import { NextResponse } from "next/server";
import type { NextRequest } from "next/server";
import { corsHeaders, forbidden, isAllowedOrigin } from "@/lib/api-route";
import { LOCALE_COOKIE, matchLocale } from "@/lib/i18n/locales";

function withCorsHeaders(response: NextResponse, origin: string | null): NextResponse {
    const headers = corsHeaders(origin);
    for (const [key, value] of Object.entries(headers)) {
        response.headers.set(key, value);
    }
    return response;
}

const RATE_LIMIT_WINDOW_MS = 60_000;
const RATE_LIMIT_MAX_REQUESTS = 30;

const rateLimitHits = new Map<string, number[]>();

export function _resetRateLimit(): void {
    rateLimitHits.clear();
}

export function clientIp(request: NextRequest): string {
    const cloudflareIp = request.headers.get("cf-connecting-ip")?.trim();
    if (cloudflareIp) {
        return cloudflareIp;
    }
    const forwardedFor = request.headers.get("x-forwarded-for")?.split(",")[0]?.trim();
    if (forwardedFor) {
        return forwardedFor;
    }
    return "direct";
}

function isRateLimited(ip: string, now: number = Date.now()): boolean {
    const cutoff = now - RATE_LIMIT_WINDOW_MS;
    const hits = (rateLimitHits.get(ip) ?? []).filter((timestamp) => timestamp > cutoff);
    if (hits.length >= RATE_LIMIT_MAX_REQUESTS) {
        rateLimitHits.set(ip, hits);
        return true;
    }
    hits.push(now);
    rateLimitHits.set(ip, hits);
    return false;
}

function rateLimited(origin: string | null): NextResponse {
    return NextResponse.json(
        { error: "Too many requests" },
        {
            status: 429,
            headers: {
                "Cache-Control": "no-store",
                "Retry-After": String(Math.ceil(RATE_LIMIT_WINDOW_MS / 1000)),
                ...corsHeaders(origin),
            },
        },
    );
}

function handleApi(request: NextRequest): NextResponse {
    const origin = request.headers.get("origin");
    if (isRateLimited(clientIp(request))) {
        return rateLimited(origin);
    }
    if (!isAllowedOrigin(request)) {
        return forbidden(origin);
    }
    if (request.method === "OPTIONS") {
        const response = new NextResponse(null, { status: 204 });
        withCorsHeaders(response, origin);
        response.headers.set("Access-Control-Allow-Methods", "GET, OPTIONS");
        response.headers.set("Access-Control-Max-Age", "86400");
        return response;
    }
    return withCorsHeaders(NextResponse.next(), origin);
}

export function proxy(request: NextRequest): NextResponse {
    if (request.nextUrl.pathname.startsWith("/api/")) {
        return handleApi(request);
    }
    if (request.cookies.has(LOCALE_COOKIE)) {
        return NextResponse.next();
    }
    const locale = matchLocale(request.headers.get("accept-language"));
    const response = NextResponse.next();
    response.cookies.set(LOCALE_COOKIE, locale, {
        path: "/",
        maxAge: 60 * 60 * 24 * 365,
        sameSite: "lax",
    });
    return response;
}

export const config = {
    matcher: [
        "/((?!_next/static|_next/image|favicon.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp|ico)).*)",
    ],
};