/**
 * IK 中文分词  版本 5.0
 * IK Analyzer release 5.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 *
 * 源代码由林良益(linliangyi2005@gmail.com)提供
 * 版权声明 2012，乌龙茶工作室
 * provided by Linliangyi and copyright 2012 by Oolong studio
 *
 *
 */
package org.wltea.analyzer.dic;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.Files;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.*;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.elasticsearch.SpecialPermission;
import org.elasticsearch.common.io.PathUtils;
import org.elasticsearch.plugin.analysis.ik.AnalysisIkPlugin;
import org.wltea.analyzer.cfg.Configuration;
import org.apache.logging.log4j.Logger;
import org.wltea.analyzer.help.ESPluginLoggerFactory;


/**
 * 词典管理类,单子模式
 */
public class Dictionary {

	/*
	 * 词典单子实例
	 */
	private static Dictionary singleton;

	private DictSegment _MainDict;

	private DictSegment _QuantifierDict;

	private DictSegment _StopWords;

	/**
	 * 配置对象
	 */
	private Configuration configuration;

	private static final Logger logger = ESPluginLoggerFactory.getLogger(Dictionary.class.getName());

	private static ScheduledExecutorService pool = Executors.newScheduledThreadPool(1);

	private static final String PATH_DIC_MAIN = "main.dic";
	private static final String PATH_DIC_SURNAME = "surname.dic";
	private static final String PATH_DIC_QUANTIFIER = "quantifier.dic";
	private static final String PATH_DIC_SUFFIX = "suffix.dic";
	private static final String PATH_DIC_PREP = "preposition.dic";
	private static final String PATH_DIC_STOP = "stopword.dic";

	private final static  String FILE_NAME = "IKAnalyzer.cfg.xml";
	private final static  String EXT_DICT = "ext_dict";
	private final static  String REMOTE_EXT_DICT = "remote_ext_dict";
	private final static  String EXT_STOP = "ext_stopwords";
	private final static  String REMOTE_EXT_STOP = "remote_ext_stopwords";

	private Path conf_dir;
	private Properties props;

	private Dictionary(Configuration cfg) {
		this.configuration = cfg;
		this.props = new Properties();
		this.conf_dir = cfg.getEnvironment().configFile().resolve(AnalysisIkPlugin.PLUGIN_NAME);
		Path configFile = conf_dir.resolve(FILE_NAME);

		InputStream input = null;
		try {
			logger.info("try load config from {}", configFile);
			input = new FileInputStream(configFile.toFile());
		} catch (FileNotFoundException e) {
			conf_dir = cfg.getConfigInPluginDir();
			configFile = conf_dir.resolve(FILE_NAME);
			try {
				logger.info("try load config from {}", configFile);
				input = new FileInputStream(configFile.toFile());
			} catch (FileNotFoundException ex) {
				// We should report origin exception
				logger.error("ik-analyzer", e);
			}
		}
		if (input != null) {
			try {
				props.loadFromXML(input);
			} catch (IOException e) {
				logger.error("ik-analyzer", e);
			}
		}
	}

	private String getProperty(String key){
		if(props!=null){
			return props.getProperty(key);
		}
		return null;
	}
	/**
	 * 词典初始化 由于IK Analyzer的词典采用Dictionary类的静态方法进行词典初始化
	 * 只有当Dictionary类被实际调用时，才会开始载入词典， 这将延长首次分词操作的时间 该方法提供了一个在应用加载阶段就初始化字典的手段
	 * 
	 * @return Dictionary
	 */
	public static synchronized void initial(Configuration cfg) {
		if (singleton == null) {
			synchronized (Dictionary.class) {
				if (singleton == null) {

					singleton = new Dictionary(cfg);
					singleton.loadMainDict();
					singleton.loadSurnameDict();
					singleton.loadQuantifierDict();
					singleton.loadSuffixDict();
					singleton.loadPrepDict();
					singleton.loadStopWordDict();

					if(cfg.isEnableRemoteDict()){
						// 建立监控线程
						for (String location : singleton.getRemoteExtDictionarys()) {
							// 10 秒是初始延迟可以修改的 60是间隔时间 单位秒
							pool.scheduleAtFixedRate(new Monitor(location), 10, 60, TimeUnit.SECONDS);
						}
						for (String location : singleton.getRemoteExtStopWordDictionarys()) {
							pool.scheduleAtFixedRate(new Monitor(location), 10, 60, TimeUnit.SECONDS);
						}
					}

				}
			}
		}
	}

	private void walkFileTree(List<String> files, Path path) {
		if (Files.isRegularFile(path)) {
			files.add(path.toString());
		} else if (Files.isDirectory(path)) try {
			Files.walkFileTree(path, new SimpleFileVisitor<Path>() {
				@Override
				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
					files.add(file.toString());
					return FileVisitResult.CONTINUE;
				}
				@Override
				public FileVisitResult visitFileFailed(Path file, IOException e) {
					logger.error("[Ext Loading] listing files", e);
					return FileVisitResult.CONTINUE;
				}
			});
		} catch (IOException e) {
			logger.error("[Ext Loading] listing files", e);
		} else {
			logger.warn("[Ext Loading] file not found: " + path);
		}
	}

	private void loadDictFile(DictSegment dict, Path file, boolean critical, String name) {
		try (InputStream is = new FileInputStream(file.toFile())) {
			BufferedReader br = new BufferedReader(
					new InputStreamReader(is, "UTF-8"), 512);
			String word = br.readLine();
			if (word != null) {
				if (word.startsWith("\uFEFF"))
					word = word.substring(1);
				for (; word != null; word = br.readLine()) {
					word = word.trim();
					if (word.isEmpty()) continue;
					dict.fillSegment(word.toCharArray());
				}
			}
		} catch (FileNotFoundException e) {
			logger.error("ik-analyzer: " + name + " not found", e);
			if (critical) throw new RuntimeException("ik-analyzer: " + name + " not found!!!", e);
		} catch (IOException e) {
			logger.error("ik-analyzer: " + name + " loading failed", e);
		}
	}

	private List<String> getExtDictionarys() {
		List<String> extDictFiles = new ArrayList<String>(2);
		String extDictCfg = getProperty(EXT_DICT);
		if (extDictCfg != null) {

			String[] filePaths = extDictCfg.split(";");
			for (String filePath : filePaths) {
				if (filePath != null && !"".equals(filePath.trim())) {
					Path file = PathUtils.get(getDictRoot(), filePath.trim());
					walkFileTree(extDictFiles, file);

				}
			}
		}
		return extDictFiles;
	}

	private List<String> getRemoteExtDictionarys() {
		List<String> remoteExtDictFiles = new ArrayList<String>(2);
		String remoteExtDictCfg = getProperty(REMOTE_EXT_DICT);
		if (remoteExtDictCfg != null) {

			String[] filePaths = remoteExtDictCfg.split(";");
			for (String filePath : filePaths) {
				if (filePath != null && !"".equals(filePath.trim())) {
					remoteExtDictFiles.add(filePath);

				}
			}
		}
		return remoteExtDictFiles;
	}

	private List<String> getExtStopWordDictionarys() {
		List<String> extStopWordDictFiles = new ArrayList<String>(2);
		String extStopWordDictCfg = getProperty(EXT_STOP);
		if (extStopWordDictCfg != null) {

			String[] filePaths = extStopWordDictCfg.split(";");
			for (String filePath : filePaths) {
				if (filePath != null && !"".equals(filePath.trim())) {
					Path file = PathUtils.get(getDictRoot(), filePath.trim());
					walkFileTree(extStopWordDictFiles, file);

				}
			}
		}
		return extStopWordDictFiles;
	}

	private List<String> getRemoteExtStopWordDictionarys() {
		List<String> remoteExtStopWordDictFiles = new ArrayList<String>(2);
		String remoteExtStopWordDictCfg = getProperty(REMOTE_EXT_STOP);
		if (remoteExtStopWordDictCfg != null) {

			String[] filePaths = remoteExtStopWordDictCfg.split(";");
			for (String filePath : filePaths) {
				if (filePath != null && !"".equals(filePath.trim())) {
					remoteExtStopWordDictFiles.add(filePath);

				}
			}
		}
		return remoteExtStopWordDictFiles;
	}

	private String getDictRoot() {
		return conf_dir.toAbsolutePath().toString();
	}


	/**
	 * 获取词典单子实例
	 * 
	 * @return Dictionary 单例对象
	 */
	public static Dictionary getSingleton() {
		if (singleton == null) {
			throw new IllegalStateException("ik dict has not been initialized yet, please call initial method first.");
		}
		return singleton;
	}


	/**
	 * 批量加载新词条
	 * 
	 * @param words
	 *            Collection<String>词条列表
	 */
	public void addWords(Collection<String> words) {
		if (words != null) {
			for (String word : words) {
				if (word != null) {
					// 批量加载词条到主内存词典中
					singleton._MainDict.fillSegment(word.trim().toCharArray());
				}
			}
		}
	}

	/**
	 * 批量移除（屏蔽）词条
	 */
	public void disableWords(Collection<String> words) {
		if (words != null) {
			for (String word : words) {
				if (word != null) {
					// 批量屏蔽词条
					singleton._MainDict.disableSegment(word.trim().toCharArray());
				}
			}
		}
	}

	/**
	 * 检索匹配主词典
	 * 
	 * @return Hit 匹配结果描述
	 */
	public Hit matchInMainDict(char[] charArray) {
		return singleton._MainDict.match(charArray);
	}

	/**
	 * 检索匹配主词典
	 * 
	 * @return Hit 匹配结果描述
	 */
	public Hit matchInMainDict(char[] charArray, int begin, int length) {
		return singleton._MainDict.match(charArray, begin, length);
	}

	/**
	 * 检索匹配量词词典
	 * 
	 * @return Hit 匹配结果描述
	 */
	public Hit matchInQuantifierDict(char[] charArray, int begin, int length) {
		return singleton._QuantifierDict.match(charArray, begin, length);
	}

	/**
	 * 从已匹配的Hit中直接取出DictSegment，继续向下匹配
	 * 
	 * @return Hit
	 */
	public Hit matchWithHit(char[] charArray, int currentIndex, Hit matchedHit) {
		DictSegment ds = matchedHit.getMatchedDictSegment();
		return ds.match(charArray, currentIndex, 1, matchedHit);
	}

	/**
	 * 判断是否是停止词
	 * 
	 * @return boolean
	 */
	public boolean isStopWord(char[] charArray, int begin, int length) {
		return singleton._StopWords.match(charArray, begin, length).isMatch();
	}

	/**
	 * 加载主词典及扩展词典
	 */
	private void loadMainDict() {
		// 建立一个主词典实例
		_MainDict = new DictSegment((char) 0);

		// 读取主词典文件
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_MAIN);
		loadDictFile(_MainDict, file, false, "Main Dict");
		// 加载扩展词典
		this.loadExtDict();
		// 加载远程自定义词库
		this.loadRemoteExtDict();
	}

	/**
	 * 加载用户配置的扩展词典到主词库表
	 */
	private void loadExtDict() {
		// 加载扩展词典配置
		List<String> extDictFiles = getExtDictionarys();
		if (extDictFiles != null) {
			for (String extDictName : extDictFiles) {
				// 读取扩展词典文件
				logger.info("[Dict Loading] " + extDictName);
				Path file = PathUtils.get(extDictName);
				loadDictFile(_MainDict, file, false, "Extra Dict");
			}
		}
	}

	/**
	 * 加载远程扩展词典到主词库表
	 */
	private void loadRemoteExtDict() {
		List<String> remoteExtDictFiles = getRemoteExtDictionarys();
		for (String location : remoteExtDictFiles) {
			logger.info("[Dict Loading] " + location);
			List<String> lists = getRemoteWords(location);
			// 如果找不到扩展的字典，则忽略
			if (lists == null) {
				logger.error("[Dict Loading] " + location + " load failed");
				continue;
			}
			for (String theWord : lists) {
				if (theWord != null && !"".equals(theWord.trim())) {
					// 加载扩展词典数据到主内存词典中
					logger.info(theWord);
					_MainDict.fillSegment(theWord.trim().toLowerCase().toCharArray());
				}
			}
		}

	}

	private static List<String> getRemoteWords(String location) {
		SpecialPermission.check();
		return AccessController.doPrivileged((PrivilegedAction<List<String>>) () -> {
			return getRemoteWordsUnprivileged(location);
		});
	}

	/**
	 * 从远程服务器上下载自定义词条
	 */
	private static List<String> getRemoteWordsUnprivileged(String location) {

		List<String> buffer = new ArrayList<String>();
		RequestConfig rc = RequestConfig.custom().setConnectionRequestTimeout(10 * 1000).setConnectTimeout(10 * 1000)
				.setSocketTimeout(60 * 1000).build();
		CloseableHttpClient httpclient = HttpClients.createDefault();
		CloseableHttpResponse response;
		BufferedReader in;
		HttpGet get = new HttpGet(location);
		get.setConfig(rc);
		try {
			response = httpclient.execute(get);
			if (response.getStatusLine().getStatusCode() == 200) {

				String charset = "UTF-8";
				// 获取编码，默认为utf-8
				HttpEntity entity = response.getEntity();
				if(entity!=null){
					Header contentType = entity.getContentType();
					if(contentType!=null&&contentType.getValue()!=null){
						String typeValue = contentType.getValue();
						if(typeValue!=null&&typeValue.contains("charset=")){
							charset = typeValue.substring(typeValue.lastIndexOf("=") + 1);
						}
					}

					if (entity.getContentLength() > 0 || entity.isChunked()) {
						in = new BufferedReader(new InputStreamReader(entity.getContent(), charset));
						String line;
						while ((line = in.readLine()) != null) {
							buffer.add(line);
						}
						in.close();
						response.close();
						return buffer;
					}
			}
			}
			response.close();
		} catch (IllegalStateException | IOException e) {
			logger.error("getRemoteWords {} error", e, location);
		}
		return buffer;
	}

	/**
	 * 加载用户扩展的停止词词典
	 */
	private void loadStopWordDict() {
		// 建立主词典实例
		_StopWords = new DictSegment((char) 0);

		// 读取主词典文件
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_STOP);
		loadDictFile(_StopWords, file, false, "Main Stopwords");

		// 加载扩展停止词典
		List<String> extStopWordDictFiles = getExtStopWordDictionarys();
		if (extStopWordDictFiles != null) {
			for (String extStopWordDictName : extStopWordDictFiles) {
				logger.info("[Dict Loading] " + extStopWordDictName);

				// 读取扩展词典文件
				file = PathUtils.get(extStopWordDictName);
				loadDictFile(_StopWords, file, false, "Extra Stopwords");
			}
		}

		// 加载远程停用词典
		List<String> remoteExtStopWordDictFiles = getRemoteExtStopWordDictionarys();
		for (String location : remoteExtStopWordDictFiles) {
			logger.info("[Dict Loading] " + location);
			List<String> lists = getRemoteWords(location);
			// 如果找不到扩展的字典，则忽略
			if (lists == null) {
				logger.error("[Dict Loading] " + location + " load failed");
				continue;
			}
			for (String theWord : lists) {
				if (theWord != null && !"".equals(theWord.trim())) {
					// 加载远程词典数据到主内存中
					logger.info(theWord);
					_StopWords.fillSegment(theWord.trim().toLowerCase().toCharArray());
				}
			}
		}

	}

	/**
	 * 加载量词词典
	 */
	private void loadQuantifierDict() {
		// 建立一个量词典实例
		_QuantifierDict = new DictSegment((char) 0);
		// 读取量词词典文件
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_QUANTIFIER);
		loadDictFile(_QuantifierDict, file, false, "Quantifier");
	}

	private void loadSurnameDict() {
		DictSegment _SurnameDict = new DictSegment((char) 0);
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_SURNAME);
		loadDictFile(_SurnameDict, file, true, "Surname");
	}

	private void loadSuffixDict() {
		DictSegment _SuffixDict = new DictSegment((char) 0);
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_SUFFIX);
		loadDictFile(_SuffixDict, file, true, "Suffix");
	}

	private void loadPrepDict() {
		DictSegment _PrepDict = new DictSegment((char) 0);
		Path file = PathUtils.get(getDictRoot(), Dictionary.PATH_DIC_PREP);
		loadDictFile(_PrepDict, file, true, "Preposition");
	}

	void reLoadMainDict() {
		logger.info("start to reload ik dict.");
		// 新开一个实例加载词典，减少加载过程对当前词典使用的影响
		Dictionary tmpDict = new Dictionary(configuration);
		tmpDict.configuration = getSingleton().configuration;
		tmpDict.loadMainDict();
		tmpDict.loadStopWordDict();
		_MainDict = tmpDict._MainDict;
		_StopWords = tmpDict._StopWords;
		logger.info("reload ik dict finished.");
	}

}