Simple Sprite Animator for Unity

[CreateAssetMenu(menuName = "Sprites/Sprite Animation", fileName = "NewSpriteAnimation")]
public class SpriteAnimation : ScriptableObject {

    [System.Serializable]
    public struct Frame {
        public Sprite sprite;
        public int milliseconds;
    }

    public bool loop = false;
    public int cancellableAt = 0;
    public float speed = 1f;
    public Frame[] frames;
}


public class SpriteAnimator : MonoBehaviour {

    [System.Serializable]
    public struct Request {
        public SpriteAnimation animation;
        public float speed;
        public bool loop;
        public int start;
        public int end;
    }


    public SpriteAnimation defaultAnimation;
    public bool playOnAwake;
    public bool ignoreTimescale;
    public bool pause;

    [ReadOnly] public int frame;
    [ReadOnly] public Request currentRequest;
    [ReadOnly] public Request nextRequest;


    SpriteRenderer spriteRenderer;
    float elapsed = 0f;
    float duration;


    void Awake() {
        spriteRenderer = GetComponent<SpriteRenderer>();
    }

    void OnEnable() {
        if (playOnAwake && defaultAnimation != null) { PlayAnimation(defaultAnimation, start: Random.Range(0, defaultAnimation.frames.Length)); }
    }

    void Update() {
        if (currentRequest.animation == null || pause) { return; }

        if (nextRequest.animation != null && frame >= currentRequest.animation.cancellableAt) {
            currentRequest = nextRequest;
            nextRequest.animation = null;
            ChangeFrame(currentRequest.start);
        }

        elapsed += ignoreTimescale ? Time.unscaledDeltaTime : Time.deltaTime;

        if (elapsed >= duration) {
            frame++;

            if (frame > currentRequest.end) {
                if (currentRequest.loop || currentRequest.animation.loop) {
                    frame = currentRequest.start;
                }
                else {
                    PlayAnimation(defaultAnimation);
                    return;
                }
            }

            ChangeFrame(frame);
        }
    }


    public void ChangeFrame(int value) {
        frame = value
        elapsed = 0f;
        duration = currentRequest.animation.frames[frame].milliseconds * 0.001f * (1f / currentRequest.animation.speed) * (1f / currentRequest.speed);
        spriteRenderer.sprite = currentRequest.animation.frames[frame].sprite;
    }

    public void PlayAnimation(SpriteAnimation animation, float speed = 1f, bool loop = false, int start = -1, int end = -1, bool force = false) {
        if (animation == null) {
            Stop();
            return;
        }

        start = start < 0 ? 0 : start;
        end = end < 0 ? animation.frames.Length - 1 : end;

        if (currentRequest.animation == null || frame >= currentRequest.animation.cancellableAt || force) {
            nextRequest.animation = null;
            currentRequest.animation = animation;
            currentRequest.speed = speed;
            currentRequest.loop = loop;
            currentRequest.start = start;
            currentRequest.end = end;
            ChangeFrame(start);
        }
        else {
            nextRequest.animation = animation;
            nextRequest.speed = speed;
            nextRequest.loop = loop;
            nextRequest.start = start;
            nextRequest.end = end;
        }
    }

    public void Stop() {
        currentRequest.animation = null;
        nextRequest.animation = null;
        spriteRenderer.sprite = null;
        frame = -1;
    }
}