const KLMANGA_ORIGIN = "https://klmanga.mom";
const RAWKUMA_ORIGIN = "https://rawkuma.net";
const DEFAULT_CACHE_TTL_MS = 30 * 60 * 1000;
const DEFAULT_CONCURRENCY = 8;
const DEFAULT_FETCH_TIMEOUT_MS = 5000;
const DEFAULT_RAWKUMA_NONCE_TTL_MS = 10 * 60 * 1000;
const DEFAULT_USER_AGENT =
	"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:139.0) Gecko/20100101 Firefox/139.0";
const MIN_MATCH_SCORE = 0.75;
const MIN_MATCH_MARGIN = 0.1;

const nativeChapterCache = new Map();
const nativeChapterInFlight = new Map();
const rawkumaNonceCache = {
	value: null,
	expiresAt: 0,
	promise: null,
};

const cacheTtlMs = (env) => {
	const milliseconds = Number.parseInt(env.RAWKUMA_CACHE_TTL_MS || "", 10);

	return Number.isFinite(milliseconds) && milliseconds > 0
		? milliseconds
		: DEFAULT_CACHE_TTL_MS;
};

const concurrencyLimit = (env) => {
	const concurrency = Number.parseInt(env.RAWKUMA_CONCURRENCY || "", 10);

	return Number.isFinite(concurrency) && concurrency > 0
		? concurrency
		: DEFAULT_CONCURRENCY;
};

const fetchTimeoutMs = (env) => {
	const milliseconds = Number.parseInt(env.RAWKUMA_FETCH_TIMEOUT_MS || "", 10);

	return Number.isFinite(milliseconds) && milliseconds > 0
		? milliseconds
		: DEFAULT_FETCH_TIMEOUT_MS;
};

const rawkumaNonceTtlMs = (env) => {
	const milliseconds = Number.parseInt(env.RAWKUMA_NONCE_TTL_MS || "", 10);

	return Number.isFinite(milliseconds) && milliseconds > 0
		? milliseconds
		: DEFAULT_RAWKUMA_NONCE_TTL_MS;
};

const getCachedChapterCount = (title) => {
	const cached = nativeChapterCache.get(title);

	if (!cached) return undefined;

	if (Date.now() >= cached.expiresAt) {
		nativeChapterCache.delete(title);

		return undefined;
	}

	return cached.chapter;
};

const setCachedChapterCount = (env, title, chapter) => {
	if (chapter === null) return;

	nativeChapterCache.set(title, {
		chapter,
		expiresAt: Date.now() + cacheTtlMs(env),
	});
};

const fetchText = async (env, requestHeaders, url, init = {}) => {
	const headers = new Headers(requestHeaders);
	const targetUrl = new URL(url);
	const initHeaders = new Headers(init.headers);
	const controller = new AbortController();
	const timeout = setTimeout(() => controller.abort(), fetchTimeoutMs(env));

	for (const [key, value] of initHeaders.entries()) headers.set(key, value);

	headers.set(
		"Accept",
		"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
	);
	headers.set("Accept-Encoding", "identity");
	headers.set("Origin", targetUrl.origin);
	headers.set("Referer", `${targetUrl.origin}/`);
	if (!headers.has("User-Agent")) headers.set("User-Agent", DEFAULT_USER_AGENT);
	headers.delete("Content-Length");

	try {
		return await (
			await fetch(url, {
				...init,
				headers,
				signal: init.signal || controller.signal,
			})
		).text();
	} finally {
		clearTimeout(timeout);
	}
};

const decodeHtml = (value) =>
	value
		.replaceAll("&", "&")
		.replaceAll("&", "&")
		.replaceAll(""", '"')
		.replaceAll("'", "'")
		.replaceAll("'", "'")
		.replaceAll("&lt;", "<")
		.replaceAll("&gt;", ">");

const normalizeTitle = (value) =>
	String(value || "")
		.toLowerCase()
		.normalize("NFKC")
		.replace(/&/g, " and ")
		.replace(/[^\p{L}\p{N}]+/gu, " ")
		.replace(/\s+/g, " ")
		.trim();

const tokenizeTitle = (value) =>
	normalizeTitle(value)
		.split(" ")
		.filter((token) => token.length > 1);

const compareTitles = (left, right) => {
	const normalizedLeft = normalizeTitle(left);
	const normalizedRight = normalizeTitle(right);

	if (!normalizedLeft || !normalizedRight) return 0;
	if (normalizedLeft === normalizedRight) return 1;
	if (
		normalizedLeft.includes(normalizedRight) ||
		normalizedRight.includes(normalizedLeft)
	)
		return 0.92;

	const leftTokens = tokenizeTitle(left);
	const rightTokens = tokenizeTitle(right);

	if (!leftTokens.length || !rightTokens.length) return 0;

	const overlappingTokenCount = leftTokens.filter((token) =>
		rightTokens.includes(token),
	).length;

	return (
		overlappingTokenCount / Math.max(leftTokens.length, rightTokens.length)
	);
};

const titleCandidates = (entry) =>
	[entry.nativeTitle, entry.englishTitle, entry.romajiTitle]
		.filter(Boolean)
		.map((title) => String(title).trim())
		.filter((title) => title && title !== "null")
		.filter((title, index, array) => array.indexOf(title) === index);

const pickBestSearchResult = (results, entry) => {
	const candidates = titleCandidates(entry);
	let best = null;
	let secondBestScore = 0;

	for (const result of results) {
		const score = candidates.reduce(
			(maximumScore, candidate) =>
				Math.max(maximumScore, compareTitles(candidate, result.title)),
			0,
		);

		if (!best || score > best.score) {
			secondBestScore = best?.score || 0;
			best = { ...result, score };

			continue;
		}

		if (score > secondBestScore) secondBestScore = score;
	}

	if (!best) return null;
	if (best.score < MIN_MATCH_SCORE) return null;
	if (best.score - secondBestScore < MIN_MATCH_MARGIN) return null;

	return best;
};

const parseRawkumaNonce = (text) =>
	text.match(/name=['"]search_nonce['"]\s+value=['"]([^'"]+)['"]/i)?.[1] ||
	null;

const parseRawkumaSearchResults = (text) =>
	[
		...text.matchAll(
			/<a[^>]+href=["'](https:\/\/rawkuma\.net\/manga\/[^"']+)["'][^>]*>[\s\S]*?<h3[^>]*>([\s\S]*?)<\/h3>/gi,
		),
	].map((match) => ({
		url: decodeHtml(match[1]).trim(),
		title: decodeHtml(match[2])
			.replace(/<[^>]+>/g, "")
			.trim(),
	}));

const parseRawkumaChapterNumbers = (text) =>
	[
		...text.matchAll(/data-chapter-number=["'](\d+(?:\.\d+)?)["']/gi),
		...text.matchAll(
			/<a[^>]+href=["'][^"']*\/chapter-[^"']*["'][^>]*>\s*Chapter\s+(\d+(?:\.\d+)?)\s*<\/a>/gi,
		),
	]
		.map((match) => Number.parseFloat(match[1]))
		.filter((value) => Number.isFinite(value))
		.sort((left, right) => right - left);

const parseRawkumaChapterListUrl = (text) =>
	decodeHtml(
		text.match(
			/<div[^>]+id=["']chapter-list["'][^>]+hx-get=["']([^"']+)["']/i,
		)?.[1] || "",
	).trim() || null;

const getRawkumaNonce = async (env, requestHeaders) => {
	if (rawkumaNonceCache.value && Date.now() < rawkumaNonceCache.expiresAt)
		return rawkumaNonceCache.value;

	if (rawkumaNonceCache.promise) return rawkumaNonceCache.promise;

	const promise = fetchText(
		env,
		requestHeaders,
		`${RAWKUMA_ORIGIN}/wp-admin/admin-ajax.php?type=search_form&action=get_nonce`,
	)
		.then((nonceText) => parseRawkumaNonce(nonceText))
		.then((nonce) => {
			if (!nonce) return null;

			rawkumaNonceCache.value = nonce;
			rawkumaNonceCache.expiresAt = Date.now() + rawkumaNonceTtlMs(env);

			return nonce;
		})
		.finally(() => {
			rawkumaNonceCache.promise = null;
		});

	rawkumaNonceCache.promise = promise;

	return promise;
};

const fetchRawkumaChapterCount = async (env, requestHeaders, entry) => {
	const nonce = await getRawkumaNonce(env, requestHeaders);

	if (!nonce) return null;

	for (const candidate of titleCandidates(entry)) {
		const searchText = await fetchText(
			env,
			requestHeaders,
			`${RAWKUMA_ORIGIN}/wp-admin/admin-ajax.php?nonce=${encodeURIComponent(
				nonce,
			)}&action=search`,
			{
				method: "POST",
				headers: {
					"Content-Type": "application/x-www-form-urlencoded; charset=UTF-8",
				},
				body: new URLSearchParams({
					query: candidate,
				}),
			},
		);
		const bestMatch = pickBestSearchResult(
			parseRawkumaSearchResults(searchText),
			entry,
		);

		if (!bestMatch) continue;

		const mangaText = await fetchText(env, requestHeaders, bestMatch.url);
		const chapterListUrl = parseRawkumaChapterListUrl(mangaText);
		const chapterListText = chapterListUrl
			? await fetchText(env, requestHeaders, chapterListUrl)
			: mangaText;
		const chapters = parseRawkumaChapterNumbers(chapterListText);

		if (!chapters.length) continue;

		return chapters[0] ?? null;
	}

	return null;
};

const parseKlmangaSearchResults = (text) =>
	[
		...text.matchAll(
			/<a[^>]+href=["'](https:\/\/klmanga\.mom\/manga-raw\/[^"']+)["'][^>]*>([\s\S]*?)<\/a>/gi,
		),
	]
		.map((match) => ({
			url: decodeHtml(match[1]).trim(),
			title: decodeHtml(match[2])
				.replace(/<[^>]+>/g, "")
				.replace(/\(Raw\s*-\s*Free\)/gi, "")
				.trim(),
		}))
		.filter((result) => result.title.length > 0);

const parseKlmangaChapterNumbers = (text) =>
	[...text.matchAll(/第(\d+(?:\.\d+)?)話/gu)]
		.map((match) => Number.parseFloat(match[1]))
		.filter((value) => Number.isFinite(value))
		.sort((left, right) => right - left);

const fetchKlmangaChapterCount = async (env, requestHeaders, entry) => {
	for (const candidate of titleCandidates(entry)) {
		const searchText = await fetchText(
			env,
			requestHeaders,
			`${KLMANGA_ORIGIN}/?s=${encodeURIComponent(candidate)}`,
		);
		const bestMatch = pickBestSearchResult(
			parseKlmangaSearchResults(searchText),
			entry,
		);

		if (!bestMatch) continue;

		const mangaText = await fetchText(env, requestHeaders, bestMatch.url);
		const chapters = parseKlmangaChapterNumbers(mangaText);

		if (!chapters.length) continue;

		return chapters[0] ?? null;
	}

	return null;
};

const fetchNativeChapterCountUncached = async (env, requestHeaders, entry) => {
	const providers = [fetchKlmangaChapterCount, fetchRawkumaChapterCount];

	for (const provider of providers) {
		const chapter = await provider(env, requestHeaders, entry).catch(
			() => null,
		);

		if (chapter !== null) return chapter;
	}

	return null;
};

const fetchNativeChapterCount = async (env, requestHeaders, entry) => {
	const normalizedTitle = entry.nativeTitle?.trim();

	if (!normalizedTitle) return null;

	const cachedChapter = getCachedChapterCount(normalizedTitle);

	if (cachedChapter !== undefined) return cachedChapter;

	const existing = nativeChapterInFlight.get(normalizedTitle);

	if (existing) return existing;

	const promise = fetchNativeChapterCountUncached(env, requestHeaders, entry)
		.catch(() => null)
		.then((chapter) => {
			setCachedChapterCount(env, normalizedTitle, chapter);

			return chapter;
		})
		.finally(() => {
			nativeChapterInFlight.delete(normalizedTitle);
		});

	nativeChapterInFlight.set(normalizedTitle, promise);

	return promise;
};

export const fetchRawkumaChapterCounts = async (env, requestHeaders, manga) => {
	const results = {};
	const entries = [...manga];
	const workerCount = Math.min(concurrencyLimit(env), entries.length);

	if (!workerCount) return results;

	let nextIndex = 0;

	await Promise.all(
		Array.from({ length: workerCount }, async () => {
			while (nextIndex < entries.length) {
				const currentIndex = nextIndex;
				nextIndex += 1;

				const entry = entries[currentIndex];
				const chapter = await fetchNativeChapterCount(
					env,
					requestHeaders,
					entry,
				);

				results[String(entry.anilistId)] = { chapter };
			}
		}),
	);

	return results;
};