import { defineMiddleware } from "astro:middleware";
import { COOKIE_LANG, localePath, resolvePreferredLocale } from "@app/i18n";
import { COOKIE_SESSION } from "@app/types";
import { authService } from "@app/trpc";

const SKIP_PREFIX = ["/api", "/_astro", "/favicon", "/robots", "/sitemap", "/llms"];

/** 需登录的基础路径（无 locale 前缀）。按需增删。 */
const PROTECTED_BASES = ["/dashboard", "/settings"] as const;

const LOCALE_SEGMENTS = new Set(["zh-CN", "en"]);

function shouldSkip(pathname: string): boolean {
    if (pathname !== "/" && pathname.includes(".")) return true;
    return SKIP_PREFIX.some((p) => pathname.startsWith(p));
}

function basePathOf(pathname: string): string {
    const segs = pathname.split("/").filter(Boolean);
    const head = segs[0];
    if (head && LOCALE_SEGMENTS.has(head)) {
        return `/${segs.slice(1).join("/")}`;
    }
    // 规范化前的 zh-cn 等在后续 redirect 处理，这里先按原样判断
    if (head && head.toLowerCase() === "zh-cn") {
        return `/${segs.slice(1).join("/")}`;
    }
    return `/${segs.join("/")}`;
}

function isProtectedPath(pathname: string): boolean {
    const base = basePathOf(pathname);
    const normalized = base === "/" ? "/" : base.replace(/\/$/, "");
    return PROTECTED_BASES.some((p) => normalized === p || normalized.startsWith(`${p}/`));
}

function localeOf(pathname: string): "zh-CN" | "en" {
    const head = pathname.split("/").filter(Boolean)[0];
    if (head === "en") return "en";
    return "zh-CN";
}

export const onRequest = defineMiddleware(async (context, next) => {
    const { request, url, cookies } = context;
    const path = url.pathname;

    if (shouldSkip(path)) {
        return next();
    }

    // 裸 `/`：cookie → Accept-Language → /zh-CN 或 /en
    if (path === "/") {
        if (request.method !== "GET") return next();
        const preferred = resolvePreferredLocale(
            cookies.get(COOKIE_LANG)?.value,
            request.headers.get("accept-language"),
        );
        return context.redirect(localePath(preferred, "/"));
    }

    // 小写 zh-cn → 规范 zh-CN（保留 rest）
    const seg = path.split("/").filter(Boolean)[0];
    if (seg && seg.toLowerCase() === "zh-cn" && seg !== "zh-CN") {
        const rest = path.slice(seg.length) || "/";
        return context.redirect(`/zh-CN${rest === "/" ? "" : rest}`);
    }

    // 指定路由鉴权：无有效 session 则跳登录
    if (request.method === "GET" && isProtectedPath(path)) {
        const token = cookies.get(COOKIE_SESSION)?.value;
        const user = await authService.getSessionUser(token);
        if (!user) {
            const locale = localeOf(path);
            const nextParam = encodeURIComponent(path + url.search);
            return context.redirect(`${localePath(locale, "/auth/login")}?next=${nextParam}`);
        }
    }

    const response = await next();
    if (request.method === "GET") {
        response.headers.set("Vary", "Accept-Language");
    }
    return response;
});