import {fuzzyMatch} from './utils.js';
import {decodeHtml} from '@ztimson/utils';

export const CATALOG_URL = 'https://library.kiwix.org';

const PAGE_SIZE = 100;

export function parseEntries(xml, catalog = CATALOG_URL) {
	const blocks = xml.match(/<entry>[\s\S]*?<\/entry>/g) || [];
	return blocks.map(b => {
		const grab = re => (b.match(re) || [])[1] || '';
		const linkMatch = b.match(/<link[^>]*type=["']application\/x-zim[^"']*["'][^>]*href=["']([^"']+)["']/);
		const iconMatch = b.match(/<link[^>]*rel=["']http:\/\/opds-spec\.org\/image\/thumbnail["'][^>]*href=["']([^"']+)["']/)
			|| b.match(/<link[^>]*type=["']image\/[^"']*["'][^>]*href=["']([^"']+)["']/);
		let tags = grab(/<tags>([^<]*)<\/tags>/);
		if(tags) tags = tags.split(';');
		const name = grab(/<name>([^<]*)<\/name>/);
		return {
			id: grab(/<id>([^<]*)<\/id>/),
			title: decodeHtml(grab(/<title>([^<]*)<\/title>/)),
			updated: new Date(grab(/<updated>([^<]*)<\/updated>/)),
			summary: decodeHtml(grab(/<summary>([^<]*)<\/summary>/)),
			language: grab(/<language>([^<]*)<\/language>/),
			name,
			category: grab(/<category>([^<]*)<\/category>/),
			tags,
			mediaCount: Number(grab(/<mediaCount>([^<]*)<\/mediaCount>/)) || 0,
			author: grab(/<author>\s*<name>([^<]*)<\/name>\s*<\/author>/m),
			publisher: grab(/<publisher>\s*<name>([^<]*)<\/name>\s*<\/publisher>/m),
			articleCount: Number(grab(/<articleCount>([^<]*)<\/articleCount>/)) || 0,
			sizeMb: linkMatch ? +(Number((b.match(/length=["'](\d+)["']/) || [])[1] || 0) / 1024 / 1024).toFixed(1) : '?',
			href: linkMatch ? linkMatch[1] : null,
			icon: iconMatch ? new URL(iconMatch[1], catalog).href : null,
			viewer: name ? new URL(`viewer#${name}`, catalog).href : null,
		};
	});
}

async function fetchEntries(term, lang, url = CATALOG_URL) {
	const params = new URLSearchParams({q: term, count: String(PAGE_SIZE), lang: lang || 'eng'});
	const res = await fetch(`${url}/catalog/v2/entries?${params}`);
	if (!res.ok) throw new Error(`${res.status} ${res.statusText}`);
	return parseEntries(await res.text());
}

/** Looks up a single catalog entry by exact `name` (used to check for available updates). */
export async function zimCatalogInfo(name, url = CATALOG_URL) {
	const params = new URLSearchParams({name, count: '5'});
	const res = await fetch(`${url}/catalog/v2/entries?${params}`);
	if (!res.ok) return null;
	return parseEntries(await res.text()).find(e => e.name === name) || null;
}

/** Searches the Kiwix catalog for ZIMs matching `terms` within `category`, ranked by term coverage then fuzzy similarity. */
export async function zimCatalog(terms, opts = {lang: 'eng', count: 20, url: CATALOG_URL}) {
	opts = Object.assign({lang: 'eng', count: 20, url: CATALOG_URL}, opts)
	const termList = [...String(terms).split(',')].filter(Boolean).map(t => t.trim().toLowerCase());
	const results = await Promise.allSettled(termList.map(t => fetchEntries(t, opts.lang, opts.url)));
	const byName = new Map();
	results.forEach((r, i) => {
		if (r.status !== 'fulfilled') return;
		const term = termList[i];
		for (const entry of r.value) {
			if (!entry.name) continue;
			if (!byName.has(entry.name)) byName.set(entry.name, {entry, hitTerms: new Set()});
			byName.get(entry.name).hitTerms.add(term);
		}
	});
	if (!byName.size) return [];

	return [...byName.values()].map(({entry, hitTerms}) => {
		const text = `${entry.title} ${entry.summary}`.trim();
		return {entry, hits: hitTerms.size, fuzzy: fuzzyMatch(text, ...termList).max};
	}).toSorted((a, b) =>
		b.hits - a.hits || b.fuzzy - a.fuzzy || b.entry.articleCount - a.entry.articleCount
	).slice(0, opts.count).map(r => r.entry);
}