import { clamp } 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)
{
    // State variables for animation
    let initial = ref.value;
    let current = ref.value;
    let end = ref.value;
    let animationFrame: number;
    let stop = true;
    let last = 0;
    
    // Velocity tracking with sign preservation
    let velocity = 0;
    const velocityDecay = 0.92;  // Slightly faster decay for more responsive feel
    
    function loop(t: DOMHighResTimeStamp) {
        // Cap the elapsed time to prevent jumps during lag or tab switches
        const elapsed = Math.min(t - last, 32);
        last = t;
        
        // Update velocity considering the sign of the movement
        velocity = velocity * velocityDecay + (end - current) * (1 - velocityDecay);
        
        // Apply velocity to current position
        // Normalize by elapsed time to maintain consistent speed regardless of frame rate
        current = clamp(current + velocity * (elapsed / 16), initial, end);

        if(current === end)
            stop = true;
        
        // Trigger callback
        then();
        
        // Continue animation if not stopped
        if (!stop) {
            animationFrame = requestAnimationFrame(loop);
        }
    }
    
    return {
        stop: () => {
            cancelAnimationFrame(animationFrame);
            stop = true;
            velocity = 0;  // Reset velocity when stopping
        },
        update: (target: number, duration: number) => {
            if (stop) {
                // Only reset initial position when starting a new animation
                initial = current;
                last = performance.now();
            }
            
            end = target;
            
            if (stop) {
                stop = false;
                loop(performance.now());
            }
        },
        refresh: () => {
            current = ref.value;
            velocity = 0;  // Reset velocity on refresh
        },
        current: () => current,
    };
}