#include <LedControl.h>

// Pin configuration for MAX7219
// DIN to pin 12, CLK to pin 11, CS to pin 10
LedControl lc = LedControl(12, 11, 10, 1); // (dataPin, clkPin, csPin, numDevices)

float num1, num2, result;
char operation;

void setup() {
  // Initialize MAX7219
  lc.shutdown(0, false);  // Wake up display
  lc.setIntensity(0, 8);  // Set brightness (0-15)
  lc.clearDisplay(0);     // Clear display
  
  Serial.begin(9600);
  
  // Display "CALC" on startup
  displayString("CALC");
  delay(2000);
  lc.clearDisplay(0);
}

void loop() {
  displayString("NUM1");
  while(Serial.available() == 0) {}
  num1 = Serial.parseFloat();
  displayNumber(num1);
  delay(1000);
  
  displayString("OPER");
  while(Serial.available() == 0) {}
  operation = Serial.read();
  displayChar(operation);
  delay(1000);
  
  displayString("NUM2");
  while(Serial.available() == 0) {}
  num2 = Serial.parseFloat();
  displayNumber(num2);
  delay(1000);
  
  switch(operation) {
    case '+': result = num1 + num2; break;
    case '-': result = num1 - num2; break;
    case '*': result = num1 * num2; break;
    case '/': 
      if(num2 != 0) result = num1 / num2;
      else {
        displayString("ERR");
        delay(2000);
        return;
      }
      break;
    default:
      displayString("ERR");
      delay(2000);
      return;
  }
  
  displayString("RES");
  delay(1000);
  displayNumber(result);
  delay(5000);
  lc.clearDisplay(0);
}

// Function to display numbers on 7-segment
void displayNumber(float number) {
  lc.clearDisplay(0);
  char numStr[8];
  dtostrf(number, 7, 2, numStr); // Convert float to string with 2 decimal places
  
  // Remove leading spaces and display
  int startPos = 7;
  for(int i = 0; i < 8 && numStr[i] != '\0'; i++) {
    if(numStr[i] != ' ') {
      if(numStr[i] == '-') {
        lc.setChar(0, startPos, '-', false);
        startPos--;
      }
      else if(numStr[i] == '.') {
        lc.setLed(0, startPos+1, 7, true); // Set decimal point
      }
      else {
        lc.setDigit(0, startPos, numStr[i] - '0', false);
        startPos--;
      }
    }
  }
}

// Function to display strings (limited characters)
void displayString(const char* str) {
  lc.clearDisplay(0);
  int len = strlen(str);
  for(int i = 0; i < len && i < 8; i++) {
    lc.setChar(0, 7-i, str[i], false);
  }
}

// Function to display single character
void displayChar(char c) {
  lc.clearDisplay(0);
  lc.setChar(0, 7, c, false);
}