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

#define DEFAULT_ADDRESS 0x08
#define MAX_NAME_LENGTH 24

// EEPROM Structure
struct Config {
  uint8_t address;
  char deviceName[MAX_NAME_LENGTH+1];
  uint8_t relayStates;
};

Config config;
const int relayPins[8] = {0, 1, 2, 3, 4, 5, 6, 7}; // GPIOs 0-7

void handleCommand(int numBytes);
void saveConfig();
void loadConfig();
void emergencyStop();

void setup() {
  Serial.begin(115200);
  EEPROM.begin(sizeof(Config));
  loadConfig();
  
  // Initialize relays
  for(int i=0; i<8; i++) {
    pinMode(relayPins[i], OUTPUT);
    digitalWrite(relayPins[i], HIGH); // Active-low logic
  }
  
  Wire.onReceive(handleCommand);
  Wire.onRequest([]() {
    String response = String(config.address) + ",8-relay," + 
                     config.deviceName + "," + 
                     String(config.relayStates, BIN);
    Wire.print(response);
  });
  
  Wire.begin((uint8_t)config.address);
}

void loop() { /* Empty */ }

void handleCommand(int numBytes) {
  uint8_t cmd = Wire.read();
  
  switch(cmd) {
    case 0xA0: // Set relay state
      if(numBytes == 3) {
        uint8_t relay = Wire.read();
        uint8_t state = Wire.read();
        if(relay < 8) {
          digitalWrite(relayPins[relay], state ? LOW : HIGH);
          bitWrite(config.relayStates, relay, state);
        }
      }
      break;
      
    case 0xB0: // Emergency stop
      emergencyStop();
      break;
      
    case 0xC0: // Set address
      if(numBytes == 2) {
        config.address = Wire.read();
        saveConfig();
        Wire.begin((uint8_t)config.address);
      }
      break;
      
    case 0xD0: // Set device name
      if(numBytes > 1) {
        uint8_t i = 0;
        while(Wire.available() && i < MAX_NAME_LENGTH) {
          config.deviceName[i++] = Wire.read();
        }
        config.deviceName[i] = '\0';
        saveConfig();
      }
      break;
  }
}

void emergencyStop() {
  for(int i=0; i<8; i++) {
    digitalWrite(relayPins[i], HIGH);
  }
  config.relayStates = 0;
}

void loadConfig() {
  EEPROM.get(0, config);
  if(config.address < 0x08 || config.address > 0x77) {
    config.address = DEFAULT_ADDRESS;
    strcpy(config.deviceName, "8-Relay Module");
    saveConfig();
  }
}

void saveConfig() {
  EEPROM.put(0, config);
  EEPROM.commit();
}