/*
 * eGov suite of products aim to improve the internal efficiency,transparency,
 *    accountability and the service delivery of the government  organizations.
 *
 *     Copyright (C) <2015>  eGovernments Foundation
 *
 *     The updated version of eGov suite of products as by eGovernments Foundation
 *     is available at http://www.egovernments.org
 *
 *     This program is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     any later version.
 *
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program. If not, see http://www.gnu.org/licenses/ or
 *     http://www.gnu.org/licenses/gpl.html .
 *
 *     In addition to the terms of the GPL license to be adhered to in using this
 *     program, the following additional terms are to be complied with:
 *
 *         1) All versions of this program, verbatim or modified must carry this
 *            Legal Notice.
 *
 *         2) Any misrepresentation of the origin of the material is prohibited. It
 *            is required that all modified versions of this material be marked in
 *            reasonable ways as different from the original version.
 *
 *         3) This license does not grant any rights to any user of the program
 *            with regards to rights under trademark law for use of the trade names
 *            or trademarks of eGovernments Foundation.
 *
 *   In case of any queries, you can reach eGovernments Foundation at contact@egovernments.org.
 */

package org.egov.infra.script.service;

import org.egov.infra.cache.impl.LRUCache;
import org.egov.infra.exception.ApplicationRuntimeException;
import org.springframework.stereotype.Component;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

@Component
public class ScriptEngineProvider {

    private static LRUCache<String, ScriptEngine> SCRIPT_ENGINE_CACHE;

    /**
     * Creates instance of script service with given sizes of engine cache and
     * script cache
     *
     * @param engineCacheMinSize
     *            Minimum (initial) size of script engine cache
     * @param engineCacheMaxSize
     *            Maximum size of script engine cache
     * @param scriptCacheMinSize
     *            Minimum (initial) Size of script cache
     * @param scriptCacheMaxSize
     *            Maximum size of script cache
     */
    public ScriptEngineProvider() {
        if (SCRIPT_ENGINE_CACHE == null)
            SCRIPT_ENGINE_CACHE = new LRUCache<String, ScriptEngine>(2, 10);
    }

    /**
     * @param scriptType
     *            Script type for which the script engine is to be fetched
     * @return Script engine for given script type
     */
    public ScriptEngine getScriptEngine(final String scriptType) {
        // Check if engine for given script type is already cached
        ScriptEngine engine = SCRIPT_ENGINE_CACHE.get(scriptType);
        if (engine == null) {
            // Engine not cached. Create and cache it.
            final ScriptEngineManager m = new ScriptEngineManager();
            engine = m.getEngineByName(scriptType);
            if (engine == null)
                // Engine could not be created. throw exception
                throw new ApplicationRuntimeException("Could not get script engine for [" + scriptType + "]");
            SCRIPT_ENGINE_CACHE.put(scriptType, engine);
        }

        return engine;
    }
}