On edit of a row in google sheet execute a formula on the data of set row and paste the result of the formula in the first column of set row

Question

I am making a database of items . As items will be edited by many people I would like formulas to be hidden so people would not manipulate them easily compromising the database.

I tried to edit a script that recognizes any edit within a row and execute a formula on column values of set row pasting the result of the formula in column A of set row.

As I am very new to google app script I don't know how to proceed and many examples I have looked through don't do what I want.

I hope what I have written is clear.

Thanks in advance for any help!

Here is the code I wrote:

function onEdit(e) {
  // Your sheet params
  var sheetName = "Sheet1";
  var ModifiedColumnIndex = 1;
  var ModifiedColumnLetter = 'A';


  var range = e.range; // range just edited
  var sheet = range.getSheet();
  if (sheet.getName() !== sheetName) {
    return;
  }

  // If the column isn't our source column
  if (range.getColumn() != ModifiedColumnIndex) { 
    var row = range.getRow();
  // Formula to be executed on the edited rows cells  
    var formula = sheet + row [lower[trim(B&" "&C&" "&D&" "&E&" "&F&" "&G&" ["&I&"]"]])
    var ModifiedRange = sheet.getRange(ModifiedColumnLetter + row.toString());
  //Inserting formula into column A                               
    ModifiedRange.setValue(formula);
  };
 };