#include <Wire.h>
#include <EEPROM.h>

// EEPROM settings
#define ADDR_EEPROM_LOC 0
#define EEPROM_SIZE 64

// Relay pins: GPIO0 to GPIO7
const int relayPins[8] = {0, 1, 2, 3, 4, 5, 6, 7}; // GPIOs 0-7

uint8_t i2cAddress;

// Unified I2C receive event
void receiveEvent(int howMany) {
  if (howMany >= 2) {
    uint8_t first = Wire.read();
    uint8_t second = Wire.read();

    // Check for address change command
    if (first == 0xAA) {
      // Change I2C address and store in EEPROM
      uint8_t newAddr = second;
      EEPROM.write(ADDR_EEPROM_LOC, newAddr);
      EEPROM.commit();
      Serial.print("I2C address changed to: 0x");
      Serial.println(newAddr, HEX);
      delay(100);
      ESP.restart();
      return;
    }

    // Otherwise, treat as relay control
    int relay = first;   // Relay number: 1-8
    int state = second;  // State: 1=ON, 0=OFF
    if (relay >= 1 && relay <= 8) {
      digitalWrite(relayPins[relay - 1], state ? LOW : HIGH); // Active LOW relays
    }
  }
}

void setup() {
  Serial.begin(115200);
  EEPROM.begin(EEPROM_SIZE);

  // Read I2C address from EEPROM or use default
  i2cAddress = EEPROM.read(ADDR_EEPROM_LOC);
  if (i2cAddress == 0xFF || i2cAddress == 0) i2cAddress = 0x08; // Default address

  Serial.print("Using I2C address: 0x");
  Serial.println(i2cAddress, HEX);

  // Initialize relay pins
  for (int i = 0; i < 8; i++) {
    pinMode(relayPins[i], OUTPUT);
    digitalWrite(relayPins[i], HIGH); // Relays OFF initially (active LOW)
  }

  // Start I2C slave
  Wire.begin(i2cAddress);
  Wire.onReceive(receiveEvent);
}

void loop() {
  // Nothing needed here for basic operation
}