/**
 * Flattens complex objects
 *
 * Original code from Muthu Krishnan
 * https://stackoverflow.com/questions/44134212
 * with modifications and additions from Stefan Schnell
 */
function flattenObject(obj) {

  var flatObj = {};

  for (var key in obj) {

    if ((typeof obj[key]) === "object" && obj[key] !== null) {

      if (obj[key] instanceof Date) {
        flatObj[key] = new Date(obj[key]);
      } else {
        var flatObject = flattenObject(obj[key]);
        if (Object.keys(flatObject).length > 0) {
          for (var flatKey in flatObject) {
            // Hint: Not every character works here
            flatObj[key + '$' + flatKey] = flatObject[flatKey];
          }
        } else {
          flatObj[key] = obj[key];
        }
      }

    } else {
      flatObj[key] = obj[key];
    }

  }

  return flatObj;

}

// Main

var obj = {
  a : 1,
  b : {
    ba : 2,
  },
  c : [1, 2, 3],
  d : [
    {
      da : ['da1', 'da2', 'da3'],
    },
    {
      db : ['db1', 'db2', 'db3'],
    },
    {
      dc : [
        {
          dca : ['dca1', 'dca2', null],
        },
      ],
    },
    null,
    undefined,
    NaN,
    0,
    '',
    ['a', 'b', ['c', 'd'], ['e', 'f']],
    [
      {
        dda : 1,
      },
      {
        ddb : 1,
      },
    ],
  ],
  e : [true, false],
  f : [[1, 2]],
  g : function() {
    return "Hello World";
  },
  h : new Date(),
  i : [],
  j : {},
  z : "End"
};

var newObj = flattenObject(obj)

System.log(JSON.stringify(newObj));

// Hint: Undefined, function and symbol values are omitted by stringify.
// Infinity and NaN, as well as the value null, are all considered null.
/* result =>
{
  "a":1,
  "b$ba":2,
  "c$0":1,
  "c$1":2,
  "c$2":3,
  "d$0$da$0":"da1",
  "d$0$da$1":"da2",
  "d$0$da$2":"da3",
  "d$1$db$0":"db1",
  "d$1$db$1":"db2",
  "d$1$db$2":"db3",
  "d$2$dc$0$dca$0":"dca1",
  "d$2$dc$0$dca$1":"dca2",
  "d$2$dc$0$dca$2":null,
  "d$3":null,"d$5":null,
  "d$6":0,
  "d$7":"",
  "d$8$0":"a",
  "d$8$1":"b",
  "d$8$2$0":"c",
  "d$8$2$1":"d",
  "d$8$3$0":"e",
  "d$8$3$1":"f",
  "d$9$0$dda":1,
  "d$9$1$ddb":1,
  "e$0":true,
  "e$1":false,
  "f$0$0":1,
  "f$0$1":2,
  "h":"2023-05-31T15:53:48.684Z",
  "i":[],
  "j":{},
  "z":"End"
}
*/