Adjust object rotation based on player direction

I'm trying to create a 2D top-down shooter. I want to setup a way for the player to hold the gun in the direction of the which he is moving in. For example, if the player is holding the W and A keys, his gun point in the top right direction. As he switches between directions, the gun also switches smoothly. If the player is going up at a straight angle (Ex. Holding W key), the whole player switches direction.

I have managed to replicate this but only in 6 directions. However, I want to make it smooth with the player movement and in all other directions.

I know there has to be a simple answer to this, I just can't figure it out. Here is my code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerController : MonoBehaviour
 {
     [Header("Character Attributes:")]
     public float movementBaseSpeed = 1.0f;
 
     [Space]
     [Header("Weapon Statistics:")]
     public float upwardSideAngle = 30f;
     public float downwardSideAgnle = -30f;
     public float idleAngle = -10f;
 
     [Space]
     [Header("Character Statistics:")]
     public Vector2 currentMovementDirection;
     public float currentMovementSpeed;
 
     [Space]
     [Header("References:")]
     public Rigidbody2D rb;
     public Animator animator;
     public GameObject weapon;
 
     // Update is called once per frame
     void Update()
     {
         ProcessInputs();
         Move();
         Animate();
         MoveAim();
     }
 
     void ProcessInputs()
     {
         currentMovementDirection = new Vector2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical"));
         currentMovementSpeed = Mathf.Clamp(currentMovementDirection.magnitude, 0.0f, 1.0f);
         currentMovementDirection.Normalize();
     }
 
     void Animate()
     {
         if (currentMovementDirection != Vector2.zero)
         {
             animator.SetFloat("Horizontal", currentMovementDirection.x);
             animator.SetFloat("Vertical", currentMovementDirection.y);
         }
         animator.SetFloat("Magnitude", currentMovementDirection.magnitude);
     }
 
     void Move()
     {
         rb.velocity = currentMovementDirection * currentMovementSpeed * movementBaseSpeed;
     }
 
     void MoveAim()
     {
         //When player is moving left
         if(currentMovementDirection.x < 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0, 180, 0);
         }
         //When player is moving right
         else if(currentMovementDirection.x > 0)
         {
             weapon.transform.rotation = Quaternion.identity;
         }
         //When player is moving top right
         if(currentMovementDirection.y > 0 && currentMovementDirection.x > 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0f, 0f, upwardSideAngle);
         }
         //When player is moving bottom right
         if(currentMovementDirection.y < 0 && currentMovementDirection.x > 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0f, 0f, downwardSideAgnle);
         }
         //When player is moving top left
         if(currentMovementDirection.y > 0 && currentMovementDirection.x < 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0, 180, upwardSideAngle);
         }
         //When player is moving bottom left
         if (currentMovementDirection.y < 0 && currentMovementDirection.x < 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0, 180, downwardSideAgnle);
         }
         //When player is standing still
         if (currentMovementDirection.y == 0 && currentMovementDirection.x == 0)
         {
             weapon.transform.rotation = Quaternion.Euler(0f, 0f, idleAngle);
         }
     }
 }