AI Avoiding Obstacles!

I need help making an AI. It's working really great, but the AI is not avoiding walls, obstacles etc. If the enemy is on the right side of the wall, and im on the left, the enemy will keep trying to go throughout the wall (Will be still facing me instead of avoiding the wall).

Can somebody edit the script to make it avoid things?

  var target : Transform;
  var gravity : float = 20;
  var moveSpeed : float = 6;  // chase speed
  var rotSpeed : float = 90;  // speed to turn to the player (degrees/second)
  var attackDistance : float = 2;  // attack distance
  var detectRange : float = 20;  // detection distance
  var otherObj : GameObject;
  var otherObj2 : GameObject;
  var dangermusic : GameObject;
  var BipedMesh : GameObject;
  var Bipedv : GameObject;
  var AllFourv : GameObject;
  
  private var transf : Transform;
  private var character: CharacterController; 
  
  function Start () { 
      if (!target) target = GameObject.FindWithTag ("Player").transform; 
      transf = transform;
      character = GetComponent(CharacterController);
  }
  
  function Update(){
      if (target){
          var tgtDir = target.position - transf.position;
          var tgtDist = tgtDir.magnitude; // get distance to the target
          if (!Physics.Raycast(transf.position, tgtDir, detectRange)){
              // stays in idle mode if can't see target
              Idle(); 
          }
          else {
              var moveDir = target.position - transf.position;
              moveDir.y = 0;  // prevents enemy tilting
              rot = Quaternion.FromToRotation(Vector3.forward, moveDir);
              transf.rotation = Quaternion.RotateTowards(transf.rotation, rot, rotSpeed * Time.deltaTime);
              if (tgtDist <= attackDistance){  // if dist <= attackDistance: stop and attack
                  // do your attack here
                  print("Attack!");
                  otherObj2.animation.Play();
                  BipedMesh.animation.Play("devmesh2");
                  otherObj.animation.Play("phoenixfreeroamjp");                                      
              }
              else {  // if attackDistance < dist < detectRange: chase the player
                  // Move towards target
                  MoveCharacter(moveDir, moveSpeed);
                  audio.volume = 1.0;
                  dangermusic.audio.volume = 0.0;
              }
          }
      }
  }
  
  var walkSpeed = 3.0; 
  var travelTime = 2.0; 
  var idleTime = 1.5;
  var rndAngle = 45;  // enemy will turn +/- rndAngle
  
  private var timeToNewDir = 0.0;
  private var turningTime = 0.0;
  private var turn: float;
  
  function Idle () { 
      // Walk around and pause in random directions 
      if (Time.time > timeToNewDir) { // time to change direction?
          turn = (Random.value > 0.5)? rndAngle : -rndAngle; // choose new direction
          turningTime = Time.time + idleTime; // will stop and turn during idleTime...
          timeToNewDir = turningTime + travelTime;  // and travel during travelTime 
      }
      if (Time.time < turningTime){ // rotate during idleTime...
          transform.Rotate(0, turn*Time.deltaTime/idleTime, 0);
      } else {  // and travel until timeToNewDir
          MoveCharacter(transform.forward, walkSpeed);
          audio.volume = 0.0;
          dangermusic.audio.volume = 1.0;       
          Bipedv.renderer.enabled = true;
          AllFourv.renderer.enabled = false;
      }
  }
  
  function MoveCharacter(dir: Vector3, speed: float){
  
      var vel = dir.normalized * speed;  // vel = velocity to move 
      // clamp the current vertical velocity for gravity purpose
      vel.y = Mathf.Clamp(character.velocity.y, -30, 2); 
      vel.y -= gravity * Time.deltaTime;  // apply gravity
      character.Move(vel * Time.deltaTime);  // move   
      Bipedv.renderer.enabled = false;
      AllFourv.renderer.enabled = true;
  }