// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

#pragma once
#include <exception>
#include <stdexcept>
#include <string>
#if _HAS_CXX17
#include <string_view>
#endif

namespace Microsoft::Common::Unicode {

  // All functions in this header offer the strong exception safety guarantee and
  // may throw the following exceptions:
  //   - std::bad_alloc,
  //   - std::overflow_error, and
  //   - UnicodeConversionException (defined below).
  //
  class UnicodeConversionException : public std::runtime_error {
  public:
    UnicodeConversionException(const char* const message, uint32_t errorCode)
      : std::runtime_error(message), m_errorCode(errorCode) {}

    inline uint32_t ErrorCode() const {
      return m_errorCode;
    }

  private:
    // The error code returned by GetLastError().
    uint32_t m_errorCode;
  };

  // The following functions convert UTF-8 strings to UTF-16BE strings.
  //
  // If the input UTF-8 string begins with the UTF-8 Byte Order Mark (BOM) (0xef
  // 0xbb 0xbf), then the output UTF-16BE string will begin with the UTF-16BE BOM
  // (0xfeff). For example, "<UTF-8 BOM>abc" (0xef 0xbb 0xbf 0x61 0x62 0x63) is
  // converted to "<UTF-16BE BOM>abc" (0xfeff 0x0061 0x0062 0x0063).
  //
  // If the input UTF-8 string omits the UTF-8 BOM, then the output UTF-16BE
  // string will also omit the UTF16-BE BOM. For example, "abc" (0x61 0x62 0x63)
  // is converted to "abc" (0x0061 0x0062 0x0063).
  //
  // For (1), utf8 does not have to be null terminated, and utf8Len must reflect
  // the length of utf8, without the null terminator if it has one. The behavior
  // is undefined otherwise.
  //
  // For (2), utf8 must be null terminated. The behavior is undefined otherwise.
  //
  /* (1) */ std::wstring Utf8ToUtf16(const char* utf8, size_t utf8Len);
  /* (2) */ std::wstring Utf8ToUtf16(const char* utf8);
  /* (3) */ std::wstring Utf8ToUtf16(const std::string& utf8);
#if _HAS_CXX17
  /* (4) */ std::wstring Utf8ToUtf16(const std::string_view& utf8);
#endif

  // The following functions convert UTF-16BE strings to UTF-8 strings. Their
  // behaviors mirror those of the above Utf8ToUtf16 functions.
  //
  // For (1) and (2), utf16 does not have to be null terminated, and utf16Len must
  // reflect the length of utf16, without the null terminator if it has one. The
  // behavior is undefined otherwise.
  //
  // For (3) and (4), utf16 must be null terminated. The behavior is undefined
  // otherwise.
  //
  /* (1) */ std::string Utf16ToUtf8(const wchar_t* utf16, size_t utf16Len);
  /* (2) */ std::string Utf16ToUtf8(const char16_t* utf16, size_t utf16Len);
  /* (3) */ std::string Utf16ToUtf8(const wchar_t* utf16);
  /* (4) */ std::string Utf16ToUtf8(const char16_t* utf16);
  /* (5) */ std::string Utf16ToUtf8(const std::wstring& utf16);
  /* (6) */ std::string Utf16ToUtf8(const std::u16string& utf16);
#if _HAS_CXX17
  /* (7) */ std::string Utf16ToUtf8(const std::wstring_view& utf16);
  /* (8) */ std::string Utf16ToUtf8(const std::u16string_view& utf16);
#endif

} // namespace Microsoft::Common::Unicode