Add a new script to the Enemy node

Add variables for

Speed
Gravity
Facing direction

In physics process add gravity

Move the enemy

Flip the sprite to face direction of travel

Call move and slide to register collisions

Check if any collision was with the player

If it was call the hurt function

If the normal is not 0, we have hit a wall

Bounce the enemy off the wall

Finally, if the enemy falls of a platform

Destroy it

You can add a constant for this

In the Enemy script

In physics process

Keep the detector ahead of the enemy

Create a function

To turn the Enemy

Add a check in physics process

To look for ledges