(function(window, undefined) {
    var dependencies = {},
        instances = {};

    var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
    function stripComments(functionString) {
        return functionString.replace(STRIP_COMMENTS, '');
    }

    var FN_NEW_LINE_REPLACE = /[\s\r\n]+/;
    function oneline(functionString) {
        return functionString.replace(FN_NEW_LINE_REPLACE, '');
    }

    var STRIP_WHITESPACE = /[\s\t]/g;
    function trimWhitespace(functionString) {
        return functionString.replace(STRIP_WHITESPACE, '');
    }

    var FN_ARGS = /^function\s*[^\(]*\(\s*([^\)]*)\)/m;
    function parseArgs(functionString) {
        return functionString.match(FN_ARGS)[1];
    }

    var FN_ARG_SPLIT = /,/;
    function getArgs(functionString) {
        if (functionString) {
            return functionString.split(FN_ARG_SPLIT);
        } else {
            return [];
        }
    }

    /**
     * [$injector description]
     * @type {[type]}
     */
    window.$injector = {
        /**
         * [annotate description]
         * @param  {[type]} constructorFn [description]
         * @return {[type]}               [description]
         */
        annotate: function(constructorFn) {
            var sanitizedFn = stripComments(constructorFn.toString());
            var onelinedFn = oneline(sanitizedFn);
            var condensedFn = trimWhitespace(onelinedFn);
            var argString = parseArgs(condensedFn);
            var args = getArgs(argString);

            constructorFn.$inject_ = args;
        },

        /**
         * [provide description]
         * @param  {[type]} name          [description]
         * @param  {[type]} constructorFn [description]
         * @return {[type]}               [description]
         */
        provide: function(name, constructorFn) {
            this.annotate(constructorFn);
            dependencies[name] = constructorFn;
            return constructorFn;
        },

        /**
         * [get description]
         * @param  {[type]} name [description]
         * @return {[type]}      [description]
         */
        get: function(name) {
            var instance = instances[name];
            if (instance) {
                return instance;
            }

            var constructorFn = dependencies[name];
            if (constructorFn) {
                var deps = [];

                for (var a = 0; a < constructorFn.$inject_.length; a++) {
                    var dependency = this.get(constructorFn.$inject_[a]);
                    deps.push(dependency);
                }

                var fn = new constructorFn();
                constructorFn.apply(fn, deps);
                instances[name] = fn;
                return fn;
            } else {
                throw new Error('Dependency [' + name + '] not registered in graph.');
            }
        }
    };
})(window);