import { bootstrapManga, syncMangadexIndex } from "./mangadex.js";
import { fetchRawkumaChapterCounts } from "./rawkuma.js";
import {
	deleteMangadexFailureRows,
	getMangadexFailureRowsByAniListIds,
	getMangadexRowsByAniListIds,
	hasSupabaseConfig,
	upsertMangadexFailureRows,
	upsertMangadexRows,
} from "./supabase.js";

const DEFAULT_ALLOWED_ORIGIN = "https://due.moe";
const DEFAULT_BOOTSTRAP_RETRY_MINUTES = 360;
const DEFAULT_PENDING_RETRY_MS = 750;
const bootstrapInFlight = new Map();

const isPrivateHostname = (hostname) =>
	hostname === "localhost" ||
	hostname === "127.0.0.1" ||
	hostname.endsWith(".local") ||
	/^10\./.test(hostname) ||
	/^192\.168\./.test(hostname) ||
	/^172\.(1[6-9]|2\d|3[0-1])\./.test(hostname);

const accessControlOrigin = (request) => {
	const origin = request.headers.get("Origin");

	if (!origin) return DEFAULT_ALLOWED_ORIGIN;

	try {
		const url = new URL(origin);

		if (
			url.hostname === "due.moe" ||
			url.hostname.endsWith(".due.moe") ||
			isPrivateHostname(url.hostname)
		)
			return origin;
	} catch {}

	return DEFAULT_ALLOWED_ORIGIN;
};

const appendCorsHeaders = (request, headers = new Headers()) => {
	headers.set("Access-Control-Allow-Origin", accessControlOrigin(request));
	headers.set("Access-Control-Allow-Methods", "GET, HEAD, POST, OPTIONS");
	headers.set("Access-Control-Allow-Headers", "Authorization, Content-Type");
	headers.append("Vary", "Origin");

	return headers;
};

const jsonResponse = (request, body, init = {}) => {
	const headers = appendCorsHeaders(request, new Headers(init.headers));

	headers.set("Content-Type", "application/json");

	return new Response(JSON.stringify(body), {
		...init,
		headers,
	});
};

const textResponse = (request, body, init = {}) =>
	new Response(body, {
		...init,
		headers: appendCorsHeaders(request, new Headers(init.headers)),
	});

const decodeProxyTarget = (url) => {
	if (url.search.includes("?q=")) return url.search.split("?q=")[1];
	if (url.search.includes("?d=")) return atob(url.search.split("?d=")[1]);
	if (url.search.includes("?d2=")) {
		const fullEncodedUrl = url.search.split("?d2=")[1];
		const key = Number.parseInt(fullEncodedUrl.slice(-2), 10);

		return atob(fullEncodedUrl.slice(0, -2))
			.split(":")
			.map((char) => String.fromCharCode(Number(char) - key))
			.join("");
	}

	return null;
};

const forwardProxyRequest = async (request) => {
	const url = new URL(request.url);
	const dropHeaders = url.search.includes("&dh");

	if (dropHeaders) url.search = url.search.replace("&dh", "");

	const target = decodeProxyTarget(url);

	if (!target)
		return textResponse(request, null, {
			status: 400,
			statusText: "Bad Request",
		});

	const targetUrl = new URL(target);
	const proxiedRequest = new Request(target, request);

	proxiedRequest.headers.set("Host", targetUrl.hostname);
	proxiedRequest.headers.set("Referrer", targetUrl.toString());
	proxiedRequest.headers.set("Origin", targetUrl.origin);
	proxiedRequest.headers.delete("X-Content-Type-Options");

	let response = await fetch(proxiedRequest);

	response = new Response(response.body, response);

	if (dropHeaders)
		for (const key of [...response.headers.keys()])
			response.headers.delete(key);

	appendCorsHeaders(request, response.headers);
	response.headers.set("Cache-Control", "max-age=300");

	return response;
};

const handleOptions = (request) =>
	new Response(null, {
		headers: appendCorsHeaders(request),
	});

const isMangadexIdConstraintConflict = (error) =>
	error instanceof Error &&
	error.message.includes("mangadex_manga_index_mangadex_id_key");

const parseMangaPayload = async (request) => {
	const body = await request.json().catch(() => null);
	const manga = Array.isArray(body?.manga) ? body.manga : [];

	return manga
		.map((entry) => ({
			anilistId: Number(entry?.anilistId),
			progress: entry?.progress ? Number(entry.progress) : 0,
			status: String(entry?.status || ""),
			startYear: entry?.startYear ? Number(entry.startYear) : null,
			nativeTitle: entry?.nativeTitle || null,
			englishTitle: entry?.englishTitle || null,
			romajiTitle: entry?.romajiTitle || null,
		}))
		.filter((entry) => Number.isFinite(entry.anilistId));
};

const bootstrapRetryMinutes = (env) => {
	const minutes = Number.parseInt(
		env.MANGADEX_BOOTSTRAP_RETRY_MINUTES || "",
		10,
	);

	return Number.isFinite(minutes) && minutes > 0
		? minutes
		: DEFAULT_BOOTSTRAP_RETRY_MINUTES;
};

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

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

const isRecentFailure = (row, retryMinutes) =>
	Date.now() - new Date(row.last_attempted_at || row.updated_at).getTime() <
	retryMinutes * 60 * 1000;

const queueBootstrap = (env, manga) =>
	manga
		.map((entry) => {
			const existing = bootstrapInFlight.get(entry.anilistId);

			if (existing) return existing;

			const promise = (async () => {
				const row = await bootstrapManga(env, entry);

				if (row) {
					try {
						await upsertMangadexRows(env, [row]);
					} catch (error) {
						if (!isMangadexIdConstraintConflict(error)) throw error;
					}

					await deleteMangadexFailureRows(env, [row.anilist_id]);

					return;
				}

				await upsertMangadexFailureRows(env, [entry.anilistId]);
			})().finally(() => {
				bootstrapInFlight.delete(entry.anilistId);
			});

			bootstrapInFlight.set(entry.anilistId, promise);

			return promise;
		})
		.filter(Boolean);

const parseOptionalNumber = (value) => {
	if (value === null || value === undefined || value === "") return null;

	const number = Number.parseFloat(String(value));

	return Number.isFinite(number) ? number : null;
};

const recommendedVolumeText = (volumeChapterBoundaries, progress) => {
	if (!volumeChapterBoundaries || !Number.isFinite(progress) || progress <= 0)
		return null;

	let recommended = null;
	let recommendedNumber = null;

	for (const [volumeText, chapterBoundary] of Object.entries(
		volumeChapterBoundaries,
	)) {
		const volumeNumber = parseOptionalNumber(volumeText);
		const boundaryNumber = parseOptionalNumber(chapterBoundary);

		if (
			volumeNumber === null ||
			boundaryNumber === null ||
			boundaryNumber > progress
		)
			continue;

		if (recommendedNumber === null || volumeNumber > recommendedNumber) {
			recommended = String(volumeNumber);
			recommendedNumber = volumeNumber;
		}
	}

	return recommended;
};

const handleMangaChapterCounts = async (request, env, ctx) => {
	if (!hasSupabaseConfig(env))
		return jsonResponse(
			request,
			{ error: "Supabase is not configured for the proxy worker." },
			{ status: 500 },
		);

	const manga = await parseMangaPayload(request);

	if (!manga.length) return jsonResponse(request, { data: {} });

	const mangaById = new Map(manga.map((entry) => [entry.anilistId, entry]));
	const anilistIds = manga.map((entry) => entry.anilistId);
	const [existingRows, failureRows] = await Promise.all([
		getMangadexRowsByAniListIds(env, anilistIds),
		getMangadexFailureRowsByAniListIds(env, anilistIds),
	]);
	const existingRowsById = new Map(
		existingRows.map((row) => [row.anilist_id, row]),
	);
	const recentFailures = new Set(
		failureRows
			.filter((row) => isRecentFailure(row, bootstrapRetryMinutes(env)))
			.map((row) => row.anilist_id),
	);
	const rowsMissingFromIndex = manga.filter((entry) => {
		const row = existingRowsById.get(entry.anilistId);

		if (!row) return !recentFailures.has(entry.anilistId);
		return false;
	});
	const rowsNeedingVolumeBackfill = manga.filter((entry) => {
		const row = existingRowsById.get(entry.anilistId);

		if (!row) return false;

		return (
			entry.progress > 0 &&
			row.volume_chapter_boundaries === null &&
			!recentFailures.has(entry.anilistId)
		);
	});
	const rowsNeedingBackfill = [
		...rowsMissingFromIndex,
		...rowsNeedingVolumeBackfill,
	];
	const pendingRows = rowsMissingFromIndex.filter((entry) =>
		bootstrapInFlight.has(entry.anilistId),
	);
	const queueableRows = rowsNeedingBackfill.filter(
		(entry) => !bootstrapInFlight.has(entry.anilistId),
	);
	const queueablePendingRows = rowsMissingFromIndex.filter(
		(entry) => !bootstrapInFlight.has(entry.anilistId),
	);

	if (queueableRows.length)
		ctx.waitUntil(
			Promise.all(queueBootstrap(env, queueableRows)).catch((error) => {
				if (!isMangadexIdConstraintConflict(error)) throw error;
			}),
		);

	const data = Object.fromEntries(
		existingRows.map((row) => {
			const entry = mangaById.get(row.anilist_id);
			const volumeText = recommendedVolumeText(
				row.volume_chapter_boundaries,
				entry?.progress || 0,
			);

			return [
				String(row.anilist_id),
				{
					chapter: row.latest_en_chapter_number,
					...(volumeText === null ? {} : { volumeText }),
				},
			];
		}),
	);
	const pending = [
		...new Set(
			[...pendingRows, ...queueablePendingRows].map((entry) => entry.anilistId),
		),
	];

	return jsonResponse(request, {
		data,
		...(pending.length
			? {
					pending,
					retryAfterMs: pendingRetryMs(env),
				}
			: {}),
	});
};

const handleMangaNativeChapterCounts = async (request, env) => {
	const manga = await parseMangaPayload(request);

	if (!manga.length) return jsonResponse(request, { data: {} });

	return jsonResponse(request, {
		data: await fetchRawkumaChapterCounts(env, request.headers, manga),
	});
};

const isAuthorisedSyncRequest = (request, env) => {
	const token = env.MANGADEX_SYNC_TOKEN;

	if (!token) return isPrivateHostname(new URL(request.url).hostname);

	return request.headers.get("Authorization") === `Bearer ${token}`;
};

const handleMangaSync = async (request, env) => {
	if (!hasSupabaseConfig(env))
		return jsonResponse(
			request,
			{ error: "Supabase is not configured for the proxy worker." },
			{ status: 500 },
		);

	if (!isAuthorisedSyncRequest(request, env))
		return jsonResponse(request, { error: "Forbidden" }, { status: 403 });

	const result = await syncMangadexIndex(env);

	return jsonResponse(request, { data: result });
};

export default {
	async fetch(request, env, ctx) {
		try {
			const url = new URL(request.url);

			if (request.method === "OPTIONS") return handleOptions(request);

			if (url.pathname === "/manga/chapter-counts" && request.method === "POST")
				return handleMangaChapterCounts(request, env, ctx);

			if (
				url.pathname === "/manga/native-chapter-counts" &&
				request.method === "POST"
			)
				return handleMangaNativeChapterCounts(request, env);

			if (url.pathname === "/manga/sync" && request.method === "POST")
				return handleMangaSync(request, env);

			if (["GET", "HEAD", "POST"].includes(request.method))
				return forwardProxyRequest(request);

			return textResponse(request, null, {
				status: 405,
				statusText: "Method Not Allowed",
			});
		} catch (error) {
			return jsonResponse(
				request,
				{ error: error instanceof Error ? error.message : "Bad Request" },
				{ status: 400 },
			);
		}
	},

	async scheduled(_controller, env, ctx) {
		if (!hasSupabaseConfig(env)) return;

		ctx.waitUntil(syncMangadexIndex(env));
	},
};