'use strict';

var curPunc;

function wordRegexp(words) {
  return new RegExp("^(?:" + words.join("|") + ")$", "i");
}
wordRegexp([]);
var keywords = wordRegexp(["@prefix", "@base", "a"]);
var operatorChars = /[*+\-<>=&|]/;

function tokenBase(stream, state) {
  var ch = stream.next();
  curPunc = null;
  if (ch == "<" && !stream.match(/^[\s\u00a0=]/, false)) {
    stream.match(/^[^\s\u00a0>]*>?/);
    return "atom";
  }
  else if (ch == "\"" || ch == "'") {
    state.tokenize = tokenLiteral(ch);
    return state.tokenize(stream, state);
  }
  else if (/[{}\(\),\.;\[\]]/.test(ch)) {
    curPunc = ch;
    return null;
  }
  else if (ch == "#") {
    stream.skipToEnd();
    return "comment";
  }
  else if (operatorChars.test(ch)) {
    stream.eatWhile(operatorChars);
    return null;
  }
  else if (ch == ":") {
    return "operator";
  } else {
    stream.eatWhile(/[_\w\d]/);
    if(stream.peek() == ":") {
      return "variableName.special";
    } else {
      var word = stream.current();

      if(keywords.test(word)) {
        return "meta";
      }

      if(ch >= "A" && ch <= "Z") {
        return "comment";
      } else {
        return "keyword";
      }
    }
    var word = stream.current();
  }
}

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

function pushContext(state, type, col) {
  state.context = {prev: state.context, indent: state.indent, col: col, type: type};
}
function popContext(state) {
  state.indent = state.context.indent;
  state.context = state.context.prev;
}

const turtle = {
  startState: function() {
    return {tokenize: tokenBase,
            context: null,
            indent: 0,
            col: 0};
  },

  token: function(stream, state) {
    if (stream.sol()) {
      if (state.context && state.context.align == null) state.context.align = false;
      state.indent = stream.indentation();
    }
    if (stream.eatSpace()) return null;
    var style = state.tokenize(stream, state);

    if (style != "comment" && state.context && state.context.align == null && state.context.type != "pattern") {
      state.context.align = true;
    }

    if (curPunc == "(") pushContext(state, ")", stream.column());
    else if (curPunc == "[") pushContext(state, "]", stream.column());
    else if (curPunc == "{") pushContext(state, "}", stream.column());
    else if (/[\]\}\)]/.test(curPunc)) {
      while (state.context && state.context.type == "pattern") popContext(state);
      if (state.context && curPunc == state.context.type) popContext(state);
    }
    else if (curPunc == "." && state.context && state.context.type == "pattern") popContext(state);
    else if (/atom|string|variable/.test(style) && state.context) {
      if (/[\}\]]/.test(state.context.type))
        pushContext(state, "pattern", stream.column());
      else if (state.context.type == "pattern" && !state.context.align) {
        state.context.align = true;
        state.context.col = stream.column();
      }
    }

    return style;
  },

  indent: function(state, textAfter, cx) {
    var firstChar = textAfter && textAfter.charAt(0);
    var context = state.context;
    if (/[\]\}]/.test(firstChar))
      while (context && context.type == "pattern") context = context.prev;

    var closing = context && firstChar == context.type;
    if (!context)
      return 0;
    else if (context.type == "pattern")
      return context.col;
    else if (context.align)
      return context.col + (closing ? 0 : 1);
    else
      return context.indent + (closing ? 0 : cx.unit);
  },

  languageData: {
    commentTokens: {line: "#"}
  }
};

exports.turtle = turtle;
