package eu.dnetlib.data.collector.plugins.opentrial;

/**
 * Created by miriam on 07/03/2017.
 */
import eu.dnetlib.data.collector.rmi.CollectorServiceException;
import eu.dnetlib.data.collector.rmi.CollectorServiceRuntimeException;
import org.apache.commons.io.IOUtils;
import java.net.*;
import java.util.Iterator;
import java.util.concurrent.ArrayBlockingQueue;
//import java.util.function.Consumer;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.json.*;



public class OpenTrialIterator implements Iterable<String> {

	private final String base_url;
	private int total ;
	private ArrayBlockingQueue<String> trials = new ArrayBlockingQueue<String>(100);
	private int current = 0;
	private static final Log log = LogFactory.getLog(OpenTrialIterator.class);

	public OpenTrialIterator(String base_url, String from_date, String to_date)throws CollectorServiceException{
		try {
			String q = "per_page=100";
			if (!(from_date == null)) {
				if (!(to_date == null)) {
					q = "q=registration_date%3A%5B" + from_date + "%20TO%20" + to_date + "%5D&" + q;

				} else
					q = "q=registration_date%3A%5B" + from_date + "%20TO%20*%5D&" + q;
			}
			this.base_url = base_url+ q;
			log.info("url from which to collect " + this.base_url);
			prepare();
		}catch(Exception ex){
			throw new CollectorServiceException(ex);
		}
	}

	private void prepare()throws Exception {
		JSONObject json = new JSONObject(getPage(1));
		total = json.getInt("total_count");
		log.info("Total number of entries to collect: " + total);
		fillTrials(json);
	}


	@Override
	public Iterator<String> iterator() {
		return new Iterator<String>(){

			private int page_number = 2;


			@Override
			public void remove(){

			}

			@Override
			public String next() {
				try {
					if (trials.isEmpty()) {
						JSONObject json = new JSONObject(getPage(page_number));
						fillTrials(json);
						page_number++;
					}
					return trials.poll();
				}catch(Exception ex){
					throw new CollectorServiceRuntimeException(ex);
				}
			}

			@Override
			public boolean hasNext(){
				log.debug("More entries to collect: (" + current + "<" + total + "=" + (current < total));
				return (current < total || !trials.isEmpty());
			}


		};

	}

	private void fillTrials(JSONObject json)throws CollectorServiceException{

		JSONArray entries = json.getJSONArray("items");
		for(Object entry: entries) {
			try {
				trials.put(XML.toString(entry));
			}catch(Exception ex){
				throw new CollectorServiceException(ex);
			}
			current++;
		}

	}
	private String getPage(int page_number)throws CollectorServiceException {

		try {
			URL url = new URL(base_url + "&page=" + page_number);
			URLConnection conn = url.openConnection();
			conn.setRequestProperty("User-Agent", "Mozilla/5.0");
			return (IOUtils.toString(conn.getInputStream()));
		}catch(Exception ex){
			throw new CollectorServiceException(ex);
		}
	}


}