couldn't load file " << this_filename << ": invalid.\n";
      } else {
        loader_cat.error()
          << "Couldn't load file " << this_filename << ": does not exist.\n";
      }
    }
  }
  return NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: Loader::try_load_file
//       Access: Private
//  Description: The implementatin of load_file(), this tries a single
//               possible file without searching further along the
//               path.
////////////////////////////////////////////////////////////////////
PT(PandaNode) Loader::
try_load_file(const Filename &pathname, const LoaderOptions &options,
              LoaderFileType *requested_type) const {
  BamCache *cache = BamCache::get_global_ptr();

  bool cache_only = (options.get_flags() & LoaderOptions::LF_cache_only) != 0;

  if (requested_type->get_allow_ram_cache(options)) {
    // If we're allowing a RAM cache, use the ModelPool to load the
    // file.
    if (!cache_only || ModelPool::has_model(pathname)) {
      PT(PandaNode) node = ModelPool::load_model(pathname, options);
      if (node != (PandaNode *)NULL &&
          (options.get_flags() & LoaderOptions::LF_allow_instance) == 0) {
        // But return a deep copy of the shared model.
        node = node->copy_subgraph();
      }
      return node;
    }
  }

  bool report_errors = (options.get_flags() & LoaderOptions::LF_report_errors) != 0;

  PT(BamCacheRecord) record;
  if (cache->get_active() && requested_type->get_allow_disk_cache(options)) {
    // See if the model can be found in the on-disk cache, if it is
    // active.
    record = cache->lookup(pathname, "bam");
    if (record != (BamCacheRecord *)NULL) {
      if (record->has_data()) {
        if (report_errors) {
          loader_cat.info()
            << "Model " << pathname << " found in disk cache.\n";
        }
        PT(PandaNode) result = DCAST(PandaNode, record->extract_data());
        if (premunge_data) {
          SceneGraphReducer sgr;
          sgr.premunge(result, RenderState::make_empty());
        }
        return result;
      }
    }
  }
  
  if (!cache_only) {
    PT(PandaNode) result = requested_type->load_file(pathname, options, record);
    if (result != (PandaNode *)NULL){ 
      if (record != (BamCacheRecord *)NULL) {
        record->set_data(result, false);
        cache->store(record);
      }
      
      if (premunge_data) {
        SceneGraphReducer sgr;
        sgr.premunge(result, RenderState::make_empty());
      }
      return result;
    }
  }

  return NULL;
}


////////////////////////////////////////////////////////////////////
//     Function: Loader::load_file_types
//       Access: Private, Static
//  Description: Loads up all of the dynamic libraries named in a
//               load-file-type Configure variable.  Presumably this
//               will make the various file types available for
//               runtime loading.
////////////////////////////////////////////////////////////////////
void Loader::
load_file_types() {
  if (!_file_types_loaded) {
    int num_unique_values = load_file_type.get_num_unique_values();

    for (int i = 0; i < num_unique_values; i++) {
      string param = load_file_type.get_unique_value(i);

      vector_string words;
      extract_words(param, words);

      if (words.size() == 1) {
        // Exactly one word: load the named library immediately.
        string name = words[0];
        Filename dlname = Filename::dso_filename("lib" + name + ".so");
        loader_cat.info()
          << "loading file type module: " << name << endl;
        void *tmp = load_dso(dlname);
        if (tmp == (void *)NULL) {
          loader_cat.warning()
            << "Unable to load " << dlname.to_os_specific()
            << ": " << load_dso_error() << endl;
        }
        
      } else if (words.size() > 1) {
        // Multiple words: the first n words are filename extensions,
        // and the last word is the name of the library to load should
        // any of those filename extensions be encountered.
        LoaderFileTypeRegistry *registry = LoaderFileTypeRegistry::get_global_ptr();
        size_t num_extensions = words.size() - 1;
        string library_name = words[num_extensions];
        
        for (size_t i = 0; i < num_extensions; i++) {
          string extension = words[i];
          if (extension[0] == '.') {
            extension = extension.substr(1);
          }
          
          registry->register_deferred_type(extension, library_name);
        }
      }
    }

    _file_types_loaded = true;
  }
}

