//
// Formatting helpers shared by the tree items.
//

const UNITS = ["B", "KB", "MB", "GB", "TB", "PB"];

function bytes(value) {
	if (typeof value !== "number" || !isFinite(value) || value < 0) {
		return "";
	}

	let index = 0;
	let size = value;

	while (size >= 1000 && index < UNITS.length - 1) {
		size = size / 1000;
		index += 1;
	}

	let precision = size >= 100 || index === 0 ? 0 : 1;
	return `${size.toFixed(precision)} ${UNITS[index]}`;
}

// Relative age, in the same spirit as Docker's "2 hours ago".
function age(value) {
	if (!value) {
		return "";
	}

	let date = value instanceof Date ? value : new Date(value);

	if (isNaN(date.getTime()) || date.getTime() === 0) {
		return "";
	}

	let seconds = Math.max(0, Math.floor((Date.now() - date.getTime()) / 1000));

	if (seconds < 60) {
		return "just now";
	}

	let steps = [
		["minute", 60],
		["hour", 60],
		["day", 24],
		["week", 7],
		["month", 4.35],
		["year", 12]
	];

	let amount = seconds;
	let label = "second";

	for (let [name, divisor] of steps) {
		if (amount < divisor) {
			break;
		}
		amount = amount / divisor;
		label = name;
	}

	let rounded = Math.floor(amount);
	return `${rounded} ${label}${rounded === 1 ? "" : "s"} ago`;
}

// Splits an image reference into its registry, repository and tag.
function reference(value) {
	let text = String(value || "");
	let digest = null;
	let tag = null;

	let atIndex = text.lastIndexOf("@");
	if (atIndex > 0) {
		digest = text.slice(atIndex + 1);
		text = text.slice(0, atIndex);
	}

	let colonIndex = text.lastIndexOf(":");
	let slashIndex = text.lastIndexOf("/");
	if (colonIndex > slashIndex) {
		tag = text.slice(colonIndex + 1);
		text = text.slice(0, colonIndex);
	}

	let registry = null;
	let repository = text;
	let firstSlash = text.indexOf("/");

	if (firstSlash > 0) {
		let candidate = text.slice(0, firstSlash);
		if (candidate.includes(".") || candidate.includes(":") || candidate === "localhost") {
			registry = candidate;
			repository = text.slice(firstSlash + 1);
		}
	}

	return {
		registry: registry,
		repository: repository,
		tag: tag || "latest",
		digest: digest,
		// docker.io/library/nginx reads better as nginx.
		short: repository.replace(/^library\//, "")
	};
}

module.exports = { bytes, age, reference };