// Pin Definitions
const int crankPin = 2;          // Crank sensor (digital input)
const int camPin = 3;            // Cam sensor (digital input)
const int coil1 = 8;             // Ignition coil 1
const int coil2 = 9;             // Ignition coil 2
const int fuelPump = 10;         // Fuel pump control
const int injectors[] = {4,5,6,7}; // Injectors 1,3,4,2 (pins 4=inj1, 5=inj3, 6=inj4, 7=inj2)
const int fanRelay = 11;         // Cooling fan control
const int ntcPin = A0;           // Temperature sensor
const int airSensorPin = A1;     // Air sensor (MAP/MAF)

// Engine parameters
volatile unsigned long crankTime;
volatile unsigned int rpm;
volatile int enginePosition;
volatile bool synced = false;
int injectorSequence[4] = {0,2,3,1}; // Order 1,3,4,2 (indexes injectors array)
int currentInjector = 0;

// Timing variables
unsigned long lastCrankUpdate;
unsigned int dwellTime = 3000;   // Coil dwell time in microseconds
unsigned int pulseWidth = 2000;  // Injector pulse width in microseconds

// Temperature control
float temperature;
const float fanOnTemp = 95.0;    // Fan activation temperature (°C)

void setup() {
  // Initialize I/O pins
  pinMode(crankPin, INPUT);
  pinMode(camPin, INPUT);
  pinMode(coil1, OUTPUT);
  pinMode(coil2, OUTPUT);
  pinMode(fuelPump, OUTPUT);
  for(int i=0; i<4; i++) pinMode(injectors[i], OUTPUT);
  pinMode(fanRelay, OUTPUT);

  // Attach interrupts
  attachInterrupt(digitalPinToInterrupt(crankPin), crankEvent, RISING);
  attachInterrupt(digitalPinToInterrupt(camPin), camEvent, RISING);

  // Initial states
  digitalWrite(fuelPump, HIGH);   // Run fuel pump
  Serial.begin(115200);           // For debugging
}

void loop() {
  // Update RPM calculation
  if((millis() - lastCrankUpdate) > 100) rpm = 0;

  // Read sensors
  temperature = readTemperature();
  controlFan(temperature);
  
  // Calculate engine parameters
  calculateFuel();
  calculateIgnition();

  // Basic fuel pump control
  digitalWrite(fuelPump, rpm > 100 ? HIGH : LOW);
}

// Interrupt Service Routines
void crankEvent() {
  unsigned long now = micros();
  rpm = 60000000 / (now - crankTime); // RPM calculation
  crankTime = now;
  lastCrankUpdate = millis();
  
  if(synced) {
    handleIgnition();
    handleInjection();
  }
}

void camEvent() {
  enginePosition = 0;  // Reset engine position
  synced = true;       // Engine is synchronized
}

// Injection control
void handleInjection() {
  static unsigned long lastInjTime;
  
  if((micros() - lastInjTime) > pulseWidth) {
    // Turn off previous injector
    digitalWrite(injectors[injectorSequence[currentInjector]], LOW);
    
    // Move to next injector in sequence
    currentInjector = (currentInjector + 1) % 4;
    
    // Activate current injector
    digitalWrite(injectors[injectorSequence[currentInjector]], HIGH);
    lastInjTime = micros();
  }
}

// Ignition control
void handleIgnition() {
  static bool fireCoil1 = false;
  
  if(fireCoil1) {
    digitalWrite(coil1, HIGH);
    delayMicroseconds(dwellTime);
    digitalWrite(coil1, LOW);
  } else {
    digitalWrite(coil2, HIGH);
    delayMicroseconds(dwellTime);
    digitalWrite(coil2, LOW);
  }
  
  fireCoil1 = !fireCoil1; // Alternate coils
}

// Temperature functions
float readTemperature() {
  int raw = analogRead(ntcPin);
  // Convert analog reading to temperature (implement proper Steinhart-Hart equation)
  return (raw * 0.48876) - 50.0; // Example conversion
}

void controlFan(float temp) {
  digitalWrite(fanRelay, temp > fanOnTemp ? HIGH : LOW);
}

// Fuel calculation (simplified)
void calculateFuel() {
  int airValue = analogRead(airSensorPin);
  // Basic fuel calculation (needs proper algorithm)
  pulseWidth = map(airValue, 0, 1023, 1000, 10000);
  pulseWidth = constrain(pulseWidth, 1000, 10000);
}

// Ignition calculation (simplified)
void calculateIgnition() {
  // Basic dwell time adjustment by RPM
  dwellTime = constrain(3000 - (rpm/100), 1000, 3000);
}