/**
 * @typedef {Command[]} Script
 * @typedef {Word[]} Command
 * @typedef {object} Word
 * @property {string} text
 */

const InterCommandWhitespace = Peg.Regex(/[^\S\n;]*/y);

const CommentPattern = Peg.Regex(/#.*\n/y);

const PreWordWhitespace = Peg.Regex(/[^\S\n;]*/y);

const BasicWord = Peg.Map(Peg.Regex(/[^\s;]+/y), ([word]) => ({
  text: word,
}));

const WordPattern = Peg.Map(
  Peg.Sequence(PreWordWhitespace, BasicWord),
  ([_, word]) => word
);

/**
 * Parse out a Notcl script into an easier-to-interpret representation.
 * No script is actually executed yet.
 *
 * @param {string} code
 * @returns Script
 */
function parseNotcl(code) {
  /* Preprocess */
  // fold line endings
  code = code.replace(/(?<!\\)((\\\\)*)\\\n/g, "$1");

  /* Parse */
  function nextWord(/* TODO: null/]/" terminator */) {
    // TODO: handle all kinds of brace/substitution stuff
    const [word, nextIndex] = WordPattern(code, 0) ?? [null, 0];
    if (word) {
      code = code.substring(nextIndex);
      return word;
    } else {
      return null;
    }
  }

  function nextCommand(/* TODO: null/]/" terminator */) {
    const command = /** @type {Word[]} */ ([]);
    while (true) {
      // Strip whitespace
      code = code.replace(/^\s*/, "");
      // Strip comments
      if (code[0] == "#") {
        code = code.replace(/^.*\n/, "");
        continue;
      }
      // Strip semicolons
      if (code[0] == ";") {
        code = code.substring(1);
        continue;
      }
      break;
    }

    while (true) {
      const word = nextWord();
      if (word) {
        command.push(word);
        continue;
      }
      break;
    }

    return command;
  }

  /* Loop through commands, with safety check */
  const script = /** @type {Command[]} */ ([]);
  for (let i = 0; i < 1000 && code != ""; i++) {
    script.push(nextCommand());
  }

  return script;
}