/**
 * Check that a host is part of Instagram's CDN.
 * @param {string} host
 */
function verifyHost(host) {
	const domains = ["fbcdn.net", "cdninstagram.com"]
	return domains.some(against => host === against || host.endsWith("." + against))
}

/**
 * Check that a resource is on Instagram.
 * @param {URL} completeURL
 */
function verifyURL(completeURL) {
	const params = completeURL.searchParams
	if (!params.get("url")) return {status: "fail", value: [400, "Must supply `url` query parameter"]}
	try {
		var url = new URL(params.get("url"))
	} catch (e) {
		return {status: "fail", value: [400, "`url` query parameter is not a valid URL"]}
	}
	// check url protocol
	if (url.protocol !== "https:") return {status: "fail", value: [400, "URL protocol must be `https:`"]}
	// check url host
	if (!verifyHost(url.host)) return {status: "fail", value: [400, "URL host is not allowed"]}
	return {status: "ok", url}
}

function proxyImage(url, width, shortcode) {
	shortcode = shortcode ? `/${shortcode}${width ? "-small" : ""}.jpg` : ""
	const params = new URLSearchParams()
	if (width) params.set("width", width)
	params.set("url", url)
	return `/imageproxy${shortcode}?${params.toString()}`
}

function proxyProfilePic(url, userID) {
	const params = new URLSearchParams()
	params.set("userID", userID)
	params.set("url", url)
	return "/imageproxy?"+params.toString()
}

function proxyVideo(url, shortcode) {
	shortcode = shortcode ? `/${shortcode}.mp4` : ""
	const params = new URLSearchParams()
	params.set("url", url)
	return `/videoproxy${shortcode}?${params.toString()}`
}

/**
 * @param {import("../types").ExtendedOwner} owner
 */
function proxyExtendedOwner(owner) {
	const clone = {...owner}
	clone.profile_pic_url = proxyProfilePic(clone.profile_pic_url, clone.id)
	return clone
}

module.exports.proxyImage = proxyImage
module.exports.proxyProfilePic = proxyProfilePic
module.exports.proxyVideo = proxyVideo
module.exports.proxyExtendedOwner = proxyExtendedOwner
module.exports.verifyHost = verifyHost
module.exports.verifyURL = verifyURL