var spreadsheet;
var sheet;
var range;
var values;
var url;

function DataMap(url){
  load(url);
  this.url = url;

  this.getURL = function(){
    return url;
  };

  this.setURL = function(urlNew){
    url = urlNew;
  }
}

function get(key) {
  load();
  for (var row in values) {
    if((values[row][0] == key)){
      return values[row][1];
    }
 }
}

function set(key, value) {
  for(j = 1; j < sheet.getMaxRows(); j++){
    if(sheet.getRange(j, 1).getValue() == key)
    {
      sheet.getRange(j, 2).setValue(value);
      return;
    }
  }
  //the key is not existent so add to a new row
  for(i = 1; i < sheet.getMaxRows(); i++){
      if(sheet.getRange(i, 1).getValue() == "" && sheet.getRange(i, 2).getValue() == "")
      {
        sheet.getRange(i, 1).setValue(key);
        sheet.getRange(i, 2).setValue(value);
        return;
      }
  }
}

//loads spreedsheet and values
function load(url){
  spreadsheet = SpreadsheetApp.openByUrl(url);
  sheet = spreadsheet.getSheets()[0];
  range = sheet.getRange(1, 1, sheet.getMaxRows(), 2);
  values = range.getValues();
}