/*
 * Copyright 2014 Mirantis, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
**/
import _ from 'underscore';
import ExpressionParser from 'expression/parser';
import * as expressionObjects from 'expression/objects';

var expressionCache = {};

class Expression {
  constructor(expressionText, models = {}, {strict = true} = {}) {
    this.strict = strict;
    this.expressionText = expressionText;
    this.models = models;
    this.compiledExpression = this.getCompiledExpression();
    return this;
  }

  evaluate(extraModels) {
    // FIXME(vkramskikh): currently Jison supports sharing state
    // only via ExpressionParser.yy. It is unsafe and could lead to
    // issues in case we start to use webworkers
    ExpressionParser.yy.expression = this;
    this.extraModels = extraModels;
    var value = this.compiledExpression.evaluate();
    delete this.extraModels;
    return value;
  }

  getCompiledExpression() {
    var cacheEntry = expressionCache[this.expressionText];
    if (!cacheEntry) {
      cacheEntry = expressionCache[this.expressionText] =
        ExpressionParser.parse(this.expressionText);
    }
    return cacheEntry;
  }
}

_.extend(ExpressionParser.yy, expressionObjects);

export default Expression;