/**
 * X (formerly Twitter) URL vocabulary shared by the X reader
 * (`web/scrapers/twitter.ts`) and the xAI search provider's `x_search` mapping
 * (`web/search/providers/xai.ts`): which hosts serve X, which path segments are
 * account handles, and which page a URL shows.
 */

/** Hosts serving X pages; developer/API subdomains are ordinary web pages. */
const X_HOSTS: Record<string, true> = {
	"x.com": true,
	"twitter.com": true,
	"www.x.com": true,
	"www.twitter.com": true,
	"mobile.x.com": true,
	"mobile.twitter.com": true,
};

/** First path segments that are X app routes, never account handles. */
const APP_ROUTES: Record<string, true> = {
	about: true,
	account: true,
	bookmarks: true,
	communities: true,
	compose: true,
	download: true,
	explore: true,
	hashtag: true,
	home: true,
	i: true,
	intent: true,
	jobs: true,
	login: true,
	logout: true,
	messages: true,
	notifications: true,
	privacy: true,
	search: true,
	settings: true,
	share: true,
	signup: true,
	tos: true,
};

const HANDLE_PATTERN = /^[A-Za-z0-9_]{1,15}$/;
const POST_ID_PATTERN = /^\d{1,20}$/;

/** Profile timeline tab an X profile URL shows. */
export type XProfileTab = "posts" | "replies" | "media";

/** Profile tabs after the handle (`/<handle>/with_replies`); a bare handle shows posts. */
const PROFILE_TABS: Record<string, XProfileTab> = { with_replies: "replies", media: "media" };

/** The X page a URL shows, as far as Grok's X tools can read it. */
export type XTarget =
	/** One post (`/<handle>/status/<id>`, `/i/web/status/<id>`) with its thread. */
	| { kind: "post"; id: string }
	/** A profile and one of its timeline tabs. */
	| { kind: "profile"; handle: string; tab: XProfileTab }
	/** Post search (`/search?q=`, `/hashtag/<tag>`); `latest` mirrors the Latest tab (`f=live`). */
	| { kind: "search"; query: string; latest: boolean }
	/** People search (`/search?q=…&f=user`). */
	| { kind: "users"; query: string }
	/** An X page no X tool reads (home, explore, lists, followers, …). */
	| { kind: "unsupported" };

/** Whether a bare, lowercased host serves X pages. */
export function isXHost(host: string): boolean {
	return X_HOSTS[host] === true;
}

/** The account handle a path segment names, or `undefined` for app routes and invalid handles. */
export function xHandle(segment: string | undefined): string | undefined {
	if (!segment || !HANDLE_PATTERN.test(segment) || APP_ROUTES[segment.toLowerCase()] === true) return undefined;
	return segment;
}

/**
 * Classify an X URL for the X reader.
 *
 * Returns `null` for non-X URLs so other handlers can claim them. A missing
 * scheme (`www.x.com/jack`, as read paths may omit it) means `https`.
 *
 * @example
 * parseXUrl("https://x.com/jack/status/20/photo/1"); // { kind: "post", id: "20" }
 * parseXUrl("https://x.com/search?q=omp&f=live"); // { kind: "search", query: "omp", latest: true }
 */
export function parseXUrl(url: string): XTarget | null {
	let parsed: URL;
	try {
		parsed = new URL(/^https?:\/\//i.test(url) ? url : `https://${url}`);
	} catch {
		return null;
	}
	if (!isXHost(parsed.hostname.toLowerCase())) return null;

	const segments = parsed.pathname.split("/").filter(Boolean);
	const [first, second] = segments;
	const filter = parsed.searchParams.get("f");

	if (first === "search") {
		const query = parsed.searchParams.get("q")?.trim();
		if (!query) return { kind: "unsupported" };
		if (filter === "user") return { kind: "users", query };
		if (filter === "media") return { kind: "search", query: `${query} filter:media`, latest: true };
		return { kind: "search", query, latest: filter === "live" };
	}
	if (first === "hashtag" && second) return { kind: "search", query: `#${second}`, latest: filter === "live" };

	// `/<handle>/status/<id>[/photo/1]`, `/i/status/<id>`, `/i/web/status/<id>`
	const [status, id] = segments.slice(first === "i" && second === "web" ? 2 : 1);
	if (status === "status" && id && POST_ID_PATTERN.test(id)) return { kind: "post", id };

	const handle = xHandle(first);
	const tab = second === undefined ? "posts" : Object.hasOwn(PROFILE_TABS, second) ? PROFILE_TABS[second] : undefined;
	if (handle && tab && segments.length <= 2) return { kind: "profile", handle, tab };
	return { kind: "unsupported" };
}