GameObject transform relative camera

 using UnityEngine;
 using System.Collections;
 public class SCR_PLAYER_MOV : MonoBehaviour
 {
     public int playerSpeed = 10;
     // Use this for initialization
     void Start()
     {}
     // Update is called once per frame
     void Update()
     {
         float left = Camera.main.ViewportToWorldPoint(new Vector3(0, 0, 0)).x;
         float right = Camera.main.ViewportToWorldPoint(new Vector3(1, 0, 0)).x;
 
         float amountToMove = Input.GetAxisRaw("Horizontal") * playerSpeed * Time.deltaTime;
         transform.Translate(Vector3.right * amountToMove);
 
         if (transform.position.x <= left)
         {
             transform.position = new Vector3(left, transform.position.y, transform.position.z);
         }
         else if (transform.position.x >= right)
         {
             transform.position = new Vector3(right, transform.position.y, transform.position.z);
         } 
     }
 }

I'm trying to get the gameobject to be restrained at the boundaries of the main camera, but it clips past it (I used a mediocre solution with a another gameobject and hardcoding). I'm also looking for a solution that keeps the object within the limit relative to the resolution and aspect ratio.

I'm not looking for someone to give me the full code, just enough for me to solve the problem.