const fetch = require("node-fetch")
const {render} = require("pinski/plugins")
const db = require("../utils/db")
const {getToken, getUser} = require("../utils/getuser")
const pug = require("pug")
const converters = require("../utils/converters")

class InstanceError extends Error {
	constructor(error, identifier) {
		super(error)
		this.identifier = identifier
	}
}

function formatOrder(format) {
	// most significant to least significant
	// key, max, order, transform
	// asc: lower number comes first, desc: higher number comes first
	const spec = [
		["second__height", 8000, "desc", x => x ? Math.floor(x/96) : 0],
		["fps", 100, "desc", x => x ? Math.floor(x/10) : 0],
		["type", " ".repeat(60), "asc", x => x.length],
	]
	let total = 0
	for (let i = 0; i < spec.length; i++) {
		const s = spec[i]
		let diff = s[3](format[s[0]])
		if (s[2] === "asc") diff = s[3](s[1]) - diff
		total += diff
		if (i+1 < spec.length) {
			s2 = spec[i+1]
			total *= s2[3](s2[1])
		}
	}
	return -total
}

async function renderVideo(videoPromise, {user, id, instanceOrigin}) {
	try {
		const video = await videoPromise
		if (!video) throw new Error("The instance returned null.")
		if (video.error) throw new InstanceError(video.error, video.identifier)
		// video data additional processing
		for (const format of video.formatStreams.concat(video.adaptiveFormats)) {
			if (!format.second__height && format.resolution) format.second__height = +format.resolution.slice(0, -1)
			if (!format.second__order) format.second__order = formatOrder(format)
		}
		for (const rec of video.recommendedVideos) {
			if (!rec.second__lengthText && rec.lengthSeconds > 0) {
				rec.second__lengthText = converters.lengthSecondsToLengthText(rec.lengthSeconds)
			}
		}
		const subscribed = user.isSubscribed(video.authorId)
		return render(200, "pug/video.pug", {video, subscribed, instanceOrigin})
	} catch (e) {
		let message = pug.render("pre= error", {error: e.stack || e.toString()})
		if (e instanceof fetch.FetchError) {
			const template = `
p The selected instance, #[code= instanceOrigin], did not respond correctly.
p Requested URL: #[a(href=url)= url]
`
			message = pug.render(template, {instanceOrigin, url: outURL})
		} else if (e instanceof InstanceError) {
			if (e.identifier === "RATE_LIMITED_BY_YOUTUBE") {
				const template = `
.blocked-explanation
	img(src="/static/images/instance-blocked.svg" width=552 height=96)
	.rows
		.row
			h3.actor You
			| Working
		.row
			h3.actor CloudTube
			| Working
		.row
			h3.actor Instance
			| Blocked by YouTube
		.row
			h3.actor YouTube
			| Working
p.
	CloudTube needs to a working Second/Invidious instance in order to get data about videos.
	However, the selected instance, #[code= instanceOrigin], has been temporarily blocked by YouTube.
p.
	You will be able to watch this video if you select a working instance in settings.
	#[br]#[a(href="/settings") Go to settings →]
p.
	(Tip: Try #[code https://invidious.snopyta.org] or #[code https://invidious.site].)
p.
	This situation #[em will] be improved in the future!
`
				message = pug.render(template, {instanceOrigin})
			} else {
				const template = `
p #[strong= error.message]
if error.identifier
	p #[code= error.identifier]
p That error was generated by #[code= instanceOrigin].
`
				message = pug.render(template, {instanceOrigin, error: e})
			}
		}
		return render(500, "pug/video.pug", {video: {videoId: id}, error: true, message})
	}
}

module.exports = [
	{
		route: "/watch", methods: ["GET", "POST"], upload: true, code: async ({req, url, body}) => {
			const user = getUser(req)
			const settings = user.getSettingsOrDefaults()
			if (req.method === "GET") {
				const id = url.searchParams.get("v")
				if (!settings.local) {
					const instanceOrigin = settings.instance
					const outURL = `${instanceOrigin}/api/v1/videos/${id}`
					const videoPromise = fetch(outURL).then(res => res.json())
					return renderVideo(videoPromise, {user, id, instanceOrigin})
				} else {
					return render(200, "pug/local-video.pug", {id})
				}
			} else { // req.method === "POST"
				const video = JSON.parse(new URLSearchParams(body.toString()).get("video"))
				const videoPromise = Promise.resolve(video)
				return renderVideo(videoPromise, {user})
			}
		}
	}
]