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

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import eu.dnetlib.data.collector.ThreadSafeIterator;
import eu.dnetlib.rmi.data.CollectorServiceRuntimeException;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpStatus;
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 java.io.BufferedInputStream;
import java.io.IOException;
import java.lang.reflect.Type;
import java.util.List;

import net.minidev.json.JSONArray;
import net.minidev.json.JSONObject;
import net.minidev.json.parser.JSONParser;
import net.minidev.json.parser.ParseException;

public class ThanadosIterator extends ThreadSafeIterator {

	private static final Log log = LogFactory.getLog(ThanadosIterator.class);
	private final CloseableHttpClient client = HttpClients.createDefault();

	private String baseUrl;
	private List<String> identifiers;
	private int counter = 0;
	private String urlFormat = "%s/%s?format=xml";
	private String fromDate;


	public ThanadosIterator(final String baseUrl, final String listAddress, final String fromDate) {
		try {
			this.baseUrl = baseUrl;
			this.identifiers = downloadIdentifierList(listAddress, fromDate);
			this.counter = 0;
			this.fromDate = fromDate;
		} catch (Exception e) {
			throw new CollectorServiceRuntimeException("Error creating iterator", e);
		}
	}

	@Override
	public boolean doHasNext() {
		return counter < this.identifiers.size();
	}

	@Override
	public String doNext() {
		try {
			if (counter < this.identifiers.size()) {
				String toDownload = String.format(urlFormat, baseUrl, identifiers.get(counter));
				log.debug("Downloading "+toDownload);
				System.out.println("Downloading "+toDownload);
				return download(toDownload);
			} else {
				throw new CollectorServiceRuntimeException("Iterator has reached the end");
			}
		} finally {
				counter++;
		}
	}

	protected List<String> downloadIdentifierList(final String listUrl, final String fromDate) throws ParseException {
		String urlToListItems = listUrl;
		if(StringUtils.isNotBlank(fromDate))
			urlToListItems = listUrl+"/"+fromDate;
		log.info("Getting list of items from "+urlToListItems);
		String response = download(urlToListItems);
		JSONObject map = (JSONObject)(new JSONParser(JSONParser.MODE_PERMISSIVE).parse(response));
		final String sites = map.getAsString("\"sites\"");
		Gson converter = new Gson();
		Type type = new TypeToken<List<String>>(){}.getType();
		return converter.fromJson(sites, type );

	}

	private String download(final String url) {
		log.debug("download:  "+url);
		final HttpGet method = new HttpGet(url);

		try(CloseableHttpResponse response = client.execute(method)) {
			int statusCode = response.getStatusLine().getStatusCode();

			if (HttpStatus.SC_OK == statusCode) {
				return IOUtils.toString(new BufferedInputStream(response.getEntity().getContent()), "utf-8");
			} else {
				throw new CollectorServiceRuntimeException("Error " + statusCode + " dowloading url: " + url);
			}

		} catch (IOException e) {
			throw new CollectorServiceRuntimeException("Error downloading url: " + url);
		}
	}


	public List<String> getIdentifiers() {
		return identifiers;
	}

	public void setIdentifiers(List<String> identifiers) {
		this.identifiers = identifiers;
	}
}