#include <tree_sitter/parser.h>
#include <string>
#include <cwctype>

namespace {

using std::wstring;
using std::iswspace;

enum TokenType {
  RAW_STRING_LITERAL,
};

struct Scanner {
  bool scan(TSLexer *lexer, const bool *valid_symbols) {
    while (iswspace(lexer->lookahead)) {
      lexer->advance(lexer, true);
    }

    lexer->result_symbol = RAW_STRING_LITERAL;

    // Raw string literals can start with: R, LR, uR, UR, u8R
    // Consume 'R'
    if (lexer->lookahead == 'L' || lexer->lookahead == 'U') {
      lexer->advance(lexer, false);
      if (lexer->lookahead != 'R') {
        return false;
      }
    } else if (lexer->lookahead == 'u') {
      lexer->advance(lexer, false);
      if (lexer->lookahead == '8') {
        lexer->advance(lexer, false);
        if (lexer->lookahead != 'R') {
          return false;
        }
      } else if (lexer->lookahead != 'R') {
        return false;
      }
    } else if (lexer->lookahead != 'R') {
      return false;
    }
    lexer->advance(lexer, false);

    // Consume '"'
    if (lexer->lookahead != '"') return false;
    lexer->advance(lexer, false);

    // Consume '(', delimiter
    wstring delimiter;
    for (;;) {
      if (lexer->lookahead == 0 || lexer->lookahead == '\\' || iswspace(lexer->lookahead)) {
        return false;
      }
      if (lexer->lookahead == '(') {
        lexer->advance(lexer, false);
        break;
      }
      delimiter += lexer->lookahead;
      lexer->advance(lexer, false);
    }

    // Consume content, delimiter, ')', '"'
    int delimiter_index = -1;
    for (;;) {
      if (lexer->lookahead == 0) return false;

      if (delimiter_index >= 0) {
        if (static_cast<unsigned>(delimiter_index) == delimiter.size()) {
          if (lexer->lookahead == '"') {
            lexer->advance(lexer, false);
            return true;
          } else {
            delimiter_index = -1;
          }
        } else {
          if (lexer->lookahead == delimiter[delimiter_index]) {
            delimiter_index++;
          } else {
            delimiter_index = -1;
          }
        }
      }

      if (delimiter_index == -1 && lexer->lookahead == ')') {
        delimiter_index = 0;
      }

      lexer->advance(lexer, false);
    }
  }
};

}

extern "C" {

void *tree_sitter_cpp_external_scanner_create() {
  return new Scanner();
}

bool tree_sitter_cpp_external_scanner_scan(void *payload, TSLexer *lexer,
                                            const bool *valid_symbols) {
  Scanner *scanner = static_cast<Scanner *>(payload);
  return scanner->scan(lexer, valid_symbols);
}

unsigned tree_sitter_cpp_external_scanner_serialize(void *payload, char *buffer) {
  return 0;
}

void tree_sitter_cpp_external_scanner_deserialize(void *payload, const char *buffer, unsigned length) {
}

void tree_sitter_cpp_external_scanner_destroy(void *payload) {
  Scanner *scanner = static_cast<Scanner *>(payload);
  delete scanner;
}

}