//===-- Implementation of mbtowc -----------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "src/wchar/mbtowc.h"

#include "hdr/types/size_t.h"
#include "hdr/types/wchar_t.h"
#include "src/__support/common.h"
#include "src/__support/libc_errno.h"
#include "src/__support/macros/config.h"
#include "src/__support/wchar/mbrtowc.h"
#include "src/__support/wchar/mbstate.h"

namespace LIBC_NAMESPACE_DECL {

LLVM_LIBC_FUNCTION(int, mbtowc,
                   (wchar_t *__restrict pwc, const char *__restrict s,
                    size_t n)) {
  // returns 0 since UTF-8 encoding is not state-dependent
  if (s == nullptr)
    return 0;
  internal::mbstate internal_mbstate;
  // temp ptr to use if pwc is nullptr
  wchar_t buf[1];
  auto ret =
      internal::mbrtowc(pwc == nullptr ? buf : pwc, s, n, &internal_mbstate);
  if (!ret.has_value() || static_cast<int>(ret.value()) == -2) {
    // Encoding failure
    libc_errno = EILSEQ;
    return -1;
  }
  return static_cast<int>(ret.value());
}

} // namespace LIBC_NAMESPACE_DECL
