package jalview.ext.ensembl;

import jalview.datamodel.AlignmentI;

import java.io.BufferedReader;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.json.simple.JSONArray;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class EnsemblInfo extends EnsemblRestClient
{

  /*
   * cached upper-cased results of REST /info/divisions service, 
   * currently (from April 2019)
   *  { "ENSEMBLFUNGI", "http://rest.ensembl.org",
   *    "ENSEMBLBACTERIA", "http://rest.ensembl.org",
   *    "ENSEMBLPROTISTS", "http://rest.ensembl.org",
   *    "ENSEMBLMETAZOA", "http://rest.ensembl.org",
   *    "ENSEMBLPLANTS",  "http://rest.ensembl.org",
   *    "ENSEMBL", "http://rest.ensembl.org" }
   *  }
   */
  private static Map<String, String> divisions;

  /**
   * Constructor
   */
  public EnsemblInfo()
  {
    super();
  }

  @Override
  public String getDbName()
  {
    return "ENSEMBL";
  }

  @Override
  public AlignmentI getSequenceRecords(String queries) throws Exception
  {
    return null;
  }

  @Override
  protected URL getUrl(List<String> ids) throws MalformedURLException
  {
    return null;
  }

  @Override
  protected boolean useGetRequest()
  {
    return true;
  }

  /**
   * Answers the domain (e.g. http://rest.ensembl.org) for the given division,
   * or null if not recognised by Ensembl
   * 
   * @param division
   * @return
   */
  public String getDomain(String division)
  {
    if (divisions == null)
    {
      fetchDivisions();
    }
    return divisions.get(division.toUpperCase());
  }

  /**
   * On first request only, populate the lookup map by fetching the list of
   * divisions known to Ensembl
   */
  void fetchDivisions()
  {
    divisions = new HashMap<>();

    BufferedReader br = null;
    try
    {
      URL url = getDivisionsUrl();
      if (url != null)
      {
        br = getHttpResponse(url, null);
      }
      parseResponse(br);
    } catch (IOException e)
    {
      // ignore
    } finally
    {
      if (br != null)
      {
        try
        {
          br.close();
        } catch (IOException e)
        {
          // ignore
        }
      }
    }
  }

  /**
   * Parses the JSON response to /info/divisions, and add each to the lookup map
   * 
   * @param br
   */
  void parseResponse(BufferedReader br)
  {
    JSONParser jp = new JSONParser();

    try
    {
      JSONArray parsed = (JSONArray) jp.parse(br);
      String domain = getDomain();

      Iterator rvals = parsed.iterator();
      while (rvals.hasNext())
      {
        String division = rvals.next().toString();
        divisions.put(division.toUpperCase(), domain);
      }
    } catch (IOException | ParseException | NumberFormatException e)
    {
      // ignore
    }
  }

  /**
   * Constructs the URL for the Ensembl /info/divisions REST service
   * 
   * @return
   * @throws MalformedURLException
   */
  URL getDivisionsUrl() throws MalformedURLException
  {
    return new URL(
            getDomain()
            + "/info/divisions?content-type=application/json");
  }

  /**
   * Returns the set of 'divisions' recognised by Ensembl
   * 
   * @return
   */
  public Set<String> getDivisions() {
    if (divisions == null)
    {
      fetchDivisions();
    }

    return divisions.keySet();
  }
}