#include <common/mmap.hpp>
#include <common/except.hpp>

bool MemoryMappedFile::open(const String& pathFileName,CreationFlags creationFlags)
{
  if(isOkay())
  {
    close();
  }
  mFD=::open(pathFileName,getFileAccessFromFlags(creationFlags));
  mCreationFlags= creationFlags;
  if(!isOkay())return false;
  struct stat sb;
  if(-1==::fstat(mFD,&sb))
  {
    close();
    return false;
  }
  mFileLength = sb.st_size;
  if(!createMemoryMap())
  {
      close();
      return false;
  }
  return true;
}

bool MemoryMappedFile::createMemoryMap(void)
{
  void *pAddress = ::mmap(NULL,mFileLength,getMemoryMapAccessFromFlags(mCreationFlags),mCreationFlags == CreationFlags::ReadOnly?MAP_PRIVATE:MAP_SHARED,mFD,0);
  if(MAP_FAILED == pAddress)
  {
    return false;
  }
  mlpMappedDataBase = (char *)pAddress;
  mIndex=0;
  return true;
}

void MemoryMappedFile::close()
{
  if(!isOkay())return;
  ::munmap((void*)mlpMappedDataBase, mFileLength);
  ::close(mFD);
  mFD=-1;
  mFileLength=-1;
}

int MemoryMappedFile::getFileAccessFromFlags(CreationFlags creationFlags)const
{
  switch(creationFlags)
  {
    case ReadOnly :
      return O_RDONLY | S_IRUSR ;
    case ReadWrite :
      return O_RDWR | O_CREAT, S_IRUSR | S_IWUSR;
    default :
      throw new Exception("Undefined creation flag");
  }
}

int MemoryMappedFile::getMemoryMapAccessFromFlags(CreationFlags creationFlags)const
{
    switch(creationFlags)
  {
    case ReadOnly :
      return PROT_READ;
    case ReadWrite :
      return PROT_READ | PROT_WRITE;
    default :
      throw new Exception("Undefined creation flag");
  }
}