package jalview.util;

import jalview.javascript.json.JSON;

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.List;

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

public class JSONUtils
{

  /**
   * Converts a JSONArray of values to a string as a comma-separated list.
   * Answers null if the array is null or empty.
   * 
   * @param jsonArray
   * @return
   */
  public static String arrayToStringList(List<Object> jsonArray)
  {
	int n;
	
    if (jsonArray == null || (n = jsonArray.size()) == 0)
    {
      return null;
    }

    /**
     * @j2sNative
     * 
     * return jsonArray.elementData.slice(0, n).join(",");
     */
    {
	    StringBuilder sb = new StringBuilder();
	    for (int i = 0; i < n; i++)
	    {
	      if (i > 0)
	      {
	        sb.append(",");
	      }
	      sb.append(jsonArray.get(i).toString());
	    }
	    return sb.toString();
    }
  }

  /**
   * The method all JSON parsing must go through for JavaScript. 
   * @param r a BufferedReader or a javascript.json.JSON.JSONReader
   * @return
   * @throws IOException
   * @throws ParseException
   */
  public static Object parse(Reader r) throws IOException, ParseException 
  {
      // Using a file reader is not currently supported in SwingJS JavaScript

	  if (r == null)
		  return null;
//	  
//	  	Platform.timeCheck("JSONUtils.parse0 ", Platform.TIME_MARK);

	Object ret;    
	if (Platform.isJS()) 
	{
	  if (r instanceof FileReader) 
	  {
   	    throw new IOException("StringJS does not support FileReader parsing for JSON -- but it could...");
	  }
	  return JSON.parse(r);
	} else {
 	 ret = new JSONParser().parse(r);
	}
//  	Platform.timeCheck("JSONUtils.parse1 ", Platform.TIME_MARK);
 	return ret;
  }

  public static Object parse(String json) throws ParseException 
  {
	return (Platform.isJS() ? JSON.parse(json) : new JSONParser().parse(json));
  }

}