Camera shake

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CameraShake : MonoBehaviour {
    public float speed = 1f;
    public float minAmplitude = 0.1f;
    public float maxAmplitude = 1.0f;
    public float minDelay = 0.01f;
    public float maxDelay = 0.1f;
    public int minShakes = 10;
    public int maxShakes = 20;

    Vector2 currentFocus;
    List<ShakeParams> shakes;
    //public bool shaking;




    static CameraShake _instance;
    // Use this for initialization
    void Awake() {
        _instance = this;
    }
    //IEnumerator Start()
    //{
    //    // example usage
    //    CameraShake.GenerateShakes();
    //    yield return new WaitForSeconds(5f);
    //    CameraShake.Shake();
    //}
    void Reset()
    {
        speed = 1f;
        minAmplitude = 0.1f;
        maxAmplitude = 1.0f;
        minDelay = 0.01f;
        maxDelay = 0.1f;
        minShakes = 10;
        maxShakes = 20;
    }

    // Update is called once per frame
    void Update() {
        transform.localPosition = Vector3.Lerp(transform.localPosition, currentFocus, Time.deltaTime * speed);
    }

    public static void GenerateShakes()
    {
        _instance.DoGenerateShakes();
    }

    void DoGenerateShakes()
    {
        shakes = new List<ShakeParams>();
        var total = Random.Range(minShakes, maxShakes);
        for (int i = 0; i < total; i++)
        {
            shakes.Add(new ShakeParams() {
                amplitude = Random.Range(minAmplitude, maxAmplitude),
                timeToMove = Random.Range(minDelay, maxDelay)
            });
        }
    }

    public static void Shake()
    {
        if (_instance.shake != null)
        {
            _instance.StopCoroutine(_instance.shake);
        }
        _instance.shake = _instance.DoShake();
        _instance.StartCoroutine(_instance.shake);
    }
    IEnumerator shake;
    IEnumerator DoShake()
    {
        //shaking = true;
        foreach (var shake in shakes)
        {
            currentFocus = Random.insideUnitCircle * shake.amplitude;
            yield return new WaitForSeconds(shake.timeToMove);
        }
        //shaking = false;
        currentFocus = new Vector2();
    }

    [System.Serializable]
    public struct ShakeParams
    {
        public float amplitude;
        public float timeToMove;

    }
}