import { h } from 'preact';
import { useRef, useLayoutEffect } from 'preact/hooks';

export const Links = ({ links, ...props }) => {
	const canvas = useRef(null);

	useLayoutEffect(() => {
		const ctx = canvas.current.getContext('2d');
		ctx.lineWidth = 4;
		ctx.lineCap = 'round';
		ctx.lineJoin = 'round';
		ctx.strokeStyle = '#696969';
		ctx.fillStyle = '#696969';
		ctx.shadowBlur = 2;
		ctx.shadowOffsetX = 2;
		ctx.shadowOffsetY = 4;

		ctx.clearRect(0, 0, canvas.current.width, canvas.current.height);

		for (const points of links) {
			ctx.shadowColor = 'rgba(0,0,0, 0.7)';
			ctx.beginPath();
			ctx.moveTo(...points[1]);
			for (let i = 4; i < points.length; i += 3) {
				const [ax, ay] = points[i - 2];
				const [bx, by] = points[i - 1];
				const [x, y] = points[i];
				ctx.bezierCurveTo(ax, ay, bx, by, x, y);
			}
			ctx.stroke();

			const [lx, ly] = points[points.length - 1];
			const [tx, ty] = points[0];
			const [dx, dy] = [tx - lx, ty - ly];
			const [hx, hy] = [dy*0.7, dx*-0.7];

			ctx.shadowColor = 'transparent';
			ctx.beginPath();
			ctx.moveTo(lx + dx*0.8, ly + dy*0.8);
			ctx.lineTo(lx - dx*0.5 + hx, ly - dy*0.5 + hy);
			ctx.lineTo(lx - dx*0.5 - hx, ly - dy*0.5 - hy);
			ctx.fill();
		}
	});

	return (
		<canvas {...props} ref={canvas} />
	);
};