// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___CHRONO_OSTREAM_H
#define _LIBCPP___CHRONO_OSTREAM_H

#include <__chrono/day.h>
#include <__chrono/duration.h>
#include <__chrono/month.h>
#include <__chrono/statically_widen.h>
#include <__chrono/weekday.h>
#include <__chrono/year.h>
#include <__concepts/same_as.h>
#include <__config>
#include <__format/format_functions.h>
#include <ostream>
#include <ratio>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)

namespace chrono {

// Depending on the type the return is a const _CharT* or a basic_string<_CharT>
template <class _CharT, class _Period>
_LIBCPP_HIDE_FROM_ABI auto __units_suffix() {
  // TODO FMT LWG issue the suffixes are always char and not STATICALLY-WIDEN'ed.
  if constexpr (same_as<typename _Period::type, atto>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "as");
  else if constexpr (same_as<typename _Period::type, femto>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "fs");
  else if constexpr (same_as<typename _Period::type, pico>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "ps");
  else if constexpr (same_as<typename _Period::type, nano>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "ns");
  else if constexpr (same_as<typename _Period::type, micro>)
#  ifndef _LIBCPP_HAS_NO_UNICODE
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "\u00b5s");
#  else
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "us");
#  endif
  else if constexpr (same_as<typename _Period::type, milli>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "ms");
  else if constexpr (same_as<typename _Period::type, centi>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "cs");
  else if constexpr (same_as<typename _Period::type, deci>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "ds");
  else if constexpr (same_as<typename _Period::type, ratio<1>>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "s");
  else if constexpr (same_as<typename _Period::type, deca>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "das");
  else if constexpr (same_as<typename _Period::type, hecto>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "hs");
  else if constexpr (same_as<typename _Period::type, kilo>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "ks");
  else if constexpr (same_as<typename _Period::type, mega>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "Ms");
  else if constexpr (same_as<typename _Period::type, giga>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "Gs");
  else if constexpr (same_as<typename _Period::type, tera>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "Ts");
  else if constexpr (same_as<typename _Period::type, peta>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "Ps");
  else if constexpr (same_as<typename _Period::type, exa>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "Es");
  else if constexpr (same_as<typename _Period::type, ratio<60>>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "min");
  else if constexpr (same_as<typename _Period::type, ratio<3600>>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "h");
  else if constexpr (same_as<typename _Period::type, ratio<86400>>)
    return _LIBCPP_STATICALLY_WIDEN(_CharT, "d");
  else if constexpr (_Period::den == 1)
    return std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "[{}]s"), _Period::num);
  else
    return std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "[{}/{}]s"), _Period::num, _Period::den);
}

template <class _CharT, class _Traits, class _Rep, class _Period>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const duration<_Rep, _Period>& __d) {
  basic_ostringstream<_CharT, _Traits> __s;
  __s.flags(__os.flags());
  __s.imbue(__os.getloc());
  __s.precision(__os.precision());
  __s << __d.count() << chrono::__units_suffix<_CharT, _Period>();
  return __os << __s.str();
}

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const day& __d) {
  return __os
      << (__d.ok()
              ? std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "{:%d}"), __d)
              // Note this error differs from the wording of the Standard. The
              // Standard wording doesn't work well on AIX or Windows. There
              // the formatted day seems to be either modulo 100 or completely
              // omitted. Judging by the wording this is valid.
              // TODO FMT Write a paper of file an LWG issue.
              : std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "{:02} is not a valid day"), static_cast<unsigned>(__d)));
}

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const month& __m) {
  return __os << (__m.ok() ? std::format(__os.getloc(), _LIBCPP_STATICALLY_WIDEN(_CharT, "{:L%b}"), __m)
                           : std::format(__os.getloc(),
                                         _LIBCPP_STATICALLY_WIDEN(_CharT, "{} is not a valid month"),
                                         static_cast<unsigned>(__m))); // TODO FMT Standard mandated locale isn't used.
}

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const year& __y) {
  return __os << (__y.ok() ? std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "{:%Y}"), __y)
                           : std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "{:%Y} is not a valid year"), __y));
}

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const weekday& __wd) {
  return __os << (__wd.ok() ? std::format(__os.getloc(), _LIBCPP_STATICALLY_WIDEN(_CharT, "{:L%a}"), __wd)
                            : std::format(__os.getloc(), // TODO FMT Standard mandated locale isn't used.
                                          _LIBCPP_STATICALLY_WIDEN(_CharT, "{} is not a valid weekday"),
                                          static_cast<unsigned>(__wd.c_encoding())));
}

} // namespace chrono

#endif //if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___CHRONO_OSTREAM_H
