import { ExternalTokenizer } from '@lezer/lr';
import { Keyword, text1, text2, text3 } from './journey.grammar.terms';

import type { InputStream } from '@lezer/lr';

const skipCodePoints = [-1, 9, 10, 13, 32];

const keywords = ['title', 'section'];

const isComment = (input: InputStream) => {
  return input.peek(0) === 37 && input.peek(1) === 37;
};

const shouldSkip = (input: InputStream) => {
  return skipCodePoints.includes(input.next) || isComment(input);
};

export const keywordTokens = new ExternalTokenizer((input) => {
  if (shouldSkip(input)) return;

  let tokens = '';

  while (!skipCodePoints.includes(input.next)) {
    tokens += String.fromCodePoint(input.next);
    input.advance();
  }

  const activeKeyword = keywords.filter((keyword) => {
    if (keyword === tokens) {
      return tokens.toLowerCase().startsWith(keyword);
    }
    return tokens.toLowerCase().startsWith(keyword + ' '); // ensure the keyword isn't used as a token unless there's a space at the end e.g. titleStuff
  });

  if (activeKeyword.length > 0) {
    input.acceptToken(Keyword, activeKeyword[0].length - tokens.length);
    return;
  }
});

export const textTokens1 = new ExternalTokenizer((input) => {
  if (shouldSkip(input)) return;

  while (input.next !== 10 && input.next !== -1) {
    input.advance();
  }

  input.acceptToken(text1);
});

export const textTokens2 = new ExternalTokenizer((input) => {
  if (shouldSkip(input)) return;

  while (input.next !== 58 && input.next !== 10 && input.next !== -1) {
    input.advance();
  }

  input.acceptToken(text2);
});

export const textTokens3 = new ExternalTokenizer((input) => {
  if (shouldSkip(input)) return;

  while (input.next !== 44 && input.next !== 10 && input.next !== -1) {
    input.advance();
  }

  input.acceptToken(text3);
});