// calculate tiles

const RADIUS_OPTS = [ 
	"const",
	"right",
	"left",
	"up",
	"down",
	"right-up",
	"right-down",
	"left-up",
	"left-down",
	"in",
	"out",
];

function distance(dx, dy) {
	return Math.sqrt(dx ** 2 + dy ** 2);
}

class DotMaker {
	constructor(width) {
		this.width = width;
		this.cx = 0.5 * width;
		this.cy = 0.5 * width;
	}

	dots(m, n) {
		if( m - n === 0 ) {
			return [];
		}
		const ps = [];
		const imin = -this.width;
		const imax = this.width / m;
		for( let i = imin; i <= imax; i++ ) {
			const jmin = m * i + (m - n) * this.width;
			const jmax = m * i;
			for( let j = jmin; j <= jmax; j++ ) {
				const x = (j - m * i) / (m - n);
				const y = m * (x + i);
				if( x > 0 && y > 0 && x < this.width && y < this.width ) {
					ps.push({i:i, j:j, x:x, y:y});
				}
			}
		}
		return ps;
	}

	radius(d, func, maxr) {
	  	switch (func) {
	    	case "const":
	      		return maxr;
	    	case "right":
	      		return maxr * d.x / this.width;
	    	case "left":
	      		return maxr * (this.width - d.x) / this.width;
	    	case "down":
	      		return maxr * d.y / this.width;
	    	case "up":
	      		return maxr * (this.width - d.y) / this.width;
	      	case "right-up":
	      		return 0.5 * maxr * (d.x + this.width - d.y) / this.width;
	      	case "left-up":
	      		return 0.5 * maxr * (this.width - d.x + this.width - d.y) / this.width;
	      	case "right-down":
	      		return 0.5 * maxr * (d.x + d.y) / this.width;
	      	case "left-down":
	      		return 0.5 * maxr * (this.width - d.x + d.y) / this.width;
	      	case "out":
	      		return 2 * maxr * distance((d.x - this.cx), (d.y - this.cy)) / this.width;
	      	case "in":
	      		return 2 * maxr * (0.5 * this.width - distance((d.x - this.cx), (d.y - this.cy))) / this.width;
	    	default:
	      		return maxr;
	  }
	}
}

export { RADIUS_OPTS, DotMaker };