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/*
 * Copyright [2017] Wikimedia Foundation
 *
 * 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.
 */

package com.o19s.es.template.mustache;

import com.github.mustachejava.Mustache;
import com.github.mustachejava.MustacheException;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.apache.logging.log4j.util.Supplier;
import org.elasticsearch.SpecialPermission;
import org.apache.logging.log4j.LogManager;

import java.io.StringReader;
import java.io.StringWriter;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Map;

public class MustacheUtils {
    public static final String TEMPLATE_LANGUAGE = "mustache";
    private static final Logger logger = LogManager.getLogger(MustacheUtils.class);
    private static final SpecialPermission SPECIAL_PERMS = new SpecialPermission();
    /**
     * We store templates internally always as json
     */
    private static final CustomMustacheFactory FACTORY = new CustomMustacheFactory();

    public static Mustache compile(String name, String template) {
        // Don't use compile(String name) to avoid caching in the factory
        try {
            return FACTORY.compile(new StringReader(template), name);
        } catch (MustacheException me) {
            throw new IllegalArgumentException(me.getMessage(), me);
        }
    }

    public static String execute(Mustache template, Map params) {
        final StringWriter writer = new StringWriter();
        try {
            // crazy reflection here
            SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                sm.checkPermission(SPECIAL_PERMS);
            }
            AccessController.doPrivileged((PrivilegedAction) () -> {
                template.execute(writer, params);
                return null;
            });
        } catch (Exception e) {
            logger.error((Supplier) () -> new ParameterizedMessage("Error running {}", template), e);
            throw new IllegalArgumentException("Error running " + template, e);
        }
        return writer.toString();

    }
}