/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   file Copyright.txt or https://cmake.org/licensing for details.  */
#include "cmDynamicLoader.h"

#include <map>
#include <string>
#include <utility>

class cmDynamicLoaderCache
{
public:
  ~cmDynamicLoaderCache();
  void CacheFile(const char* path, cmsys::DynamicLoader::LibraryHandle /*p*/);
  bool GetCacheFile(const char* path,
                    cmsys::DynamicLoader::LibraryHandle& /*p*/);
  bool FlushCache(const char* path);
  void FlushCache();
  static cmDynamicLoaderCache* GetInstance();

private:
  std::map<std::string, cmsys::DynamicLoader::LibraryHandle> CacheMap;
  static cmDynamicLoaderCache* Instance;
};

cmDynamicLoaderCache* cmDynamicLoaderCache::Instance = nullptr;

cmDynamicLoaderCache::~cmDynamicLoaderCache() = default;

void cmDynamicLoaderCache::CacheFile(const char* path,
                                     cmsys::DynamicLoader::LibraryHandle p)
{
  cmsys::DynamicLoader::LibraryHandle h;
  if (this->GetCacheFile(path, h)) {
    this->FlushCache(path);
  }
  this->CacheMap[path] = p;
}

bool cmDynamicLoaderCache::GetCacheFile(const char* path,
                                        cmsys::DynamicLoader::LibraryHandle& p)
{
  std::map<std::string, cmsys::DynamicLoader::LibraryHandle>::iterator it =
    this->CacheMap.find(path);
  if (it != this->CacheMap.end()) {
    p = it->second;
    return true;
  }
  return false;
}

bool cmDynamicLoaderCache::FlushCache(const char* path)
{
  std::map<std::string, cmsys::DynamicLoader::LibraryHandle>::iterator it =
    this->CacheMap.find(path);
  bool ret = false;
  if (it != this->CacheMap.end()) {
    cmsys::DynamicLoader::CloseLibrary(it->second);
    this->CacheMap.erase(it);
    ret = true;
  }
  return ret;
}

void cmDynamicLoaderCache::FlushCache()
{
  for (auto const& it : this->CacheMap) {
    cmsys::DynamicLoader::CloseLibrary(it.second);
  }
  delete cmDynamicLoaderCache::Instance;
  cmDynamicLoaderCache::Instance = nullptr;
}

cmDynamicLoaderCache* cmDynamicLoaderCache::GetInstance()
{
  if (!cmDynamicLoaderCache::Instance) {
    cmDynamicLoaderCache::Instance = new cmDynamicLoaderCache;
  }
  return cmDynamicLoaderCache::Instance;
}

cmsys::DynamicLoader::LibraryHandle cmDynamicLoader::OpenLibrary(
  const char* libname)
{
  cmsys::DynamicLoader::LibraryHandle lh;
  if (cmDynamicLoaderCache::GetInstance()->GetCacheFile(libname, lh)) {
    return lh;
  }
  lh = cmsys::DynamicLoader::OpenLibrary(libname);
  cmDynamicLoaderCache::GetInstance()->CacheFile(libname, lh);
  return lh;
}

void cmDynamicLoader::FlushCache()
{
  cmDynamicLoaderCache::GetInstance()->FlushCache();
}