import { DbEntry } from '../datas.ts'

const domParser = new DOMParser()

/**
 * Construct db by scrapping site.
 * @param siteUrl - Index page url
 * @returns DbEntries[]
 */
export async function fetchDbFromSite(siteUrl: string) {
	//Index page
	const index = await fetch(siteUrl, { mode: 'no-cors' })
		.then((response) => response.text())
		.then((raw) => domParser.parseFromString(raw, 'text/html'))

	//Get nodes from index page links
	const nodes = Array.from(
		index.querySelectorAll<HTMLAnchorElement>('#episodes>a'),
	)
		.map((a) => ({ href: a.href, title: a.innerText }))

	const db: DbEntry[] = []

	//Fill db with nodes
	for (const node of nodes) {
		const id = getNodeId(node)
		const title = node.title
		const content = node.href
		const links = await getNodeLinks(node)

		db.push({ id, title, content, links })
	}

	return db
}

/**
 * Determine id from node link href attribute.
 * @returns node id
 */
function getNodeId({ href }: { href: string }): number {
	const { pathname } = new URL(href)
	return Number.parseInt(pathname.slice(1, -5))
}

/**
 * Get ids of nodes related to current nodes by listing all links in current node web page.
 * @returns List of ids related to current node.
 */
async function getNodeLinks({ href }: { href: string }): Promise<number[]> {
	const page = await fetch(href, { mode: 'no-cors' })
		.then((response) => response.text())
		.then((raw) => domParser.parseFromString(raw, 'text/html'))

	return Array.from(page.querySelectorAll<HTMLAnchorElement>('.cell-p>a')).map(
		getNodeId,
	)
}