Check for collision with wall and move in a new direction

I made a post similar to this but it seems to be dead and being as I have new version of code I thought it would be best to explain in more detail.

The problem is that my code doesnt seem to work - the cube moves through the wall somtimes and other times freezes after hitting a wall.

Goal:
To automate the movement of a cube within a enclosed area with four walls. If it collides with a wall the cube should move in a new random direction. It can only move forward/backward , and digonally.

My approach:

Check for collisions:

Code (csharp):

1.  
2. function OnTriggerEnter (hit: Collider)
3.  
4.  
5. {
6.     if(hit.gameObject.tag == "wall")
7.  
8.    
9.     {
10. //rotate in new direction
11. transform.rotation = Quaternion.AngleAxis(180, Vector3.up);
12. FishAI.directionAvailable = false;
13.     }  
14.     else
15.     {
16.         FishAI.directionAvailable = true;      
17.  
18.     }
19.    
20. }
21.  

Then generate a random direction and move in that direction:

Code (csharp):

1.  
2. static var directionAvailable = false;
3. static var randomNumber: int;
4.  
5.  
6. function Awake()
7. {
8. //print ("no collision as of yet");
9.    
10. }  
11.  
12.  
13.  
14. function Update () {
15.    
16.  
17. if (directionAvailable == false)
18.     {
19.         //randomNumber = (Random.Range(1, 4));
20.         randomNumber = (randomNumber + Random.Range(1, 3)) % 3;
21.         print (randomNumber);
22.         directionAvailable = true;
23.        
24.     }
25.    
26.  
27.    
28.     //Use values obtained from above to move Fish
29.     //forward
30. if (randomNumber == 1)
31.     {
32.         transform.position.x += 0.04;
33.        
34.     }
35.    
36. // left diagonal
37. if (randomNumber == 2)
38.     {
39.     transform.position.z += 0.04;
40.     transform.position.x += 0.04;
41.     }
42.    
43.  
44. // Right Diagonal
45.  
46. if (randomNumber == 3)
47.     {
48.     transform.position.z += 0.04;
49.     transform.position.x -= 0.04;
50.     }
51.    
52.    
53.    
54.    
55. }
56.  

It might be worth me starting from scratch?

 

Generally, triggers work much better as stationery objects than they do when they move. You will probably get better results by using a normal collider with your object and using OnCollisionEnter to tell you when it runs into a wall. Also, make sure the moving objects each have a rigidbody component with the Is Kinematic property switched on.