var Calculator = {
  init: function() {
    this.output = document.getElementById('output');
    this.resultText = '';
    this.resultNumber = 0;
  },

  onClick: function(e) {
    console.log(e.target.innerHTML);
    const buttonText = e.target.innerHTML;
    switch(buttonText) {
      case '+': this.operationPlus(buttonText); break;
      case '-': this.operationMinus(buttonText); break;
      case '*': this.operationMultiply(buttonText); break;
      case '÷': this.operationDevide(buttonText); break;
      case '=': this.operationEval(); break;
      default: this.operationInputNumber(buttonText);
    }
  },

  printText: function(text) {
    this.output.value = text;
  },

  printResult: function() {
    this.printText(this.resultText);
  },

  operationEval: function() {
    this.resultText = String(this.resultNumber);
    this.printResult();
  },

  operationPlus: function(buttonText) {
    if (!this.isNumberInput) {
      this.resultNumber += this.lastNumber;
    }

   this.lastNumber = Number(this.resultText);
   this.printText(buttonText);
   this.isNumberInput = false;
  },

  operationMinus: function() {},

  operationMultiply: function() {},

  operationDevide: function() {},

  operationInputNumber: function(buttonText) {
    if (!this.isNumberInput) {
      this.resultText = '';
    }

    this.isNumberInput = true;
    this.resultText += buttonText;
    this.printResult();
  }

}n