#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64

#include "util/file.hh"

#include "util/exception.hh"

#include <cstdlib>
#include <cstdio>
#include <sstream>
#include <iostream>

#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>

#if defined __MINGW32__
#include <windows.h>
#include <unistd.h>
#warning "The file functions on MinGW have not been tested for file sizes above 2^31 - 1.  Please read https://stackoverflow.com/questions/12539488/determine-64-bit-file-size-in-c-on-mingw-32-bit and fix"
#elif defined(_WIN32) || defined(_WIN64)
#include <windows.h>
#include <io.h>
#include <algorithm>
#include <limits.h>
#include <limits>
#else
#include <unistd.h>
#endif

namespace util {

scoped_fd::~scoped_fd() {
  if (fd_ != -1 && close(fd_)) {
    std::cerr << "Could not close file " << fd_ << std::endl;
    std::abort();
  }
}

scoped_FILE::~scoped_FILE() {
  if (file_ && std::fclose(file_)) {
    std::cerr << "Could not close file " << std::endl;
    std::abort();
  }
}

// Note that ErrnoException records errno before NameFromFD is called.
FDException::FDException(int fd) throw() : fd_(fd), name_guess_(NameFromFD(fd)) {
  *this << "in " << name_guess_ << ' ';
}

FDException::~FDException() throw() {}

EndOfFileException::EndOfFileException() throw() {
  *this << "End of file";
}
EndOfFileException::~EndOfFileException() throw() {}

int OpenReadOrThrow(const char *name) {
  int ret;
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW_IF(-1 == (ret = _open(name, _O_BINARY | _O_RDONLY)), ErrnoException, "while opening " << name);
#else
  UTIL_THROW_IF(-1 == (ret = open(name, O_RDONLY)), ErrnoException, "while opening " << name);
#endif
  return ret;
}

int CreateOrThrow(const char *name) {
  int ret;
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW_IF(-1 == (ret = _open(name, _O_CREAT | _O_TRUNC | _O_RDWR | _O_BINARY, _S_IREAD | _S_IWRITE)), ErrnoException, "while creating " << name);
#else
  UTIL_THROW_IF(-1 == (ret = open(name, O_CREAT | O_TRUNC | O_RDWR, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)), ErrnoException, "while creating " << name);
#endif
  return ret;
}

uint64_t SizeFile(int fd) {
#if defined __MINGW32__
  struct stat sb;
  // Does this handle 64-bit?
  int ret = fstat(fd, &sb);
  if (ret == -1 || (!sb.st_size && !S_ISREG(sb.st_mode))) return kBadSize;
  return sb.st_size;
#elif defined(_WIN32) || defined(_WIN64)
  __int64 ret = _filelengthi64(fd);
  return (ret == -1) ? kBadSize : ret;
#else // Not windows.

#ifdef OS_ANDROID
  struct stat64 sb;
  int ret = fstat64(fd, &sb);
#else
  struct stat sb;
  int ret = fstat(fd, &sb);
#endif
  if (ret == -1 || (!sb.st_size && !S_ISREG(sb.st_mode))) return kBadSize;
  return sb.st_size;
#endif
}

uint64_t SizeOrThrow(int fd) {
  uint64_t ret = SizeFile(fd);
  UTIL_THROW_IF_ARG(ret == kBadSize, FDException, (fd), "Failed to size");
  return ret;
}

void ResizeOrThrow(int fd, uint64_t to) {
#if defined __MINGW32__
    // Does this handle 64-bit?  
    int ret = ftruncate
#elif defined(_WIN32) || defined(_WIN64)
    errno_t ret = _chsize_s
#elif defined(OS_ANDROID)
    int ret = ftruncate64
#else
    int ret = ftruncate
#endif
    (fd, to);
  UTIL_THROW_IF_ARG(ret, FDException, (fd), "while resizing to " << to << " bytes");
}

namespace {
std::size_t GuardLarge(std::size_t size) {
  // The following operating systems have broken read/write/pread/pwrite that
  // only supports up to 2^31.
#if defined(_WIN32) || defined(_WIN64) || defined(__APPLE__) || defined(OS_ANDROID) || defined(__MINGW32__)
  return std::min(static_cast<std::size_t>(static_cast<unsigned>(-1)), size);
#else
  return size;
#endif
}
}

std::size_t PartialRead(int fd, void *to, std::size_t amount) {
#if defined(_WIN32) || defined(_WIN64)
  int ret = _read(fd, to, GuardLarge(amount));
#else
  errno = 0;
  ssize_t ret;
  do {
    ret = read(fd, to, GuardLarge(amount));
  } while (ret == -1 && errno == EINTR);
#endif
  UTIL_THROW_IF_ARG(ret < 0, FDException, (fd), "while reading " << amount << " bytes");
  return static_cast<std::size_t>(ret);
}

void ReadOrThrow(int fd, void *to_void, std::size_t amount) {
  uint8_t *to = static_cast<uint8_t*>(to_void);
  while (amount) {
    std::size_t ret = PartialRead(fd, to, amount);
    UTIL_THROW_IF(ret == 0, EndOfFileException, " in " << NameFromFD(fd) << " but there should be " << amount << " more bytes to read.");
    amount -= ret;
    to += ret;
  }
}

std::size_t ReadOrEOF(int fd, void *to_void, std::size_t amount) {
  uint8_t *to = static_cast<uint8_t*>(to_void);
  std::size_t remaining = amount;
  while (remaining) {
    std::size_t ret = PartialRead(fd, to, remaining);
    if (!ret) return amount - remaining;
    remaining -= ret;
    to += ret;
  }
  return amount;
}

void PReadOrThrow(int fd, void *to_void, std::size_t size, uint64_t off) {
  uint8_t *to = static_cast<uint8_t*>(to_void);
#if defined(_WIN32) || defined(_WIN64)
  UTIL_THROW(Exception, "This pread implementation for windows is broken.  Please send me a patch that does not change the file pointer.  Atomically.  Or send me an implementation of pwrite that is allowed to change the file pointer but can be called concurrently with pread.");
  const std::size_t kMaxDWORD = static_cast<std::size_t>(4294967295UL);
#endif
  for (;size ;) {
#if defined(_WIN32) || defined(_WIN64)
    /* BROKEN: changes file pointer.  Even if you save it and change it back, it won't be safe to use concurrently with write() or read() which lmplz does. */
    // size_t might be 64-bit.  DWORD is always 32.
    DWORD reading = static_cast<DWORD>(std::min<std::size_t>(kMaxDWORD, size));
    DWORD ret;
    OVERLAPPED overlapped;
    memset(&overlapped, 0, sizeof(OVERLAPPED));
    overlapped.Offset = static_cast<DWORD>(off);
    overlapped.OffsetHigh = static_cast<DWORD>(off >> 32);
    UTIL_THROW_IF(!ReadFile((HANDLE)_get_osfhandle(fd), to, reading, &ret, &overlapped), Exception, "ReadFile failed for offset " << off);
#else
    ssize_t ret;
    errno = 0;
    do {
      ret =
#ifdef OS_ANDROID
        pread64
#else
        pread
#endif
        (fd, to, GuardLarge(size), off);
    } while (ret == -1 && errno == EINTR);
    if (ret <= 0) {
      UTIL_THROW_IF(ret == 0, EndOfFileException, " for reading " << size << " bytes at " << off << " from " << NameFromFD(fd));
      UTIL_THROW_ARG(FDException, (fd), "while reading " << size << " bytes at offset " << off);
    }
#endif
    size -= ret;
    off += ret;
    to += ret;
  }
}

void WriteOrThrow(int fd, const void *data_void, std::size_t size) {
  const uint8_t *data = static_cast<const uint8_t*>(data_void);
  while (size) {
#if defined(_WIN32) || defined(_WIN64)
    int ret;
#else
    ssize_t ret;
#endif
    errno = 0;
    do {
      ret =
#if defined(_WIN32) || defined(_WIN64)
        _write
#else
        write
#endif
        (fd, data, GuardLarge(size));
    } while (ret == -1 && errno == EINTR);
    UTIL_THROW_IF_ARG(ret < 1, FDException, (fd), "while writing " << size << " bytes");
    data += ret;
    size -= ret;
  }
}

void WriteOrThrow(FILE *to, const void *data, std::size_t size) {
  if (!size) return;
  UTIL_THROW_IF(1 != std::fwrite(data, size, 1, to), ErrnoException, "Short write; requested size " << size);
}

void FSyncOrThrow(int fd) {
// Apparently windows doesn't have fsync?
#if !defined(_WIN32) && !defined(_WIN64)
  UTIL_THROW_IF_ARG(-1 == fsync(fd), FDException, (fd), "while syncing");
#endif
}

namespace {

// Static assert for 64-bit off_t size.
#if !defined(_WIN32) && !defined(_WIN64) && !defined(OS_ANDROID)
template <unsigned> struct CheckOffT;
template <> struct CheckOffT<8> {
  struct True {};
};
// If there's a compiler error on the next line, then off_t isn't 64 bit.  And
// that makes me a sad panda.
typedef CheckOffT<sizeof(off_t)>::True IgnoredType;
#endif

// Can't we all just get along?
void InternalSeek(int fd, int64_t off, int whence) {
  if (
#if defined __MINGW32__
    // Does this handle 64-bit?
    (off_t)-1 == lseek(fd, off, whence)
#elif defined(_WIN32) || defined(_WIN64)
    (__int64)-1 == _lseeki64(fd, off, whence)
#elif defined(OS_ANDROID)
    (off64_t)-1 == lseek64(fd, off, whence)
#else
    (off_t)-1 == lseek(fd, off, whence)
#endif
  ) UTIL_THROW_ARG(FDException, (fd), "while seeking to " << off << " whence " << whence);
}
} // namespace

void SeekOrThrow(int fd, uint64_t off) {
  InternalSeek(fd, off, SEEK_SET);
}

void AdvanceOrThrow(int fd, int64_t off) {
  InternalSeek(fd, off, SEEK_CUR);
}

void SeekEnd(int fd) {
  InternalSeek(fd, 0, SEEK_END);
}

std::FILE *FDOpenOrThrow(scoped_fd &file) {
  std::FILE *ret = fdopen(file.get(), "r+b");
  UTIL_THROW_IF_ARG(!ret, FDException, (file.get()), "Could not fdopen for write");
  file.release();
  return ret;
}

std::FILE *FDOpenReadOrThrow(scoped_fd &file) {
  std::FILE *ret = fdopen(file.get(), "rb");
  UTIL_THROW_IF_ARG(!ret, FDException, (file.get()), "Could not fdopen for read");
  file.release();
  return ret;
}

// Sigh.  Windows temporary file creation is full of race conditions.
#if defined(_WIN32) || defined(_WIN64)
/* mkstemp extracted from libc/sysdeps/posix/tempname.c.  Copyright
   (C) 1991-1999, 2000, 2001, 2006 Free Software Foundation, Inc.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.  */

/* This has been modified from the original version to rename the function and
 * set the Windows temporary flag. */

static const char letters[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

/* Generate a temporary file name based on TMPL.  TMPL must match the
   rules for mk[s]temp (i.e. end in "XXXXXX").  The name constructed
   does not exist at the time of the call to mkstemp.  TMPL is
   overwritten with the result.  */
int
mkstemp_and_unlink(char *tmpl)
{
  int len;
  char *XXXXXX;
  static unsigned long long value;
  unsigned long long random_time_bits;
  unsigned int count;
  int fd = -1;
  int save_errno = errno;

  /* A lower bound on the number of temporary files to attempt to
     generate.  The maximum total number of temporary file names that
     can exist for a given template is 62**6.  It should never be
     necessary to try all these combinations.  Instead if a reasonable
     number of names is tried (we define reasonable as 62**3) fail to
     give the system administrator the chance to remove the problems.  */
#define ATTEMPTS_MIN (62 * 62 * 62)

  /* The number of times to attempt to generate a temporary file.  To
     conform to POSIX, this must be no smaller than TMP_MAX.  */
#if ATTEMPTS_MIN < TMP_MAX
  unsigned int attempts = TMP_MAX;
#else
  unsigned int attempts = ATTEMPTS_MIN;
#endif

  len = strlen (tmpl);
  if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
    {
      errno = EINVAL;
      return -1;
    }

/* This is where the Xs start.  */
  XXXXXX = &tmpl[len - 6];

  /* Get some more or less random data.  */
  {
    SYSTEMTIME      stNow;
    FILETIME ftNow;

    // get system time
    GetSystemTime(&stNow);
    stNow.wMilliseconds = 500;
    if (!SystemTimeToFileTime(&stNow, &ftNow))
    {
        errno = -1;
        return -1;
    }

    random_time_bits = (((unsigned long long)ftNow.dwHighDateTime << 32)
                        | (unsigned long long)ftNow.dwLowDateTime);
  }
  value += random_time_bits ^ (unsigned long long)GetCurrentThreadId ();

  for (count = 0; count < attempts; value += 7777, ++count)
  {
    unsigned long long v = value;

    /* Fill in the random bits.  */
    XXXXXX[0] = letters[v % 62];
    v /= 62;
    XXXXXX[1] = letters[v % 62];
    v /= 62;
    XXXXXX[2] = letters[v % 62];
    v /= 62;
    XXXXXX[3] = letters[v % 62];
    v /= 62;
    XXXXXX[4] = letters[v % 62];
    v /= 62;
    XXXXXX[5] = letters[v % 62];

    /* Modified for windows and to unlink */
    //      fd = open (tmpl, O_RDWR | O_CREAT | O_EXCL, _S_IREAD | _S_IWRITE);
    int flags = _O_RDWR | _O_CREAT | _O_EXCL | _O_BINARY;
    flags |= _O_TEMPORARY;
    fd = _open (tmpl, flags, _S_IREAD | _S_IWRITE);
    if (fd >= 0)
    {
      errno = save_errno;
      return fd;
    }
    else if (errno != EEXIST)
      return -1;
  }

  /* We got out of the loop because we ran out of combinations to try.  */
  errno = EEXIST;
  return -1;
}
#else
int
mkstemp_and_unlink(char *tmpl) {
  int ret = mkstemp(tmpl);
  if (ret != -1) {
    UTIL_THROW_IF(unlink(tmpl), ErrnoException, "while deleting delete " << tmpl);
  }
  return ret;
}
#endif

// If it's a directory, add a /.  This lets users say -T /tmp without creating
// /tmpAAAAAA
void NormalizeTempPrefix(std::string &base) {
  if (base.empty()) return;
  if (base[base.size() - 1] == '/') return;
  struct stat sb;
  // It's fine for it to not exist.
  if (-1 == stat(base.c_str(), &sb)) return;
  if (
#if defined(_WIN32) || defined(_WIN64)
    sb.st_mode & _S_IFDIR
#else
    S_ISDIR(sb.st_mode)
#endif
    ) base += '/';
}

int MakeTemp(const std::string &base) {
  std::string name(base);
  name += "XXXXXX";
  name.push_back(0);
  int ret;
  UTIL_THROW_IF(-1 == (ret = mkstemp_and_unlink(&name[0])), ErrnoException, "while making a temporary based on " << base);
  return ret;
}

std::FILE *FMakeTemp(const std::string &base) {
  util::scoped_fd file(MakeTemp(base));
  return FDOpenOrThrow(file);
}

int DupOrThrow(int fd) {
  int ret = dup(fd);
  UTIL_THROW_IF_ARG(ret == -1, FDException, (fd), "in duplicating the file descriptor");
  return ret;
}

namespace {
// Try to name things but be willing to fail too.
bool TryName(int fd, std::string &out) {
#if defined(_WIN32) || defined(_WIN64)
  return false;
#else
  std::string name("/proc/self/fd/");
  std::ostringstream convert;
  convert << fd;
  name += convert.str();

  struct stat sb;
  if (-1 == lstat(name.c_str(), &sb))
    return false;
  out.resize(sb.st_size + 1);
  ssize_t ret = readlink(name.c_str(), &out[0], sb.st_size + 1);
  if (-1 == ret)
    return false;
  if (ret > sb.st_size) {
    // Increased in size?!
    return false;
  }
  out.resize(ret);
  // Don't use the non-file names.
  if (!out.empty() && out[0] != '/')
    return false;
  return true;
#endif
}
} // namespace

std::string NameFromFD(int fd) {
  std::string ret;
  if (TryName(fd, ret)) return ret;
  switch (fd) {
    case 0: return "stdin";
    case 1: return "stdout";
    case 2: return "stderr";
  }
  ret = "fd ";
  std::ostringstream convert;
  convert << fd;
  ret += convert.str();
  return ret;
}

} // namespace util