'use strict';

function findAlphaBounds(rgba, width, height, threshold = 4) {
	let left = width, top = height, right = 0, bottom = 0;
	for (let y = 0; y < height; y++) {
		for (let x = 0; x < width; x++) {
			if (rgba[(y * width + x) * 4 + 3] <= threshold) continue;
			left = Math.min(left, x);
			top = Math.min(top, y);
			right = Math.max(right, x + 1);
			bottom = Math.max(bottom, y + 1);
		}
	}
	return right > left && bottom > top ? { left, top, right, bottom } : null;
}

function toWorldBounds(pixels, width, height, scale, centerX, centerY) {
	if (!pixels || !isFinite(scale) || scale <= 0) return null;
	const left = centerX + (pixels.left - width / 2) / scale;
	const right = centerX + (pixels.right - width / 2) / scale;
	const top = centerY - (pixels.top - height / 2) / scale;
	const bottom = centerY - (pixels.bottom - height / 2) / scale;
	return { x: left, y: bottom, width: right - left, height: top - bottom };
}

module.exports = { findAlphaBounds, toWorldBounds };