#include <stdexcept>

#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#include "common.hh"
#include "util.hh"

MmapFile::MmapFile(std::string fileName)
  : name_(std::move(fileName)), fd_(fopen(name_.c_str(), "rb")), size_(0), base_(nullptr)
{
  if (!fd_)
    throw POSIXException{errno, "Could not open "s + name_};
 
  struct stat statBuf;
  
  if (fstat(fileno(fd_.get()), &statBuf) != 0)
    throw POSIXException(errno, "Could not stat");
  

  if (statBuf.st_size <= 0)
    throw Exception{"File size is zero or less"};

  size_ = static_cast<size_t>(statBuf.st_size);
  
  base_ = mmap(nullptr, size_, PROT_READ, MAP_SHARED, fileno(fd_.get()), 0);
  if (!base_)
    throw POSIXException(errno, "mmap failed");
}

MmapFile::MmapFile(MmapFile && move):
  name_(std::move(move.name_)), fd_(std::move(move.fd_)), size_(move.size_),
  base_(move.base_)
{
  move.base_ = nullptr;
}

MmapFile::~MmapFile()
{
  if (base_) {
    if (munmap(base_, size_) != 0)
      fprintf(stderr, "Warning: munmap failed: %s\n", strerror(errno));
    base_ = nullptr;
  }
}

MmapFile& MmapFile::operator=(MmapFile && move)
{
  fd_ = std::move(move.fd_);
  if (base_)
    if (munmap(base_, size_) != 0)
      fprintf(stderr, "Warning: munmap failed: %s\n", strerror(errno));
  base_ = move.base_;
  move.base_ = nullptr;
  size_ = move.size_;
  name_ = std::move(move.name_);

  return *this;
}

std::string const& MmapFile::name() const
{
  if (!*this)
    throw std::logic_error("name() called on invalid MmapFile");
  return name_;
}

size_t MmapFile::size() const
{
  if (!*this)
    throw std::logic_error("size() called on invalid MmapFile");
  return size_;
}

char const* MmapFile::data() const
{
  if (!*this)
    throw std::logic_error("data() called on invalid MmapFile");
  return static_cast<char const*>(base_);
}

MmapFile::operator bool() const
{
  return base_;
}