package eu.dnetlib.data.collector.plugins.ariadneplus.ads;

import java.io.File;
import java.io.FileReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.stream.JsonReader;

import eu.dnetlib.data.collector.plugins.FileCollectorPlugin;
import eu.dnetlib.rmi.data.CollectorServiceException;
import eu.dnetlib.rmi.data.InterfaceDescriptor;

public class FileJSONCollectorPlugin extends FileCollectorPlugin {

	private static final Log log = LogFactory.getLog(FileJSONCollectorPlugin.class);
	
	@Override
	public Iterable<String> collect(final InterfaceDescriptor interfaceDescriptor, final String fromDate, final String untilDate)
			throws CollectorServiceException {
		log.info("FileJSONCollectorPlugin");
		final String identifierFieldKey = interfaceDescriptor.getParams().get("identifierFieldKey");

		URL u = null;
		try {
			u = new URL(interfaceDescriptor.getBaseUrl());
		} catch (MalformedURLException e1) {
			e1.printStackTrace();
			throw new CollectorServiceException(e1);
		}
		final String baseUrl = u.getPath();

		log.info("base URL = " + baseUrl);

		try {
			final FileReader fileReader = new FileReader(new File(baseUrl));
			return new Iterable<String>() {

				@Override
				public Iterator<String> iterator() {
					return new FileJSONIterator(fileReader, identifierFieldKey);
				}
			};
		} catch (Exception e) {
			e.printStackTrace();
			throw new CollectorServiceException(e);
		}
	}

	class FileJSONIterator implements Iterator<String> {

		private String next;
		private String identifierFieldKey;
		private Iterator<JsonElement> aatInfosIterator;
		private JsonReader jsonReader;

		public FileJSONIterator(final FileReader fileReader, final String identifierFieldKey) {
			this.identifierFieldKey = identifierFieldKey;
			jsonReader = new JsonReader(fileReader);
			JsonElement jsonElement = new JsonParser().parse(jsonReader);
			JsonArray jsonArrays = jsonElement.getAsJsonArray();
			aatInfosIterator = jsonArrays.iterator();
			next = calculateNext();
		}
		
		@Override
		public boolean hasNext() {
			return next != null;
		}

		@Override
		public String next() {
			String s = next;
			next = calculateNext();
			return s;
		}

		private String calculateNext() {
			try {
				Document document = DocumentHelper.createDocument();
				Element root = document.addElement("Entry");

				if (!aatInfosIterator.hasNext()) {
					log.info("json entries finished, closing RESULT SET");
					jsonReader.close();
					return null;
				}
				JsonElement aatInfos = aatInfosIterator.next();
				JsonObject aatInfoJsonObj = aatInfos.getAsJsonObject();
				Set<Entry<String, JsonElement>> keys = aatInfoJsonObj.entrySet();
				for(Map.Entry<String,JsonElement> entry : keys) {
					String key = entry.getKey();
					JsonElement jsonElement = aatInfoJsonObj.get(key);
					if (jsonElement.isJsonNull()) {
						continue;
					}
					String value =  jsonElement.getAsString();
					if (StringUtils.isEmpty(value)) {
						continue;
					}
					String name = new String(key);
					Element element = root.addElement(name);
					value = StringEscapeUtils.escapeXml11(value.replace('\r',' ').replace('\t',' '));
					element.addText(value);
		    	}
				String xmlRecord = new String(document.asXML());
				log.debug(xmlRecord);
				return xmlRecord;
			} catch (Exception e) {
				log.error("Error calculating next json element", e);
			}
			return null;
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}

	}

}