'use strict';

function wordObj(words) {
  var res = {};
  for (var i = 0; i < words.length; ++i) res[words[i]] = true;
  return res;
}
var commonAtoms = ["NULL", "NA", "Inf", "NaN", "NA_integer_", "NA_real_", "NA_complex_", "NA_character_", "TRUE", "FALSE"];
var commonBuiltins = ["list", "quote", "bquote", "eval", "return", "call", "parse", "deparse"];
var commonKeywords = ["if", "else", "repeat", "while", "function", "for", "in", "next", "break"];
var commonBlockKeywords = ["if", "else", "repeat", "while", "function", "for"];

var atoms = wordObj(commonAtoms);
var builtins = wordObj(commonBuiltins);
var keywords = wordObj(commonKeywords);
var blockkeywords = wordObj(commonBlockKeywords);
var opChars = /[+\-*\/^<>=!&|~$:]/;
var curPunc;

function tokenBase(stream, state) {
  curPunc = null;
  var ch = stream.next();
  if (ch == "#") {
    stream.skipToEnd();
    return "comment";
  } else if (ch == "0" && stream.eat("x")) {
    stream.eatWhile(/[\da-f]/i);
    return "number";
  } else if (ch == "." && stream.eat(/\d/)) {
    stream.match(/\d*(?:e[+\-]?\d+)?/);
    return "number";
  } else if (/\d/.test(ch)) {
    stream.match(/\d*(?:\.\d+)?(?:e[+\-]\d+)?L?/);
    return "number";
  } else if (ch == "'" || ch == '"') {
    state.tokenize = tokenString(ch);
    return "string";
  } else if (ch == "`") {
    stream.match(/[^`]+`/);
    return "string.special";
  } else if (ch == "." && stream.match(/.[.\d]+/)) {
    return "keyword";
  } else if (/[\w\.]/.test(ch) && ch != "_") {
    stream.eatWhile(/[\w\.]/);
    var word = stream.current();
    if (atoms.propertyIsEnumerable(word)) return "atom";
    if (keywords.propertyIsEnumerable(word)) {
      // Block keywords start new blocks, except 'else if', which only starts
      // one new block for the 'if', no block for the 'else'.
      if (blockkeywords.propertyIsEnumerable(word) &&
          !stream.match(/\s*if(\s+|$)/, false))
        curPunc = "block";
      return "keyword";
    }
    if (builtins.propertyIsEnumerable(word)) return "builtin";
    return "variable";
  } else if (ch == "%") {
    if (stream.skipTo("%")) stream.next();
    return "variableName.special";
  } else if (
    (ch == "<" && stream.eat("-")) ||
      (ch == "<" && stream.match("<-")) ||
      (ch == "-" && stream.match(/>>?/))
  ) {
    return "operator";
  } else if (ch == "=" && state.ctx.argList) {
    return "operator";
  } else if (opChars.test(ch)) {
    if (ch == "$") return "operator";
    stream.eatWhile(opChars);
    return "operator";
  } else if (/[\(\){}\[\];]/.test(ch)) {
    curPunc = ch;
    if (ch == ";") return "punctuation";
    return null;
  } else {
    return null;
  }
}

function tokenString(quote) {
  return function(stream, state) {
    if (stream.eat("\\")) {
      var ch = stream.next();
      if (ch == "x") stream.match(/^[a-f0-9]{2}/i);
      else if ((ch == "u" || ch == "U") && stream.eat("{") && stream.skipTo("}")) stream.next();
      else if (ch == "u") stream.match(/^[a-f0-9]{4}/i);
      else if (ch == "U") stream.match(/^[a-f0-9]{8}/i);
      else if (/[0-7]/.test(ch)) stream.match(/^[0-7]{1,2}/);
      return "string.special";
    } else {
      var next;
      while ((next = stream.next()) != null) {
        if (next == quote) { state.tokenize = tokenBase; break; }
        if (next == "\\") { stream.backUp(1); break; }
      }
      return "string";
    }
  };
}

var ALIGN_YES = 1, ALIGN_NO = 2, BRACELESS = 4;

function push(state, type, stream) {
  state.ctx = {type: type,
               indent: state.indent,
               flags: 0,
               column: stream.column(),
               prev: state.ctx};
}
function setFlag(state, flag) {
  var ctx = state.ctx;
  state.ctx = {type: ctx.type,
               indent: ctx.indent,
               flags: ctx.flags | flag,
               column: ctx.column,
               prev: ctx.prev};
}
function pop(state) {
  state.indent = state.ctx.indent;
  state.ctx = state.ctx.prev;
}

const r = {
  startState: function(indentUnit) {
    return {tokenize: tokenBase,
            ctx: {type: "top",
                  indent: -indentUnit,
                  flags: ALIGN_NO},
            indent: 0,
            afterIdent: false};
  },

  token: function(stream, state) {
    if (stream.sol()) {
      if ((state.ctx.flags & 3) == 0) state.ctx.flags |= ALIGN_NO;
      if (state.ctx.flags & BRACELESS) pop(state);
      state.indent = stream.indentation();
    }
    if (stream.eatSpace()) return null;
    var style = state.tokenize(stream, state);
    if (style != "comment" && (state.ctx.flags & ALIGN_NO) == 0) setFlag(state, ALIGN_YES);

    if ((curPunc == ";" || curPunc == "{" || curPunc == "}") && state.ctx.type == "block") pop(state);
    if (curPunc == "{") push(state, "}", stream);
    else if (curPunc == "(") {
      push(state, ")", stream);
      if (state.afterIdent) state.ctx.argList = true;
    }
    else if (curPunc == "[") push(state, "]", stream);
    else if (curPunc == "block") push(state, "block", stream);
    else if (curPunc == state.ctx.type) pop(state);
    else if (state.ctx.type == "block" && style != "comment") setFlag(state, BRACELESS);
    state.afterIdent = style == "variable" || style == "keyword";
    return style;
  },

  indent: function(state, textAfter, cx) {
    if (state.tokenize != tokenBase) return 0;
    var firstChar = textAfter && textAfter.charAt(0), ctx = state.ctx,
        closing = firstChar == ctx.type;
    if (ctx.flags & BRACELESS) ctx = ctx.prev;
    if (ctx.type == "block") return ctx.indent + (firstChar == "{" ? 0 : cx.unit);
    else if (ctx.flags & ALIGN_YES) return ctx.column + (closing ? 0 : 1);
    else return ctx.indent + (closing ? 0 : cx.unit);
  },

  languageData: {
    wordChars: ".",
    commentTokens: {line: "#"},
    autocomplete: commonAtoms.concat(commonBuiltins, commonKeywords)
  }
};

exports.r = r;
