/** 
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-18 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.aai.edges;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.*;
import java.util.Map.Entry;

import org.onap.aai.setup.SchemaVersion;

import com.jayway.jsonpath.DocumentContext;
import com.jayway.jsonpath.JsonPath;

/**
 * JsonIngestor produces DocumentContexts from json files
 */
public class JsonIngestor {
	
	/**
	 * Reads in given json files to queryable DocumentContexts.
	 * 
	 * @param filesToIngest - map of filenames to ingest
	 * 			per Version
	 * @return Map<SchemaVersion, List<DocumentContext>> - map of DocumentContexts per Version
	 */
	public Map<SchemaVersion, List<DocumentContext>> ingest(Map<SchemaVersion, List<String>> filesToIngest) {
		Map<SchemaVersion, List<DocumentContext>> result = new HashMap<>();
		
		for (Entry<SchemaVersion, List<String>> verFiles : filesToIngest.entrySet()) {
			SchemaVersion v = verFiles.getKey();
			List<String> files = verFiles.getValue();
			
			List<DocumentContext> docs = new ArrayList<>();
			
			for (String rulesFilename : files) {
				String fileContents = readInJsonFile(rulesFilename);
				docs.add(JsonPath.parse(fileContents));
			}
			result.put(v, docs);
		}
		
		return result;
	}
	
	/**
	 * Reads the json file at the given filename into an in-memory String.
	 * 
	 * @param rulesFilename - json file to be read (must include path to the file)
	 * @return String json contents of the given file
	 */
	private String readInJsonFile(String rulesFilename) {
		StringBuilder sb = new StringBuilder();
		try(BufferedReader br = new BufferedReader(new FileReader(rulesFilename))) {
			String line;
			while ((line = br.readLine()) != null) {
				sb.append(line);
			}
		} catch (IOException e) {
			throw new ExceptionInInitializerError(e);
		}
		return sb.toString();
	}
}