import { clamp, lerp } from "~/shared/general.utils";

export const linear = (progress: number): number => progress;
export const ease = (progress: number): number => -(Math.cos(Math.PI * progress) - 1) / 2;

export function useTween(ref: Ref<number>, animation: (progress: number) => number, then: () => void)
{
    let initial = ref.value, current = ref.value, end = ref.value, progress = 0, time = 0, animationFrame: number, stop = true, last = 0;

    function loop(t: DOMHighResTimeStamp)
    {
        const elapsed = t - last;
        progress = clamp(progress + elapsed, 0, time);
        last = t;

        const step = animation(clamp(progress / time, 0, 1));
        current = lerp(initial, end, step);
        then();

        if(progress < time && !stop)
        {
            animationFrame = requestAnimationFrame(loop);
        }
        else
        {
            progress = 0;
            stop = true;
        }
    }

    return {
        stop: () => {
            cancelAnimationFrame(animationFrame);
            stop = true;
        },
        update: (target: number, duration: number) => {
            initial = current;
            time = duration + progress;
            end = target;

            ref.value = target;

            if(stop)
            {
                stop = false;
                last = performance.now();

                loop(performance.now());
            }
        },
        refresh: () => { current = ref.value; },
        current: () => { return current; },
    };
}