How to Control AC Load With Bluetooth

#define r1 5
int relay1 = LOW;
#define r2 6
int relay2 = LOW;
#define r3 7
int relay3 = LOW;
#define r4 8
int relay4 = LOW;

void setup() {
Serial.begin(9600);
    pinMode(r1, OUTPUT); 
    pinMode(r2, OUTPUT);
    pinMode(r3, OUTPUT); 
    pinMode(r4, OUTPUT);
 }

void loop() {
  // put your main code here, to run repeatedly:
 if(Serial.available()>0) 
   {     
      char data= Serial.read(); // reading the data received from the bluetooth module
      switch(data)
      {
        case 'a':
            digitalWrite(r1,0);
            digitalWrite(r2,0);  //all off
            digitalWrite(r3,0);
            digitalWrite(r4,0);
            delay(250);
            break;        
            case 'b':
            relay1 = ~ relay1;
            digitalWrite(r1,relay1);
            delay(250);
            break;
            case 'c':
            relay2 = ~ relay2;
            digitalWrite(r2,relay2);
            delay(250);
            break;
            case 'd':
            relay3 = ~ relay3;
            digitalWrite(r3,relay3);
            delay(250);
            break;
            case 'e':
            relay4 = ~ relay4;
            digitalWrite(r4,relay4);
            delay(250);
            break;
      }
      Serial.println(data);
   }
   delay(50);
}