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/**
 * Copyright 2016 Peter Nerg
 * 
 * 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 org.dmonix.servlet;

import com.google.gson.Gson;
import javascalautils.Option;
import javascalautils.OptionCompanion;
import javascalautils.Try;
import javascalautils.TryCompanion;

import javax.servlet.http.HttpServletRequest;
import java.io.InputStreamReader;

/**
 * Utility class for parsing JSON stuff.
 * @author Peter Nerg
 * @since 1.0
 */
interface ParserUtils {
    Gson gson = new Gson();

    /**
     * Get the path info as specified in the URI.
     *
     * @param req The HTTP request
     * @return The path info, i.e. the last part of the URI
     */
    static Option getPathInfo(HttpServletRequest req) {
        return OptionCompanion.Option(req.getPathInfo()).map(p -> p.substring(1));
    }

    /**
     * Parses an object from the json stream in the HTTP request
     * @param req The HTTP request
     * @param type The type to parse
     * @param  The return type
     * @return The parsed object
     */
    static  Try fromJson(HttpServletRequest req, Class type) {
        return fromJson(req, "UTF-8", type);
    }

    /**
     * Parses an object from the json stream in the HTTP request
     * @param req The HTTP request
     * @param charsetName The charset to expect
     * @param type The type to parse
     * @param  The return type
     * @return The parsed object
     */
    static  Try fromJson(HttpServletRequest req, String charsetName, Class type) {
        return TryCompanion.Try(() -> gson.fromJson(new InputStreamReader(req.getInputStream(), charsetName), type));
    }
}