import createMiddleware from "next-intl/middleware";
import { NextResponse } from "next/server";
import { routing } from "./i18n/routing";

const intlMiddleware = createMiddleware(routing);

const SUPPORTED_LOCALES = routing.locales;

function parseAcceptLanguage(header) {
	if (!header) return [];
	return header
		.split(",")
		.map((part) => {
			const [langRange, qPart] = part.trim().split(";");
			let q = 1.0;
			if (qPart) {
				const match = qPart.match(/q=([\d.]+)/);
				if (match) {
					const parsed = parseFloat(match[1]);
					if (!isNaN(parsed)) q = parsed;
				}
			}
			return { lang: langRange.trim().toLowerCase(), q };
		})
		.sort((a, b) => b.q - a.q);
}

function matchLocale(lang) {
	if (lang.startsWith("pt")) return "pt";
	if (lang.startsWith("es")) return "es";
	if (lang.startsWith("fr")) return "fr";
	if (lang.startsWith("de")) return "de";
	if (lang.startsWith("zh")) return "zh-CN";
	if (lang.startsWith("en")) return "en";
	return null;
}

function resolveRootLocale(request) {
	const cookieValue = request.cookies.get("NEXT_LOCALE")?.value;
	if (cookieValue && SUPPORTED_LOCALES.includes(cookieValue)) {
		return cookieValue;
	}
	const acceptLang = request.headers.get("accept-language");
	const parsed = parseAcceptLanguage(acceptLang);
	for (const { lang } of parsed) {
		const matched = matchLocale(lang);
		if (matched) return matched;
	}
	return "en";
}

export default function middleware(request) {
	const { pathname, search } = request.nextUrl;

	// Exclusões de caminhos e arquivos estáticos
	if (
		pathname.startsWith("/api") ||
		pathname.startsWith("/_next") ||
		pathname === "/robots.txt" ||
		pathname === "/sitemap.xml" ||
		pathname === "/google21a790a2c23c0ec5.html" ||
		/\.[a-zA-Z0-9]+$/.test(pathname)
	) {
		return NextResponse.next();
	}

	// 1. Raiz: negociação de idioma (307)
	if (pathname === "/") {
		const targetLocale = resolveRootLocale(request);
		const url = new URL(`/${targetLocale}/`, request.url);
		url.search = search;
		const response = NextResponse.redirect(url, 307);
		response.headers.set("Vary", "Accept-Language, Cookie");
		response.headers.set("Cache-Control", "private, no-store");
		return response;
	}

	// 2. Livro fora do português: 404
	if (/^\/(en|es|fr|de|zh-CN)\/livro(\/.*)?$/.test(pathname)) {
		return new NextResponse(null, { status: 404 });
	}

	// 3. URLs antigas sem prefixo reconhecido: redirecionamento 308 para /pt/<caminho>
	const hasLocalePrefix = SUPPORTED_LOCALES.some(
		(loc) => pathname === `/${loc}` || pathname.startsWith(`/${loc}/`)
	);

	if (!hasLocalePrefix) {
		const url = new URL(`/pt${pathname}`, request.url);
		url.search = search;
		return NextResponse.redirect(url, 308);
	}

	// 4. Delegação para o roteamento do next-intl
	return intlMiddleware(request);
}

export const config = {
	matcher: [
		"/((?!api|_next|_vercel|.*\\..*|robots\\.txt|sitemap\\.xml|google21a790a2c23c0ec5\\.html).*)",
	],
};