#!/usr/bin/node

require('ptrc')

const fs = require('fs')
const dns = require('node:dns/promises')

const ACME_PATH = '/var/www/acme/.well-known/acme-challenge/'

const config = fs.readFileSync('/etc/uacme/config.json', 'utf8').apply(JSON.parse)
const [ , , action, method, domain, token, recordValue ] = process.argv

function findZone(fullDomain) {
	let domain = fullDomain
	while (true) {
		if (Object.keys(config.domains).includes(domain)) {
			return domain
		}

		const newDomain = domain.split('.').slice(1).join('.')
		if (!newDomain.includes('.')) {
			throw new Error(`cannot find keys for ${fullDomain}`)
		}

		domain = newDomain
	}
}

const recordName = `_acme-challenge.${domain}`
const zone = findZone(domain)
const shortRecordName = recordName.replaceAll(`.${zone}`, '')

console.log(`> ${action} ${recordName} [${shortRecordName} at ${zone}] ${token} = '${recordValue}'`)

class Hetzner {
	ns = 'hydrogen.ns.hetzner.com'

	async _fetch (url, opts) {
		if (!opts) {
			opts = {}
		}
		opts.headers ??= {}
		opts.headers['Auth-API-Token'] = config.secrets.hetzner
		if (opts.body) {
			opts.method ??= 'POST'
			opts.headers['Content-Type'] = 'application/json'
		}
		const res = await fetch('https://dns.hetzner.com/api/v1' + url, opts)
		if (res.status !== 200) {
			const body = await res.text()
			throw new Error(`status ${res.status}: ${body}`)
		}
		return res.json()
	}

	async init() {
		const { zones } = await this._fetch('/zones')
		this.zoneID = zones.find(x => x.name === zone).id
	}

	async create () {
		await this.remove()

		console.log(`>> [hetzner] creating ${shortRecordName}.${zone} (zone ${this.zoneID}) with value ${recordValue}`)
		await this._fetch('/records', {
			body: JSON.stringify({
				value: recordValue,
				ttl: 300,
				type: 'TXT',
				name: shortRecordName,
				zone_id: this.zoneID
			})
		})
	}

	async remove () {
		const { records } = await this._fetch(`/records?zone_id=${this.zoneID}`)
		for (let record of records) {
			if (record.name === shortRecordName) {
				console.log(`>> [hetzner] removing ${recordName} (${record.id})`)
				try {
					await this._fetch(`/records/${record.id}`, { method: 'DELETE' })
				} catch (err) {
					console.error('>> [hetzner] failed to remove record:', err)
				}
			}
		}
	}
}

class Cloudflare {
	ns = 'aida.ns.cloudflare.com'

	init () {
		process.env['CF_API_TOKEN'] = config.secrets.cloudflare
	}

	_exec (args) {
		const res = exec('flarectl', [ '--json', ...args ])
		if (res.status !== 0) {
			throw new Error(`'flarectl --json ${args.join(" ")}' exited with ${res.status}:\n${res.stderr}`)
		}
		return res.stdout
	}

	async create () {
		await this.remove()

		console.log(`>> [cloudflare] creating ${recordName} with value ${recordValue}`)
		this._exec([
			'dns', 'create',
			'--zone', zone,
			'--type', 'TXT',
			'--name', recordName,
			'--content', recordValue
		])
	}

	async remove () {
		const records = this._exec(['dns', 'list', '--zone', zone])
		for (let record of records) {
			if (record.Name === recordName) {
				console.log(`>> [cloudflare] removing ${recordName} (${record.ID})`)
				try {
					this._exec(['dns', 'delete', '--zone', zone, '--id', record.ID])
				} catch (err) {
					console.error('>> [cloudflare] failed to remove record:', err)
				}
			}
		}
	}
}

class Http {
	init () {
		this.path = ACME_PATH + token
	}

	async create () {
		console.log(`>> [http] creating ${this.path} with contents ${recordValue}`)
		fs.writeFileSync(this.path, recordValue, 'utf8')
	}

	async remove () {
		console.log(`>> [http] removing ${this.path}`)
		fs.unlinkSync(this.path)
	}
}

const handlers = {
	hetzner: new Hetzner(),
	cloudflare: new Cloudflare(),
	http: new Http()
}

async function main() {
	const handlerName = config.domains[zone]
	if ((method === 'dns-01') === (handlerName === 'http')) {
		console.log(`> handler is ${handlerName} for method ${method}, try again`)
		process.exit(1)
	}

	console.log('> using handler:', handlerName)
	const handler = handlers[handlerName]
	await handler.init()

	if (action === 'begin') {
		await handler.create()
	} else {
		await handler.remove()
	}

	if (method === 'dns-01') {
		const dns4 = await dns.resolve4(handler.ns)
		const dns6 = await dns.resolve6(handler.ns)
		dns.setServers(dns4.concat(dns6))
		let tries = 0
		while (tries < 5) {
			console.log(`> checking DNS (attempt ${tries+1}/5)`)
			let values
			try {
				values = (await dns.resolveTxt(recordName)).flat()
			} catch (err) {
				if (err.code === 'ENOTFOUND') {
					console.log('> got ENOTFOUND from DNS')
					values = []
				} else {
					console.error(`> error when querying TXT ${recordName}:`, err)
				}
			}
			console.log('> DNS result:', values)
			if ((action === 'begin') === values.includes(recordValue)) {
				process.exit(0)
			}

			await new Promise((resolve, reject) => setTimeout(resolve, 5000))
			tries++
		}
		console.log('> could not ensure the DNS record was created!!')
	}
}
main().catch(err => {
	console.error('> uncaught error:', err.toString().split('\n').join('\n> '))
	process.exit(1)
})