CodeMirror.defineMode("sass", function(config) {
  var tokenRegexp = function(words){
    return new RegExp("^" + words.join("|"));
  };

  var keywords = ["true", "false", "null", "auto"];
  var keywordsRegexp = new RegExp("^" + keywords.join("|"));

  var operators = ["\\(", "\\)", "=", ">", "<", "==", ">=", "<=", "\\+", "-", "\\!=", "/", "\\*", "%", "and", "or", "not"];
  var opRegexp = tokenRegexp(operators);

  var pseudoElementsRegexp = /^::?[\w\-]+/;

  var urlTokens = function(stream, state){
    var ch = stream.peek();

    if (ch === ")"){
      stream.next();
      state.tokenizer = tokenBase;
      return "operator";
    }else if (ch === "("){
      stream.next();
      stream.eatSpace();

      return "operator";
    }else if (ch === "'" || ch === '"'){
      state.tokenizer = buildStringTokenizer(stream.next());
      return "string";
    }else{
      state.tokenizer = buildStringTokenizer(")", false);
      return "string";
    }
  };
  var multilineComment = function(stream, state) {
    if (stream.skipTo("*/")){
      stream.next();
      stream.next();
      state.tokenizer = tokenBase;
    }else {
      stream.next();
    }

    return "comment";
  };

  var buildStringTokenizer = function(quote, greedy){
    if(greedy == null){ greedy = true; }

    function stringTokenizer(stream, state){
      var nextChar = stream.next();
      var peekChar = stream.peek();
      var previousChar = stream.string.charAt(stream.pos-2);

      var endingString = ((nextChar !== "\\" && peekChar === quote) || (nextChar === quote && previousChar !== "\\"));

      /*
      console.log("previousChar: " + previousChar);
      console.log("nextChar: " + nextChar);
      console.log("peekChar: " + peekChar);
      console.log("ending: " + endingString);
      */

      if (endingString){
        if (nextChar !== quote && greedy) { stream.next(); }
        state.tokenizer = tokenBase;
        return "string";
      }else if (nextChar === "#" && peekChar === "{"){
        state.tokenizer = buildInterpolationTokenizer(stringTokenizer);
        stream.next();
        return "operator";
      }else {
        return "string";
      }
    }

    return stringTokenizer;
  };

  var buildInterpolationTokenizer = function(currentTokenizer){
    return function(stream, state){
      if (stream.peek() === "}"){
        stream.next();
        state.tokenizer = currentTokenizer;
        return "operator";
      }else{
        return tokenBase(stream, state);
      }
    };
  };

  var indent = function(state){
    if (state.indentCount == 0){
      state.indentCount++;
      var lastScopeOffset = state.scopes[0].offset;
      var currentOffset = lastScopeOffset + config.indentUnit;
      state.scopes.unshift({ offset:currentOffset });
    }
  };

  var dedent = function(state){
    if (state.scopes.length == 1) { return; }

    state.scopes.shift();
  };

  var tokenBase = function(stream, state) {
    var ch = stream.peek();

    // Single line Comment
    if (stream.match('//')) {
      stream.skipToEnd();
      return "comment";
    }

    // Multiline Comment
    if (stream.match('/*')){
      state.tokenizer = multilineComment;
      return state.tokenizer(stream, state);
    }

    // Interpolation
    if (stream.match('#{')){
    state.tokenizer = buildInterpolationTokenizer(tokenBase);
      return "operator";
    }

    if (ch === "."){
      stream.next();

      // Match class selectors
      if (stream.match(/^[\w-]+/)){
        indent(state);
        return "atom";
      }else if (stream.peek() === "#"){
        indent(state);
        return "atom";
      }else{
        return "operator";
      }
    }

    if (ch === "#"){
      stream.next();

      // Hex numbers
      if (stream.match(/[0-9a-fA-F]{6}|[0-9a-fA-F]{3}/)){
        return "number";
      }

      // ID selectors
      if (stream.match(/^[\w-]+/)){
        indent(state);
        return "atom";
      }

      if (stream.peek() === "#"){
        indent(state);
        return "atom";
      }
    }

    // Numbers
    if (stream.match(/^-?[0-9\.]+/)){
      return "number";
    }

    // Units
    if (stream.match(/^(px|em|in)\b/)){
      return "unit";
    }

    if (stream.match(keywordsRegexp)){
      return "keyword";
    }

    if (stream.match(/^url/) && stream.peek() === "("){
      state.tokenizer = urlTokens;
      return "atom";
    }

    // Variables
    if (ch === "$"){
      stream.next();
      stream.eatWhile(/[\w-]/);

      if (stream.peek() === ":"){
        stream.next();
        return "variable-2";
      }else{
        return "variable-3";
      }
    }

    if (ch === "!"){
      stream.next();

      if (stream.match(/^[\w]+/)){
        return "keyword";
      }

      return "operator";
    }

    if (ch === "="){
      stream.next();

      // Match shortcut mixin definition
      if (stream.match(/^[\w-]+/)){
        indent(state);
        return "meta";
      }else {
        return "operator";
      }
    }

    if (ch === "+"){
      stream.next();

      // Match shortcut mixin definition
      if (stream.match(/^[\w-]+/)){
        return "variable-3";
      }else {
        return "operator";
      }
    }

    // Indent Directives
    if (stream.match(/^@(else if|if|media|else|for|each|while|mixin|function)/)){
      indent(state);
      return "meta";
    }

    // Other Directives
    if (ch === "@"){
      stream.next();
      stream.eatWhile(/[\w-]/);
      return "meta";
    }

    // Strings
    if (ch === '"' || ch === "'"){
      stream.next();
      state.tokenizer = buildStringTokenizer(ch);
      return "string";
    }

    // Pseudo element selectors
    if (ch == ':' && stream.match(pseudoElementsRegexp)){
      return "keyword";
    }

    // atoms
    if (stream.eatWhile(/[\w-&]/)){
      // matches a property definition
      if (stream.peek() === ":" && !stream.match(pseudoElementsRegexp, false))
        return "property";
      else
        return "atom";
    }

    if (stream.match(opRegexp)){
      return "operator";
    }

    // If we haven't returned by now, we move 1 character
    // and return an error
    stream.next();
    return null;
  };

  var tokenLexer = function(stream, state) {
    if (stream.sol()){
      state.indentCount = 0;
    }
    var style = state.tokenizer(stream, state);
    var current = stream.current();

    if (current === "@return"){
      dedent(state);
    }

    if (style === "atom"){
      indent(state);
    }

    if (style !== null){
      var startOfToken = stream.pos - current.length;
      var withCurrentIndent = startOfToken + (config.indentUnit * state.indentCount);

      var newScopes = [];

      for (var i = 0; i < state.scopes.length; i++){
        var scope = state.scopes[i];

        if (scope.offset <= withCurrentIndent){
          newScopes.push(scope);
        }
      }

      state.scopes = newScopes;
    }


    return style;
  };

  return {
    startState: function() {
      return {
        tokenizer: tokenBase,
        scopes: [{offset: 0, type: 'sass'}],
        definedVars: [],
        definedMixins: []
      };
    },
    token: function(stream, state) {
      var style = tokenLexer(stream, state);

      state.lastToken = { style: style, content: stream.current() };

      return style;
    },

    indent: function(state) {
      return state.scopes[0].offset;
    }
  };
});

CodeMirror.defineMIME("text/x-sass", "sass");