// Copyright 2022 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef SRC_TEXT_UNICODE_H_
#define SRC_TEXT_UNICODE_H_

#include <cstddef>
#include <cstdint>
#include <ostream>
#include <utility>

namespace tint::text {

/// CodePoint is a unicode code point.
struct CodePoint {
  /// Constructor
  inline CodePoint() = default;

  /// Constructor
  /// @param v the code point value
  inline explicit CodePoint(uint32_t v) : value(v) {}

  /// @returns the code point value
  inline operator uint32_t() const { return value; }

  /// Assignment operator
  /// @param v the new value for the code point
  /// @returns this CodePoint
  inline CodePoint& operator=(uint32_t v) {
    value = v;
    return *this;
  }

  /// @returns true if this CodePoint is in the XID_Start set.
  /// @see https://unicode.org/reports/tr31/
  bool IsXIDStart() const;

  /// @returns true if this CodePoint is in the XID_Continue set.
  /// @see https://unicode.org/reports/tr31/
  bool IsXIDContinue() const;

  /// The code point value
  uint32_t value = 0;
};

/// Writes the CodePoint to the std::ostream.
/// @param out the std::ostream to write to
/// @param codepoint the CodePoint to write
/// @returns out so calls can be chained
std::ostream& operator<<(std::ostream& out, CodePoint codepoint);

namespace utf8 {

/// Decodes the first code point in the utf8 string.
/// @param ptr the pointer to the first byte of the utf8 sequence
/// @param len the maximum number of bytes to read
/// @returns a pair of CodePoint and width in code units (bytes).
///          If the next code point cannot be decoded then returns [0,0].
std::pair<CodePoint, size_t> Decode(const uint8_t* ptr, size_t len);

/// @returns true if all the utf-8 code points in the string are ASCII
/// (code-points 0x00..0x7f).
bool IsASCII(std::string_view);

}  // namespace utf8

}  // namespace tint::text

#endif  // SRC_TEXT_UNICODE_H_