'use client';
function wordRegexp(words) {
  return new RegExp("^((" + words.join(")|(") + "))\\b");
}

var singleOperators = /[\^@!\|<>#~\.\*\-\+\\/,=]/;
var doubleOperators = /(<-)|(:=)|(=<)|(>=)|(<=)|(<:)|(>:)|(=:)|(\\=)|(\\=:)|(!!)|(==)|(::)/;
var tripleOperators = /(:::)|(\.\.\.)|(=<:)|(>=:)/;

var middle = ["in", "then", "else", "of", "elseof", "elsecase", "elseif", "catch",
              "finally", "with", "require", "prepare", "import", "export", "define", "do"];
var end = ["end"];

var atoms = wordRegexp(["true", "false", "nil", "unit"]);
var commonKeywords = wordRegexp(["andthen", "at", "attr", "declare", "feat", "from", "lex",
                                 "mod", "div", "mode", "orelse", "parser", "prod", "prop", "scanner", "self", "syn", "token"]);
var openingKeywords = wordRegexp(["local", "proc", "fun", "case", "class", "if", "cond", "or", "dis",
                                  "choice", "not", "thread", "try", "raise", "lock", "for", "suchthat", "meth", "functor"]);
var middleKeywords = wordRegexp(middle);
var endKeywords = wordRegexp(end);

// Tokenizers
function tokenBase(stream, state) {
  if (stream.eatSpace()) {
    return null;
  }

  // Brackets
  if(stream.match(/[{}]/)) {
    return "bracket";
  }

  // Special [] keyword
  if (stream.match('[]')) {
    return "keyword"
  }

  // Operators
  if (stream.match(tripleOperators) || stream.match(doubleOperators)) {
    return "operator";
  }

  // Atoms
  if(stream.match(atoms)) {
    return 'atom';
  }

  // Opening keywords
  var matched = stream.match(openingKeywords);
  if (matched) {
    if (!state.doInCurrentLine)
      state.currentIndent++;
    else
      state.doInCurrentLine = false;

    // Special matching for signatures
    if(matched[0] == "proc" || matched[0] == "fun")
      state.tokenize = tokenFunProc;
    else if(matched[0] == "class")
      state.tokenize = tokenClass;
    else if(matched[0] == "meth")
      state.tokenize = tokenMeth;

    return 'keyword';
  }

  // Middle and other keywords
  if (stream.match(middleKeywords) || stream.match(commonKeywords)) {
    return "keyword"
  }

  // End keywords
  if (stream.match(endKeywords)) {
    state.currentIndent--;
    return 'keyword';
  }

  // Eat the next char for next comparisons
  var ch = stream.next();

  // Strings
  if (ch == '"' || ch == "'") {
    state.tokenize = tokenString(ch);
    return state.tokenize(stream, state);
  }

  // Numbers
  if (/[~\d]/.test(ch)) {
    if (ch == "~") {
      if(! /^[0-9]/.test(stream.peek()))
        return null;
      else if (( stream.next() == "0" && stream.match(/^[xX][0-9a-fA-F]+/)) || stream.match(/^[0-9]*(\.[0-9]+)?([eE][~+]?[0-9]+)?/))
        return "number";
    }

    if ((ch == "0" && stream.match(/^[xX][0-9a-fA-F]+/)) || stream.match(/^[0-9]*(\.[0-9]+)?([eE][~+]?[0-9]+)?/))
      return "number";

    return null;
  }

  // Comments
  if (ch == "%") {
    stream.skipToEnd();
    return 'comment';
  }
  else if (ch == "/") {
    if (stream.eat("*")) {
      state.tokenize = tokenComment;
      return tokenComment(stream, state);
    }
  }

  // Single operators
  if(singleOperators.test(ch)) {
    return "operator";
  }

  // If nothing match, we skip the entire alphanumerical block
  stream.eatWhile(/\w/);

  return "variable";
}

function tokenClass(stream, state) {
  if (stream.eatSpace()) {
    return null;
  }
  stream.match(/([A-Z][A-Za-z0-9_]*)|(`.+`)/);
  state.tokenize = tokenBase;
  return "type"
}

function tokenMeth(stream, state) {
  if (stream.eatSpace()) {
    return null;
  }
  stream.match(/([a-zA-Z][A-Za-z0-9_]*)|(`.+`)/);
  state.tokenize = tokenBase;
  return "def"
}

function tokenFunProc(stream, state) {
  if (stream.eatSpace()) {
    return null;
  }

  if(!state.hasPassedFirstStage && stream.eat("{")) {
    state.hasPassedFirstStage = true;
    return "bracket";
  }
  else if(state.hasPassedFirstStage) {
    stream.match(/([A-Z][A-Za-z0-9_]*)|(`.+`)|\$/);
    state.hasPassedFirstStage = false;
    state.tokenize = tokenBase;
    return "def"
  }
  else {
    state.tokenize = tokenBase;
    return null;
  }
}

function tokenComment(stream, state) {
  var maybeEnd = false, ch;
  while (ch = stream.next()) {
    if (ch == "/" && maybeEnd) {
      state.tokenize = tokenBase;
      break;
    }
    maybeEnd = (ch == "*");
  }
  return "comment";
}

function tokenString(quote) {
  return function (stream, state) {
    var escaped = false, next, end = false;
    while ((next = stream.next()) != null) {
      if (next == quote && !escaped) {
        end = true;
        break;
      }
      escaped = !escaped && next == "\\";
    }
    if (end || !escaped)
      state.tokenize = tokenBase;
    return "string";
  };
}

function buildElectricInputRegEx() {
  // Reindentation should occur on [] or on a match of any of
  // the block closing keywords, at the end of a line.
  var allClosings = middle.concat(end);
  return new RegExp("[\\[\\]]|(" + allClosings.join("|") + ")$");
}

const oz = {
  name: "oz",

  startState: function () {
    return {
      tokenize: tokenBase,
      currentIndent: 0,
      doInCurrentLine: false,
      hasPassedFirstStage: false
    };
  },

  token: function (stream, state) {
    if (stream.sol())
      state.doInCurrentLine = 0;

    return state.tokenize(stream, state);
  },

  indent: function (state, textAfter, cx) {
    var trueText = textAfter.replace(/^\s+|\s+$/g, '');

    if (trueText.match(endKeywords) || trueText.match(middleKeywords) || trueText.match(/(\[])/))
      return cx.unit * (state.currentIndent - 1);

    if (state.currentIndent < 0)
      return 0;

    return state.currentIndent * cx.unit
  },

  languageData: {
    indentOnInut: buildElectricInputRegEx(),
    commentTokens: {line: "%", block: {open: "/*", close: "*/"}}
  }
};

export { oz };
