#ifndef WILLOWC_INCLUDE_TOKENIZER_HPP
#define WILLOWC_INCLUDE_TOKENIZER_HPP

#include <willow/IR/Location.h>

namespace willowc {

enum class TokenKind {
  Function,
  Variable,
  Constant,
  Type,
  Label,
  Inst,

  Comma,
  Semicolon,
  LParen,
  RParen,
  LCurly,
  RCurly,
  Equals,
  RArrow,
  Comment,

  FuncKW,
  Eof,
  Invalid,
};

struct Token {
  std::size_t start, end;
  TokenKind kind;
};

class Tokenizer {
  std::string_view buf;
  std::size_t offset;

  void skip(std::size_t idx = 1) { offset += idx; }

  char eat(std::size_t num = 1) {
    if (offset >= buf.length())
      return '\0';

    char c = buf[offset];
    offset += num;
    return c;
  }

  char peek(std::size_t idx = 0) {
    if (offset + idx >= buf.length())
      return '\0';

    return buf[offset + idx];
  }

  bool scan_id(bool accept_digits);
  bool scan_dec();
  bool scan_hex();
  bool scan_constant();
public:
  explicit Tokenizer(std::string_view buf, std::size_t offset = 0)
      : buf{buf}, offset{offset} {}

  Token scan();
  void seek(uint64_t offset);
};

} // namespace willowc

#endif // WILLOWC_INCLUDE_TOKENIZER_HPP