// Pararius HTML parsing. Pure functions, no network: the worker fetches, these parse.
//
// Pararius has no public API, so everything here reads markup that can change
// without notice. Each parser prefers structured data (ld+json, the analytics
// blob) and falls back to looser text matching, so a redesign degrades fields
// instead of dropping listings.
import type { ListingCard, ListingDetail, Offer, PropertyType } from './types';

export const PARARIUS_ORIGIN = 'https://www.pararius.nl';

const listingPath =
	/\/(appartement|huis|kamer|studio|woning|[a-z]+)-te-(huur|koop)\/([a-z0-9-]+)\/([0-9a-f]{8})\/([a-z0-9-]+)/;

const typeWords: Record<string, PropertyType> = {
	appartement: 'apartment',
	apartment: 'apartment',
	huis: 'house',
	house: 'house',
	kamer: 'room',
	room: 'room',
	studio: 'studio'
};

const entities: Record<string, string> = {
	amp: '&',
	lt: '<',
	gt: '>',
	quot: '"',
	apos: "'",
	nbsp: ' ',
	euro: '€',
	sup2: '²',
	sup3: '³'
};

export function decodeEntities(value: string): string {
	return value.replace(/&(#x[0-9a-f]+|#\d+|[a-z0-9]+);/gi, (match, code: string) => {
		if (code[0] === '#') {
			const n =
				code[1] === 'x' || code[1] === 'X' ? parseInt(code.slice(2), 16) : Number(code.slice(1));
			return Number.isFinite(n) ? String.fromCodePoint(n) : match;
		}
		return entities[code.toLowerCase()] ?? match;
	});
}

export function textOf(html: string): string {
	return decodeEntities(html.replace(/<[^>]*>/g, ' '))
		.replace(/\s+/g, ' ')
		.trim();
}

/** Bot challenges (Cloudflare "Just a moment...") instead of real content. */
export function isChallenge(html: string, status = 200): boolean {
	if (status === 403 || status === 429 || status === 503) return true;
	const head = html.slice(0, 20_000);
	return (
		/<title>\s*Just a moment/i.test(head) ||
		head.includes('challenges.cloudflare.com/turnstile') ||
		head.includes('cf-chl-') ||
		/<title>\s*Attention Required/i.test(head)
	);
}

export type ListingRef = {
	sourceId: string;
	url: string;
	offer: Offer;
	propertyType: PropertyType;
	citySlug: string;
};

export function listingRef(href: string): ListingRef | null {
	const match = listingPath.exec(href);
	if (!match) return null;
	const [, type, offer, citySlug, shortId, slug] = match;
	return {
		sourceId: shortId,
		url: `${PARARIUS_ORIGIN}/${type}-te-${offer}/${citySlug}/${shortId}/${slug}`,
		offer: offer === 'koop' ? 'buy' : 'rent',
		propertyType: typeWords[type] ?? 'other',
		citySlug
	};
}

/** Whole euros from "€ 1.558 per maand", "€1,558 per month", "€ 425.000 k.k." */
export function parseEuros(value: string | null | undefined): number | null {
	if (!value) return null;
	const match = /€\s*([\d.,]+)/.exec(value) ?? /([\d][\d.,]*)/.exec(value);
	if (!match) return null;
	const digits = match[1].replace(/[.,]\d{2}$/, '').replace(/[.,]/g, '');
	const n = Number(digits);
	return digits && Number.isSafeInteger(n) ? n : null;
}

export function parseInteger(value: string | null | undefined): number | null {
	const match = value ? /(\d[\d.]*)/.exec(value) : null;
	if (!match) return null;
	const n = Number(match[1].replace(/\./g, ''));
	return Number.isSafeInteger(n) ? n : null;
}

/** "2801 BC Gouda (Centrum)" → postal code, city and neighbourhood. */
export function parseLocation(value: string | null | undefined) {
	const out = {
		postalCode: null as string | null,
		city: null as string | null,
		neighbourhood: null as string | null
	};
	if (!value) return out;
	let rest = value.trim();
	const hood = /\(([^)]+)\)\s*$/.exec(rest);
	if (hood) {
		out.neighbourhood = hood[1].trim();
		rest = rest.slice(0, hood.index).trim();
	}
	const postal = /^(\d{4})\s?([A-Z]{2})\b/.exec(rest);
	if (postal) {
		out.postalCode = `${postal[1]} ${postal[2]}`;
		rest = rest.slice(postal[0].length).trim();
	}
	if (rest) out.city = rest;
	return out;
}

function classText(html: string, className: string): string | null {
	const re = new RegExp(
		`<([a-z0-9-]+)[^>]*class="[^"]*\\b${className}\\b[^"]*"[^>]*>([\\s\\S]*?)</\\1>`,
		'i'
	);
	const match = re.exec(html);
	if (!match) return null;
	const value = textOf(match[2]);
	return value || null;
}

function firstImage(html: string): string | null {
	const tag = /<img\b[^>]*>/i.exec(html)?.[0];
	if (!tag) return null;
	const src =
		/\bsrc="(https:[^"]+)"/i.exec(tag)?.[1] ??
		/\bsrcset="(https:[^"\s,]+)/i.exec(tag)?.[1] ??
		/\bdata-src="(https:[^"]+)"/i.exec(tag)?.[1];
	return src ? decodeEntities(src) : null;
}

export type SearchPage = {
	cards: ListingCard[];
	nextPageUrl: string | null;
	totalResults: number | null;
};

/**
 * Parse a search results page (`/huurwoningen/gouda/1300-1700`).
 * Splits on the listing card wrappers when present; otherwise falls back to
 * one chunk per unique listing link so a markup change still yields ids.
 */
export function parseSearchPage(html: string, pageUrl: string): SearchPage {
	const chunks: string[] = [];
	const marker =
		/<(section|li|article|div)\b[^>]*class="[^"]*\blisting-search-item\b(?!__)[^"]*"/gi;
	const starts = [...html.matchAll(marker)].map((m) => m.index!);
	if (starts.length) {
		for (let i = 0; i < starts.length; i++) {
			chunks.push(html.slice(starts[i], starts[i + 1] ?? starts[i] + 20_000));
		}
	} else {
		const links = /href="([^"]*-te-(?:huur|koop)\/[^"]+)"/gi;
		const seen = new Set<string>();
		for (const m of html.matchAll(links)) {
			const ref = listingRef(m[1]);
			if (!ref || seen.has(ref.sourceId)) continue;
			seen.add(ref.sourceId);
			chunks.push(html.slice(Math.max(0, m.index! - 3000), m.index! + 6000));
		}
	}

	const cards: ListingCard[] = [];
	const seen = new Set<string>();
	for (const chunk of chunks) {
		const href = /href="([^"]*-te-(?:huur|koop)\/[^"]+)"/i.exec(chunk)?.[1];
		const ref = href ? listingRef(decodeEntities(href)) : null;
		if (!ref || seen.has(ref.sourceId)) continue;
		seen.add(ref.sourceId);

		const titleLink = /<a\b[^>]*class="[^"]*link--title[^"]*"[^>]*>([\s\S]*?)<\/a>/i.exec(chunk);
		const title =
			(titleLink ? textOf(titleLink[1]) : null) ?? classText(chunk, 'listing-search-item__title');
		const location = parseLocation(
			classText(chunk, 'listing-search-item__sub-title') ??
				classText(chunk, 'listing-search-item__location')
		);
		const priceText =
			classText(chunk, 'listing-search-item__price') ?? /€\s*[\d.,]+[^<]{0,30}/.exec(chunk)?.[0];
		const area =
			classText(chunk, 'illustrated-features__item--surface-area') ??
			/(\d+)\s*m(?:²|&sup2;|2)/i.exec(chunk)?.[0];
		const rooms = classText(chunk, 'illustrated-features__item--number-of-rooms');
		const agentBlock = classText(chunk, 'listing-search-item__info');

		cards.push({
			sourceId: ref.sourceId,
			url: ref.url,
			offer: ref.offer,
			propertyType: ref.propertyType,
			title: title?.slice(0, 200) ?? null,
			postalCode: location.postalCode,
			city: location.city ?? cityFromSlug(ref.citySlug),
			neighbourhood: location.neighbourhood,
			priceEur: parseEuros(priceText),
			areaM2: parseInteger(area),
			rooms: parseInteger(rooms),
			interior: classText(chunk, 'illustrated-features__item--interior'),
			agent: agentBlock?.slice(0, 160) ?? null,
			imageUrl: firstImage(chunk)
		});
	}

	const nextHref =
		/<a\b[^>]*class="[^"]*pagination__link--next[^"]*"[^>]*href="([^"]+)"/i.exec(html)?.[1] ??
		/<a\b[^>]*href="([^"]+)"[^>]*class="[^"]*pagination__link--next[^"]*"/i.exec(html)?.[1] ??
		/<link\b[^>]*rel="next"[^>]*href="([^"]+)"/i.exec(html)?.[1];
	const total =
		classText(html, 'search-list-header__count') ??
		/(\d[\d.]*)\s+(?:huurwoningen|koopwoningen|woningen|results|resultaten)/i.exec(
			textOf(html.slice(0, 200_000))
		)?.[1];

	return {
		cards,
		nextPageUrl: nextHref ? new URL(decodeEntities(nextHref), pageUrl).toString() : null,
		totalResults: parseInteger(total)
	};
}

/** `/huurwoningen/gouda/1300-1700` → page N url (`.../page-2`). */
export function searchPageUrl(base: string, page: number): string {
	const url = new URL(base);
	url.pathname = url.pathname.replace(/\/page-\d+\/?$/, '').replace(/\/$/, '');
	if (page > 1) url.pathname += `/page-${page}`;
	return url.toString();
}

export function cityFromSlug(slug: string): string {
	return slug
		.split('-')
		.map((part) =>
			part === 'aan' || part === 'den' || part === 'de'
				? part
				: part[0]?.toUpperCase() + part.slice(1)
		)
		.join(' ')
		.replace(/^\w/, (c) => c.toUpperCase());
}

function jsonBlocks(html: string): unknown[] {
	const out: unknown[] = [];
	for (const m of html.matchAll(/<script[^>]*application\/ld\+json[^>]*>([\s\S]*?)<\/script>/gi)) {
		try {
			out.push(JSON.parse(m[1]));
		} catch {
			// Ignore malformed blocks; other sources may still have the data.
		}
	}
	return out;
}

type LdListing = {
	'@type'?: string | string[];
	name?: string;
	description?: string;
	image?: string | string[];
	address?: {
		streetAddress?: string;
		addressLocality?: string;
		addressRegion?: string;
		postalCode?: string;
	};
	numberOfRooms?: { value?: number }[] | { value?: number } | number;
	floorSize?: { value?: number };
	yearBuilt?: number;
	numberOfBedrooms?: number;
	numberOfBathroomsTotal?: number;
	datePosted?: string;
	offers?: { price?: number; url?: string };
};

function ldListing(html: string): LdListing | null {
	for (const block of jsonBlocks(html)) {
		const items = Array.isArray(block) ? block : [block];
		for (const item of items) {
			if (!item || typeof item !== 'object') continue;
			const type = (item as LdListing)['@type'];
			const types = Array.isArray(type) ? type : [type];
			if (types.includes('RealEstateListing')) return item as LdListing;
		}
	}
	return null;
}

/** The flat `odp.*` analytics object Pararius embeds on listing pages. */
export function analyticsBlob(html: string): Record<string, string> {
	const candidates = [html, decodeEntities(html)];
	for (const source of candidates) {
		const match = /\{[^{}]*"odp\.listing_id"[^{}]*\}/.exec(source);
		if (!match) continue;
		try {
			const parsed = JSON.parse(match[0]) as Record<string, unknown>;
			const out: Record<string, string> = {};
			for (const [key, value] of Object.entries(parsed)) {
				if (key.startsWith('odp.') && (typeof value === 'string' || typeof value === 'number'))
					out[key.slice(4)] = String(value);
			}
			return out;
		} catch {
			// Fall through to the next candidate.
		}
	}
	return {};
}

/** The "Kenmerken" definition list: `Borg → € 1.600`, `Interieur → Gestoffeerd`. */
export function featureList(html: string): Record<string, string> {
	const out: Record<string, string> = {};
	const re =
		/<dt\b[^>]*class="[^"]*listing-features__term[^"]*"[^>]*>([\s\S]*?)<\/dt>\s*<dd\b[^>]*>([\s\S]*?)<\/dd>/gi;
	for (const m of html.matchAll(re)) {
		const key = textOf(m[1]).slice(0, 80);
		const value = textOf(m[2].replace(/<[^>]*class="[^"]*tooltip[^"]*"[\s\S]*?<\/[a-z]+>/gi, ''))
			.replace(/\s*Meer info$/i, '')
			.slice(0, 500);
		if (key && value && !(key in out)) out[key] = value;
	}
	return out;
}

const interiorWords: Record<string, string> = {
	shell: 'kaal',
	upholstered: 'gestoffeerd',
	furnished: 'gemeubileerd'
};

const firstNumber = (value: LdListing['numberOfRooms']): number | null => {
	if (typeof value === 'number') return value;
	const item = Array.isArray(value) ? value[0] : value;
	return typeof item?.value === 'number' ? item.value : null;
};

/** Parse a listing page. Returns null when the page is not a listing. */
export function parseDetailPage(html: string, fallbackUrl?: string): ListingDetail | null {
	const canonical =
		/<link\b[^>]*rel="canonical"[^>]*href="([^"]+)"/i.exec(html)?.[1] ??
		/<link\b[^>]*href="([^"]+)"[^>]*rel="canonical"/i.exec(html)?.[1];
	const ref = listingRef(canonical ?? '') ?? listingRef(fallbackUrl ?? '');
	if (!ref) return null;

	const ld = ldListing(html);
	const odp = analyticsBlob(html);
	const features = featureList(html);
	const summaryTitle = classText(html, 'listing-detail-summary__title');
	const location = parseLocation(classText(html, 'listing-detail-summary__location'));

	const lat = Number(
		/data-latitude="(-?[\d.]+)"/.exec(html)?.[1] ?? /"latitude"\s*:\s*(-?[\d.]+)/.exec(html)?.[1]
	);
	const lng = Number(
		/data-longitude="(-?[\d.]+)"/.exec(html)?.[1] ?? /"longitude"\s*:\s*(-?[\d.]+)/.exec(html)?.[1]
	);

	const offeredAt =
		odp.offered_since && !Number.isNaN(Date.parse(odp.offered_since))
			? new Date(odp.offered_since).toISOString()
			: ld?.datePosted
				? new Date(`${ld.datePosted}T00:00:00Z`).toISOString()
				: null;

	const price =
		(odp.price_pcm ? Number(odp.price_pcm) : null) ??
		(typeof ld?.offers?.price === 'number' ? ld.offers.price : null) ??
		parseEuros(features['Huurprijs'] ?? features['Vraagprijs'] ?? features['Koopprijs']);

	const image = Array.isArray(ld?.image) ? ld.image[0] : ld?.image;
	const typeFromOdp = odp.property ? typeWords[odp.property] : undefined;
	const interior =
		(odp.interior ? (interiorWords[odp.interior] ?? odp.interior) : null) ??
		features['Interieur']?.toLowerCase() ??
		null;

	const street = ld?.address?.streetAddress ?? null;
	const title =
		summaryTitle?.replace(/^Te (huur|koop):\s*/i, '') ?? (ld?.name ? `${ld.name}` : null);

	return {
		sourceId: ref.sourceId,
		url: ref.url,
		offer: odp.offer === 'buy' || ref.offer === 'buy' ? 'buy' : 'rent',
		propertyType: typeFromOdp ?? ref.propertyType,
		externalId: odp.listing_id ?? null,
		title: title?.slice(0, 200) ?? null,
		street,
		postalCode: ld?.address?.postalCode
			? ld.address.postalCode.replace(/^(\d{4})\s?([A-Z]{2})$/, '$1 $2')
			: location.postalCode,
		city: ld?.address?.addressLocality ?? location.city ?? cityFromSlug(ref.citySlug),
		neighbourhood: ld?.address?.addressRegion ?? location.neighbourhood,
		priceEur: Number.isFinite(price) ? price : null,
		areaM2:
			parseInteger(odp.floor_space) ??
			(typeof ld?.floorSize?.value === 'number' ? ld.floorSize.value : null) ??
			parseInteger(features['Woonoppervlakte']),
		rooms:
			parseInteger(odp.rooms) ??
			firstNumber(ld?.numberOfRooms) ??
			parseInteger(features['Aantal kamers']),
		bedrooms:
			parseInteger(odp.bedrooms) ??
			ld?.numberOfBedrooms ??
			parseInteger(features['Aantal slaapkamers']),
		bathrooms: ld?.numberOfBathroomsTotal ?? parseInteger(features['Aantal badkamers']),
		constructionYear:
			parseInteger(odp.construction_year) ?? ld?.yearBuilt ?? parseInteger(features['Bouwjaar']),
		energyLabel: odp.energy_rating ?? features['Energielabel'] ?? null,
		interior,
		depositEur: parseEuros(features['Borg']),
		availableFrom: features['Beschikbaar'] ?? null,
		contractType: features['Contractvorm'] ?? features['Huurperiode'] ?? null,
		agent: classText(html, 'agent-card__title'),
		imageUrl: image ?? null,
		lat: Number.isFinite(lat) && lat !== 0 ? lat : null,
		lng: Number.isFinite(lng) && lng !== 0 ? lng : null,
		offeredAt,
		description: ld?.description?.slice(0, 6000) ?? null,
		features
	};
}