import { Comp, Layer } from 'expression-globals-typescript';

const version = '_npmVersion';
const thisComp = new Comp();
const thisLayer = new Layer();
let thisProperty;

function get_functions(time: number = thisLayer.time)
{
	function get_key_index(forward = false, input_property = thisProperty)
	{
		let n = 0;
		if (input_property.numKeys > 0)
		{
			n = input_property.nearestKey(time).index;
			if      (input_property.key(n).time >  time && !forward) n--;
			else if (input_property.key(n).time <= time &&  forward) n++;
		}
		return Math.min(n, input_property.numKeys);
	}

	function angle_offset(rot: number, pos: number)
	{
		rot = thisLayer.degreesToRadians(rot - 90);
		const x = Math.cos(rot);
		const y = Math.sin(rot);
	
		return [pos*x, pos*y];
	}

	// https://gist.github.com/animoplex/aafd6a157282351c8dfeea385d969ef2
	function inertial_bounce(amp: number, freq: number, decay: number, input_property = thisProperty)
	{
		const n = get_key_index();
		let t = 0;

		if (n != 0)
		{
			t = time - input_property.key(n).time;
		}

		if (n > 0 && t < 1)
		{
			const v = input_property.velocityAtTime(input_property.key(n).time - thisComp.frameDuration/10);
			return input_property.value + v * (amp / 100) * Math.sin(freq * t * 2 * Math.PI) / Math.exp(decay*t);
		}
		else
		{
			return t;
		}
	}

	const YTPMV = {
		flip: function(input_property = thisProperty, mult = 100)
		{
			const n = get_key_index(undefined, input_property);
			return (n % 2 != 0 || n == 0) ? 1*mult : -mult;
		},

		time_reset: function(input_property = thisProperty)
		{
			const n = get_key_index(undefined, input_property);
			return (n > 0) ? time - input_property.key(n).time : 0;
		}
	};

	return {
		get_key_index,
		angle_offset,
		inertial_bounce,
		YTPMV
	};
}

export {
	version,
	get_functions
};