Help Controlling Servo with Button

I’m new to Arduino and I need help, tweaking my code. I need the servo to turn 180 to 0 on the initial press. Then when pressed again, I need the servo to go from 0 back to 180. So far all I have is the servo to go from 180 to 0 on the first press but wont go back on another press or at all (we have to manually wind it back and press again). Im also using an arduino uno

#include <Servo.h>

Servo servo1;      
const int BUTTON = 4;    
                          
int val = 0; 

int old_val = 0; 

int state = 0;  
void setup() {
  servo1.attach(7);  
  pinMode(BUTTON, INPUT); 
  digitalWrite(4, HIGH);
}

void loop() {
 val - digitalRead(BUTTON);   
                              
 
  if ((val == HIGH) && (old_val == LOW)){
    state = 1 - state;                            
  }
  old_val = val; 

   if (state == 1) {
    servo1.write(0);  
   } else {
    servo1.write(180);
   }
   }

I reckon this

val - digitalRead(BUTTON);

should be

val = digitalRead(BUTTON);

…R