/**
 * Write a calculator than can execute three operations:
 * - "add"     : to sum up a list of integer numbers
 * - "count"   : to count the amount of substrings in a larger string
 * - "weekday" : to specify the week day of a given date, where 1=Sunday, 2=Monday, ...
 *
 * The input for the calculator is given as a JSON string that needs to be parsed. Each string only 
 * contains one command. The output for each calculation is just a long number of the result.
 *
 * Examples for the three operations in JSON are:
 * - {"operator":"add", "operands":[5,8,-3]}" to add the 5+8+(-3). Result: 10
 * - {"operator":"count", "text":"abbaabbababb", "searchToken":"bb"} to count the "bb" is the string. Result: 3
 * - {"operator":"weekday", "date":"1976-03-12"} to extract Friday, thus Result: 6
 * 
 * Hint:
 * - You may use any of the installed libraries: JSON-Simple, JUnit 4 and Apache Commons Lang3.
 * - If needed, you are allowed to use the internet to search for documentations and code snippets. 
 * - You can run your code as often as you like by pressing "Run" in the lower left corner of this screen.
 * - When everything is correct, the result 10 / 3 / 6 should appear on the console.
 * - Try to use clean coding techniques as much as possible to create a good readable source code.
 *
 * Last remark: All actions you perform in this screen are recorded for a later review by CAS.
 * Please send an email back to CAS as soon as you have finished.
 */

import java.io.*;
import org.json.simple.*;
import org.json.simple.parser.*;
// TODO: add additional imports if needed

class Calculator {
	public static void main (String[] args) throws Exception {
    String[] expressions = new String[3];    
    expressions[0] = "{\"operator\":\"add\",\"operands\":[5,8,-3]}";
    expressions[1] = "{\"operator\":\"count\",\"text\":\"abbaabbababb\",\"searchToken\":\"bb\"}";
    expressions[2] = "{\"operator\":\"weekday\",\"date\":\"1976-03-12\"}";
    
    for (int i = 0; i < expressions.length; i++) {
      long result = execute(expressions[i]);
      System.out.println(result);
    }
  }
    
  private static long execute(String jsonExpression) throws Exception {
    // TODO: Put in your code here.     
    return 0;       
  }  
  
  // TODO: Add additional helper methods here if needed.
}